Use of the monocationic fragment [Ru(η5-C5H5)(MeCN)3]+ as an ionic coupling reagent in the synthesis of mixed-metal phosphine clusters †

Abstract

Deprotonation of [Os3H2(CO)10(PPh3)], with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), and subsequent treatment with the ionic coupling reagent [Ru(η5-C5H5)(MeCN)3][PF6] afforded the tetrahedral cluster [Os3H(CO)10(PPh3){Ru(η5-C5H5)}]. Reduction of the trinuclear osmium cluster [Os3(CO)11(PPh3)] with K/Ph2CO and subsequent coupling with [Ru(η5-C5H5)(MeCN)3][PF6] yielded the pentanuclear clusters [Os3(CO)11(PPh3){Ru(η5-C5H5)}2], [Os3H2(CO)11(PPh3){Ru(η5-C5H5)}2] and the butterfly cluster [Os3H(CO)11(PPh3){Ru(η5-C5H5)}]. In an analogous reaction using [Os3(CO)11{P(OMe)3}] only one complex [Os3(CO)11{P(OMe)3}{Ru(η5-C5H5)}2] was isolated. This undergoes an orthometallation when heated under reflux in toluene to yield the novel spiked tetrahedral cluster [Os3Ru2H(CO)11{P(OMe)3}(η5-C5H5)(μ3-η5-C5H4)]. All the new complexes have been characterised spectroscopically and the molecular and crystal structures of three have been determined by single-crystal X-ray diffraction. The structure of [Os3Ru2H(CO)11{P(OMe)3}(η5-C5H5)(μ3-η5-C5H4)] shows an uncommon μ3-η5-bonding mode for the deprotonated cyclopentadiene ring.