Syntheses of platinum(II) complexes of cyclo-octenyl group and isolation of a self-assembled oxo-bridged macrocyclic complex [Pt 4(Spy) 4(C 8H 12OC 8H 12) 2]

Journal of Organometallic Chemistry 696 (2011) 3491e3498 Contents lists available at ScienceDirect Journal of Organometallic Chemistry journal homepage: www.elsevier.com/locate/jorganchem Syntheses of platinum(II) complexes of cyclo-octenyl group and isolation of a self-assembled oxo-bridged macrocyclic complex [Pt4(Spy)4(C8H12-O-C8H12)2] Ninad Ghavale, Sandip Dey*, Amey Wadawale, Vimal K. Jain* Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India a r t i c l e i n f o a b s t r a c t Article history: Received 12 July 2011 Received in revised form 12 July 2011 Accepted 20 July 2011 Reactions of [Pt2(m-Cl)2(C8H12OMe)2] (1) (C8H12OMe ¼ 8-methoxy-cyclooct-4-ene-1-yl) with various anionic chalcogenolate ligands have been investigated. The reaction of 1 with Pb(Spy)2 (HSpy ¼ pyridine2-thiol) yielded a binuclear complex [Pt2(Spy)2(C8H12OMe)2] (2). A trinuclear complex [Pt3(Spy)4(C8H12OMe)2] (3) was isolated by a reaction between 2 and [Pt(Spy)2]n. The reaction of 1 with HSpy in the presence of NaOMe generated 2 and its demethylated oxo-bridged tetranuclear complex [Pt4(Spy)4(C8H12O-C8H12)2] (4). Treatment of 1 with ammonium diisopropyldithiophosphate completely replaced C8H12OMe resulting in [Pt(S2P{OPri}2)2] (5), whereas non-rigid 5-membered chelating ligand, Me2NCH2CH2E , produced mononuclear complexes [Pt(ECH2CH2NMe2)(C8H12OMe)] (E ¼ S (6), Se (7)). These complexes have been characterized by elemental analyses, NMR (1H, 13C{1H}, 195Pt{1H}) and absorption spectroscopy. Molecular structures of 2, 3, 4, 5 and 7 were established by single crystal X-ray diffraction analyses. Thermolysis of 2, 6 and 7 in HDA gave platinum nanoparticles. Ó 2011 Elsevier B.V. All rights reserved. Keywords: Platinum 8-Methoxy-cyclooct-4-ene-1-yl Cyclometalation Pyridine-2-thiolate 1. Introduction The chemistry of cyclometalated palladium and platinum complexes has been extensively explored for about five decades. There are several obvious reasons for this sustained interest as these complexes find numerous applications in many fields such as organic synthesis [1e3], metallomesogens [4e6], solar cells [7,8], opto-electronic devices [9e11] and materials science [12e14], etc. Platinum complexes such as [Pt2(m-OR)2(C8H12OMe)2] (R ¼ Me, Ac) [14] and PtMe2(COD) (COD ¼ cycloocta-diene) [15,16] have been used to prepare platinum thin films and nanoparticles. Cyclometalated binuclear palladium and platinum complexes [M2(m-X)2(LXC)2] (M ¼ Pd or Pt; X ¼ Cl or OAc; L ¼ N, P, etc.), undergo a wide range of reactions. These can broadly be clubbed into (i) bridge cleavage reactions by neutral donor ligands; (ii) reaction at the metalecarbon bond, and (iii) substitution of the bridging Cl/OAc with another ionic ligand. The latter reaction yields a myriad of complexes. Structure of the resulting complex is governed by the nature of L, metal atom and the incoming anionic ligand. Recently we have described reactions of [Pt2(mCl)2{But2PC(Me2)CH2}2] [17] and [Pt2(m-Cl)2(ppy)2] (ppy ¼ metalated 2-phenylpyridine) [18] with a variety of anionic ligands. The * Corresponding authors. Tel.: þ91 22 25592589; fax: þ91 22 25505151. E-mail address: dsandip@barc.gov.in (S. Dey). 0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jorganchem.2011.07.025 nature of L (N or P) and the size of the metalacycle greatly influenced the reactivity as well as the structural features of the resulting complex. In pursuance of our work on cyclometalated platinum complexes and development of platinum group metal chalcogenolates as precursors for the synthesis of platinum group metal chalcogenides [19,20], we have chosen a precursor with a very large metalacycle ring (6-membered) and a weak L ligand (polefinic group) as in [Pt2(m-Cl)2(C8H12OMe)2] and explored its reactions with a variety of chalcogenolate ligands. The results of this work are reported herein. 2. Experimental 2.1. General procedures Solvents were dried and distilled prior to use by standard methods. All reactions were carried out in Schlenk flasks under a nitrogen atmosphere. The compounds 2-mercaptopyridine (HSpy), Me2NCH2CH2SH∙HCl and other reagents were procured from commercial sources. The compounds, (Me2NCH2CH2Se)2 [21], K2PtCl4 [22], PtCl2(COD) [23] and [Pt2(m-Cl)2(C8H12OMe)2] (1) [24] were prepared according to the literature methods. Syntheses and analytical data for [Pb(Spy)2] and [Pt(Spy)2] are given in Supplementary information, Fig. S2. Melting points were determined in capillary tubes and are uncorrected. Elemental analyses were carried out on a Carlo-Erba 3492 N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 EA-1110 CHN-O instrument. Electronic spectra were recorded on a Chemito Spectrascan UV 2600 spectrophotometer. Mass spectra were recorded on a Waters Q-TOF micro (YA-105) time of flight mass spectrometer. 