zyxwvu
zyxwvu
Znorg. Chem. 1981,20, 165-171
165
zyxwvu
zyxwvut
tively large thermal displacements for the p-H atom are
consistent with the deformability of the Cr-H-Cr linkage.
Despite the fact that it is surrounded by the cryptate molecule,
the K+ ion is not totally screened from interacting with atoms
outside its immediate coordination environment. Consequently,
whenever a cryptate cation is employed as the counterion for
structural studies of polynuclear anions, the potential imnot be
portan= Of cation-anion interactions
Acknowledgment. This work was performed under the
auspices of the Office of Basic Energy Sciences of the U.S.
Department of Energy. This collaborative study was partially
supported by the National Science Foundation under Project
No. CHE78-20698 (to J.M.W.).'
Registry No. [K(~rypt-222)]'[Cr,(CO),~(p-H)]-,
75198-25-3;
c r ( c o l 6 , 13007-92-6.
Supplementary Material Available: Tables of positional and thermal
parameters, interatomic distances and bond angles, root-mean-square
thermal displacements, and observed and calculated structure factor
amplitudes (40pages). Ordering information is given on any current
masthead page.
Contribution from the Istituto di Chimica Generale, Universitl di Pisa, 56 100 Pisa, Italy,
and the Istituto di Strutturistica Chimica, Universitl di Parma, 43 100 Parma, Italy
Activation of C02-like Molecules: Synthetic and Structural Studies on a v2-C,N
Metal-Bonded Carbodiimide and Its Conversion into a q2-C,N Metal-Bonded Amidinyl
Ligand
zyxwvutsrqponm
zyxwvutsrqpon
zyxwvutsrqpo
zyxwvu
zyxwvutsr
M A R C 0 PASQUALI, SANDRO GAMBAROTTA, CARLO FLORIANI,* ANGIOLA CHIESI-VILLA,
and CARLO GUASTINI
Received May 14, 1980
Vanadocene reacts with ptolylcarbodiiide (pTCD) producing a metallaazacyclopropane-likecomplex C p 2 V ( R h - k = N R )
(I) (R = p-CH3C6H4;Cp = q5-C5H5;ucN(Nujol) 1645 cm-'; peff= 1.76pe at 293.5 K). The X-ray analysis performed
on complex I shows that vanadium is q5 bonded to the two Cp rings, which are in a bent arrangement, making a cavity
in the equatorial plane for the CN2 unit. The C-N bond distances agree with the presence of a single C-N bond interacting
with the metal and a free C=N double bond. Complex I reacts with both 0, and I,, releasing p-TCD. Coordinated p-TCD
is converted in a q2-C,N metal-bonded trialkylamidinyl ligand by the action of CH31 on complex I. The reaction with
CH31, followed by the addition of I,, allowed isolation of [Cp2V(R(CH3)Nk=hR)]13 (11) (R = p-CH3C.a4; vcn(Nujol)
1680 cm-I; peff = 1.78 p B at 293 K). The X-ray analysis showed an overall structure of the cation similar to that of I,
with the amidinyl ligand acting as a three-electron-donor ligand and displaying a bonding mode similar to that observed
for q2-C,0 acyls and q2-C,N iminoacyls. The two C-N bond distances within the CN2unit have a high double-bond character
(1.26 (2)and 1.33 (2)A),indicating a significant electronic delocalizationall over the VCN, unit with a carbenoid character
for the carbon bonded to the vanadium atom. In both complexes, V-C bond distances (about 2.0 A) fall in the expected
range for a V-C (sp2) bond. Crystallographic details for complex I: space group Pn02~(orthorhombic); a = 14.446 (3)
A, b = 14.186 (2)A, c = 20.903(4)A, V = 4283.7A'; Z = 8; Dald = 1.251 g ~ m - ~The
. final R factor was 8.4% for
1439 observed reflections. Crystallographic details for complex 11: space group P21/c(monoclinic); u = 14.260 (6)A,
b = 19.176 (5) A, c = 10.628 (4) A; @ = 106.92 (5)'; V = 2780.4A3; 2 = 4;Dd = 1.910g ~ m - ~The
. final R factor
was 6.3% for 2283 observed reflections.
Introduction
The interest in carbodiimide-transition metal chemistry is
justified by the nature of carbodiimides, which closely imitate
carbon dioxide, as well as by the possibility of modifying their
reactivity] with the assistance of a metal center.
The so far reported results concerning the reaction between
carbodiimides and transition-metal complexes have been
summarized below.
(i) Carbodiimides have been found to be u bonded through
a nitrogen atom to the metal
(PPh3)2Ni(PhN=C=NPh)3 was structurally proven in
Cp2V(pTCD) (Cp = v5-CsH5;p T C D = ptolylcarbodiimide),
whose synthesis and structure are described in this paper. This
is the first structural report on a metal-carbcdiimide complex.
(iii) Metal-carbonyl complexes promote the so-called disproportionation of c a r b ~ d i i m i d e s ~to- ~ dihydrotrialkylguanidinium dianion, A, being complexed by the metal and
A
in some Pd(I1) complexes.2
(ii) Carbene-like metals add to one of the C=N bonds, as
in
This metal-carbodiimide
interaction suggested for
*To whom correspondence should be addressed at the Universiti di F'isa.
0020-1669/81/1320-0165$01.00/0
isocyanide. This metal-promoted carbodiimide transformation
seems to involve the dimerization of the organic molecule as
a key step in a sequence likeG9
(1) Reichen, W. Chem. Rev. 1978, 78, 569.
(2) Bycroft, B. M.; Cotton, J. D. J . Chem. Soc., Dalton Trans. 1973, 1867.
(3) Hoberg, H.;Korff, J. J . Organomet. Chem. 1978, 150, C20.
(4) Bremer, N. J.; Cutcliffe, A. B.; Farona, M. F.; Kofron, W. G. J . Chem.
SOC.A 1971, 3264.
(5) Cotton, J. D.; Zornig, S. D. Znorg. Chim. Acta 1977, 25, L133.
