ISOLATION AND CHARACTERIZATION OF A MONOMERIC METALLAPYRIDINE COMPLEX- MODELS FOR PYRIDINE HYDRODENITROGENATION INTERMEDIATES

We report the preparation of a stable metallapyridine complex of tanta lum prepared in the course of model studies of hydrodenitrogenation re actions. Monomeric Ta(=NC(t)Bu=CHC(t)Bu=CH)(OAr)(2)(THF)(5 . THF) is i solated upon thermolyzing the eta(2)(N,C)-pyridine complex [eta(2)(N,C )-2,4,6-NC(5)(t)Bu(3)H(2)]Ta(OAr)(2)Me (2) in THF, while the metallapy ridine dimer [Ta(mu-NC(t)Bu=CH--C(t)Bu=CH)(OAr)(2)](2) (6) is isolated when this reaction is carried out in benzene. Complete NMR characteri zation of 5 . THF is described along with its conversion into 6.