1H, 13C{1H}, 31P{1H}, 77Se{1H} and 195Pt{1H} NMR spectra were recorded on a Bruker Avance II-300 NMR spectrometer operating at 300, 75.47, 121.5, 57.24 and 64.29 MHz, respectively. Chemical shifts are relative to internal chloroform peak (d 7.26 1H and 77.0 for 13C), external Me2Se for 77Se{1H} (secondary reference Ph2Se2 in CDCl3 d 463 ppm) and Na2PtCl6 in D2O for 195Pt{1H}. TG curves were obtained at a heating rate of  10 C min 1 under flowing argon on a Setaram Setsys evolution1750 instrument. Powder XRD patterns were recorded on a Philips PW1820 using Cu-Ka radiation. 2.2. Synthesis of [Pt2(Spy)2(C8H12OMe)2] (2) (a) To a benzene solution (20 mL) of [Pt2(m-Cl)2(C8H12OMe)2] (0.206 g, 0.278 mmol), solid Pb(Spy)2 (0.122 g, 0.285 mmol) was added and stirred for 2 h. A yellow solution containing a white precipitate of PbCl2 was obtained. The reaction mixture was filtered through celite and the filtrate was concentrated to 3 mL and 1 mL of hexane was added and cooled at 10  C to yield yellow crystals of 2 (0.172 g, 0.193 mmol, 69%). [In some preparations a few red crystals were also formed which were separated manually and characterized as [Pt3(Spy)4(C8H12OMe)2] (3) (see later).] Data of 2. m.p. 182  C (darkens above 165  C). Anal. Calcd. for C28H38N2O2Pt2S2: C, 37.8; H, 4.3; N, 3.1; S, 7.2. Found: C, 37.9; H, 4.3; N, 3.0; S, 7.3%. 1H NMR (300 MHz, C6D6): d ¼ 8.26 (m), 8.03, 7.88 (br, s) (2H, H-6), 7.45 (m, 2H, H-4), 6.56 (m, 2H, H-5), 6.13, 6.02 (br s, 2H, H-3), 5.58 (br s, 2JHPt ¼ 73.2 Hz), 5.48 (br s, 2JHPt ¼ 67.8 Hz), 4.84 (br s, 3 JHPt ¼ 53.1 Hz), 3.99 (br s) (4H, CH]CH), 4.49, 4.12 (br s, 2H, MeOCH), 3.70, 3.64, 3.61 (each s, 6H, OMe), 2.85e1.80 (m, 8H, CH2); 13 1 C{ H} NMR (75 MHz, C6D6): d ¼ 171.5, 170.3 (br s, Δ1/2 ¼ 40 Hz, C2), 150.6, 150.1, 149.8 (s, C-6), 134.9, 134.8 (s, C-4), 131.0, 130.6, 130.0 (s, C-3), 120.3, 119.9, 119.5 (s, C-5), 88.9, 87.6, 86.6, 86.3, 85.0, 84.7, 83.9, 83.6, 81.0, 80.6 (C]C, COMe) (The platinum satellites could not be assigned), 56.4, 56.2 (s, COMe), 36.2 (s, 3JCPt ¼ 38.1 Hz; CH2COMe), 34.8 (s, CH2CH2COMe), 31.0, 30.6 (s, CH2CH2CHPt), 29.4 (m, CH2CHPt), 25.4, 24.1, 23.2 (each s, 1JCPt ¼ 628, 620, 632 Hz respec3508 (Δ1/ tively; PteC); 195Pt{1H} NMR (64 MHz, C6D6): 2 ¼ 272 Hz); 3541 (Δ1/2 ¼ 679 Hz) ppm (2:1) ratio; UV/Vis (CH2Cl2) lmax (3 ): 277 (18,000), 324 (8000), 371 nm (sh, 3000 M 1 cm 1); ESIeMS, m/z (%): 778 ([M (Spy)]þ, 100%), 748 ([Pt2(Spy)2(C8H12OMe) H]þ, 20%), 638 ([Pt2(Spy)(C8H12OMe) H]þ, 13%), 413 ([Pt(Spy)2 2H]þ, 49%) (Supplementary information, Fig. S1). (b) To a methanolic solution (15 mL) of NaSpy (freshly prepared by reaction between HSpy (0.062 g, 0.563 mmol) and NaOMe in methanol (1.1 mL, 0.53 N, 0.572 mmol)), a dichloromethane solution (10 mL) of [Pt2(m-Cl)2(C8H12OMe)2] (0.209 g, 0.282 mmol) was added and stirred for 3 h. The solvents were evaporated under reduced pressure and the residual solid was chromatographed on a silica gel column (3  40 cm), 30:70 v/v ethylacetate/hexane to elute [Pt4(Spy)4(C8H12-O-C8H12)2] (4) and 10:90 v/v methanol/ chloroform to elute 2. The solvent was removed from the product containing fractions by rotary evaporation and oil pump vacuum to give yellow crystalline solid of 2 (0.160 g, 0.180 mmol, 64%), m.p. 184  C. The volume of fraction containing 4 was made up to 5 mL, few drops of diethylether added to yield pale yellow crystals of 4$OEt2 (0.037 g, 0.021 mmol, 15%). 2.3. Synthesis of [Pt3(Spy)4(C8H12OMe)2] (3) To a benzene solution (15 mL) of PtCl2(COD) (0.027 g, 0.072 mmol), solid Pb(Spy)2 (0.030 g, 0.070 mmol) was added and stirred. After 30 min, benzene solution (10 mL) of [Pt2(Spy)2(C8H12OMe)2] (0.060 g, 0.067 mmol), was added and the contents were further stirred for 3 h. The reaction mixture was dried by evaporating the solvents under vacuum, washed with ether (2  2 mL) and hexane (2  2 mL), and extracted from dichloromethane. The latter on volume reduction to 3 mL followed by refrigeration gave reddish solid of 3 (0.043 g, 0.032 mmol, 48%), m.p. 145  C. Anal. Calcd. for C38H46N4O2Pt3S4: C, 35.0; H, 3.5; N, 4.3; S, 9.8. Found: C, 34.8; H, 3.5; N, 4.3; S, 9.2%; UV/Vis (CH2Cl2) lmax (3 ): 275 (21,000), 297 nm (16,000 M 1 cm 1); 1H NMR (300 MHz, CDCl3): d ¼ 8.46, 8.35 (br m, 4H, H-6), 7.63 (br s, 4H, H-4), 7.15 (m, 4H, H-5), 6.95, 6.57 (m, 4H, H-3), 5.61 (s, 2JHPt ¼ 66.9 Hz, 4H, CH]CH), 3.71 (br, 2H, MeOCH), 3.50, 3.48, 3,36 (s, 6H, OMe), 2.92e2.40 (m, 8H, CH2), 2.27 (d, 3JHH ¼ 9 Hz, PtCH), 2.05e1.55 (m, 8H, CH2); 195Pt{1H} NMR (64 MHz, CDCl3): d ¼ 3470 (Δ1/2 ¼ 458 Hz), 3333, other minor broad peaks at 3447, 3454 and 3481 ppm; ESI-MS, m/z (%): 859 (5%), 415 [{Pt(Spy)2}]þ (100%) [M Pt(Spy)(C8H12OMe)] (Supplementary information, Fig. S2). Data of [Pt4(Spy)4(C8H12-O-C8H12)2] (4). M.p. 198  C (dec.). Anal. Calcd. for C56H74N4O3Pt4S4 (4∙OEt2): C, 38.2; H, 4.2; N, 3.2; S, 7.3. Found: C, 38.3; H, 4.0; N, 3.1; S, 7.7%. 