(6) Duggan, M. D. Znorg. Chem. 1979, 18, 903.
0 1981 American Chemical Society
zyxwvutsrqpon
zyxwvutsr
zyxwvuts
zyxwvutsrqponm
166 Inorganic Chemistry, Vol. 20, No. 1, 1981
LM
,
t RN=C=NR
,C=NR
LnM\I
NR
-+
RN=C=NR
Pasquali et al.
-
.. .
(iv) Two molecules of p-tolylcarbodiimide @-TCD) have
been reductively coupled to a tetra-ptolyloxalylamidinyl ligand
via a C - C bond formation:1°
2RN=C=NR
t 2e-
-
Table I. Summary of Crystal Data and Intensity Collection
NR
RN %c
*-
I
RN/'%R
R = p-MeC, H,
An interesting relationship can be found between C 0 2 and
carbodiimides in their interaction with metal centers. Some
of the presented carbodiimide metal-induced transformations
occur with C02,while others represent a prospect of the C 0 2
metal-promoted reactivity.
The present report concerns the synthesis and the structure
of a &C,N metal-bonded ptolylcarbodiimide. The alkylation
of the coordinated carbodiimide gives a T~-C,Nmetal-bonded
trialkylamidinyl ligand. This carbodiimide metal-controlled
transformation represents a modeling study of carbon dioxide
alkylation.
.
14.446 (3)
14.186 (2)
20.903 (4)
90
90
90
8
403.4
1.251
h 2 ,
Ni-filtered Cu Ka
( h = 1.541 78 A)
3.97
0.5
..
.
.
14.260 (6)
19.176 ( 5 )
10.628 (4)
90
106.92 (5)
90
4
799.2
1.910
-,IC
Nb-filtered Mo KO!
( h = 0.710 69 A)
3.66
0.3
8-28
8-28
scan range
i0.5" from peak center
scan speed
23-10' 8/min
bkgd
stationary cryst at k0.5"
28 limits, deg
6-110
5-46
criterion for obsn I > 2 4 4
1>20(1)
unique obsd data 1439
2283
unique total data 2776
3867
cryst dimens, mm 0.11 x 0.36 X 0.50 0.10 x 0.26 x 0.45
suddenly formed (70%), while the supernatant green-maroon solution
showed a strong C-N band at 2120 an-].Anal. Calcd for Cp2V12,
CId-IlOIIV:C, 27.59; H, 2.30; I, 58.39. Found: C, 27.79; H, 2.46;
I, 57.90.
X-ray Data Collection and Structure Refmment. Complex I.I2
Preliminary examination of the crystals revealed an orthorhombic
Experimental Section
unit cell. A summary of the crystal data and intensity data collection
is given in Table I. Lattice constants came from a least-squares
All the reactions described were carried out under an atmosphere
refinement of the 28 values for 21 reflections having 219 > 60".
of purified nitrogen. Solvents were purified by standard methods.
Data were collected at room temperature on a singlecrystal Siemens
Bis(v-cyclopentadienyl)vanadium(II) was prepared as in the literaAED automated diffractometer using a crystal mounted with its [ 1001
ture." pTolylcarbodiimide (pTCD) was recrystallized from toluene.
axis along the axis of the diffractometer. The crystals were wedged
IR spectra were measured with a Perkin-Elmer 282 spectrophotometer.
into a thin-walled glass capillary and sealed under nitrogen. The
Magnetic susceptibility measurements were made with a Faraday
pulse-height discriminator was set to accept 90% of the Cu Ka peak.
balance.
The intensity of a standard reflection was monitored every 20 reSynthesis of ChV(p-TCD). Bis(cyclopentadieny1)vanadium (1.8 1
flections as a check on crystal and instrument stability. No significant
g, 10.0 mmol) dissolved in a toluene-hexane mixture (30 mL + 10
change in the measured intensity of this reflection was observed during
mL), reacted with p-tolylcarbcdiimide (2.22 g, 10.0 mmol) a t room
data collection. For intensity and background, the "five-point
temperature. The color of the solution changed suddenly from violet
technique"" was used. The structure amplitudes were obtained after
to deep red. The addition of 5 mL of hexane after 2 h induced the
the usual Lorentz and polarization reduction, and the absolute scale
crystallization of a deep red solid (65%). Anal. Calcd for Cp2Vwas established by Wilson's method." No correction for absorption
(pTCD), C25H24N2V:C, 74.44; H, 5.96; N, 6.95. Found: C, 74.1;
was made. The space group Pna2, was confirmed by structure deH , 5.83; N, 6.82. VCN(NUjO1) = 1645 cm-I. pelf = 1.76 p~ at 293.5
termination and systematic absences.
K. Complex I reacts with O2both in the solid state and in solution,
The analysis of a three-dimensional Patterson map indicated that
releasing pTCD, as was indicated by the IR spectrum showing a strong
the vector distribution could be interpreted either on the basis of the
C-N band a t 2120 cm-I.
Pnma centrosymmetric space group or on the basis of the P n ~ 7 2 ~
Synthesis of [Cp2V(p-MeC6H,N(Me)C=NC6H4Me-p)]13. A
noncentrosymmetric one, in the first case with the assumption that
toluene (30 mL) solution of Cp2V(p-TCD) (1.0 g, 2.48 mmol) was
the two independent vanadium atoms to lie on the mirror plane. The
treated with neat CH31 (0.25 mL, 4.0 mmol) at room temperature.
high number of the peaks around the metal centers in the Fourier
The solution did not change color. When the solution was heated
map, phased on the positions of the two vanadium a t o m and computed
at 80 "C for 10 min, a red oil was formed. Toluene was completely
in the two space groups, indicated the structure to be probably
evaporated, and the residue dissolved in T H F (20 mL). When iodine
noncentrosymmetric. Nevertheless we tried to solve the structure in
was added (0.67 g, 2.64 mmol), the color of the solution changed from
the Pnma space group. The attempts were unsuccessful, and the
deep red to violet. The addition of toluene (25 mL) precipitated
red-maroon crystals of [ChV(pMeC,H4N(Me)C=NC,H4Me-p)]13. centrosymmetric model was abandoned. The impossibility of removing
the centrosymmetric distribution of the peaks, imposed by the parAnal. Cakd for C26H2713N2V:c , 39.05; H, 3.38; I, 47.65; N, 3.50.
