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

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(eta (5)-C5H5)(MeCN)(3)][PF6] afforded the tetrahedral cluster [Os3H(CO)(10)(PPh3){Ru(eta (5)-C5H5)}]. Reduction of the trinuclear osmium cluster [Os-3(CO)(11)(PPh3)] with K/Ph2CO and subsequent coupling with [Ru(eta (5)-C5H5)(MeCN)(3)][PF6] yielded the pentanuclear clusters [Os-3(CO)(11)(PPh3){Ru(eta (5)-C5H5)}(2)], [Os3H2(CO)(11)(PPh3){Ru(eta (5)-C5H5)}(2)] and the butterfly cluster [Os3H(CO)(11)(PPh3){Ru(eta (5)-C5H5)}]. In an analogous reaction using [Os-3(CO)(11){P(OMe)(3)}] only one complex [Os-3(CO)(11){P(OMe)(3)}{Ru(eta (5)-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)}(eta (5)-C5H5)(mu (3)-eta (5)-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)}(eta (5)-C5H5)(mu (3)-eta (5)-C5H4)] shows an uncommon mu (3)-eta (5)-bonding mode for the deprotonated cyclopentadiene ring.