1H NMR (300 MHz, CDCl3): d ¼ 8.10 (m, 4H, 6-H), 7.46 (m, 4H, H-4), 7.07 (m, 4H, H-5), 6.54 (m, 4H, H-3), 5.58 (br s, 8H, CH]CH), 3.68 (br s, 4H, OCH), 2.85e1.45 (m, 36H, CH2 þ PtCH). The peaks at d 4.12 (q), 1.26 (t) are due to the solvated Et2O in the crystals of 4; 13C{1H} NMR (75 MHz, CDCl3): d ¼ 170.1 (br s, C-2), 150.3 (s), 149.5, 149.0 (br s, C-6), 134.62 (s), 134.60 (br s, C-4), 129.8, 128.8 (br s, C-3), 119.6, 119.5 (br s, C-5), 87.3 (s, MeOCH), 80.6, 79.7 (s, C]C), 35.8, 30.0, 29.7, 28.3, 26.8 (s, CH2), 25.05, 24.9 (br s, PtC); 195Pt{1H} NMR (64 MHz, CDCl3): d ¼ 3495 (major, Δ1/2 ¼ 312 Hz), other minor broad peaks at 3523, 3554, 3607 (each approx. of Δ1/2 ¼ 624 Hz) ppm. 2.4. Synthesis of [Pt(S2P{OPri}2)2] (5) To a dichloromethane (10 mL) solution of [Pt2(m-Cl)2(C8H12 OMe)2] (0.104 g, 0.140 mmol), methanolic (5 mL) NH4S2P(OPri)2 (0.065 g, 0.280 mmol) was added. The color of the solution turned yellow and the whole reaction mixture was stirred for 2 h. The solvents were evaporated under reduced pressure and the residue was extracted with dichloromethane (2  5 mL) and passed through a Florisil column. The filtrate was concentrated to 3 mL and 1 mL of hexane was added to yield yellow crystals of 5 (0.125 g, 0.201 mmol, 71%), m.p. 123  C (dec.). Anal. Calcd. for C12H28O4P2PtS4: C, 23.2; H, 4.5; S, 20.6. Found: C, 23.2; H, 4.4; S, 20.0%; 1H NMR (300 MHz, CDCl3): d ¼ 4.98 (hep, 3JHH ¼ 6 Hz, 4H, CHMe2), 1.41 (d, 3JHH ¼ 6 Hz, 24H, CHMe2); 13C{1H} NMR (75 MHz, CDCl3): d ¼ 74.2 (s, CHMe2), 23.8 (s, CHMe2); 31P{1H} NMR (121 MHz, CDCl3): d ¼ 97.4 (t, 4 JPP ¼ 10.2 Hz, 2JPPt ¼ 441 Hz); 195Pt{1H} NMR (64 MHz, CDCl3): d ¼ 3981 (2JPPt ¼ 441 Hz) ppm. 2.5. Synthesis of [Pt(SCH2CH2NMe2)(C8H12OMe)] (6) To a methanolic solution of Me2NCH2CH2SH∙HCl (0.072 g, 0.508 mmol), NaOMe in methanol (1.95 mL, 0.52 N) was added and stirred for 15 min. To this reaction mixture [Pt2(m-Cl)2(C8H12OMe)2] (0.187 g, 0.248 mmol) was added and the whole was further stirred for 2 h. The solvent was evaporated to dryness and the residual solid was extracted with dichloromethane (3  6 mL) to yield 6 as a colorless solid (0.184 g, 0.419 mmol, 83%), m.p. 178  C (dec.). Anal. calcd for C13H25NOPtS: C 35.6, H 5.7, N 3.2, S 7.3; found: C 35.6, H 5.7, N 3.0, S 6.3%; UV/Vis (CH2Cl2) lmax (3 ): 275 (sh) (4400), 293 nm (5400 M 1 cm 1); 1H NMR (300 MHz, CDCl3): d ¼ 4.23 (t, 3 JHH ¼ 8.7 Hz, 2JHPt ¼ 70 Hz, 1H, CH2CH]CH), 3.90e3.87 (m, 2 JHPt ¼ 62 Hz, 1H, CH2CH]CH), 3.50 (m, 1H, MeOCH), 3.24 (s, 3H, OMe), 2.92 (m, 2H, NCH2), 2.84 (t, 3JHH ¼ 5.4 Hz, 2H, SCH2), N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 2.65e2.79 (m, 4H, CH2); 2.48, 2.42 (each s, 3JHPt ¼ 13.4 Hz, 6H, NMe2), 2.15 (q, 3JHH ¼ 8.4 Hz, 1H, PtCH), 1.72e1.80 (m, 4H, CH2); 13C {1H} NMR (75 MHz, CDCl3): d ¼ 86.6 (s, 1JCPt ¼ 159 Hz, CH2CH]CH), 83.5 (s, MeOCH), 81.9 (s, 1JCPt ¼ 170 Hz, CH2CH]CH), 71.1 (s, 2 JCPt ¼ 53 Hz, NCH2), 55.8 (s, OMe), 49.2, 46.5 (each s, NMe2), 33.7 (s, 3 JCPt ¼ 15 Hz, CH2CHOMe), 29.4 (s, 2JCPt ¼ 14 Hz, CH2CH2COMe), 28.9 (s, 2JCPt ¼ 16 Hz, CH2CH2CHPt), 27.8 (s, 2JCPt ¼ 18 Hz, CH2CHPt); 26.9 (s, 2JCPt ¼ 29 Hz, SCH2), 17.9 (s, 1JCPt ¼ 647 Hz; PtC); 195Pt{1H} NMR (64 MHz, CDCl3): d ¼ 3722 (s) ppm. 2.6. Synthesis of [Pt(SeCH2CH2NMe2)(C8H12OMe)] (7) To a freshly prepared methanolic solution (5 mL) of NaSeCH2CH2NMe2 (prepared from (SeCH2CH2NMe2)2 (0.147 g, 0.486 mmol) and solid NaBH4 (0.040 g, 1.057 mmol)) was added [Pt2(m-Cl)2(C8H12OMe)2] (0.357 g, 0.482 mmol). The reaction mixture was stirred for 2 h. The solvent was evaporated to dryness and the residual solid was extracted with dichloromethane (3  10 mL) to yield a pale yellow solid 7 (0.385 g, 0.793 mmol, 82%), m.p. 187  C (dec.). Anal. Calcd. for C13H25NOPtSe: C, 32.2; H, 5.2; N, 2.9. Found: C, 32.1; H, 5.1; N, 2.3%; UVevis (CH2Cl2) lmax (3 ): 274 (4400); 302 nm (7700 M 1 cm 1); 1H NMR (300 MHz, CDCl3): d ¼ 4.27 (t, 3JHH ¼ 7.4 Hz, 2JHPt ¼ 69.9 