Ruthenium Silyl Complexes Containing the Cp(PMe₃)₂Ru Moiety:  Preparation, Substituent Effects, and Silylene Character in the Ru−Si Bond

Abstract

The preparation and characterization of new ruthenium(II) silyl complexes containing the Cp(PM3)2Ru moiety are described. The ruthenium(II) hydride Cp(PMe3)2RuH reacts with a variety of chlorosilanes to produce the ruthenium(II) silyl complexes Cp(PMe3)2RuSiR3 [SiR3 = SiCl3 (1), SiHCl2 (2), SiH2Cl (3), SiMeCl2 (4), SiMeHCl (5), SiMe2Cl (6)] and the ruthenium(IV) dihydride [Cp(PMe3)2RuH2]Cl. Silyl complexes 1−6 undergo chloride/hydride exchange with LiAlH4 to give the corresponding ruthenium(II) hydrosilyl complexes Cp(PMe3)2RuSiHR2 [SiHR2 = SiH3 (7), SiMeH2 (8), SiMe2H (9)]. Methylation of 6 with AlMe3 produces Cp(PMe3)2RuSiMe3 (10). A method for recovering the Cp(PMe3)2Ru moiety is described. The structure of 1 was determined by X-ray crystallography. Complexes 1−10 represent the first complete set of metal silicon compounds that contain every possible combination of H, Cl, and Me groups on silicon. The effects of the substituents on the spectroscopic properties of 1−10 were examined as a function of Tolman's electronic parameter (χ i ) for the substituents on silicon. The infrared stretching frequency, ν(Si−H), and the NMR coupling constants, 2 J SiP and 1 J SiH, exhibit a linear relationship with ∑χ i , consistent with Bent's rule. However, when the NMR resonances SiR3 δ(29Si), SiH δ(1H), and SiMe δ(13C) were examined as a function of ∑χ i , the silyl groups differentiated into three classes: dichlorosilyl, monochlorosilyl, and “non-chlorosilyl”; within each class a linear but inverse relationship with ∑χ i was observed. Silylene character in the Ru−Si bond resulting from d(Ru)−σ*(Si−Cl) π-back-bonding interactions was used to explain the origin of the three silyl classes.

MOLECULAR STRUCTURE OF ORGANOSILICON COMPOUNDS WITH Si - Ru, Si - Rh and Si - Pd BONDS

“…Table 4 summarizes selected geometric parameters for compounds 59. The shortest Rh -Si bond distances of 2.229 and 2.293 A (for two independent molecules) were obtained for complex 59 [R 3 Si=(MeO) 3 Si, X=PhS] bearing electron-acceptor methoxy groups at the silicon atom. Complexes 60 (R 3 Si=Ph 2 ClSi [71], Ph 2 (PhS)Si [73,74] are characterized by facial arrangement of three Me 3 P ligands and mutually cis position of two hydrides.…”

“…?7 5 -Cyclopentadienyl (Cp) and rj 5 -pentamethylcyclopentadienyl (Cp*) derivatives 1 [3][4][5][6][7] as well as rj 6 -arene complexes 2-4 [8][9][10] adopt a three-legged piano stool geometry around ruthenium with legs composed of silyl and carbonyl or trimethylphosphine groups. The Ru -Si bond distance in trichlorosilyl complex 1 (Cp, L=Me 3 P) of 2.265 A, is consistent with a single bond.…”

“…Geometric parameters of compounds 1 are presented in Table 1. Pentamethylcyclopentadienyl compounds 5 (R 3 Si=PhMe 2 Si, L=(Pyr) 3 In compounds 8 [16] and 9 [17] the trimethylsilyl group is attached to the ruthenium atom coordinated with different ring π-systems. In complex 8 five carbon atoms of the 7-membered ring are coplanar and π-bonded to ruthenium.…”

“…The 2-amino-6-methylpyridine ligand occupies three coordination sites in complexes 38 [48] and 39 [49], being linked to one ruthenium atom through the pyridinic nitrogen and to other two Ru atoms though the exocyclic nitrogen. The coordination mode of acenaphthylene ligand to the Ru 3 moiety in cluster 40 [50] is μ 3 , η 2 : η 3 The molecular structure of the silylene-bridged ruthenium complex 43 [52] was studied by X-ray diffraction. The short Ru -Ru bond distance of 2.569 A is consistent with the presence of a Ru = Ru double 424 Brought to you by | Western University Authenticated Download Date | 6/10/15 9:14 PM bond.…”

DFT calculations of 29Si-NMR chemical shifts in Ru(ii) silyl complexes: Searching for trends and accurate values

“…Computational determination of nuclear magnetic shielding of various nuclei can contribute to better associate NMR measurements with detailed structure. Computational determination of NMR chemical shifts leads to good results for atoms like 13 C, 14 N, 29 Si, at least when these atoms are not in the vicinity of heavy atoms.…”