Coordination of ortho chlorines in nickel and zinc 4-substituted 2,6-dichlorophenolates. Crystal and molecular structures of (N,N,N',N'-tetramethyl-1,2-ethanediamine)bis(2,4,6-trichlorophenolato-O,Cl)nickel(II) and tris(pyridine)bis(2,4,6-trichlorophenolato-O)nickel(II)

Syntheses and Structures of Molecular Diphenolatonickel Compounds Containing Trimethylphosphane Ligands

“…The diamagnetic square-planar complexes 2 and 3 exhibit shorter NiϪO and NiϪP bond lengths. While NiϪP distances are as expected for 16-electron (trimethylphosphane)nickel complexes [11] [12] the NiϪO distances of trans-bis(trimethyl- [13] [NiϪO ϭ 2.014(4) Å ] NiϪO distances such as 1.868(3) Å for 2 and 1.861(3) Å for 3 are considerably shorter. There is no structural indication for magnetic shielding of the aromatic 6-H nucleus by a close approach to the metal atom (see NMR Spectroscopy) because the calculated distance NiϪH(7) ϭ 2.627 Å seems too large for such interaction.…”

“…As is revealed by variable temperature 1 H-and 13 C-NMR spectroscopy the complexes constitute a mixture of two isomers, each of which can be observed separately at lower temperatures when interMany low-valent metal compounds, if combined with a proton source and dioxygen, form an oxidizing system. Examples are Fentons reagent, Bartons Gif systems and the Wacker process.…”

Metal–Halogen Secondary Bonding in a 2,5‐Dichlorohydroquinonate Cobalt(II) Complex: Insight into Substrate Coordination in the Chlorohydroquinone Dioxygenase PcpA

“…These metal–halogen secondary bonds have not been observed in any hydroquinone complexes but were recently characterized in complexes with ortho ‐chloro‐ and ortho ‐bromophenolates coordinated to divalent transition‐metal ions,6b,7 including iron(II) 7j,7k. In these complexes, the ortho ‐halophenolate binds as a bidentate ligand with the halogen atom occupying a coordination site on the metal.…”

“…In these complexes, the ortho ‐halophenolate binds as a bidentate ligand with the halogen atom occupying a coordination site on the metal. The length of the metal–halogen secondary bond can vary considerably, up to the normal metal–halide bond length plus 1 Å (Wulfsberg's criterion) 6b. We recently investigated the strength of the metal–halogen interaction in the complex Tp Ph2 Co(2,6‐dcp) [2,6‐dcp = 2,6‐dichlorophenolate, Tp Ph2 = tris(3,5‐diphenylpyrazolyl)borate] by using variable‐temperature NMR spectroscopy and found that the Co–Cl secondary interaction has a strength of about 30 kJ mol –1 ,7k which is comparable to the strength of a hydrogen bond 8…”

Effect of N‐methylimidazole and 3,5‐dimethylpyrazole ligands on the polymerization of di(2,6‐dichlorophenolato) Cu(II)/Co(II) complexes in the solid state

“…Metal complexes have been observed to have a variety of structures. Copper(II)/ N ‐ligand complexes17–21 and N ‐ligand/transition‐metal/phenolate complexes,22–35 in which imidazoles and pyrazoles are used as the N ‐ligands, have been widely synthesized and characterized. Copper(II) complexes of the type L n Cu (phenolato) 2 (where L is a chelating N ‐ligand with n = 1 and a nonchelating N ‐ligand with n = 2 and phenolato is a phenolate substituted by halogens in the 2,4,6‐positions or methoxy or nitro groups in the 2‐ or 4‐positions)24–28, 31–36 are especially attractive because they are either studied as model systems for coordination in metalloproteins or decomposed to yield poly(dihalophenylene oxide)s.…”