Lewis-like structures in transition metal bonding

6 LEWIS-LIKE STRUCTURES IN TRANSITION METAL BONDING 

The remarkable Lewis-like bonding of transition metals (see V B, pp. 365-387) is based on the primacy of sd hybridization and the associated 12-electron ( duodectet rule ) modification of Lewis structure diagrams. The idealized bond angles cDy between sd hybrid h, and sd - hybrid h, are found to satisfy an equation analogous to the Coulson orthogonality theorem (4.9) for the geometric mean hybridization parameter jx = namely, 

6 Lewis-Like Structures in Transition Metal Bonding 87 ----------f/0 4,16--------------------------------- 

As a simple illustration of transition metal hybridization and Lewis-like structures, let us consider tungsten hexahydride (WHg) as a prototype of idealized sd hybridized bonding. The input file and chosen atomic numbering for the optimized (B3LYP/LANL2DZ-level) geometry of WHs are given in FO-4.16. 

NBO analysis of WHg proceeds routinely, leading to the expected six W-H bonds (and no lone pairs) consistent with the formal Lewis-like diagram 

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