Reaction of diphenyl(vinyl)phosphine with carbonyls [M3(CO)12](M = Ru or Os); oxidative addition at [Ru3(CO)12]. Spectroscopic characterization and crystal structure of [Ru3(µ-H)(CO)8(Ph2PCHCH2)(µ3-Ph2PCHCH)]

Abstract

The reaction of PPh₂(CHCH₂) with [Os₃(CO)₁₂] in aliphatic hydrocarbons gives the monosubstituted derivative [Os₃(CO)₁₁(Ph₂PCHCH₂)] in medium yield. By contrast [Ru₃(CO)₁₂] gives, as the final product, [Ru₃(µ-H)(CO)₈(Ph₂PCHCH₂)(µ₃-Ph₂PCHCH)](2) in high yield; this reaction represents an example of oxidative addition of PPh₂(CHCH₂), occurring in two steps and presumably favoured by the t.l.c. support material used during purification. These compounds have been characterized by elemental analyses and spectroscopy, in particular ¹H, ¹³C, and ³¹P n.m.r. The structure of complex (2) has also been determined by X-ray diffraction methods. It crystallizes in the orthorhombic space group P2₁2₁2₁, with Z= 4 in a unit cell of dimensions a= 15.984(6), b= 22.441(7), and c= 10.327(4)Å. The structure has been solved from diffractometer data by direct and Fourier methods and refined by full-matrix least squares to R= 0.0430 for 1 634 observed reflections. The structure consists of a scalene triangle of Ru atoms [Ru(1)–Ru(2) 2.759(3), Ru(1)–Ru(3) 3.024(3) and Ru(2)–Ru(3) 2.862(3)Å] bound to eight terminal carbonyls. The PPh₂(CHCH₂) is σ-bound to one Ru atom through the P atom, while the Ph₂PCHCH ligand interacts with all three metals, being σ-bound to two Ru atoms (through the P and C atom) and π-bound to the third Ru atom through the double bond. This latter ligand is formed by stepwise oxidative addition of PPh₂(CHCH₂) to the cluster, with hydrogen transfer to give a hydride ligand bridging the longest edge of the cluster.