ORTHOMETALLATION REACTION IN DIRHODIUM(II) COMPOUNDS - SELECTIVE FORMATION OF DOUBLY-METALATED COMPOUNDS WITH HEAD-TO-HEAD STRUCTURE

The reaction of the mono-metallated compound Rh2(O2CCH3)3[(C6H4)P(CH3) (C6H5)].2(HO2CCH3) With PPh3 (1:1 molar ratio) has been studied by P- 31 NMR spectroscopy. The reaction yields the doubly-metallated compoun d Rh2(O2CCH3)2[(C6H4) P(CH3)(C6H5)][(C6H4)P(C6H5)2].2(HO2CCH3) with a head-to-head (H-H) configuration. An intermediate reaction compound, n ot previously observed, has been spectroscopically detected in solutio n. Analogous intermediate compounds have been detected using P(p-CH3C6 H4)3 and P(p-ClC6H4)3 instead of triphenylphosphine.