Heavier group 13 metal(I) heterocycles stabilized by sterically demanding diiminophosphinates : a structurally characterized monomer-dimer pair for gallium

Abstract

We have synthesized and characterized the monomeric diiminophosphinate-stabilized group 13 metal(I) complexes [DipLE:], DipL = Ph2P(NDip)2, Dip = 2,6-iPr2C6H3; E = Ga ( 1 ), In ( 2 ) and Tl ( 3 ). In addition, we structurally characterized the dimeric complex [(DipLGa)2], 12 . Similar synthetic attempts using MesL = Ph2P(NMes)2, Mes = 2,4,6-Me3C6H2 afforded product mixtures from which the mixed oxidation state species [(MesL)3Ga4I3] 4 was isolated. [DipLGa:] 1 is converted with dry air to the gallium(III) oxide species [(DipLGaO)2] 5 . Density Functional Theory studies on [DipLE:] and [(DipLE)2], E = Al-Tl, shed light on the bonding in these compounds and show that the newly formed E-E bonding interactions can be described as weak single σ-bond with no significant π-bonding contribution for E = Al, Ga. A large contribution to the dimer binding enthalpies results from London dispersion forces.