CONVERSION OF RECTANGULAR TETRASULFIDE LIGAND IN TETRARHODIUM COMPLEX, (RHCP*)2(MU -CH2)22(MU 4-S4)2+ (CP* = ETA 5-C5ME5), INTO DISULFIDE LIGANDS IN D IRHODIUM COMPLEX, (RHCP*)2(MU -CH2)2(MU -CH2)2(MU -S2) BY CHEMICAL REDUCTIO NE