Mark Elsegood
Loughborough University, Chemistry, Faculty Member
- Chemical Crystallographer and Senior Lecturer in Inorganic Chemistry at Loughborough University, UK.edit
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The steroid 3, with three independently-addressable, rigidly-positioned functional groups, has been synthesized in an efficient, multi-gram sequence from inexpensive cholic acid 1. Compound 3 should prove valuable as a starting point for... more
The steroid 3, with three independently-addressable, rigidly-positioned functional groups, has been synthesized in an efficient, multi-gram sequence from inexpensive cholic acid 1. Compound 3 should prove valuable as a starting point for combinatorial libraries with preorganised, co-directed arrays of substituents.Graphic
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The molecular structures of a number of solvates of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][O(2-C6H4N)2]}2 (R = Me L(1)H2, tBu L(2)H2, Cl L(3)H2), formed by reacting 2,6-dicarboxy-4-R-phenol with... more
The molecular structures of a number of solvates of the [2 + 2] Schiff-base macrocycles {[2-(OH)-5-(R)-C6H2-1,3-(CH)2][O(2-C6H4N)2]}2 (R = Me L(1)H2, tBu L(2)H2, Cl L(3)H2), formed by reacting 2,6-dicarboxy-4-R-phenol with 2,2'-oxydianiline (2-aminophenylether), (2-NH2C6H4)2O, have been determined. Reaction of L(n)H2 with two equivalents of AlR'3 (R' = Me, Et) afforded dinuclear alkylaluminium complexes [(AlR'2)2L(1-3)] (R = R' = Me (1), R = tBu, R' = Me (2), R = Cl, R' = Me (3), R = Me, R' = Et (4), R = tBu, R' = Et (5), R = Cl, R' = Et (6)). For comparative studies, reactions of two equivalents of AlR'3 (R' = Me, Et) with the macrocycle derived from 2,2'-ethylenedianiline and 2,6-dicarboxy-R-phenols (R = Me L(4)H2, tBu L(5)H2) were conducted; the complexes [(AlMe)(AlMe2)L(5)]·2¼MeCN (7·2¼MeCN) and [(AlEt2)2L(4)] (8) were isolated. Use of limited AlEt3 with L(3)H2 or L(5)H2 afforded mononuclear bis(macrocyclic) complexes [Al(L(3))...
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... Preparation of New N-Heterocyclic Carbene Metal-Alkyne Complexes and Application to a Stereocontrolled Pauson-Khand Reaction. Andrew M. Poulton a , Steven DR Christie* a , RossFryatt a , Sophie H. Dale a , Mark RJ Elsegood a , David... more
... Preparation of New N-Heterocyclic Carbene Metal-Alkyne Complexes and Application to a Stereocontrolled Pauson-Khand Reaction. Andrew M. Poulton a , Steven DR Christie* a , RossFryatt a , Sophie H. Dale a , Mark RJ Elsegood a , David M. Andrews b,. ...
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ABSTRACT A simple two-step route to a series of carboxylic acid functionalized ditertiary phosphine oxides is described, including the X-ray crystal structures of three representative examples namely {Ph2P(O)CH2}2N(CH2)nCO2H (n = 3−5).... more
ABSTRACT A simple two-step route to a series of carboxylic acid functionalized ditertiary phosphine oxides is described, including the X-ray crystal structures of three representative examples namely {Ph2P(O)CH2}2N(CH2)nCO2H (n = 3−5). Strong intermolecular O−H···O H-bonding is observed in all cases leading to distinct packing arrangements.
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Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] with trimethylborate, B(OMe)3, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu2-2-(O)C6H2CHNR]B(OMe)}... more
Treatment of the ligands 3,5-tBu2-2-(OH)C6H2CHNR [R=2-(CO2H)C6H4 (1a) and 2-(CO2H)C10H6 (1b)] with trimethylborate, B(OMe)3, in toluene yields, after work-up, the yellow crystalline complexes {[3,5-tBu2-2-(O)C6H2CHNR]B(OMe)} [R=2-(CO2)C6H4 (2a) and 2-(CO2)C10H6 (2b)], respectively. Further treatment of these complexes with trifluoromethanesulfonic (triflic) acid, CF3SO3H, followed by recrystallisation from tetrahydrofuran (thf) afforded the triflate salts [{3,5-tBu2-2-(O)C6H2CHNR}B(thf)][CF3SO3] [R=2-(CO2)C6H4 (3a) and 2-(CO2)C10H6 (3b)]. An electroluminescent device was constructed using 2a, which produced orange-green light with broad emission spectra (maximum brightness of 5cd/m2 being observed at 13V). Compounds 1a and 2b·2MeCN have been characterised by single crystal X-ray structure determinations.
