P4 Activation at Ni0: Selective Formation of an NHC-Stabilized, Dinuclear Nickel Complex [Ni2(iPr2Im)4(μ,η2:2-P2)]



The reaction of [Ni2(iPr2Im)4(cod)] (1) with white phosphorus led to dinuclear [{Ni(iPr2Im)2}2(μ,η2:2-P2)] (2) in excellent yield. This reaction represents the first example of a conversion of white phosphorus into a complex of the type [{L2Ni}2(μ,η2:2-P2)] and the first example of the formation of a complex of the type [{L2M}2(μ,η2:2-P2)] for a group-10 metal stabilized by two simple, nonchelating, two-electron donor ligands by the reaction of a suitable precursor with P4. The X-ray structure of 2 revealed a bent Ni2P2 core with an Ni–P–P–Ni dihedral angle in the solid state of 102.95°. According to DFT calculations on the symmetrized model systems planar-D2h- and bent-C2v-[{Ni(iPr2Im)2}2(μ,η2:2-P2)], this deviation of the Ni2P2 core from planarity is caused by a second-order Jahn–Teller distortion. Calculations on the related platinum compound [{Pt(iPr2Im)2}2(μ,η2:2-P2)] confirmed this type of bent structure for the higher congener with an even higher barrier to planarization than that calculated for the nickel complex. Energy decomposition analysis and fragment molecular orbital analysis further illustrate the bonding mechanisms in these complexes.