Hz, 1H, CH2CH]CH), 4.01e3.90 (m, 2JHPt ¼ 61.2 Hz,1H, CH2CH]CH), 3.51e3.45 (m,1H, MeOCH), 3.24 (s, 3H, OMe); 3.01e3.53 (m, 2H, NCH2), 2.90e2.65 (m, 4H, CH2), 2.48, 2.39 (each s, 3JHPt ¼ 13.5 Hz; NMe2, the peak due to SeCH2 merged in the base), 2.13 (q, 3JHH ¼ 8.7 Hz, 1H, PtCH), 1.90e1.55 (m, 4H, CH2); 13 1 C{ H} NMR (75 MHz, CDCl3): d ¼ 87.3 (s, 1JCPt ¼ 157 Hz, CH2CH] CH), 83.6 (s, MeOCH), 82.2 (s, 1JCPt ¼ 170 Hz, CH2CH]CH), 71.9 (s, 2 JCPt ¼ 47 Hz, NCH2), 55.9 (s, OMe), 49.2, 46.6 (each s, NMe2), 34.0 (s, 3 JCPt ¼ 15 Hz, CH2COMe), 29.4 (s, 2JCPt ¼ 16 Hz, CH2CH2COMe), 29.0 (s, 2JCPt ¼ 17 Hz, CH2CH2CHPt), 27.7 (s, 2JCPt ¼ 18 Hz, CH2CHPt), 15.0 (s, 1JCPt ¼ 634 Hz, PtC); 13.4 (s, SeCH2, 2JCPt ¼ 28 Hz, 1JCSe ¼ 58 Hz); 77 Se{1H} NMR (57 MHz, CDCl3): d ¼ 214 (1JSePt ¼ 157 Hz); 195Pt{1H} NMR (64 MHz, CDCl3): d ¼ 3720 ppm. 2.7. Crytallography experiments Single crystal X-ray diffraction measurements were made on Rigaku AFC 7S diffractometer at room temperature (298  2 K) A) radiation. using graphite monochromated Mo-Ka (l ¼ 0.71069  The structures were solved by direct methods [25] and refinement was on F2 [26] using data corrected for Lorentz and polarization effects with an empirical procedure [27,28]. The non-hydrogen atoms were refined with anisotropic displacement parameters and hydrogen atoms were fitted in their calculated positions and refined in isotropic approximation using riding model. Neutral atom scattering factors were taken from Cromer and Waber [29]. All calculations were performed using crystal structure crystallographic software package [30,31]. Molecular structures were drawn using ORTEP [32]. 3. Results and discussion 3.1. Synthesis and spectroscopy Reactions of 1 with various anionic chalcogenolate ligands differing in mode of coordination to metal atom and the ligand bite have been investigated (Scheme 1). Treatment of 1 with freshly prepared Pb(Spy)2 afforded a binuclear Spy-bridged complex [Pt2(Spy)2(C8H12OMe)2] (2) as a yellow crystalline solid. The 2, unlike 1 which converts in PtCl2(COD) in halogenated solvents [33], was quite stable both in polar and non-polar solvents like benzene, CH2Cl2, CHCl3 at least for a week without any decomposition or disproportionation (by NMR). It is worth 3493 noting that a similar reaction between [Pt2(m-Cl)2(ppy)2] (ppy ¼ metalated 2-phenylpyridine) with Pb(Spy)2 readily yields a platinum(III) complex [Pt2Cl2(Spy)2(ppy)2] [18]. The NMR spectra (1H, 13C{1H}, 195Pt{1H}) of 2 revealed the existence of more than one isomeric species in solution (Supplementary information, Figs. S3eS5). The 1H NMR spectrum showed three peaks due to OMe protons. Similarly the 13C{1H} NMR spectrum displayed three sets of resonances for the pyridyl group and s-bonded carbon atom (with 195Pt couplings). The 195Pt{1H} NMR spectrum exhibited two resonances in 1:2 ratio. The complex 2 may exist in different geometrical and optical configurations. In case of geometrical configurations cis and trans isomers are possible [34] (Supplementary information, Fig. S6). For trans isomer only one set of olefinic, OMe and pyridyl ring proton/ carbon resonances are expected whereas cis isomer, in which the relative disposition of the ligands around Pt centers is different, would display two sets of olefinic, OMe and pyridyl ring proton/ carbon resonances in the NMR spectra. Also the OMe groups can be endo or exo or at the same or different side with respect to the plane passing by the mid points of the two olefinic bonds and the PtCeC(OMe) bonds which would generate different isomeric forms. In addition to above geometrical isomers, the presence of two chiral centers in octenyl group, the complex 2 is capable to generate various diastereomers having different chemical shifts in NMR spectra. All the above isomeric forms may not give at different chemical shifts as for example the broadness of one of the 195Pt{1H} NMR resonance ( 3541 ppm, Δ1/2 ¼ 679 Hz) indicates the presence of mixtures of similar but different species. In some reactions between 1, when slightly contaminated with PtCl2(COD), and Pb(Spy)2, a red crystalline trinuclear complex [Pt3(Spy)4(C8H12OMe)2] (3) (by X-ray analysis) was also formed in poor yield together with 2 as a major product. The structure of 3 can be compared with an allyl complex [Pd3(SMes)4(C4H7)2] [35]. The latter could be isolated by refluxing [Pd(SMes)2]n with [Pd2(SMes)2(C4H7)2] in dichloromethane. Thus the reaction between 2 and freshly prepared [Pt(Spy)2] (as the sample showed poor solubility on aging) in refluxing benzene afforded 3, structure of which was again