Silyl, Hydrido Silylene or Alternative Bonding Modes: The Many Possible Structures of [(C5H5)(PH3)IrX]+ (X = SiHR2 and SiR3; R = H, CH3, SiH3, and Cl)

A Quasi-Atomic Analysis of Three-Center Two-Electron Zr-H-Si Interactions

A comprehensive analysis of the bonding structure of the disilyl zirconocene amide cation {Cp₂Zr[N(SiHMe₂)₂]}⁺ is conducted by application of an intrinsic orbital localization method that yields quasi-atomic orbitals (QUAOs). An emphasis is placed on describing a previously characterized three-center two-electron interaction between zirconium, hydrogen, and silicon that presents structural and spectroscopic features similar to that of agostic bonds. Expressions of the first-order density matrix in terms of the QUAOs yields bond orders (BOs), kinetic bond orders (KBOs), and the extent of transfer of charge that are useful to determine the electronic nature of the Zr-H-Si bond. The interactions between the QUAOs demonstrate the importance of vicinal interactions in the stabilization of the molecule. In addition, the evolution of the QUAOs during reactions with Lewis bases reveals the role of the Zr-H-Si interaction in facilitating the reaction.

Isolation of a hydrogen-bridged bis(silylene) tungsten complex: a snapshot of a transition state for 1,3-hydrogen migration

A hydrogen-bridged bis(silylene) complex, which can be viewed as a snapshot of a transition state for 1,3-hydrogen migration, was isolated, and its unprecedented WSi2H four-membered-ring structure with a short diagonal Si-Si distance was revealed by X-ray crystallography. NMR studies including determination of the W-Si, Si-Si, and Si-H coupling constants and theoretical calculations suggest that a novel multicenter bond is formed in the WSi2H system, in which the bridging hydrogen takes on a hydridic nature.