Square planar Ni complexes

Scheme 5.2-6 Synthesis of a deuterated analogue of the square-planar Ni-complex (i -4-...

The selective, Ni-catalyzed, biphasic dimerization of 1-butene to linear octenes has been studied in the author s group. A catalytic system well loiown for its ability to form linear dimers from 1-butene in conventional organic solvents - namely the square-planar Ni-complex (q-4-cycloocten-l-yl](l,l,l,5,5,5,-hexafluoro-2,4-pen-tanedionato-0,0 )nickel [(H-COD)Ni(hfacac)] [103] - was therefore used in chloroaluminate ionic liquids. 

Di-/-butyl-6-aminothiophenol gives complex (497) under strictly anaerobic conditions. In the presence of air, deep blue-violet solutions are obtained from which mixtures of solid deep blue-black cis/trans-(498) can be isolated.1345 For the square planar Ni complex, the cis-trans isomerization rate is fast. (498) is best described as a singlet diradical due to strong antiferromagnetic coupling of the benzosemiquinonate 7r-radicals.19, 134S... 

Potassium peroxomonosulfate (Oxone ) is also an effective oxidizing agent for the epoxidation of various alkenes in the presence of Mn porphyrin and a PT catalyst [79]. The biphasic epoxidation of various olefins is readily catalyzed by Co and Ni" phthalocyanines with NaClO as the oxygen donor and Bu4N" Br" as the PT agent [80]. The PTC oxidation of alkenes with NaClO is also catalyzed by square-planar Ni complexes [81-83]. 

Figure 5.2-3 2H NMR spectra of the deuterated analogue of the square planar Ni-complex (r -4-cycloocten-l-yl](l,5-diphenyl-2,4-pentanedionato-0,0 )nicl

Lu and Crabtree described a Ni-based catalytic model system that operates in the reverse direction, i.e., CO oxidation to The square-planar Ni complexes are dimeric in the... 

If nickel(II) cyanide, Ni(CN)2, is dissolved in excess potassium cyanide, the orange-red complex salt K2Ni(CN)4. HjO can be crystallised out this contains the stable square-planar [Ni(CN)4] anion. 

Ni(niox)2] Quadrupole splitting of a square-planar nickel complex, the sign of which demonstrates that the EFG of the nonbonding electrons outweighs that of the bonding electrons donated by the ligands... 

The square planar Ni11 complex (131) is formed upon reaction of MeCN with the dinuclear complex (132). A sequence of Ni-mediated hydrolytic transformations, MeCN —> acetamide and NH3 — acetamidine — TV-acetimidoylacetamidine, is proposed.488 While the A-acetimidoylacet-amidine ligands are isoelectronic with acac, they have a much stronger ligand field. 

A comparative study of the electronic structures of A,A-diethyldithiocarbamate and pyrrole-A-carbodithioate has been undertaken.961 The enthalpy of formation of [Ni(S2CNMe2)2] (—146.1 10.9 kJmol-1) has been measured.962 The square planar dithiocarbamate complexes can be oxidized to the corresponding five-coordinate Ni111 dithiocarbamate complexes [Ni(S2CNR2)2X] (X = I, Br, C104) using Br2, I2, or (N0)C104.963,964... 

Quinazoline-2-thione-4-one (522) and its 3-phenyl derivative coordinate to Ni11 after deprotonation via the S and the NI donor resulting in a square planar complex.1372 The related 2-isopropylquinoline-8-thiolate (523) forms a distorted tetrahedral complex.1 73 For deprotonated 2-thiocarbamyl-thiazoline (HL = (524)) the octahedral complex [NiL(H20)4]+ is favored over the square planar [NiL2] complex.1374... 

Square planar Ni11 complexes with saturated macrocyclic ligands usually have Ni—N bond distances ranging from 1.90 A to 1.95 A, depending on the type of ligand. The Ni—N bond distances increase when square planar Ni11 complexes bind axial ligands to form octahedral species.91... 

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