ascertained by X-ray crystallography. The 1H NMR spectrum of 3 showed different resonances for OMe group and the 195Pt{1H} NMR spectrum displayed two major peaks at d 3470 ppm (terminal Pt) and 3333 ppm (central Pt) together with other small peaks indicative of the existence of other isomeric forms in solution (Supplementary information, Fig. S7). In an attempt to prepare 2 by an alternative route, reaction of 1 with 2-mercaptopyridine in the presence of sodium methoxide was carried out. The reaction gave a mixture of products as revealed by 195 Pt{1H} NMR spectroscopy. From this mixture at least two complexes, viz. 2 (64% yield) and a self-assembled tetranuclear complex [Pt4(Spy)4(C8H12-O-C8H12)2] (4) (15% yield) could be separated by column chromatography on silica gel. The 4 appears to be formed by demethylation of 2 during the reaction in the presence of 2-mercaptopyridine and NaOMe in CH2Cl2eMeOH mixture. Demethylation of aliphatic as well as aromatic methylethers is well documented in literature [36e38]. Demethylation of ether involving metal complex, to our knowledge, is the first example. Other probable route, i.e. first demethylation of 1 to form [Pt4(m-Cl)4(C8H12-OC8H12)2], followed by substitution of chloro-bridge by pyS , is ruled out in the presence of strong nucleophilic pyS . The reaction at higher temperature was not attempted to improve the yield of 4 due to decomposition of thermodynamically unstable metalated octenyl groups which is discussed in thermal studies. The decomposition of 2 begins at 80  C. The 195Pt{1H} NMR spectrum of 4 showed a relatively sharp resonance at d 3495 ppm and three small broad peaks at d 3523, 3554 and 3607 ppm due to the existence of other possible isomeric forms with different coordination environment 3494 N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 OMe N S S N N S Pt Pt Pt S N OMe 3 (48%) [Pt(Spy)2] benzene OMe S N N S Pt Pt MeO 2 (69%) Pb(Spy)2 benzene OPri i OPr Pt P S OPri S S P S NH4{S2P(OPri)2} MeOH i 1 OMe 2 NaECH2CH2NMe2 MeOH E Pt OPr N 5 (71%) 2 pySH, 2 NaOMe MeOH, CH2Cl2 E = S (6, 83%); Se (7, 82%) N Pt 2 (64%) S S N O O Pt Pt N S S Pt N 4 (15%) Scheme 1. around platinum in solution (Supplementary information, Fig. S8). The resonance due to OMe group, as expected, was absent in the 1H and 13C{1H} NMR spectra of 4. The reaction of 1 with a large bite thiolate ligand, diisopropyldithiophosphate, gave [Pt{S2P(OPri)2}2] (5), formed by extrusion of metalated octenyl ligand. Extrusion of metalated dienylmethoxy moiety in platinum complexes by neutral and anionic ligands is not uncommon [39e41]. The reaction of 1 with non-rigid 5-membered chelating ligands, afforded mononuclear platinum complexes Me2NCH2CH2E [Pt(ECH2CH2NMe2)(C8H12OMe)] (E ¼ S (6), Se (7)) in w82% yield as colorless (6)/pale-yellow (7) crystalline solids. These complexes showed expected resonances in the 1H and 13C{1H} NMR spectra. The 195Pt{1H} NMR spectra of 6 and 7 displayed a sharp singlet at w 3720 ppm. 3.2. Crystal structures Crystal and molecular structures of 2, 3, 4, 5 and 7 have been established unambiguously by single crystal X-ray diffraction analyses. The ORTEP drawings with crystallographic numbering scheme are shown in Figs. 1e5, and the selected interatomic parameters are given in Table 1. The complexes 3 and 4 were crystallized each with a molecule of dichloromethane and diethylether, respectively. The metalated C8H12OMe group in 2, 3, 4 and 7 has a distorted boat conformation and is bonded to platinum atom through a s and olefinic bond. The olefinic bond and the platinum coordination plane are at an angle varying between 73.76 and 83.66 . The methoxy group of cyclooctene adopts an exo configuration with respect to the platinum. The PteCs and PteC(olefin) distances are similar to those observed in [PtCl(py)(C8H12OMe)] [42] and [Pt2(OMe)2(C8H12OMe)2] [43,44]. The PteC(olefin) bond in the case of 7 is, however, significantly shorter (w2.05  A) than those observed for 2, 3, 4 and also [PtCl(py)(C8H12OMe)] [42]. The pyridine-2-thiolate ion (pyS ) in 2, 3 and 4 acts as a bridging ligand and binds two platinum atoms through SXN coordination. The thiolate sulfur in these complexes occupies a position trans to olefinic bond while the nitrogen atom is trans to the PteCs bond. Such a trend e a strong trans influencing ligand (e.g. PPh3) N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 3495 Fig. 1. Molecular structure of [Pt2(Spy)2(C8H12OMe)2] (2), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity. occupying a position trans to olefinic bond, has been reported