ticular positions of the two independent vanadium atoms, prevented
Found: C, 38.25; H, 3.31; I, 48.1; N, 3.42. vcN(Nujol) = 1680 cm-'.
us from solving the structure on the basis of the Pn02, space group
pcff= 1.78 pB at 298 K.
with the use of the heavy-atom technique. Direct methods (MULTAN)
Reaction of Cp2V(p-TCD) with Iodine. A T H F (30 mL) solution
were then used, and an E map computed with 100 phases having IEl
of [Cp2V(pTCD)] (2.25 g, 5.58 mmol) was reacted with a T H F (20
> 1.96 yielded the coordinates of the metal atoms and those of a
mL) solution of I2 (2.60 g, 10.24 mmol). A brown crystalline solid
cyclopentadienyl ring. The Fourier map phased on these positions
zyxw
zyxwvuts
(7) Fachinetti, G.; Biran, C.; Floriani, C.; Chiesi-Villa,A.; Guastini, C. J .
Am. Chem. Soc. 1978,100,921; Inorg. Chem. 1918, 17, 2995.
(8) Fachinetti, G.; Biran, C.; Floriani, C.; Chiesi-Villa, A,; Guastini, C. J .
Chem. SOC.,Dalton Trans. 1919, 792.
(9) Fachinetti, G.; Floriani, C.; Chisi-Villa,A,; Guastini, C. J. Am. Chem.
1979, 101, 1767.
(10) Pasquali, M.;
Floriani, C.; Chiesi-Villa,A.; Guastini, C. J . Am. Chem.
Soc. 1919, 101, 4740.
(11) Fischer, E. 0.;
Vigoureux, S. Chem. Ber. 1958, 91, 2205.
(1 2) Data reduction and structure solution and refinement were carried out
on a CYBER 7600 computer of the Centro di Calcolo dell'Italia
Nord-Orientale, by using the SHELX-76 system of crystallographiccom-
puter programs (G. Sheldrick, University of Cambridge, 1976). Calculations were performed with the financial support of the University
of Parma.
(13) Hoppe, W. Acta Crystallogr., Sect. A 1969, A25, 67.
(14) Wilson, A. J. C. Nature (London) 1942, 150, 151.
zyxw
zyx
zyxwvutsrqpo
zyxwvutsrq
zyxw
zyxwvutsrqpo
Inorganic Chemistry, Vol. 20, No. 1, 1981 167
Activation of C02-like Molecules
Table 11. Final Atomic Fractional Coordinates (X l o 4 )for Complex 1“
molecule B
molecule A
atom
x la
1152 (2)
2204 (17)
2983 (13)
2252 (18)
687 (9)
1297 (9)
2184 (9)
2122 (9)
1196 (9)
-188 (16)
-390 (16)
23 (16)
480 (16)
349 (16)
2580 (14)
3384 (14)
3837 (14)
3485 (14)
2681 (14)
2229 (14)
3694 (22)
2973 (14)
3736 (14)
3963 (14)
3426 (14)
2662 (14)
2436 (14)
3928 (32)
-46
1024
2738
2726
1005
-444
-758
67
890
575
3634
446 1
2460
1633
4179
4569
2213
1823
a
Ylb
2484 (2)
1778 (17)
1224 (11)
1685 (16)
4024 (10)
3897 (10)
3664 (10)
3647 (10)
3869 (10)
2102 (11)
2376 (11)
1708 (11)
1021 (11)
1264 (11)
1554 (11)
1010 (11)
818 (11)
1170 (11)
1715 (11)
1907 (11)
1083 (25)
1318 (12)
800 (12)
778 (12)
1273 (12)
1791 (12)
1814 (12)
1121 (35)
4212
3894
3473
3530
3987
2515
2959
1647
392
928
7 97
378
1925
2344
395
406
2158
2147
zlc
2446 (4)
1924 (20)
2768 (9)
2628 (21)
2390 (15)
1864 (15)
2111 (15)
2789 (15)
2961 (15)
1973 (13)
2611 (13)
3029 (13)
2649 (13)
1996 (13)
1324 (9)
1323 (9)
748 (9)
174 (9)
175 (9)
750 (9)
-540 (18)
3526 (10)
3733 (10)
4382 (10)
4823 (10)
4615 (10)
3967 (10)
5459 (23)
2373
1342
1756
3042
3423
1593
2825
3558
2780
1565
1776
779
-314
683
3439
4592
4965
3812
xla
1131 (2)
51 (10)
-833 (11)
-102 (10)
1284 (15)
1782 (15)
1136 (15)
239 (15)
330 (15)
1827 (18)
2495 (18)
2621 (18)
2031 (18)
1540 (18)
-294 (11)
-1134 (11)
-1516 (11)
-1057 (11)
-217 (11)
164 (11)
-1301 (20)
-822 (9)
-1572 (9)
-1642 (9)
-963 (9)
-213 (9)
-143 (9)
-1240 (26)
1637
2516
1238
-432
- 185
1602
2858
3096
1987
1063
-1487
-2138
109
76 0
-2145
-2198
390
443
Y lb
2264 (1)
1732 (11)
1259 (10)
1638 (9)
3631 (15)
3721 (15)
3679 (15)
3563 (15)
3534 (15)
1044 (18)
1764 (18)
1875 (18)
1224 (18)
710 (18)
1452 (11)
969 (11)
726 (11)
967 (11)
1451 (11)
1693 (11)
688 (27)
1242 (10)
755 (10)
641 (10)
1014 (10)
1501 (10)
1615 (10)
789 (26)
3637
3788
3705
3502
3460
746
2129
2419
1216
182
718
26 3
1662
2117
481
343
1809
1947
ZIC
7432 (4)
6877 (8)
7799 (10)
7537 (12)
8014 (8)
7432 (8)
6920 (8)
7187 (8)
7863 (8)
7026 (11)
7123 (11)
7793 (11)
8109 (11)
7635 (11)
6331 (8)
6305 (8)
5714 (8)
5150 ( 8 )
5176 (8)
5767 (8)
4460 (18)
8508 (10)
8768 (10)
9429 (10)
9830 (10)
9570 (10)
8908 (10)
10541 (14)
8423
7293
6360
6912
8187
6611
6757
8018
8651
7782
6716
5666
4722
5772
8517
9696
9831
865 1
Estimated standard deviations in parentheses.
