Reaction of metallophosphanide anions with MLnX (X = halide) species as a simple route to heterometallic transition metal complexes

The reaction of metallophosphanides with MLnX leads to the formation of mixed-metal clusters via complexes that consist of a metallophosphine coordinated through the lone pair on the phosphorus atom to another metal fragment. This synthetic strategy has been employed to initially form trinuclear complexes with the general formula [(Ph2PMLn)(OC)2Co(mu-DMAD)Mo(CO)2Cp](MLn= Mn(CO)53, WCp(CO)24, FeCp(CO)25; DMAD = dimethylacetylenedicarboxylate) from the reaction of the anion [(Ph2P)(OC)2Co(mu-DMAD)Mo(CO)2Cp]–, 2, with metal halide complexes, MLnX (X = Cl, Br). The complexes 3, 4 and 5 have been characterised spectroscopically, and an X-ray crystal structure of 5 shows that the Ph2PFe(CO)2Cp unit has coordinated to the cobalt centre through the lone pair on the phosphorus centre. Subsequent heating of 3 leads to carbonyl loss, and metal–metal bond formation, to yield [(OC)6CpCoMnMo(mu-CO)(mu-PPh2)(mu3-eta2(//)-DMAD)], 6. An X-ray structure determination of 6 confirms that it contains a closed metal triangle. In a related series of reactions the cluster anion [Os3(CO)10(mu-PPh2)]– was treated with a variety of metal-containing synthons, MLnX. With [FeCp(CO) 2Cl] the cluster [Os3(CO)10FeCp(CO)(mu-PPh2)(mu-CO)]9 was obtained in good yield, and has been shown crystallographically to consist of an osmium triangle spiked by an iron atom, with the Os–Fe bond bridged by the PPh2 group and a carbonyl ligand. With [(Ph3P)MCl](M = Ag, Au) the tetranuclear butterfly clusters [Os3 (CO)10(mu-PPh2)(mu-MPR3)](10: M = Au, R = Ph; 11: M = Ag, R = Me) are obtained. These two complexes have been characterised spectroscopically and crystallographically.