Oxidative Addition of Group 14 Hydrides to an Unsaturated Metal Cluster. Kinetics of Addition of HER₃ (ER₃ = SiEt₃, SiPh₃, GeBu₃, SnBu₃, SnPh₃) to H₂Os₃(CO)₁₀

Abstract

The kinetics and mechanism of oxidative addition of HER3 = HSiEt3, HGeBu3, HSnBu3, HSnPh3 to the unsaturated cluster H2Os3(CO)10, initially forming H3Os3(CO)10(ER3), are reported. For HSiEt3 the addition is readily reversible, with an equilibrium constant of 100 M-1 at 303 K. In each case the rate law for the forward reaction is first-order in both reagents. Rate constants (M-1 s-1) at 303 K are as follows: HSnBu3 (23) > HSnPh3 (1.5) > HGeBu3 (0.15) > HSiEt3 (3.8 × 10-3). Comparisons are made to additions of group 14 element hydrides to 16-electron Ir(I) complexes. The reaction with HSiPh3, which forms H3Os3(CO)9(SiPh3) and further addition products, was also examined.

Comparison of Steric and Electronic Requirements for C−C and C−H Bond Activation. Chelating vs Nonchelating Case

“…Theoretical calculations demonstrate that in the case of neutral rhodium-PCP systems with bulky substituents ( i Pr, t Bu), the three-coordinate reaction intermediates are stabilized by an agostic interaction with one of the C−H bonds . In the case of less bulky substituents, coordination to the aromatic ring can play a role in the stabilization of the intermediates. , An analysis of our computational results with regard to the lowest energy reactive intermediates leads to a number of important observations.…”

Reactions of Hydrosilanes with Transition Metal Complexes and Characterization of the Products

“…The former complex gave H 3 Os 3 (CO) 10 SiEt 3 (as a mixture of three isomers), and upon longer reaction times, up to three Et 3 Si groups were incorporated (see 3-161). 226 The latter complex gave both an unsaturated cluster Os 3 (µ-H) 2 (µ-SiPh 3 ){µ 3 -Ph 2 PCH 2 -PPh(C 6 H 4 )}(CO) 7 (3-162b) and a saturated cluster, Os 3 (µ-H)(µ-SiPh 3 )(CO) 9 (µ-dppm) (3-162a). 227 The PhPt in [Pt 3 Ph][(µ-PPh 2 ) 3 (PPh 3 ) 2 ] was replaced with PtSi(OSiMe 3 ) 3 on reaction with HSi(OSiMe 3 ) 3 , leaving the triangular Pt 3 unit intact and giving 3-299.…”

Synthesis of new heterometallic complexes by tin–sulfur bond cleavage of pySSnPh3 (pySH = pyridine-2-thiol) at triruthenium and triosmium centres

“…The most widely used method is the oxidative-addition of organotin hydrides and using this methodology a number of transition metal-tin clusters with intriguing structural features have been synthesized, as exemplified by the work of Adams and co-workers [15][16][17][18][19][20][21][22][23][24][25][26]. More recently other tin-element oxidative-addition reactions have been exploited, for example Gárate-Morales and Fernández-G have prepared amine-containing osmium-tin compounds via the cleavage of the nitrogen-tin bond in aminostannanes [27][28][29].…”