showed a partial releasing of centrosymmetry and gave the coordinates
of some atoms of p-TCD ligands. The remaining nonhydrogen atoms
of the two independent molecules were located by five successive
Fourier difference syntheses. Refinement was camed out isotropically
down to R = 0.17 by using full-matrix least squaresis and a rigid-body
constraint for the Cp and Ph Mgs. As refinement proceeded, it became
evident that many of the parameters were oscillating. This prompted
us to examine the possibility that the two unique molecules might
be crystallographically related, especially since they are essentially
identical and related by a pseudo c glide plane passing through the
two independent vanadium atoms and perpendicular to [loo] (see
Figure 1). Reexamination of the row data, axial photos, and cell
constantsi6indicated that no higher symmetry existed and supported
our choice of unit cell. We concluded that the presence of the
pseudosymmetry element caused complications in the final stages of
refinement. Inclusion of anisotropic parameters tended to make the
thermal ellipsoids non positive definite for some carbon atoms. These
(15) Atomic form factors were from: Cromer, D. T.; Mann, J. B. Acta
Crystallogr., Sect. A 1968, A24, 321 (for nitrogen and carbon);
“International Tables for X-ray Crystallography”; Kynoch Press:
Birmingham, England, 1974;Vol. IV,p 99 (for vanadium and iodine).
(16) Lawton, S.L.;Jacobson, R. A. “TRACER: The Reduced Cell and Its
Crystallographic Applications”, Report IS-1141; USAEC, Ames Laboratory: Ames, Iowa, 1965.
were then refined isotropically. After introduction of the cyclopentadienyl and phenyl hydrogen atoms” in calculated positions as
fEed contributors, refinement was stopped at R = 0.084. An electron
density synthesis for the final rigid-group model showed no unusual
features with no peaks above the general background. This model
was considered satisfactory, although poorly refined, in view of the
large number of variables with respect to the number of observations
and in view of the high correlations between the two pseudosymmetry-related molecules. The effects of anomalous dispersion were
included in all structure factor calculations. No evidence for secondary
extinction was found. During the final stage of refinement, no parameter shifted by more than 1 . 5 ~ .The function minimized during
least-squares refinement was CwlAFl’. A value of 0.003 for g was
used in the calculation of the weight, w (w-’= uF: + ldF2). Final
atomic coordinates are given in Table 11. Thermal parameters are
reported in Table VI.’8
Complex 11. Preliminary examination of the crystals revealed a
monoclinic unit cell. A summary of the crystal data and intensity
data collection is given in Table I. The unit cell parameters were
obtained from a least-squares refinement of the 20 values of 20
zyxwv
(1 7) Scattering factors for hydrogen atoms were taken from: Stewart, R.
F.; Davidson, E. R.;Simpson, W. T. J . Chem. Phys. 1965, 42, 3175.
(18) See paragraph at the end of the paper regarding supplementary material.
zyxwvutsrqpo
zyxwvutsrqp
zyxwvuts
zyxwvutsrq
zyxwvutsrq
zyxwvuts
zyxwvutsr
168 Inorganic Chemistry, Vol. 20, No. 1, 1981
Pasquali et al.
Table 111. Final Atomic Fractional Coordinates (X lo4) for Complex IIa
atom
V
I(2)
I(')
N(l)
C(30)
N(2)
C(31)
C(1)
C(2)
C(3)
C(4)
C(5)
C(6)
C(7)
C(8)
C(10)
(311)
C(12)
(313)
(314)
C(15)
C(16)
~(17)
xla
2684 (2)
-254 (1)
1707 (1)
3743 (1)
2365 (9)
2892 (9)
2688 (11)
3087 (12)
1357 (24)
1842 (18)
1870 (18)
1378 (21)
1038 (18)
3887 (25)
4236 (19)
4285 (17)
3934 (27)
3690 (22)
1874 (11)
1441 (11)
918 (11)
808 (12)
1235 (14)
1747 (12)
285 (15)
Ylb
729 (2)
863 (1)
1127 (1)
1417 (1)
-295 (7)
-674 (7)
-238 (8)
-356 (9)
1337 (22)
1744 (10)
1433 (17)
822 (14)
757 (20)
1531 (16)
994 (32)
431 (15)
554 (32)
1182 (35)
-773 (8)
-1352 (9)
-1807 (9)
-1645 (9)
-1031 (10)
-581 (8)
-2141 (9)
ZIC
637 (3)
3326 (1)
4889 (1)
6488 (1)
837 (12)
-1000 (12)
-142 (16)
-2181 (16)
723 (24)
140 (30)
-992 (24)
-1121 (35)
-105 (50)
1387 (62)
749 (23)
1502 (58)
2464 (36)
2470 (47)
1415 (14)
804 (14)
1405 (15)
2643 (15)
3218 (16)
2634 (15)
3306 (19)
atom
xla
3125 (10)
3688 (12)
3934 (11)
3652 (11)
3091 (11)
2839 (11)
3912 (14)
1172
2160
2257
1312
559
3792
4419
46 19
3887
3396
1514
589
1158
2053
3940
4358
2844
2403
ylb
zlc
-1387 (8)
- 1590 (9)
-2269 (10)
-2808 (9)
-2575 (9)
-1898 (10)
-3544 (9)
1368
2242
1660
468
289
2086
1055
-50
100
1396
-1483
-2287
-883
-84
-1197
-2421
-2963
-1745
-712 (16)
531 (15)
719 (14)
-171 (16)
-1400 (15)
-1657 (16)
99 (19)
1658
589
-1660
-1977
-84
1140
-184
1223
3108
3 246
- 170
905
4178
3110
1307
1786
-2185
-2667
Estimated standard deviations in parentheses.
dispersion were included in all structure factor calculations. No
evidence for secondary extinction was found. During the final stage
of refinement, no parameter shifted by more than 0 . 4 ~ .
