The bimolecular reaction of ReVOCl3(dppz), 1, (where dppz is 3,6-di(2-pyridyl) pyridazine) with excess diphosphine Ph2P(CH2)xPPh2 (x=1-4) has furnished ReIII(OPPh2 (CH2)x PPh2)Cl3 (dppz), 2 with a dangling phosphine function which is spontaneously converted in solution to ReIII(PPh2 (CH2)xP(O)Ph2)Cl3 (dppz), 3. The complex 2 (x=1) on reaction with excess 1 affords mononuclear ReIII(OPPh2 (CH2)P(O)Ph2)Cl3(dppz), 4 while for x= 2-4 binuclear complex (dppz)Cl3ReIII(OPPh2 (CH2)xPPh2O)ReIIICl3 (dppz), 5 was obtained. Rate studies of the twin isomerization (linkage-cum-geometrical) reaction 2→3 revealed that the reaction is intramolecular in nature. It is initiated by the nucleophilic attack of the metal by the dangling phosphine function. The process slows down nearly exponentially as the diphosphine spacer length x increases. The oxidized complex [ReIV(OPPh2 (CH2)PPh2)Cl3 (dppz)]ReO4, 6 does not isomerize.
Oxygen atom transfer, Twin isomerization, Pyridylpyridazine, Rhenium