Octahedral Molybdenum(0) Monodinitrogen Complexes Facially Coordinated by the Tripodal Ligand 1,1,1‐Tris(diphenylphosphanylmethyl)ethane – Influence of Diphosphane Coligands on the Activation of N₂

Abstract

Abstract The synthesis and physicochemical properties of the new molybdenum dinitrogen complexes [Mo(N 2 )(tdppme)(dmpm)] ( 2 ) and [Mo(N 2 )(tdppme)(dppm)] ( 3 ) are reported. Complexes 2 and 3 are facially coordinated by the tripodal ligand 1,1,1‐tris(diphenylphosphanylmethyl)ethane (tdppme) and contain the bidentate coligands bis(dimethylphosphanyl)methane (dmpm) and bis(diphenylphosphanyl)methane (dppm), respectively. They are accessible by amalgam reduction of the Mo III precursor [MoBr 3 (tdppme)] ( 1 ) under nitrogen in the presence of dppm and dmpm, respectively. Protonation of 2 with trifluoromethanesulfonic acid (triflic acid, HOTf) leads to the NNH 2 complex [Mo(NNH 2 )(tdppme)(dmpm)](OTf) 2 ( 4 ) with retention of the pentaphosphane coordination. The structural, electronic and vibrational properties of 2 , 3 and 4 have been investigated by NMR, IR and Raman spectroscopy coupled with DFT calculations. The crystal structure of 2 has been determined and is discussed in relation to the calculated structures of 2 and 3 . The results of the investigations are compared with those obtained earlier for the pentaphosphane complexes [Mo(N 2 )(dpepp)(dppm)] and [Mo(NNH 2 )(dpepp)(dppm)](OTf) 2 [dpepp = bis(diphenylphosphanylethyl)phenylphosphane].