The function minimized was CdAJl*.A value of 0.003 for g was
used in the calculation of w. Final atomic coordinates are given in
Table 111. Thermal parameters are reported in Table VII.'*
Results and Discussion
Vanadocene, Cp,V (Cp = $-CsHs), reacts readily with
p-tolylcarbodiimide @-TCD) dissolved in toluene, giving a
red-brown solution from which the addition of hexane induces
the crystallization of I. Complex I, which is very sensitive
Cp2V t RN=C=NR
-
C//NR
(11
Cpp2<cR
I
R = p-CH,C, H,
to oxygen, releases p-TCD. The magnetic moment of 1.76
W B at 293.5 K as well as the IR spectrum justifies the formulation given for I. The drastic lowering of the C=N
stretching vibration from 2120 cm-l (free p-TCD) to 1645
cm-l indicates that the cumulene structure is no longer present.
Analogous lowering was observed for (PPh,),NiFigure 1. Projection on (010) showing the two crystallographically
independent molecules related by the pseudo c glide in complex I.
reflections (28 > 30'). Data collection and data reduction techniques
have been described above.'* No corrections for absorption were made.
The structure was solved by the usual heavy-atom method. From
the three-dimensional Patterson synthesis, approximate coordinates
were obtained for the three independent iodine atoms in general
positions. Two successive Fourier syntheses established the coordinates
of the remaining nonhydrogen atoms. Refinement was by full-matrix
least squares first isotropically down to R = 0.17 and then anisotropically for iodine and vanadium down to R = 0.077. An improvement to R = 0.065 was obtained with the anisotropic refinement
of all the atoms. The hydrogen atoms were included in idealized
positions as fxed contributors with isotropic thermal parameters qual
to those of the carbon atoms to which they are bonded. The subsequent
refinement of the nonhydrogen atoms stopped at R = 0.063. The
final difference map showed several peaks of height 0.6-1.4 e A-' in
the environment of the 13- ion. In the other regions the height of the
most important peaks was about 0.4 e A-3. The effects of anomalous
(PhN=b-NPh),
whose C=N band is at 1660 cm-'. The
X-ray structure analysis confirmed the reported formulation.
The possibility of modifying the carbodiimide reactivity with
the assistance of a metal center deserves much attention. On
this subject, we note that complex I is the intermediate which,
adding a further carbodiimide, gives the metallacycle preceding
the carbodiimide's disproportionation (see Introduction). A
related process is the recently reported cocyclization of diphenylcarbodiimide with acetylene^'^
zyxwvutsrqp
\
I
?NYNPh
A
zyxw
zyx
zy
Inorganic Chemistry, Vol. 20, No. 1, 1981 169
Activation of C02-like Molecules
:2
C'2
C6
Figure 2. View of the molecular shape of the two crystallographically
independent molecules Cp,V(p-TCD).
which involves in a first step the formation of A followed by
the reaction with acetylenes. This reactivity bears relevance
to incorporating COz in unsaturated organic substrates.20
Moreover, various kinds of cycloadditions to the uncomplexed C=N bond can be devised. This application requires,
however, restoring the starting C=N bond from the coordinated C-N unit. With regard to this, we found that complex
I reacts with I2 giving the starting p-TCD and Cp2V12.21
The alkylation of the $-C,N-bonded p-TCD, here reported,
represents a model study for converting COz into the corresponding $-C,O metal-bonded formato esters. This reaction,
which finds rather wide application for transforming coordinated CS2 into coordinated methoxy dithioester~,2~*~~
has never
been applied to other C02-like molecules.
A toluene solution of I reacts at 80 "C with CH31,giving
a red oil which was dissolved in T H F and reacted with iodine.
r
CH3
Figure 3. View of the molecular structure of [Cp2V(p-CH3C6H4N(CH3)C=NC6H4CH3-p)]+in complex 11.
zyxwvutsrqpon
1
C o m p l e x (11)
Figure 4.
+C'
-
\\
zyxwvut
C O ? d
\'hR
13-
n
R = p-CH,C,H,
I1 was isolated as red-brown crystals (1.78 pB at 298 K;
vcN(Nujol) 1680 cm-I). Although the isolation of B was not
realized, its existence is proposed on the basis of the nature
of I1 and of the sequence observed in the alkylation of coordinated CS2.23Complex I1 represents the first complex containing an amidinyl ligand. Should this alkylation be accomplished on C 0 2 , this could produce q2-C,0 metal-bonded
formato esters. The structures of I and I1 greatly help in
understanding the carbodiimide and amidinyl ligand bonding
modes and the related interconversion.
Description of the Structures of I and I1
In the asymmetric unit of complex I there are two crystallographically independent molecules (Figure l ) , Cp2V(p-
TCD), whose geometries are not significantly different (Figure
2). The crystals of I1 are built up by monomeric cations
[Cp2V(p-MeC6H4N=C-N(Me)C6H4Me-p)]+ (Figure 3)
and 13- anions separated by the usual van der Waals interactions. In both cases the two Cp rings, which are $ bonded
to vanadium, make a cavity in the equatorial plane for the
accommodation of the carbodiimide ligand, $-C,N bonded
to the metal. The nonbonded nitrogen lies in the plane of the
VCN unit in both complexes (Table VIII). The reciprocal
orientation of the Cp rings is staggered for molecule A in I
and midway (neither staggered nor eclipsed) for molecule B
in complex 11; C p V - C p angles are 140.0 (10) and 138.9 (18)"
in I and 11, respectively. V-C(Cp) and V-Cp(centroid) distances (Tables IV and V) fall in the usual range.zlJ3,24 In
11, the C(Cp)-C(Cp) ring distances, which are shorter than
those usually found (1.43 A),25are influenced by thermal
motion or disorder by which cyclopentadienyls are affected,
as indicated by the high values of the anisotropic thermal
parameters of the ring carbon atoms.