in bridge splitting reactions of [Pt2(m-Cl)2(C8H12OMe)2] with neutral donor ligands [45]. The PteS distances (2.277(5)e2.323(4)  A) are well within the range reported in platinum(II) thiolate complexes, e.g., [Pt3(Stol)4(dppm)2][SO3CF3]2 [46], [Pt{(OPPh2)N(PPh2S)}(C8H12 OMe)] [47], [Pt{(SPPh2)N(PPh2S)}(C8H12OMe)] [48] and [PtMe2 (Spy)2] [49]. The PteN distances (2.160(15)e2.239(17)  A) reflects the large trans influence of the s-bonded carbon atom and are slightly longer than those reported in [PtCl(SCH2CH(Me)NMe2)(PA) [50] and [Pt2(ppy)2(Spy)2] (2.142(7)  A) [51]. Me2Ph)] (2.130(9)  The complex 2 is a Spy-bridged binuclear platinum(II) complex with a trans or anti configuration. The molecule adopts a head-to-tail configuration similar to the other cyclometalated binuclear platinum complexes containing bridging Spy ligands, Fig. 2. Molecular structure of [Pt3(Spy)4(C8H12OMe)2] (3), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity. 3496 N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 Fig. 3. Molecular structure of [Pt4(Spy)4(C8H12-O-C8H12)2] (4), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity. e.g. [Pt2(Spy)2(ppy)2] [51], [Pt2(Spy)2(bipy)2]2þ [52], [Pt2(Spy)2 (dtby)2]2þ (dtby ¼ 4,40 -di-tert-butyl-2,20 -bipyridine) [53]. The Pt/Pt separation in 2 is much larger (3.448  A) than those reported in Spy-bridged binuclear platinum complexes, e.g. [Pt2(Spy)2 (ppy)2] (2.849(4)  A) [51]. The 3 is a trinuclear complex in which three platinum atoms are held together by double-edge bridges of Spy ligand. The trinuclear complex has a two-fold axis on the central Pt square plane passing between SePteS and NePteN angles. The coordination environment around the central platinum atom is defined by trans disposed S and N donor atoms. In the tetranuclear complex 4, the two “Pt2(Spy)2” units are held together by bridging dicyclooctene-yl groups. The molecular structure can be compared with the structure of chloro(allyl) platinum(II) [54] and tetranuclear palladium complexes [Pd4(OAc)4(CXN)2] formed by double metalation of organic ligands by palladium acetate [20]. The Pd/Pd separation in the latter is w2.9  A while in 4 the two platinum atoms in ‘Pt2(Spy)2’ units are 3.804  A apart possibly to relieve crowding of the two bulkier ether ligands. The molecule has a two-fold axis perpendicular to the Pt/Pt axis containing two platinum atoms of the same binuclear unit. The angle between the two Pt square planes (four atom least square plane [55]) decreases as Pt/Pt separation decreases in complexes 4, 2 and 3, which agrees well with the literature [56]. The two dithiophosphate ligands in 5 are coordinated to platinum atom in a chelating bidentate fashion. The platinum coordination plane and the two four-membered chelate rings all lie in a plane. The PteS distances are as expected [57]. The complex 7 is a discrete monomer having distorted square planar platinum atom. The chalcogenolate ligand is coordinated to the metal atom in a bidentate mode. The PteSe distance is unusually short (2.266(11)  A). The PteSe distances in [PtCl(SeCH2CH(Me)NMe2)(PMe2Ph)] [50] and [Pt2Cl2(m-Cl)(mA. This may be due to SeCH2CH2COOMe)(PPr3)2] [58] are w2.38  very weak trans influence of olefin. The five-membered “PtSCCN” ring is puckered. 3.3. Thermal studies Fig. 4. Molecular structure of [Pt(S2P{OPri}2)] (5), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity. Recently we have employed binuclear platinum complexes [Pt2(OR)2(C8H12OMe)2] (R ¼ Me, Ac) for the preparation of platinum nanoparticles (w10 nm) by thermolysis in HDA (1hexadecylamine) [14]. The complexes with chalcogenolate ligands may yield platinum chalcogenides on pyrolysis as several palladium chalcogenolate complexes have been used as single source molecular precursors for the synthesis of palladium chalcogenides [35,19,59,60]. The complexes described here may serve as precursors for the preparation of platinum chalcogenides as the presence of comparatively stronger PteE bond in these complexes than the PteO bond in the earlier complexes [14]. The complex [Pt2(Spy)2(C8H12OMe)2] (2) underwent a three-step decomposition N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 3497 Fig. 5. Molecular structure of [Pt(SeCH2CH2NMe2)(C8H12OMe)] (7), ellipsoids drawn at 50% probability. Hydrogen atoms are omitted for clarity. as revealed by TG curve (Supplementary information, Fig. S9). The weight loss in the first step corresponds to the loss of methoxy groups at 80  C (wt. loss found 6.9%, calcd. 7.0%). The second step of decomposition (at 180  C) can be attributed to the loss of cyclooctenyl group (wt. loss found 23%, calcd. 