THE UNPRECEDENTED FORMATION OF MOLYBDENUM-CENTERED 1,1,4,4-TETRAKIS(PHOSPHINO)BUTA-1,3-DIENE FROM NIOBIUM-CENTERED BIS(PHOSPHINO)ACETYLENE

Photoreaction between [NbI(CO)(2)(PMe(2)Ph)(2)(Ph(2)PC=C-PPh(2))] (wit h the side-on coordinated alkyne acting as a four-electron donor) and [Mo(CO)(6)] yields the C-C coupling product o(CO)(4)}(2){mu-(Ph(2)P)(2 )C=CHCH=C-(PPh(2))(2)}], where the ligand coordinates end-on through t he four phosphine functions.