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(Ph2PCHCH2)(µ3-Ph2PCHCH)

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)A. 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)A] 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.