Synthesis and crystal structure of the allyl(carborane)nickel complex [N(PPh3)2][Ni(η3-C3H5)(η6-7,9-Me2-7,9-C2B10H10)

Abstract

Treatment of [Ni2(µ-Br)2(η3-C3H5)2] with Na2[nido-7,9-C2B10H12] in THF (tetrahydrofuran) affords the anionic species [Ni(η3-C3H5)(η6-7,9-C2B10H12)]−, which was isolated as its [NEt4]+ salt 8a. A similar reaction between Na2[nido-7,9-Me2-7,9-C2B10H10] and [Ni2(μ-Br)2(η3-C3H5)2] in thf gives the anionic species [Ni(η3-C3H5)(η6-7,9-Me2-7,9-C2B10H10)]− isolated as [N(PPh3)2]+ (8b) and [NEt4]+ (8c) salts, respectively. The molecular structure of 8b has been established by X-ray diffraction. Crystals are monoclinic, space group P21/c (No. 14) with a = 14.685(3) Å, b = 18.346(2) Å, c = 16.319(1) Å, β = 99.93(1)°, and Z = 4. The nickel atom is ligated by the nido-7,9-Me2-7,9-C2B10H10 cage in an η6 manner, as well as by the allyl group, with the latter adopting an η3-bonding mode (Ni—C = 2.023(5), 1.939(8), and 1.988(5) Å). The palladium analog 8d was similarly prepared from Na2[nido-7,9-Me2-7,9-C2B10H10] and [Pd2(µ-Cl)2(η3-C3H5)2], followed by addition of [NEt4]Cl•H2O, but in contrast with the nickel species this product was unstable, especially its solutions in air. Keywords: nickel, palladium, allyl complex, carborane.