Nickel complexes homoleptic structures

The group 8 (VIII) metals comprise almost 80% of the structurally characterized homoleptic bis(dithiolene) units. Nickel complexes alone account for... 

Some homoleptic unsymmetrical (dmit/mnt, dmit/tdas) dithiolene nickel complex-based D-A compounds with D = TTF and EDT-TTF also exhibit metal-like conductivity (see Table I) (101). Their molecular structure is shown in Scheme 3. The unsymmetrical tetraalkylammonium salts [MLjLJ- (M = Ni, Pd, Pt) have been prepared by ligand exchange reaction between tetraalkylammonium salts of MLj and ML21 (128, 129) and the D-A compounds have been synthesized by electrooxidation. Among these complexes, only the Ni derivatives exhibit metallic-like properties, namely, TTF[Ni(dmit)(mnt)] (metallic down to --30 K), a-EDT-TTF[Ni(dmit)(mnt)] (metallic down to 30 K), TTF[Ni(dmit)(tdas)] (metallic down to 4.2 K), and EDT-TTF[Ni(dmit)(tdas)] (metallic down to --50 K) (see Table I). The complex ot-EDT-TTF-[Ni(dmit)(mnt)J is isostructural (130) to a-EDT-TTF[Ni(dmit)2)] [ambient pressure superconductor, Section II.B.2 (124)]. Under pressure, conductivity measurements up to 18 kbar show a monotonous decrease of the resistivity but do not reveal any superconducting transition (101). 

Reaction of [NiCPRsKti rri -1,6-diene)] (R = Me, Ph) complexes with 1,6-heptadiyne afforded 1 the bis-alkyne nickel complexes [Ni(PR3)(T 2 Ti2. 6.( . H8)], structurally characterised for R = Me. The synthesis, reaction chemistry and X-ray crystal structure of bis(tetramethylbutynediol)nickel(0), [Ni(Ti2-H0CMe2CCCMe20H)2l, which represents the first homoleptic monoalkyne complex of nickel has been reported. ... 

The orange, air-stable, homoleptic tetrakis( 71-phosphabenzene)nickel (1046) is tetrahedral (point symmetry 54) and can be obtained from phosphabenzene and [Ni(cod)2].2 25 It features a short Ni—P bond length of 2.1274(5) A with considerable N i P 7r-backbonding and a i/(Ni—P) stretch at 168 cm-1. In solution, partial dissociation of one phosphabenzene ligand is observed. 2-Diphenylphosphino-3-methylphosphinine forms with [Ni(cod)2] in the presence of the CO the dinuclear complex (1047) with a W-frame structure.2526... 

Homoleptic fourteen electron bis(carbenes) of nickel and platinum Scheme 21) have been structurally characterised the compormds are linear with both planar ring. In the nickel compound the inter planar twist is 53° while the angle is 51° for the platinum complex.231... 

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