Reaction of [(Rh(p-CI)(C0)2}2] with PPh2H in benzene affords, in the presence of a base and under an atmosphere of CO, a yellow crystalline product, believed to be [Rh3(p-PPh2),(CO)9] and which degrades to an orange-red species, characterised as the heptacarbonyl [Rh3(p-PPh2)3(C0)7], on recrystallisation from methanol under CO at 15 "C. The same reaction in ethanol, also under an atmosphere of CO but in the absence of a base, gave an orange-red crystalline derivative established to be [Rh3(p-PPh2)3(CO)s( PPh2H)]. All three complexes are unstable under any atmosphere but CO and are readily and reversibly decarbonylated, with loss of PPh2H as well in the case of [Rh3(p-PPh2)3(CO)6(PPh2H)], to a green crystalline species characterized as [ Rh,(p-PPh2) ,( CO) 4. The latter condenses slowly in polar solvents to afford the tetranuclear cluster [ R h 4 ( ~-P P h 2 ) 4 ( p -C 0 ) 2 ( C 0 ) 4 ] while it reacts with C12 to give the 50-electron species [Rh,(p-PPh,),(p-CI),(p-CO) (CO),]. Crystal structure determinations on [Rh3(p-PPh,),(CO)5] [monoclinic, space grcup P2,/n, a = 14.003(5), b = 17.471 (5), c = 16.523(5) A,
'*The results of the study of the reaction of these two species in -t Prt,.\t~tif addr-csv . Council for Mineral Technology, Prikate Bag X3015, Randhurg, Republic of South Africa.
