Molybdenum complexes derived from the oxydianiline [(2-NH2C6H4)2O]: synthesis, characterization and ε-caprolactone ROP capability.

The reaction of Na2MoO4 with 2,2'-oxydianiline (2-aminophenylether), (2-NH2C6H4)2O, LH4, in DME (DME = 1,2-dimethoxyethane) in the presence of Et3N and Me3SiCl afforded either the bis(imido) molybdenum(vi) complex {Mo(L)Cl2(DME)} (), where L = (2-NC6H4)2O, or the molybdenum(v) salt [Mo(L')Cl4][Et3NH] (), where L' = [(2-NH2C6H4)(2-NC6H4)O], depending on the work-up method employed. The same diamine reacted with in situ [Mo(NtBu)2Cl2(DME)] afforded a tetra-nuclear complex [Mo4Cl3(NtBu)3(OSiMe3)(μ4-O)(L)2(L')2]·2MeCN (·2MeCN). The crystal structures of , and ·2MeCN have been determined. The structure of the bis(imido) complex contains two unique molecules paired up via weak π-stacking, whereas the structure of contains a chelating amine/imido ligand, and is made up of discrete units of two cations and two anions which are interacting via H-bonding. The tetra-nuclear structure contains four different types of distorted octahedral molybdenum centre, and a bent Me3SiO group thought to originate from the precursor synthesis. Complexes have been screened for their ability to ring open polymerize (ROP) ε-caprolactone. For and (not ), conversion rates were good (>90%) at high temperatures (100 °C) over 6-24 h, and the polymerization proceeded in a living manner.