24.3%). The final step of decomposition corresponds to the loss of pyS ligand (wt. loss found 23%, calcd. 24.5%) leading to the formation of platinum metal. The TG curve of 6 (Supplementary information, Fig. S10) showed a two-step decomposition wherein the first step corresponds to the loss of (C8H12OMe) and the second step corresponds to the loss of SCH2CH2NMe2 group. The TG curve of 7 showed a single step of decomposition corresponding to the loss of (C8H12OMe) group. When 2, 6 and 7 are thermolysed in HDA in the temperature range 210e250  C platinum nanoparticles, rather than platinum chalcogenides, were formed. The observed lattice planes in the XRD pattern indicate the formation of fcc phase of platinum particles [61]. The average size estimated from XRD pattern (Supplementary Table 1 Selected interatomic distances [ A] and angles [ ]. 2 3$CH2Cl2 4$OEt2 7 Pt(1)eC(10) Pt(1)eC(6) Pt(1)eC(13) Pt(1)eS(1)/Se(1) Pt(2)eC(19) Pt(2)eC(23) Pt(2)eC(26) Pt(2)eS(2) C(6)eC(13) 2.15(2) 2.15(2) 2.11(2) 2.282(5) 2.15(2) 2.02(2) 2.13(2) 2.277(5) 1.332 2.046(19) 2.151(19) 2.18(2) 2.323(4) e e e 2.295(5) 1.411 2.033(15) 2.124(19) 2.10(2) 2.308(5) 2.145(17) 2.009(15) 2.113(19) 2.297(5) 1.350 2.039(9) 2.061(9) 2.045(8) 2.2660(11) e e e e 1.411(14) C(13)ePt(1)eC(6) C(13)ePt(1)eC(10) C(13)ePt(1)eS(1) C(23)ePt(2)eC(26) C(26)ePt(2)eC(19) C(26)ePt(2)eS(2) Pt/Pt 36.4(8) 81.8(10) 153.4(9) 82.1(9) 38.2(9) 165.8(9) 3.448 38.1(7) 80.2(7) 168.7(7) e e e 3.136 40.2(4) 82.2(4) 158.8(3) e e e e Pt sq. planea 52.75 33.37 37.4(8) 81.2(8) 153.8(6) 82.2(7) 38.9(7) 154.0(5) 3.832 (Pt1) 3.775 (Pt2) 69.44 (Pt1) 63.41 (Pt2) a e The angle between two platinum square planes. As the metal planes are distorted square planar, so four atom least square plane and their angle has been calculated [55]. information, Figs. S11eS13) as prepared samples corresponds to 20 (from 2); 4 (from 6); 7 (from 7) nm. 4. Conclusions Mono-, bi- and trinuclear complexes 7, 2 and 3, respectively with weakly coordinated octenyl group and strongly bonded chalcogenolate ligand have been synthesized and structurally characterized. A new oxo-bridged tetranuclear macrocyclic complex 4 has been isolated and structurally characterized. Thermolysis of mono- or binuclear complexes of platinum containing strong PteE bond in HDA yields fcc phase of platinum nanoparticles. Acknowledgments We thank Drs. T. Mukherjee and D. Das for encouragement of this work. One of the authors (NG) is thankful to the DAE-Mumbai University Collaborative Scheme for the award of a Senior Research Fellowship (SRF). Appendix. Supplementary information Details of synthesis of [Pb(Spy)2], [Pt(Spy)2], crystallographic and structure refinement data tables of all complexes, mass spectra of 2 and 3; 1H 13C{1H} and 195Pt{1H}NMR spectra of 2; 195Pt{1H} NMR spectra of 3 and 4; TG curves of 2 and 6 and powder XRD pattern of platinum nanoparticles, single crystal X-ray diffraction studies (cif file) of 2, 3, 4, 5 and 7 are provided in supplementary information. CCDC 801696, 801697, 801698, 801695 and 801694 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via HYPERLINK “http://www.ccdc. cam.ac.uk/data_request/cif ” www.ccdc.cam.ac.uk/data_request/cif. Supplementary data associated with this article can be found in the on-line version at doi:10.1016/j.jorganchem.2011.07.025. References [1] N. Selander, K.J. Szabo, Dalton Trans. (2009) 6267e6279. [2] R.B. Bedford, Chem. Commun. (2003) 1787e1796. [3] M. Pfeffer, Pure Appl. Chem. 64 (1992) 335e342. 3498 N. Ghavale et al. / Journal of Organometallic Chemistry 696 (2011) 3491e3498 [4] A.S. Mocanu, M. Ilis, F. Dumitrascu, M. Ilie, V. Circu, Inorg. Chim. Acta 363 (2010) 729e736. [5] A.P. Polishchuk, T.V. Timofeeva, Russ. Chem. Rev. 62 (1993) 291e321. [6] M. Ghedini, D. Pucci, A. Crispini, G. Barberio, Organometallics 18 (1999) 2116e2124. [7] E.A.M. Geary, L.J. Yellowlees, L.A. Jack, I.D.H. Oswald, S. Parsons, N. Hirata, J.R. Durrant, N. Robertson, Inorg. Chem. 44 (2005) 242e250. [8] M. Hissler, J.E. McGarrah, W.B. Connick, D.K. Geiger, S.D. Cummings, R. Eisenberg, Coord. Chem. Rev. 208 (2000) 115e137. [9] Y. Chi, P.