In spite of the poor reliability of the structure of I, some
interesting comparisons can be done between M(CN2) units
of the two complexes. The most relevant structural parameters
(Tables IV and V) are associated with these parts in complexes
(Figure 4). The same trend of distorted trigonal angles around
C(30) is observed in both complexes.
The C(30)-N(1) and C(30)-N(2) distances in I are different, although the high values of a d ' s make the comparison
uncertain, and approximate closely a single and a double bond,
zyxwvutsrqp
Hoberg, H.; Burkhart, G. Angew. Chem., Int. Ed. Engl. 1979, 18, 525.
Sasaki, Y . ;Inoue, Y . ;Hashimoto, H. J . Chem. Sot., Chem. Commun.
1976,605; Bull. Chem. SOC.Jpn. 1978, 51, 2375. Musco, A,; Perego,
C.; Tartiari, V. Inorg. Chim. Acta 1978.28, L147. Jolly, P. W.; Stobk,
S.; Wilke, G.; Goddard, R.; Kruger, C.; Sekutowski, J. C.; Tsay, Y. H.
Angew. Chem., Int. Ed. Engl. 1978, 17, 124.
Gambarotta, S.; Pasquali, M.;Floriani, C.; Chiesi-Villa, A.; Guastini,
C. Inorg. Chem., in press.
Fowles, G. W. A.; Pu, L. S.; Rice, D. A. J . Organomet. Chem. 1973,
54 C17. Grundy, K. R.; Harris, R. 0.;
Roper, W. R. Ibid. 1975, 90,
C34. Collins, T. J.; Roper, W. R.; Town, K. G. Ibid. 1976, 121, C41.
Clark, G. R.; Collins, T. J.; James, J. M.; Roper, W. R. Ibid. 1977, 125,
C23. Waters, J. M.; Ibers, J. A. Inorg. Chem. 1977, 16, 3273.
Fachinetti, G.; Floriani, C.; Chiesi-Villa, A,; Guastini, C. J. Chem. Soc.,
Dalron Trans. 1979, 1612.
zyxwvutsr
(24) Fachinetti, G.; Floriani, C.; Chiesi-Villa, A,; Guastini, C. Inorg. Chem.
1979, 18, 2282 and references cited therein.
(25) Wheatly, D. J. Perspect. Srruct. Chem. 1967, 1, 1.
zyxwvutsrqpon
zyxwvutsrqp
zyxwvutsr
zyxwvu
zyxwvutsrqpo
zyxwvutsrq
170 Inorganic Chemistry, Vol. 20, No. 1, 1981
Pasquali et al.
Table IV. Bond Distances (A) and Bond Angles (Deg) in Complex I,a with Estimated Standard Deviations in Parentheses
v-C( 1)
V-C(2)
V-C(3)
V-C(4)
V-C(5)
average
V-CP( 1)
V-CP(2)
V-N(l)
V-C(30)
C(30)-N(U
C( l)-V-C( 2)
C(2)-V-C(3)
C(3)-V-C(4)
C(4)-V-C(5)
C(S)-V-C(l)
average
N(l)-V-C(30)
N( 1)-V-Cp (11
N( ~)-V-CP(~)
C(30)-V-Cp(l)
C(30)-V-Cp(2)
CP (1k.V-CP (2)
V-N(1)-C(30)
V-N(l)-C( 11)
C( 11)-N( 1)-C(30)
V-C(30)-N(l)
V-C(30)-N(2)
a
mol A
mol B
2.29 (2)
2.35 (2)
2.35 (2)
2.28 (2)
2.24 (2)
2.30 (3)
1.96 (2)
1.94 (2)
2.12 (3)
1.99 (3)
1.48 (6)
2.30 (2)
2.27 (2)
2.27 (2)
2.30 (2)
2.32 (2)
2.29 (1)
1.95 (2)
1.95 (3)
2.09 (2)
2.00 (2)
1.40 (3)
mol A
mol A
mol B
35.6 (9)
35.2 (6)
35.7 (11)
36.6 (5)
36.5 (7)
36.0 (6)
42.0 (12)
105.2 (8)
108.4 (8)
110.7 (8)
108.8 (8)
140.0 (7)
64.2 (15)
147.5 (19)
148.3 (23)
73.8 (15)
175.7 (35)
36.2 (7)
36.4 (7)
36.1 (7)
35.7 (7)
35.8 (7)
36.0 (3)
40.1 (6)
106.9 (8)
110.7 (9)
108.5 (7)
108.9 (8)
140.0 (10)
66.8 (10)
151.7 (13)
140.3 (15)
73.1 (10)
161.5 (25)
mol B
2.24 (2)
2.26 (2)
2.32 (2)
2.33 (2)
2.29 (2)
2.29 (2)
1.28 (3)
1.40 (4)
1.59 (3)
1.53 (4)
1.53 (5)
mol A
2.17 (3)
2.19 (3)
2.35 (3)
2.42 (3)
2.32 (3)
2.29 (5)
1.31 (2)
1.31 (2)
1.48 (3)
1.54 (4)
1.57 (4)
mol B
36.8 (9)
36.2 (7)
35.6 (6)
35.8 (8)
36.6 (7)
36.1 (4)
108.2 (39)
100.3 (23)
116.7 (19)
123.1 (19)
105.0 (16)
135.0 (17)
137.7 (20)
102.2 (19)
103.9 (23)
136.1 (24)
C(6)-V-C(7)
c(?-V-C@)
C(S)-V-C(S)
C(9)-V-C(10)
C(l O)-V-C(6)
aver age
N(l)-C(30)-N(2)
C(30)-N(2)-C(21)
N(l)-C(ll)-C(l2)
N(l)-C(l 1)-C( 16)
N(2)-C(2 1)-C (2 2)
N(2)-C(2 1)-C(26)
C(13)-C(14)-C(17)
C( 15)-C(14)-C( 17)
C(23)-C(24)-C(27)
c(25 )-c(24)-c(27)
38.0 (10)
36.3 (9)
34.6 (9)
34.8 (8)
36.7 (9)
35.9 (7)
125.4 (22)
114.7 (15)
121.0 (16)
118.9 (15)
112.9 (15)
127.0 (15)
128.4 (18)
111.3 (18)
108.2 (17)
131.8 (17)
zyxw
zyxwvutsrqpo
Cp(1) and Cp(2) are referred to the centroids of the rings C(l)-C(5) and C(6)-C(10), respectively. All the average values were calculated
by using the formulas
ZWpj
x,=-
1
ZW&7
I”zyxwvut
wi = u i 2
-(--xm2)t-
N - 1 zwi
are the individual observations and ui are their standard deviations.
