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

Abstract

The reactions of a series of half-sandwich trihydrides of ruthenium, Cp*(R₃P)Ru(H)₃ (R₃P\n= Prⁱ₃P, Prⁱ₂MeP, PrⁱMe₂P, PhMe₂P), with a family of chlorosilanes (ClSiHMe₂, Cl₂SiHMe,\nCl₃SiH) 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\ntwo types of products, Cp*(R₃P)Ru(H)₂(SiClMe₂) (<b>1</b>) and Cp*(R₃P)Ru(H)₂(SiCl₂Me) (<b>2</b>). The\nyield of complexes <b>2</b> increases with the decrease of the size of the phosphine ligand. X-ray\nstructures of Cp*(Prⁱ₃P)Ru(H)₂(SiClMe₂) (<b>1a</b>) and Cp*(Prⁱ₂MeP)Ru(H)₂(SiClMe₂) (<b>1b</b>) are\nconsistent with the presence of interligand hypervalent interactions Ru−H···Si−Cl. The\ncompounds Cp*(R₃P)Ru(H)(Cl)(SiCl₂Me) (<b>3</b>) 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) (<b>3a</b>) reacts with excess PMe₃ to give the H−Si elimination product\nCp*(PMe₃)₂RuCl. The reactions of Cp*(R₃P)Ru(H)₃ (R₃P = Prⁱ₃P, Prⁱ₂MeP) with Cl₂SiHMe\nin the presence of NEt₃ at 90 °C give the dihydridesilyls Cp*(R₃P)Ru(H)₂(SiCl₂Me) (R₃P =\nPrⁱ₃P (<b>2a</b>), R₃P = Prⁱ₂MeP (<b>2b</b>)). X-ray structures of these products may be rationalized as\ncontaining a double interligand hypervalent interaction Ru−H₂···Si−Cl₂. NMR reaction\nbetween Cp*(MePrⁱ₂P)Ru(H)₃ and excess Cl₃SiMe at 100 °C resulted in a clean formation of\nCp*(MePrⁱ₂P)Ru(H)(Cl)(SiCl₂Me). Complexes Cp*(R₃P)Ru(Cl)(SiCl₃)(H) (<b>5</b>) were prepared by\nthe reaction of Cp*(R₃P)Ru(H)₃ with Cl₃SiH at room temperature and characterized by NMR\nand IR spectroscopy. The reactions of Cp*(R₃P)Ru(H)₃ (R₃P = Prⁱ₃P, Prⁱ₂MeP) with Cl₃SiH\nin the presence of NEt₃ at 60 °C give the dihydridesilyls Cp*(R₃P)Ru(H)₂(SiCl₂H) (R₃P =\nPrⁱ₃P (<b>6a</b>), R₃P = Prⁱ₂MeP (<b>6b</b>)) along with a mixture of some other compounds, whereas\nthe analogous reactions in the presence of NPrⁱ₂Et afford the dihydridesilyls Cp*(R₃P)Ru(H)₂(SiClH₂) (R₃P = Prⁱ₃P (<b>7a</b>), R₃P = Prⁱ₂MeP (<b>7b</b>)). Complex Cp*(Prⁱ₃P)RuH₂(SiH₃) (<b>8a</b>),\nprepared by the reduction of Cp*(Prⁱ₃P)Ru(Cl)(SiCl₃)(H) (<b>5a</b>) by LiAlH₄, reacts with [NHMe₂Ph]Cl to give a mixture of Cp*(Prⁱ₃P)Ru(H)₃ and Cp*(Prⁱ₃P)Ru(H)₂(SiClH₂) (<b>7a</b>). The crystal\nstructures of <b>1a</b>,<b>1b</b>, <b>2a</b>, <b>2c</b>, <b>5b</b>, <b>5c</b>, <b>5d</b>, and <b>8a</b> have been determined by X-ray structure\nanalysis.