Syntheses and X-ray Diffraction Studies of Half-Sandwich Hydridosilyl Complexes of Ruthenium

Abstract

The reactions of a series of half-sandwich trihydrides of ruthenium, Cp*(R3P)Ru(H)3 (R3P = Pri3P, Pri2MeP, PriMe2P, PhMe2P), with a family of chlorosilanes (ClSiHMe2, Cl2SiHMe, Cl3SiH) have been studed with the aim of preparing the dihydridesilyl derivatives Cp*(R3P)Ru(H)2(SiR3). The reaction of Cp*(R3P)Ru(H)3 with ClSiHMe2 occurs at 90 °C and gives two types of products, Cp*(R3P)Ru(H)2(SiClMe2) (1) and Cp*(R3P)Ru(H)2(SiCl2Me) (2). The yield of complexes 2 increases with the decrease of the size of the phosphine ligand. X-ray structures of Cp*(Pri3P)Ru(H)2(SiClMe2) (1a) and Cp*(Pri2MeP)Ru(H)2(SiClMe2) (1b) are consistent with the presence of interligand hypervalent interactions Ru−H···Si−Cl. The compounds Cp*(R3P)Ru(H)(Cl)(SiCl2Me) (3) were prepared by the reaction of Cp*(R3P)Ru(H)3 with Cl2SiHMe at 60 °C and characterized by NMR and IR spectroscopy. Complex Cp*(Pri3P)Ru(Cl)(SiCl2Me)(H) (3a) reacts with excess PMe3 to give the H−Si elimination product Cp*(PMe3)2RuCl. The reactions of Cp*(R3P)Ru(H)3 (R3P = Pri3P, Pri2MeP) with Cl2SiHMe in the presence of NEt3 at 90 °C give the dihydridesilyls Cp*(R3P)Ru(H)2(SiCl2Me) (R3P = Pri3P (2a), R3P = Pri2MeP (2b)). X-ray structures of these products may be rationalized as containing a double interligand hypervalent interaction Ru−H2···Si−Cl2. NMR reaction between Cp*(MePri2P)Ru(H)3 and excess Cl3SiMe at 100 °C resulted in a clean formation of Cp*(MePri2P)Ru(H)(Cl)(SiCl2Me). Complexes Cp*(R3P)Ru(Cl)(SiCl3)(H) (5) were prepared by the reaction of Cp*(R3P)Ru(H)3 with Cl3SiH at room temperature and characterized by NMR and IR spectroscopy. The reactions of Cp*(R3P)Ru(H)3 (R3P = Pri3P, Pri2MeP) with Cl3SiH in the presence of NEt3 at 60 °C give the dihydridesilyls Cp*(R3P)Ru(H)2(SiCl2H) (R3P = Pri3P (6a), R3P = Pri2MeP (6b)) along with a mixture of some other compounds, whereas the analogous reactions in the presence of NPri2Et afford the dihydridesilyls Cp*(R3P)Ru(H)2(SiClH2) (R3P = Pri3P (7a), R3P = Pri2MeP (7b)). Complex Cp*(Pri3P)RuH2(SiH3) (8a), prepared by the reduction of Cp*(Pri3P)Ru(Cl)(SiCl3)(H) (5a) by LiAlH4, reacts with [NHMe2Ph]Cl to give a mixture of Cp*(Pri3P)Ru(H)3 and Cp*(Pri3P)Ru(H)2(SiClH2) (7a). The crystal structures of 1a,1b, 2a, 2c, 5b, 5c, 5d, and 8a have been determined by X-ray structure analysis.