ZWi
where x i
[.-;
ZWj
zyx
Table V. Bond Distances (A) and Bond Angles (Des), with Estimated Standard Deviations in Parentheses, in Complex I1
V-C(l)
V-C(2)
V-C(3)
V-C(4)
V-C(5)
average
V-Wl)
V-CP(2)
V-N(l)
V-C(30)
C(30)-N(U
I(1)-1(2)
I(2)-1(3)
C(l)-V-C(2)
C(2)-V-C(3)
C(3)-V-C(4)
C(4)-V-C(5)
C(S)-V-C( 1)
average
N( l)-V-C( 30)
N(l)-V-Cp(l)
N( 1)-V-Cp(2)
C(30)-V-Cp(l)
C(30)-V-Cp( 2)
CP(l)-V-CP(2)
V-N(1)-C(30)
V-N(l)-C(ll)
C(l l)-N(l)-C(30)
V-C(30)-N( 1)
V-C(30)-N(2)
N(l)-C(30)-N(2)
2 2 5 (4)
2.27 (2)
2 2 4 (3)
2.23 (3)
2.25 (3)
2.25 (2)
1.93 (3)
1.94 (4)
2.04 (1)
2.03 (2)
1.26 (2)
2 8 5 2 (3)
2.959 (3)
33.8 (12)
35.0 (11)
35.3 (10)
34.1 (15)
36.5 (14)
35.0 (7)
36.0 (6)
109.3 (10)
110.2 (15)
110.3 (11)
108.1 (15)
138.9 (18)
71.6 (9)
146.2 (11)
140.3 (14)
72.4 (10)
151.7 (13)
135.8 (15)
V-C(6)
V-C(7)
V-C(8)
V-C(9)
v-C(10)
average
C(30)-N(2)
N(l)-C(ll)
N(2)-C(21)
N(2)-C(31)
C(14)-C( 17)
C(24)-C(27)
C(6)-V-C(7)
C(7)-V-C(8)
C(S)-V-C(9)
C(g)-V-C(lO)
C(lO)-V-C(6)
average
C(30)-N(2)-C(21)
C(30)-N(2)-C(31)
C(31)-N(2)-C(21)
N( 1)-C( 11)-C( 12)
N(l)-C(ll)-C(l6)
N( 2)-C( 2 1)-C( 22)
N(2)-C(21)-C(26)
C(13)-C(14)-C(17)
C(15)-C(14)-C(17)
C(23)-C(24)-C(27)
C(25)-C(24)-C(27)
2.27 (4)
2.24 (3)
2.27 (4)
2.25 (4)
2.23 (5)
2.25 (2)
1.33 (2)
1.40 (2)
1.42 (2)
1.49 (2)
1.50 (3)
1.47 (2)
36.2 (17)
34.4 (16)
33.0 (17)
32.5 (22)
37.0 (20)
34.7 (11)
22.8 (13)
16.8 (13)
19.1 (13)
23.2 (14)
116.6 (13)
120.7 (14)
121.8 (15)
120.3 (15)
123.1 (15)
124.0 (15)
122.4 (16)
1.31 (4)
1.35 (4)
1.35 (4)
1.31 (6)
1.41 (6)
1.34 (3)
1.34 (2)
1.42 (2)
1.40 (2)
1.38 (3)
1.39 (3)
1.41 (2)
1.39 (2)
C(l2)-C(ll)-C(l6)
C(ll)-C(l2)-C(l3)
C(12)-C(13)-C(14)
C(13)-C(14)-C(15)
C(14)-C(15)-C(16)
C(l5)-C(l6)-C(ll)
average
107.1 (28)
108.3 (25)
108.9 (25)
107.7 (30)
108.0 (30)
108.1 (12)
119.8 (15)
121.3 (14)
120.2 (15)
116.6 (16)
123.6 (16)
118.3 (15)
119.2 (26)
1.40 (6)
1.33 (7)
1.28 (6)
1.25 (9)
1.43 (7)
1.35 (5)
1.39 (2)
1.35 (3)
1.42 (2)
1.39 (2)
1.35 (3)
1.38 (2)
1.39 (1)
C(22)-C(21)-C(26)
C(21)-C(22)-C(23)
C(22)-C(23)-C(24)
C(23)-C(24)-C(25)
C(24)-C(25)-C(26)
C(25)-C(26)-C(21)
average
103.1 (37)
105.6 (33)
111.4 (38)
110.7 (45)
109.0 (40)
107.5 (23)
117.5 (15)
120.0 (15)
123.9 (14)
113.6 (15)
122.9 (16)
122.0 (15)
119.7 (29)
zyxwvutsr
zyxwvu
zyxwvu
zyxw
zyx
Inorg. Chem. 1981, 20, 171-174
respectively. In I1 both C-N distances have a high doublebond character. The unhybridized p orbital on C(30) in I1
may have some interaction with the two nitrogen atoms and
the metal, so that considerable electronic delocalization occurs
over the three atoms. This is the pattern observed in many
carbenoid complexes and supports the carbenoid nature of
C( 30).
The C=N stretching frequencies of I and I1 parallel the
structural data, indicating an increasing C=N double-bond
character of the C(30)-N( 1) unit passing from I to 11. This
and other features of the q2-C,N-bonded amidinyl are highly
reminiscent of q2-C,O-bonded acyls26 and q2-C,N-bonded
iminoa~yls.~
Amidinyl
~
ligands in this form, like the ligands
cited above, can be viewed as three-electron donors.