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Group 14 and 15 elements (M′= Pb, As, Sb, Bi), which are known to form corner-shared double cube derivatives [Mo 6 M′ S 8 (H 2 O) 18] 8+ of [Mo 3 S 4 (H 2 O) 9] 4+, are here shown to react with [M 3 Se 4 (H 2 O) 9] 4+(M= Mo, W). Using... more
Group 14 and 15 elements (M′= Pb, As, Sb, Bi), which are known to form corner-shared double cube derivatives [Mo 6 M′ S 8 (H 2 O) 18] 8+ of [Mo 3 S 4 (H 2 O) 9] 4+, are here shown to react with [M 3 Se 4 (H 2 O) 9] 4+(M= Mo, W). Using similar procedures, no ...
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Reaction of [Mo(NNPh2)Cl3] with mesitylMgCl (mesityl=2,4,6-Me3C6H2) followed by addition of pentafluorophenol affords the bis(alkylated) complex [Mo(NNPh2)(NPh2)(mesityl)2(OC6F5)] (1) in poor yield (20–30%). In the case of [WO2Cl2(dme)],... more
Reaction of [Mo(NNPh2)Cl3] with mesitylMgCl (mesityl=2,4,6-Me3C6H2) followed by addition of pentafluorophenol affords the bis(alkylated) complex [Mo(NNPh2)(NPh2)(mesityl)2(OC6F5)] (1) in poor yield (20–30%). In the case of [WO2Cl2(dme)], reaction with Ph2NNH2·HCl in refluxing triethylamine/trimethylsilylchloride affords the binuclear complex {[W(NNPh2)(NPh2)(OSiMe3)]2(μ-Cl)2(μ-O)} (2) in good yield (approximately 75%). The crystal structures of 1 and 2 have been determined. In 1, the trigonal-bipyramidal Mo atom is coordinated by an axial linear isodiazene group trans to a pentafluorophenoxide ligand, whilst equatorial positions are occupied by two mesityl groups and an amide (NPh2) group. For 2, the molecule is best described as possessing a triply bridging (2x μ-Cl, μ-O) confacial bioctahedral geometry, with the longer bridging bonds trans to the isodiazene group The amide groups (NPh2) in each structure must arise through NN bond cleavage.
The five-coordinate mixed-imido complex [Mo(Nt-Bu)(NC6F5)(L)] (1) can be prepared in high yield via treatment of [Mo(Nt-Bu)(NC6F5)(Ot-Bu)2] with LH2, where LH2 is 2,6-bis(2-hydroxy-2,2-diphenylethyl)pyridine. Contrastingly, the reaction... more
The five-coordinate mixed-imido complex [Mo(Nt-Bu)(NC6F5)(L)] (1) can be prepared in high yield via treatment of [Mo(Nt-Bu)(NC6F5)(Ot-Bu)2] with LH2, where LH2 is 2,6-bis(2-hydroxy-2,2-diphenylethyl)pyridine. Contrastingly, the reaction of [Mo(NAd)(NC6F5)(Ot-Bu)2] (Ad=adamantyl, C6H10) with LH2 gave [Mo(NAd)2(L)] (2) via an imido-exchange reaction. Complex 2 can also be synthesised via treatment of in situ generated [Mo(NAd)2(Ot-Bu)2] with LH2; the latter method also results in trace
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The reaction between the bridged bis(imido) complexes {[(CH2)n(2-C6H4N)2]MoCl2(dme)} (n=1,2); dme=1,2-dimethoxyethane) and one equivalent of potassium hydridotris(3,5-dimethylpyrazolyl)borate (KTp′) in refluxing thf gives... more
The reaction between the bridged bis(imido) complexes {[(CH2)n(2-C6H4N)2]MoCl2(dme)} (n=1,2); dme=1,2-dimethoxyethane) and one equivalent of potassium hydridotris(3,5-dimethylpyrazolyl)borate (KTp′) in refluxing thf gives {[(CH2)n(2-C6H4N)2](Tp′)MoCl} (n=1 (1), n=2 (2)) as red crystalline solids in good yields. Similarly, the reaction between [Mo(NAr)2Cl2(dme)] or [Mo(NAr)(NBut)Cl2(dme)] (Ar=2,6-Pri2C6H3) and KTp′ gives green [Tp′Mo(NAr)2Cl] (3) or brown/black [Tp′Mo(NAr)(NBut)Cl] (4), respectively. X-ray crystal structures of the compounds 1, 3 and 4 have been determined. All have octahedral structures with fac coordination for the tridentate Tp′ ligands and near-linear imido groups.Three bis(imido) complexes of molybdenum with Tp′ as a tridentate ligand have octahedral coordination geometry with a cis arrangement of the two imido ligands; Mo–N bond lengths show the strong trans influence of the imido ligands compared with chloro in the sixth coordination site.
