Elucidation of the bonding in Mn(η²-SiH) complexes by charge density analysis and T₁NMR measurements: asymmetric oxidative addition and anomeric effects at silicon

Abstract

The bonding in Mn(eta2-SiH) complexes is interpreted in terms of an asymmetric oxidative addition whose extent is controlled by the substitution pattern at the hypercoordinate silicon centre, and especially by the ligand trans to the eta2-coordinating SiH moiety.

Conciliatory Inductive Model Explaining the Origin of Changes in the η2-SiH Bond Length Caused by Presence of Strongly Electronegative Atoms X (X = F, Cl) in Cp(OC)2Mn[η2-H(SiH3–nXn)] (n= 0–3) Complexes

“…the η 2 -SiH bond shortening, must be considered as normal. Therefore, there is no need to invoke the hypervalent properties of Si 12,15 when trying to explain the η 2 -SiH bond shortening if halogen is present at position either 1 or 2 in the -SiR 3 group of Cp(OC) 2 Mn[η 2 -H(SiR 3 )]. Instead, it is simply a result of the inductive influence of halogen atoms as clearly shown in this article.…”

“…Therefore, from this point of view, the trans position at -SiR 3 is unique in Cp(OC) 2 Mn[η 2 -H(SiH 3−n X n )] and similar complexes. 2 We have very recently shown 18 that, contrary to the well-known elongation of the η 2 -SiH bond caused by the presence of a halogen atom being trans to this bond, [15][16][17][18] halogens at other positions lead, instead, to the shortening of this bond. Thus, we have shown that the length of the η 2 -SiH bond in Cp(OC) 2 Mn[η 2 -H(SiH 3−n X n )] results from two opposite effects, i.e.…”

“…8). This peculiarity is due to the fact that the electronegative atom (or subsitutent) in the trans position to the η 2 -SiH bond particularly activates this bond [15][16][17][18] making it specifically long. Therefore, from this point of view, the trans position at -SiR 3 is unique in Cp(OC) 2 Mn[η 2 -H(SiH 3−n X n )] and similar complexes.…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] This, at least partly, results from the fact that the Mn· · · (η 2 -SiH) unit can present various binding motifs, from the one where the hydrogen atom belonging to the HSiR 3 moiety is still strongly bonded to silicon to the situation corresponding to considerable separation of H and Si atoms, i.e., to a fully oxidatively added silane. Moreover, the intermediate stages, as the saying goes "at the arrested degree of oxidative addition", are not uncommon at all.…”

The UV‐Light Initiated Reaction of Organosilanes with Tungsten Hexacarbonyl: Formation of an Organosilylene Complex and Organosilylium Salts

“…Associated with this is the desire to get more insight into the mechanism of Si-H bond activation by transition metal compounds [20][21][22][23][24][25][26][27][28][29] which in turn is relevant even for the topic of C-H bond activation [30] as well as for the understanding of transition metal-catalyzed oligo-and polysilane formation [31].…”