STERICALLY-INDUCED REARRANGEMENTS OF THE TRIPODAL LIGAND HB(PRIMEC3N2H)3 IN SOME MOLYBDENUM MONONITROSYL DERIVATIVES

The new complexes [Mo(NO){HB(PriMeC3N2H)3}XY] (X = Y = CO, I, OMe, OEt; X = I and Y = OMe, OEt, OPri, OBut, OCH2SiMe3, OPh, OC6H4-4-Me, NHPh or NHC6H4-4-Me) have been synthesized. In the cases where X = I, or where X = Y = CO or I, these compounds were isolated as a mixture of at least two isomers. However, 1H NMR studies show that the complexes with X = I and Y = OPri, OBut, NHPh, NHC6H4- 4-Me undergo rearrangement reactions at elevated temperature to give selectively a single isomer. These reactions involve 1,2-boratropic shifts of the substituted pyrazolyl moieties and appear to be promoted by the more bulky of the co-ligands X and Y. © 1990.