ABSTRACT Six new monocationic trialkylphosphines, [P(CH2NH2R){CH2N(R)CH2N(R)CH2}] (R = C6H5CH2, 4-FC6H4CH2, 4-ClC6H4CH2, 4-CH3C6H4CH2) as their Cl (1c, 1d) or BPh4 (2a−2d) salts, are described. All compounds have been characterized by... more
ABSTRACT Six new monocationic trialkylphosphines, [P(CH2NH2R){CH2N(R)CH2N(R)CH2}] (R = C6H5CH2, 4-FC6H4CH2, 4-ClC6H4CH2, 4-CH3C6H4CH2) as their Cl (1c, 1d) or BPh4 (2a−2d) salts, are described. All compounds have been characterized by P{H} spectroscopy, FTIR spectroscopy, and elemental analysis. A single crystal X-ray structure determination of 2a has been performed. In contrast to recent examples reported by us, only one intramolecular N−H···N hydrogen bond was observed in molecules of 2a; the other N‒H was involved in an N‒H···π intermolecular interaction to the BPh4 anion.
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Hydrothermal reactions in the system Mo, MoO2−4, Na+, H2O3PC6H5, and R4N (R = CH3, C3H7) yielded two compounds Na6 [ (CH3) 4N] 3 {Na [Mo6O12 (OH) 3 (O3PC6H5) 4] 2} · 27.5 H2O 2, and Na6 [ (C3H7) 2NH2] 2 (C3H7) NH3 {Na [Mo6O12 (OH) 3... more
Hydrothermal reactions in the system Mo, MoO2−4, Na+, H2O3PC6H5, and R4N (R = CH3, C3H7) yielded two compounds Na6 [ (CH3) 4N] 3 {Na [Mo6O12 (OH) 3 (O3PC6H5) 4] 2} · 27.5 H2O 2, and Na6 [ (C3H7) 2NH2] 2 (C3H7) NH3 {Na [Mo6O12 (OH) 3 (O3PC6H5) 4] 2} · 4 H2O 4. The crystal structures of 2 and 4 are compared to the known structures of (NH4) 5Na4 {Na [Mo6O12 (OH) 3 (O3PC6H5) 4] 2} · 6 H2O 1 and Na3 (H3O) 4 [ (C2H5) 4N] 2 {Na [Mo6O12 (OH) 3 (O3PC6H5) 4] 2} · ∼ 14 H2O 3 and the influence of the ammonium cations on the structure is assessed. While 1–3 are structures of a ribbon motif, compound 4 is a layered structure because of the decomposition of the tetrapropylammonium ions during the synthesis conditions.
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... The reaction between Cr(NAr)2Cl2 and LiNHAr afforded the amide complex Cr(NAr)2(NHAr) Cl 3. Attempts to generate the half-sandwich species CrCp(NAr)2Cl through treatment of the dichloride with LiCp, Mg(Cp)2 or NaCp resulted in the... more
... The reaction between Cr(NAr)2Cl2 and LiNHAr afforded the amide complex Cr(NAr)2(NHAr) Cl 3. Attempts to generate the half-sandwich species CrCp(NAr)2Cl through treatment of the dichloride with LiCp, Mg(Cp)2 or NaCp resulted in the dimeric chromium() complex [Cr(NAr ...
