Mixed-ligand complexes square-planar structures

Mixed N,S,0 donor sets are useful to compare the coordination ability and the structural consequences of various donor sets and to induce a variety of structural properties. The solid-state structures of [Ni(pyzs)]BF4, [Ni(pyrs)]BF4 and [Ni(pyzo)]BF4 containing dissymetric tetradentate ligands with N2S2 (543) and N2SO (544) donor sets are square planar.1397 The phenolate-based complexes are essentially planar in nitromethane, but distorted octahedral in methanol, while thiophenolate-containing complexes remain square planar in both solvents. 

The tris(2-cyanoethyl)phosphine can act either as a monodentate phosphorus donor ligand or as a bidentate mixed donor ligand. The red square planar [NiX2L<2] complexes (X = Cl, Br) transform in the solid state into blue six-coordinate isomers which have a polymeric structure involving bridging bidentate ligands (Scheme (2).1178,1184,1192... 

The macrocyclic phthalocyanine ligand will form a complex Pt(phthalocyanine).1106 The crystal structure shows two polymorphs present because of molecular packing.1107 The platinum is in a square planar coordination geometry with a mean Pt—N distance of 1.98 A. The complex can be partially oxidized with iodine to give conducting mixed valence solids.1108 Eighteen fundamental and overtone combination bands are observed in the resonance Raman spectrum of platinum phthalocyanine, and from this data the symmetry of the excited singlets are found to be Dy.. Qlv or D2.1109... 

Mixed dithiocarbamato-dithiolene complexes show a number of interesting phenomena. For Au111 complexes containing JV,lV-di-n-butyl-dtc and mnt ligands, both the salt (dtc)2Au+ Au(mnt)f (27) and the neutral, square planar (dtc)Au(mnt) complex (28) have been isolated and structurally characterized.43... 

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