TY - JOUR
T1 - New metal-organic polygons involving MM quadruple bonds
T2 - M 8(O2CtBu)4(μ-SC4H 2-3,4-{CO2}2)6 (M = Mo, W)
AU - Byrnes, Matthew J.
AU - Chisholm, Malcolm H.
AU - Patmore, Nathan J.
PY - 2005/12/12
Y1 - 2005/12/12
N2 - The reactions between M2(O2CtBu) 4, where M = Mo or W, and thienyl-3,4-dicarboxylic acid (0.5-1.5 equiv) in toluene proceed via a series of detectable intermediates to the compounds M8(O2CtBu)4(μ-SC 4H2-SC4H2-3,4-{CO2} 2)6, which are isolated as air-sensitive yellow (M = Mo) or red (M = W) powders and show parent molecular ions in , their mass spectra (MALDI). The structure of the molybdenum complex was determined by single-crystal X-ray crystallography and shown to contain an unusual M 8 polygon involving four Mo2 quadruply bonded units linked via the agency of the six 3,4-thienylcarboxylate groups. The structure has crystallographically imposed S4 symmetry and may be described in terms of a highly distorted tetrahedron of Mo2 units or a bisphenoid in which two Mo2 units are linked by a thienyldicarboxylate such that intramolecular Mo2⋯O bonding is present, while the other thienylcarboxylate bridges merely serve to link these two [Mo 2]⋯[Mo2] units together. The color of the compounds arises from intense M2 δ-to-thienyl π* transitions and, in THF, the complexes are redox-active and show four successive quasi-reversible oxidation waves. The [M8]+ radical cations, generated by one-electron oxidation with AgPF6, are shown to be valence-trapped (class II) by UV-vis-near-IR and electron paramagnetic resonance spectroscopy. These results are supported by the electronic structure calculations on model compounds M8(O2CH) 4(μ-SC4H2-3,4-{CO}2)6 employing density functional theory that reveal only a small splitting of the M2 δ manifold via mixing with the 3,4-thienylcarboxylate π system.
AB - The reactions between M2(O2CtBu) 4, where M = Mo or W, and thienyl-3,4-dicarboxylic acid (0.5-1.5 equiv) in toluene proceed via a series of detectable intermediates to the compounds M8(O2CtBu)4(μ-SC 4H2-SC4H2-3,4-{CO2} 2)6, which are isolated as air-sensitive yellow (M = Mo) or red (M = W) powders and show parent molecular ions in , their mass spectra (MALDI). The structure of the molybdenum complex was determined by single-crystal X-ray crystallography and shown to contain an unusual M 8 polygon involving four Mo2 quadruply bonded units linked via the agency of the six 3,4-thienylcarboxylate groups. The structure has crystallographically imposed S4 symmetry and may be described in terms of a highly distorted tetrahedron of Mo2 units or a bisphenoid in which two Mo2 units are linked by a thienyldicarboxylate such that intramolecular Mo2⋯O bonding is present, while the other thienylcarboxylate bridges merely serve to link these two [Mo 2]⋯[Mo2] units together. The color of the compounds arises from intense M2 δ-to-thienyl π* transitions and, in THF, the complexes are redox-active and show four successive quasi-reversible oxidation waves. The [M8]+ radical cations, generated by one-electron oxidation with AgPF6, are shown to be valence-trapped (class II) by UV-vis-near-IR and electron paramagnetic resonance spectroscopy. These results are supported by the electronic structure calculations on model compounds M8(O2CH) 4(μ-SC4H2-3,4-{CO}2)6 employing density functional theory that reveal only a small splitting of the M2 δ manifold via mixing with the 3,4-thienylcarboxylate π system.
UR - http://www.scopus.com/inward/record.url?scp=29544439039&partnerID=8YFLogxK
U2 - 10.1021/ic051516s
DO - 10.1021/ic051516s
M3 - Article
AN - SCOPUS:29544439039
VL - 44
SP - 9347
EP - 9352
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 25
ER -