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The intermolecular addition of 1,3-dicarbonyl equivalents to endoperoxides in the presence of an organocatalyst yields trans-fused butyrolactones in high yield and enantioselectivities. This methodology expands the synthetic utility of... more
The intermolecular addition of 1,3-dicarbonyl equivalents to endoperoxides in the presence of an organocatalyst yields trans-fused butyrolactones in high yield and enantioselectivities. This methodology expands the synthetic utility of endoperoxides and further underlines their potential as sources of oxygen functionality for natural and non-natural product target synthesis.
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Reaction of ferrocenylmethanol, FcCH2OH, with β-cyano-N,N-diisopropyl chlorophosphoramidite in dichloromethane yields the ferrocenylmethylphosphonate derivative, FcCH2P(O)(N(iPr)2)(OCH2CH2CN), 2a. The crystal and molecular structure of 2a... more
Reaction of ferrocenylmethanol, FcCH2OH, with β-cyano-N,N-diisopropyl chlorophosphoramidite in dichloromethane yields the ferrocenylmethylphosphonate derivative, FcCH2P(O)(N(iPr)2)(OCH2CH2CN), 2a. The crystal and molecular structure of 2a is presented. 31P NMR data suggest that this is formed from FcCH2OP(N(iPr)2)(OCH2CH2CN) via a Michaelis–Arbusov-type rearrangement. Similar behaviour was also observed for 1,2-phenylene chlorophosphite and diethyl chlorophosphite.
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The reaction of CaCO3 with isophthalic acid in water yields nonaaquapenta-mu-isophthalato-pentacalcium octahydrate, [[Ca(5)(C(8)H(4)O(4))(5)(H(2)O)(9)].8H(2)O](n), a complex polymeric one-dimensional column structure bearing... more
The reaction of CaCO3 with isophthalic acid in water yields nonaaquapenta-mu-isophthalato-pentacalcium octahydrate, [[Ca(5)(C(8)H(4)O(4))(5)(H(2)O)(9)].8H(2)O](n), a complex polymeric one-dimensional column structure bearing metal-carboxylate bonds and Ca-bound terminal and bridging water molecules, in addition to hydrogen-bonded water molecules of crystallization. The asymmetric unit comprises half of the formula unit, with one Ca(2+) ion located on a twofold axis, and contains 16 unique strong O-H.O hydrogen bonds, some of which link the columns together.
... pp. 4488-4496. [CrossRef] [ChemPort] Bruker (2001). SMART (Version 5.611) and SAINT (Version 6.02A). Bruker AXS Inc., Madison, Wisconsin, USA. ... Acta, 357, 219-224. [CrossRef] [ChemPort] Therrien, B., Vielle-Petit, L.,... more
... pp. 4488-4496. [CrossRef] [ChemPort] Bruker (2001). SMART (Version 5.611) and SAINT (Version 6.02A). Bruker AXS Inc., Madison, Wisconsin, USA. ... Acta, 357, 219-224. [CrossRef] [ChemPort] Therrien, B., Vielle-Petit, L., Jeanneret-Gris, J., Stepnicka, P. & Süss-Fink, G. (2004). ...
The title compound, (C30H25NPS)2[Pd2Br6] or (Ph3PNSPh2)2[Pd2Br6], was crystallized from the reaction of (Ph3PNSPh2)[BPh4] with (PPh4)2[Pd2Br6], giving a salt rather than the intended coordination complex [PdBr3(Ph3PNSPh2)]. The compound... more
The title compound, (C30H25NPS)2[Pd2Br6] or (Ph3PNSPh2)2[Pd2Br6], was crystallized from the reaction of (Ph3PNSPh2)[BPh4] with (PPh4)2[Pd2Br6], giving a salt rather than the intended coordination complex [PdBr3(Ph3PNSPh2)]. The compound crystallizes in the non-centrosymmetric space group Cc with one complete formula unit in the asymmetric unit. One of the two independent cations is disordered. The geometry of the two cations is compared with that of the only previously crystallized example of this cation, viz. its [SbCl6]- salt [Reck et al. (1982). Chem. Ber. 115, 2981-2996]. The bond angles within the P-N-S triad in the two cations in the title compound are narrower than those observed in the literature example, while the S-N bond lengths are slightly longer in the title compound. The P-N bond length in the ordered cation shows excellent agreement with that determined by Reck and co-workers, but the P-N bond lengths are lengthened slightly in the disordered cation. Weak C-H...Br interactions create a three-dimensional network, with cations and anions alternating along the crystallographic c direction.