Conformation analysis of triphenylphosphine in trans and cis triphenylphosphine-substituted Fischer carbene complexes

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Authors

Landman, Marile
Levell, Tamzyn J.
Van Rooyen, Petrus H.
Conradie, Jeanet

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Elsevier

Abstract

The synthesis and selected crystal structures of novel (M = Cr or Mo) and known (M =W) [(CO)4(PPh3) M = C(OEt)R] complexes, M = Cr, R = 2-thienyl (1), 2-furyl (2); M = Mo, R = 2-thienyl (3), 2-furyl (4); M = W, R = 2-thienyl (5), 2-furyl (6), are presented. Experimental crystal structures and DFT calculations of selected trans- and cis-triphenylphosphine-substituted Fischer carbene complexes, illustrate that the minimum energy conformation of triphenylphosphine (PPh3) in octahedral [(CO)4(PPh3)ML]-complexes generally have distinct features that can be described in terms of the ‘‘plane of nadir energy’’, a plane linking all points of minimum steric compression between the ligands. The generally observed orientation of PPh3 involves a correlated feathering of the phenyl groups with the PACipso bond of one phenyl group orientated near parallel to the nadir plane, and a meta carbon (Cm) of the other two phenyl groups orientated as near as possible to the nadir plane, orthogonal to the first. Although the orientation of PPh3 in 6-trans, [(CO)4(PPh3)W = C(OEt)2-furyl], deviates from this, DFT correctly calculated the unexpected and not generally observed PPh3 orientation.

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Keywords

Fischer carbene, Phosphine, Conformational analysis, Density functional theory (DFT)

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Citation

Landman, M, Levell, T, Van Rooyen, PH & Conradie, J 2014, 'Conformation analysis of triphenylphosphine in trans and cis triphenylphosphine-substituted Fischer carbene complexes', Journal of Molecular Structure, vol. 1065-1066, no. 1, pp. 29-38.