Molybdenum dinitrogen complexes facially coordinated by linear tridentate PEP ligands (E = N or P): impact of the central E donor in trans-position to N2

Abstract

The syntheses of molybdenum dinitrogen complexes supported by the tridentate PEP ligands (E = N, P) prPP(Ph)P = (Ph₂PCH₂CH₂CH₂)₂P(Ph), prPPHP = (Ph₂PCH₂CH₂CH₂)₂PH, PN(Ph)P = (Ph₂PCH₂CH₂)₂N(Ph) and prPN(Ph)P = (Ph₂PCH₂CH₂CH₂)₂N(Ph) are reported. Together with the coligand dmpm = (CH₃)₂PCH₂P(CH₃)₂ dinitrogen complexes of the type [Mo(N₂)(PEP)(dmpm)] are formed. The new systems are characterized by IR and NMR spectroscopy and compared with the literature-known complex [Mo(N₂)(dpepp)(dmpm)] (1) (dpepp = PhP(CH₂CH₂PPh₂)₂). The consequences of the substitution of the central P-donor of dpepp by N and the replacement of its C₂ by C₃ linkages as well as the exchange of the EPh by an EH function are investigated with respect to the stability of the corresponding N₂-complexes. Importantly, the activation of the N₂ ligand drastically increases upon replacing the trans-phosphine with a trans-amine donor.