-T. Chou, Chem. Soc. Rev. 39 (2010) 638e655. [10] J.A.G. Williams, Chem. Soc. Rev. 38 (2009) 1783e1801. [11] R.C. Evans, P. Douglas, C.J. Winscom, Coord. Chem. Rev. 250 (2006) 2093e2126. [12] M. Albrecht, Chem. Rev. 110 (2010) 576e623. [13] Y. Unger, D. Meyer, O. Molt, C. Schildknecht, I. Münster, G. Wagenblast, T. Strassner, Angew. Chem. Int. Ed. 49 (2010) 10214e10216. [14] N. Ghavale, S. Dey, V.K. Jain, R. Tewari, Bull. Mater. Sci. 32 (2009) 15e18. [15] C. Thurier, P. Doppelt, Coord. Chem. Rev. 252 (2008) 155e169. [16] J.C. Hierso, R. Feurer, P. Kalck, Coord. Chem. Rev. 178e180 (1998) 1811e1834. [17] N. Ghavale, S. Dey, A. Wadawale, V.K. Jain, J. Organomet. Chem. 695 (2010) 2296e2304. [18] N. Ghavale, A. Wadawale, S. Dey, V.K. Jain, J. Organomet. Chem. 695 (2010) 1237e1245. [19] S. Dey, V.K. Jain, Platinum Met. Rev. 48 (2004) 16e29. [20] V.K. Jain, L. Jain, Coord. Chem. Rev. 254 (2010) 2848e2903. [21] S. Dey, V.K. Jain, S. Chaudhary, A. Knoedler, F. Lisner, W. Kaim, J. Chem. Soc. Dalton Trans. (2001) 723e728. [22] R.N. Keller, T. Moeller, J.V. Quagliano, Inorg. Synth. 2 (1963) 247e250. [23] D. Drew, J.R. Doyle, A.G. Shaver, Inorg. Synth. 13 (1972) 47e55. [24] J. Chatt, L.M. Vallarino, L.M. Venanzi, J. Chem. Soc. (1957) 2496e2505. [25] SIR-92, A. Altomare, G. Cascarano, C. Gracovazzo, A. Guagliardi, J. Appl. Crystallogr. 26 (1993) 343e350. [26] G.M. Sheldrick, Programs SHELXS97 (Crystal Structure Solution) and SHELXL97 (Crystal Structure Refinement). University of Göttigen, Germany, 1997. [27] T. Higashi, ABSCOR e Empirical Absorption Correction based on Fourier Series Approximation. Rigaku Corporation, 3-9-12 Matsubara, Akishima, Japan, 1995. [28] PSISCANS, A.C.T. North, D.C. Phillips, F.S. Mathews, Acta Crystallogr. A 24 (1968) 351e359. [29] D.T. Cromer, J.T. Waber, International Tables for X-ray Crystallography, vol. IV, The Kynoch Press, Birmingham, England, 1974, Table 2.2 A. [30] Crystal Structure 3.7.0: Crystal Structure Analysis Package, Rigaku and Rigaku MSC 2000e2005, 9009 New Trials Dr. The Woodlands, TX 77381, USA. [31] D.J. Watkins, C.K. Prout, J.R. Carruthers, P.W. Betteridge, Chemical Laboratory, Oxford (U.K.), 1996. [32] C.K. Johnson, ORTEP-II, Report ORNL-5136. Oak Ridge National Laboratory, Oak Ridge, TN, 1976. [33] J.K. Stille, R.A. Morgan, J. Am. Chem. Soc. 88 (1966) 5135e5141. [34] V.K. Jain, S. Kannan, R.J. Butcher, J.P. Jasinski, J. Organomet. Chem. 468 (1994) 285e290. [35] N. Ghavale, S. Dey, A. Wadawale, V.K. Jain, Organometallics 27 (2008) 3297e3302. [36] L.F. Frey, K.M. Marcantonio, C.-Y. Chen, D.J. Wallace, J.A. Murry, L. Tan, W. Chen, U.H. Dolling, E.J.J. Grabowski, Tetrahedron 59 (2003) 6363e6373. [37] M. Node, K. Nishide, K. Fuji, E. Fujita, J. Org. Chem. 45 (1980) 4275e4277. [38] S. Berényi, C. Csutorás, S. Gyulai, G. Rusznyák, Synth. Commun. 31 (2001) 1987e1992. [39] G. Carturan, L. Busetto, A. Palazzi, U. Belluco, J. Chem. Soc. A (1971) 219e222. [40] R. Pietropaolo, F. Cusmano, E. Rotondo, A. Spadaro, J. Organomet. Chem. 155 (1978) 117e122. [41] H.C. Clark, A.B. Goel, S. Goel, J. Organomet. Chem. 216 (1981) C25eC28. [42] G. Bombieri, E. Forsellini, R. Graziani, J. Chem. Soc. Dalton Trans. (1972) 525e527. [43] A.B. Goel, S. Goel, D.G. Vanderveer, Inorg. Chim. Acta 54 (1981) L169eL170. [44] F. Giordano, A. Vitagliano, Inorg. Chem. 20 (1981) 633e635. [45] J. Soulie, J.-C. Chottard, D. Mansuy, J. Organomet. Chem. 171 (1979) 113e120. [46] A. Singhal, V.K. Jain, A. Klein, M. Niemeyer, W. Kaim, Inorg. Chim. Acta 357 (2004) 2134e2142. [47] A.M.Z. Slawin, M.B. Smith, J.D. Woollins, J. Chem. Soc. Dalton Trans. (1996) 3659e3665. [48] P. Bhattacharyya, A.M.Z. Slawin, M.B. Smith, J. Chem. Soc. Dalton Trans. (1998) 2467e2476. [49] K.J. Bonnington, M.C. Jennings, R.J. Puddephatt, Organometallics 27 (2008) 6521e6530. [50] S. Dey, L.B. Kumbhare, V.K. Jain, T. Schurr, W. Kaim, A. Klein, F. Belaj, Eur. J. Inorg. Chem. (2004) 4510e4520. [51] T. Koshiyama, A. Omura, M. Kato, Chem. Lett. 33 (2004) 1386e1387. [52] M. Kato, A. Omura, A. Toshikawa, S. Kishi, Y. Sugimoto, Angew. Chem. Int. Ed. 41 (2002) 3183e3185. [53] B.-C. Tzeng, W.-F. Fu, C.-M. Che, H.-Y. Chao, K.-K. Cheung, S.-M. Peng, J. Chem. Soc. Dalton Trans. (1999) 1017e1024. [54] G. Raper, W.S. McDonald, J. Chem. Soc. Dalton Trans. (1972) 265e269. [55] W. Mohr, J. Stahl, F. Hampel, J.A. Gladysz, Chem. Eur. J. 9 (2003) 3324e3340. [56] B. Ma, J. Li, P.I. Djurovich, M. Yousufuddin, R. Bau, M.E. Thompson, J. Am. Chem. Soc. 127 (2005) 28e29. [57] V.K. Jain, S. Chaudhury, A. Vyas, R. Bohra, J. Chem. Soc. Dalton Trans. (1994) 1207e1211. [58] L.B. Kumbhare, V.K. Jain, P.P. Phadnis, M. Nethaji, J. Organomet. Chem. 692 (2007) 1546e1556. [59] B. Radha, G.U. Kulkarni, Adv. Funct. Mater. 20 (2010) 879e884 and references therein. [60] S. Dey, V.K. Jain, J. Singh, V. Trehan, K.K. Bhasin, B. Varghese, Eur. J. Inorg. Chem. (2003) 744e750. [61] Powder Diffraction File No. 04-0802, Compiled by JCPDS. International Centre for Diffraction Data, USA, 1997.