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

Treatment of [Ni 2 (µ-Br) 2 (η 3 -C 3 H 5 ) 2 ] with Na 2 [nido-7,9-C 2 B 10 H 12 ] in THF (tetrahydrofuran) affords the anionic species [Ni(η 3 -C 3 H 5 )(η 6 -7,9-C 2 B 10 H 12 )] − , which was isolated as its [NEt 4 ] + salt 8 a. A similar reaction between Na 2 [nido-7,9-Me 2 -7,9-C 2 B 10 H 10 ] and [Ni 2 (μ-Br) 2 (η 3 -C 3 H 5 ) 2 ] in thf gives the anionic species [Ni(η 3 -C 3 H 5 )(η 6 -7,9-Me 2 -7,9-C 2 B 10 H 10 )] − isolated as [N(PPh 3 ) 2 ] + ( 8 b) and [NEt 4 ] + ( 8 c) salts, respectively. The molecular structure of 8 b has been established by X-ray diffraction. Crystals are monoclinic, space group P2 1 /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-Me 2 -7,9-C 2 B 10 H 10 cage in an η 6 manner, as well as by the allyl group, with the latter adopting an η 3 -bonding mode (NiC = 2.023(5), 1.939(8), and 1.988(5) Å). The palladium analog 8 d was similarly prepared from Na 2 [nido-7,9-Me 2 -7,9-C 2 B 10 H 10 ] and [Pd 2 (µ-Cl) 2 (η 3 -C 3 H 5 ) 2 ], followed by addition of [NEt 4 ]Cl*H 2 O, but in contrast with the nickel species this product was unstable, especially its solutions in air. Keywords: nickel, palladium, allyl complex, carborane.