Structure of W(CH3)6

Abstract

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Valence Bond Concepts Applied to the Molecular Mechanics Description of Molecular Shapes. 3. Applications to Transition Metal Alkyls and Hydrides

“…We previously have reported the structure calculated by our method of one sd 5 hybridized complex, W(Me) 6 . The distorted trigonal prismatic geometry that was predicted for this complex is virtually identical to that found by Pfenning and Seppelt in the crystal structure.…”

“…Previous MM approaches to transition metals have relied on (1) identification of an idealized, predetermined shape, − (2) steric repulsion between ligands, − or (3) the incorporation of ligand-field perturtabations of d-electron energies . We have shown that valence bond concepts, such as hybridization and resonance, may be developed into robust MM algorithms for normal and hypervalent main group compounds. , Qualitatively, we have demonstrated that the concepts of hybridization and resonance lead to unique insights into the factors controlling the shapes of transition metal alkyl and hydride complexes. − This paper discusses the application of the Hypervalent-VALBOND (HV-VB) MM method to computing the shapes of transition metal hydride and alkyl complexes.…”

Structure and Electron Counting in Ternary Transition Metal Hydrides

“…Valence Bond Concepts. Previously we have shown that the geometries of transition metal hydride and alkyl complexes can be considered the outcome of hybridization of the valence s and d metal atomic orbitals to give sd n metal hybrid orbitals. ,,, The shapes of these metal hybrid orbitals control the shapes of the transition metal complexes (in the absence of steric effects). The idealized arrangements of metal hybrid orbitals are summarized in Figure .…”

A Valence Bond Perspective on the Molecular Shapes of Simple Metal Alkyls and Hydrides

“…Further support of the hybridization model has come from experimental 53 and computational 25 analyses of 12-electron W(CH 3 ) 6 and the crystal structure of the isoelectronic [ZrMe 6 ]. − These structures are minor distortions of the least congested C 3 v geometry, a , obtained from hybridization considerations. The preference for this geometry is rationalized readily as the result of minimization of intermethyl steric effects.…”

“…In this paper we describe the general methods of a revised qualitative VB theory of molecular shapes. This work has been stimulated by the recent observation of transition metal alkyls (e.g., W(CH 3 ) 6 − ) and hydrides (e.g., WH 6 ,, ) which computation and experiment show to adopt complex, non-VSEPR structures. We show that the concepts of hybridization and resonance form the basis of a general method for understanding the shapes of molecules throughout the periodic table.…”