Low-Temperature-Matrix and Room-Temperature-Solution Photochemistry of Ru(CO)₃(dmpe) (dmpe = Me₂PCH₂CH₂PMe₂)

Abstract

The photochemistry of Ru(CO) 3 (dmpe) ( II; dmpe = Me 2 PCH 2 CH 2 PMe 2 ), has been studied by matrix isolation at 12 K and laser flash photolysis with UV−visible and IR detection at ambient temperature. UV photolysis in a matrix results in the formation of Ru(CO) 2 (dmpe)·S (S = matrix host), which shows two distinctive UV−visible bands with λ max dependent on S (Ar, 410, 600 nm; CH 4, 357, 500 nm; Xe, 345, 457 nm). These shifts are the largest yet observed for any matrix-solvated species. The reactions are partially reversed by long-wavelength (λ > 420 nm) photolysis. Laser flash photolysis in heptane solution (λ exc = 266 or 308 nm) with IR or UV−visible detection reveals that Ru(CO) 2 (dmpe)·heptane is a short-lived fragment which decays rapidly by reaction with Ru(CO) 3 (dmpe) ( k 2 ≈ 1 × 10 9 dm 3 mol - 1 s - 1 ). Steady-state photolysis of II in heptane in the presence of hydrogen or triethylsilane yields Ru(CO) 2 (dmpe)H 2 and Ru(CO) 2 (dmpe)(SiEt 3 )H, respectively, which have been characterized by IR and NMR spectroscopy.