Comparative reactivity of triorganosilanes, HSi(OEt)3 and HSiEt3, with IrCl(CO)(PPh3)2. Formation of IrCl(H)2(CO)(PPh3)2 or Ir(H)2(SiEt3)(CO)(PPh3)2 depending on the substituents at Si

Reaction of HSi(OEt)(3) with IrCl(CO)(PPh3)(2) (5:1 molar ratio) at room temperature for 1 h gives IrCl(H){Si(OEt)(3)}(CO)(PPh3)(2) (1), which is observed by the H-1 and P-31{H-1} NMR spectra of the reaction mixture. The same reaction, but in 20:1 molar ratio at 50 degrees C for 24 h produces IrCl(H)(2)(CO)(PPh3)(2) (2) rather than the expected product Ir(H)(2){Si(OEt)(3)}(CO)(PPh3)(2) (3) that was previously reported to be formed by this reaction. Accompanying formation of Si(OEt)(4), (EtO)(3)SiOSi(OEt)(3), and (EtO)(2)HSiOSi(OEt)(3) is observed. On the other hand, trialkylhydrosilane HSiEt3 reacts with IrCl(CO)(PPh3)(2) (10:1 molar ratio) at 80 degrees C for 84 h to give Ir(H)(2)(SiEt3)(CO)(PPh3)(2) (4) in a high yield, accompanying with a release of ClSiEt3. (C) 2009 Elsevier B.V. All rights reserved.