The Nature of the Metal—Silicon Bond in [M(SiR₃)H₃(PPh₃)₃] (M = Ru, Os) And the Crystal Structure of [Os{Si(N‐pyrrolyl)₃}H₃(PPh₃)₃]

Abstract

(1: M = Ru, R = Itortion along the 0s-Si axis from an idealised tetrahedral geometry for the central OsSiP, heavy-atom skeleton. The structure can be described as two face-shared octahedra, one based on osmium (OsH,P,) Keywords ab initio calculations hydrides osmium * ruthenium silicon and the other based on silicon (SiH,N,). Studies of the bonding situation in 2a reveal that the N-pyrrolyl substituents have a marked shortening cffect on the osmium-silicon distance (229.3 (3) pm) and that each of the three hydride ligands participates in partial three-centre bonding involving osmium, silicon and hydrogen.'H, I 3 C , 2ySi and 31P N M R spectra were used to determine the solution structures of complexes 1 and 2a.

σ‐Silane Ruthenium Complexes: The Crucial Role of Secondary Interactions

“…Hübler et al proposed a bonding scheme that allows a facile rotation when considering the contribution represented in Figure 7 (b) to be preponderant. [23] On the contrary, Nikonov pleads an electron-density transfer from the σ(M-H) bonding orbitals into the σ‫(ء‬Si-N) antibonding orbitals to be the main contribution, thus leading to a rigid structure ( Figure 6 and Figure 7, a). [26] However, Nikonov uses a DFT study reported by Hübler et al to support his argumentation, but this was actually a MP2 study of an osmium analogue, which is certainly not transposable to the ruthenium case.…”

A DFT Study of SiH4 Activation by Cp2LnH

“…6 The key to the low-energy barriers for the two reactions is the ability of Si to stabilize pentacoordination with an overall negative charge. Such a bonding situation has been found in the solid-state structures of several systems, [47][48][49][50][51][52][53][54][55][56] which suggests that it can also correspond to a low transition state in the appropriate case. The stabilization of the transition state is more important when the hypervalent Si species is more stable.…”

Similarities and Contrasts between Silyl and Stannyl Derivatives of Ruthenium and Osmium

“…This effect is also evident from the theoretical calculations. 16 In the crystal structure of 22 the hydrides are located and the measured Os-H distances are 1.52(3), 1.66(3), and 1.57(3) Å. The calculated distances between silicon and hydrogen are Si‚‚‚H(1) ) 2.06(4) Å, Si‚‚ ‚H(2) ) 2.00(4) Å, and Si‚‚‚H (3) …”