171
V-C(30) bond distances fall in the range of the very few
V-C (sp2) distances so far reported.24 The counteranion I<
has the usual structural features (Table V)28 and does not
interact significantly with the macrocation, the shortest contact
distance being 3.87 (13) A [I(l)-N(2) (X, p, Z)].
Conclusions
Besides the structural models for metal-bonded C 0 2 and
carboxylato esters, the present report describes the alkylation
of a coordinated carbodiimide viewed as a reaction which can
be considered a modeling study for the alkylation of metalbonded C 0 2 . Moreover, vanadocene can be proposed as a
blocking agent for one double bond of a cumulene, so that it
may promote a new kind of reactivity for the coordinated
molecule.
Acknowledgment. We thank the CNR (Rome) for financial
support.
RegistrJl NO.I, 75102-51-1; 11,75102-53-3;CP~VII,75102-54-4;
Cp2V, 1277-47-0; CH31, 74-88-4.
Supplementary Material Available: Listings of structure factor
amplitudes for complexes I and 11, anisotropic thermal parameters
(Tables VI and VII), and least-squares planes (Table VIII) (32 pages).
Ordering information is given on any current masthead page.
zyxwvutsrq
zyxwvutsrq
(26) Fachinetti, G.; Floriani, C.; Marchetti, F.; Merlino, S. J . Chem. Soc.,
Chem. Commun. 1976, 522. Fachinetti, G.; Fochi, G.; Floriani, C. J.
Chem. Soc., Dalton Trans. 1977, 1946. Fachinetti, G.; Floriani, C.;
Stoeckli-Evans, H. Ibid. 1977, 2297.
(27) Adams, R. D.; Chodosh, D. F. J . Am. Chem. Soc. 1977,99,6544; Inorg.
Chem. 1978,17,41. Adams, R. D.; Golembeski, N. M. Ibid. 1978,17,
1969. van Bolhuis, F.; de Boer, E. J. M.; Teuben, J. H. J . Orgunornet.
Chem. 1979, 170, 299.
(28) Runsink, J.; Swen-Valstra, S.; Migchelsen, T. Acta Crystallogr., Secf.
B 1972, B28, 1331.
Contribution from the Department of Chemistry and Molecular Structure Center,
Indiana University, Bloomington, Indiana 47405
The Molybdenum-Molybdenum Triple Bond. 7.'
Bis( 1,3-di-p-tolyltriazenido)tetrakis(dimethylamido) dimolybdenum
M. H. CHISHOLM,* D. A. HAITKO, J. C. HUFFMAN, and K. FOLTING
Received May 14, 1980
zyxwvu
zyx
M o ~ ( N Mreacts
~ ~ ) in
~ hydrocarbon solvents with 1,3-di-p-tolyltriazine,C7H8NNNHC7H8,to give the title compound,
M O ~ ( N M ~ ~ ) ~ ( C ~ H as
~N
a red,
~ Ccrystalline
~ H ~ ) ~ solid.
.
An X-ray study shows that in the solid state each molybdenum
atom is coordinated to four nitrogen atoms which lie in a plane; there is an unbridged molybdenum-to-molybdenum triple
bond with a Mo-Mo distance of 2.212 (1) A, and the molecule has crystallographically imposed C2symmetry. Variable-temperature IH NMR spectra recorded at 220 MHz support the view that this form of the molecule is present in solution.
These observrtions are compared with other findings in dimolybdenum and ditun sten chemistry. Crystal data for
M O ~ ( N M ~ ~ ) ~ ( C ~ Hare
~ Na, =C27.529
~ H ~ )(7)
~ A, b = 8.728 (2) A, c = 18.294 (4) fl = 58.34 (l)', V = 3741.58 A',
Z = 4, dald = 1.45 g ~ m - and
~ , space group C2/c.
1,
Introduction
Previously we have shown that 1,3-diphenyltriazine and
W2(NMe2)6react to give W2(NMe2)4(PhN3Ph)22
and Mo2(NMe2)6 and 2-hydroxy-6-methylpyridinereact to give
M O ~ ( N M ~ ~ ) ~ ( C ~ H In
~ Nboth
O ) reactions,
~.'
the replacement
of two dimethylamido groups is accomplished by an increase
in coordination number of the metal, since the triazenido and
pyridine ligands act as bidentate ligands. However, the molybdenum and tungsten compounds adopt bridged and unbridged structures, respectively, as shown in 1 and 2. The
1
2
(1) Part 6: M. H. Chisholm, J. C. Huffman, K. Folting, and I. P. Rothwell,
submitted for publication in Inorg. Chem.
(2) M. H. Chisholm, J. C. Huffman, and R. L. Kelly, Inorg. Chem., 18,
3554 (1979).
0020-1669/81/1320-0171$01.00/0
preference for the bridged or nonbridged structure could be
determined by the subtle differences that exist within the
coordination chemistry of molybdenum and tungsten. For
example, in closely related compounds containing metal-tometal triple bonds, the Mo-to-Mo distance is shorter by ca.
0.08 A than the W-to-W distance, and the triazenido ligand
is known to bridge the molybdenum-to-molybdenumquadruple
bond in the compound M O ~ ( P ~ Nwhich
~ P ~has
) ~a Mo-to-Mo
distance of 2.083 (2) A.3 As part of our continuing program
which is aimed at establishing the coordination chemistry
surrounding the (MEM)~' moiety (M = Mo, W), we decided
to prepare and structurally characterize the related pair of
molybdenum and tungsten compounds. We report here the
preparation and characterization of Mo2(NMe2)*(C7H8N3C7H8)2.
Results
~~)~
Synthesis. In hydrocarbon solvents, M O ~ ( N M and
1,3-di-p-tolyltriazine react upon mixing at room temperature
(3) F. A. Cotton, G. W. Rice, and J. C. Sekutowski, Inorg. Chem., 18,1143
(1979).
0 1981 American Chemical Society
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