Hydrido-silyl-komplexe

Dérivés hydrosilylés des complexes (η-arène) tricarbonylchrome, de type (η C6R6)(CO)2Cr(H)SiHPh2; liaison à 2 électrons/3 centres, Cr—H—Si

“…Un rtsultat analogue a CtC observe pour les complexes isoelectroniques du manganese ( q C5R5)(CO)LMn(H)SiHPh2 (8).…”

“…Les complexes du manganese de type (q C5R;)L2Mn(H)-/ siR1R2R3, dCcrits dCja en 1970-197 1 (6, 7), ont CtC, depuis, l'objet d'Ctudes exhaustives (8,9). En effet, la mise en Cvidence dans ces complexes d'une liaison a 2 Clectrons/3 centres Mn-H-Si, comparable a la liaison agostique C-H-M (lo), permet de les considCrer comme des Ctats <<gelCs n des coordonnCes de la rkaction d'addition oxydante des silanes (1 1).…”

Silane(silyl) and Bis(silyl)hydrido Manganese Complexes with Different Mn···H···Si Interaction: Observation of Gradual Si–H Bond Activation on the Metal Center

“…The electronic effect is based on the relatively electron-deficient Mn(I) center of the [Mn(CO) 4 ] fragment that causes the weak ³-back donation to the silane ligand. 9 On the other hand, the steric factor is based on the steric repulsion between the xantsil(H) ligand and the [Mn(CO) 4 ] fragment. This is reflected on some interatomic distances between carbon atoms in SiMe groups and a CO ligand, i.e., C(2)£C (22) 1 in 1 to η 2 in 2 is attributable in part to the increase of electron richness of the Mn center by substitution of one CO ligand with xantheneoxygen, which leads to a stronger ³-back donation from manganese to the SiH bond.…”

“…This is reflected on some interatomic distances between carbon atoms in SiMe groups and a CO ligand, i.e., C(2)£C (22) 1 in 1 to η 2 in 2 is attributable in part to the increase of electron richness of the Mn center by substitution of one CO ligand with xantheneoxygen, which leads to a stronger ³-back donation from manganese to the SiH bond. 9 The decrease of the steric repulsion in 2 can also contribute to the stronger ³-back donation. Thus, some closest interatomic distances between carbon atoms in SiMe groups and CO ligands, i.e., C(1)£C (4) X-ray analysis shows that 3 can be best described as a bis(silyl)hydrido complex with a four-legged piano stool geometry composed of an η 6 -toluene, a CO, a hydrido, and a xantsil ligand (Figure 3).…”

Low-temperature neutron diffraction study of [ReH5(PPh i Pr2)2(SiHPh2)2] and low-temperature X-ray diffraction study of [ReH5(PCyp3)2(SiH2Ph)2]

“…As in the monosilyl hexahydride complex [ReH6(PPh3)2-(SiPh3)] (Luo, Baudry, Boydell, Charpin, Nierlich, Ephritikhine & Crabtree, 1990), the Re--Si bond lengths are somewhat shorter than the sum of the covalent radii of rhenium and silicon (2.65 A), and Luo et al suggested that this might be due to a weak interaction between the Si atom and one or more of the hydrides. Unsupported metal-hydrogen-silicon two-electron three-centre bonds typically have a Si-..H distance of 1.6 to 1.8 A (Schubert, Ackerman & Worle, 1986;Schubert, Bahr & Mfiller, 1987 …”