REACTIONS OF DIRHODIUM(II) MONOMETALATED COMPOUNDS WITH PHOSPHINES - FACTORS AFFECTING THE REACTIVITY AND THE STRUCTURE OF THE DOUBLY-METALATED COMPOUNDS - MOLECULAR-STRUCTURE OF RH2(O2CCH3)2[(C6H4)P(C6H5)2][(P-CLC6H3)P(P-CLC6H4)2]BULLET(HO2CCH3)2-BULLET-1/2(C6H6), A COMPOUND WITH 2 DIFFERENT METALATED PHOSPHINES

Monometallated compounds of formula Rh2(O2CCH3)3[(p-XC6H3)P(p-XC6H4)2](HO2CCH3)2 (X = CH3, Cl) have been prepared in good yield. The reactions with p-substituted triarylphosphines P(p-X'C6H4)3 (X' = CH3, H, Cl) have been studied. For X = X' and [P]/[Rh2] = 1 all the resulting doubly metallated compounds Rh2(O2CCH3)2[(p-XC6H3)P(p-XC6H4)2](HO2CCH3)2 (X = CH3, Cl) have head-to-tail (H-T) structure. For [P]/[Rh2] = 3 reaction progress is observed at room temperature. When X = X' a 1:1 mixture of H-T and H-H compounds is formed for X = Cl but only the H-H compound is obtained for X = CH3. For X not-equal X' mixtures of H-T and H-H compounds are obtained. The entering phosphine, and to a less extent the phosphine in the monometallated compound, seems to influence the rate of the process and the product distribution. The crystal structure of Rh2(O2CCH3)2[(C6H4)P(C6H5)][(p-ClC6H3)P(p-ClC6H4)2](HO2CCH3)2.1/2(C6H6) a doubly metallated compound with two different metallated phosphines in a head-to-tail configuration, is also described.