[Cp(PMe₃)₂Ru(η²-HSiCl₃)]⁺:  Structure and Bonding of a Rare Cationic η²-Silane Complex

Abstract

Protonation of Cp(PMe3)2RuSiCl3 (1) leads to the formation of [Cp(PMe3)2Ru(η2-HSiCl3)]+ (2 + ), a rare example of a cationic η2-silane complex. The η2-silane coordination in 2 + is confirmed by an X-ray crystallographic study. The short Ru−H and long Si−H interactions in 2 + model the latter stages of hydrosilane oxidative addition to a metal center.

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

“…In the absence of any other hydride, further stabilization can only be gained by the formation of a secondary interaction between Si and Ru-Cl. Such an interaction is maximized for a Ru-Cl not orientated trans to Si-H. As discussed above, a similar situation has been observed when considering the RuH 2 [39] Compound 21 was formulated as a σ-silane species on the basis of X-ray diffraction and NMR spectroscopic data (see Figure 11). The silane ligand was characterized by a Si-H bond length of 1.77(5) Å in the typical range for σ-silane ligands.…”

Electrophilic Activation of Silicon–Hydrogen Bonds in Catalytic Hydrosilations

“…[27,28] The greater degree of Si-H activation in 34 is consistent with a structure that had previously been reported for a closely related ruthenium complex [Cp(Me3P)2Ru(η 2 -HSiCl3)] + (Scheme 40). [77] This structure's short Ru-H (dRu-H = 1.60(5) Å) and Ru-Si (dRu-Si = 2.329(1) Å) distances and elongated Si-H bond (dSi-H = 1.77(5) Å) point to significant activation of the Si-H bond. Despite the greater degree of back-donation apparent in 34 relative to many other electrophilic hydrosilation catalysts, DFT calculations showed that the ionic hydrosilation mechanism was favored in this system.…”

Structural and Spectroscopic Characterization of an Unprecedented Cationic Transition‐Metal η1‐Silane Complex

“…[2,3] There are examples of isolated neutral silane s-complexes, but cationic complexes of this type are rarely isolable presumably due to the extreme sensitivity of the electrophilic Si center to nucleophiles. [4,5] Moreover, all of the structurally characterized s-complexes are h 2 -SiH complexes, in which the silane is bound side-on with significant metal-silicon interaction (Scheme 1, B). [6,7] We report here the first example of a fully characterized cationic transition-metal h 1 -silane complex (Scheme 1, A) in which the silane is bound to a metal center in an end-on fashion with no appreciable metal-silicon interaction.…”

“…In h 2 -SiH complexes, the MSi distances remain relatively short. [4c,b, 5a] To provide insight into the structural and bonding features of the h 1 -H(Si) binding mode, DFT studies [13] were performed on the HSiMe 3 analogue of 2 (3), as well as the HSiMe 3 complex of model systems in which Me replaces all four tBu groups (4), and Me replaces two cis tBu groups distal to the hydride ligand (5). Selected metric parameters for the calculated minima are listed in Table 1 and selected minima for 3 and 4 are shown in Figure 2.…”