Polynuclear complexes squares

Classical or Werner complexes have a metal in a positive oxidation state coordinated by donor ligands. The coordination number and geometry are determined by size and bonding factors, octahedral and tetrahedral being common for 3d ions, and square-planar coordination for some (ft ions. Polynuclear complexes can have bridging ligands and/or metal-metal bonding. 

The experimental data indicate quite clearly that polynuclear complexes are formed and that only small amounts of mononuclear complexes are present in the system under the experimental conditions used. The experimental data were reanalysed using least-squares methods as discussed in [1964HIE/SIL]. 

In the course of our research, which focused on the synthesis of pentachloro or pentafluorophenyl-containing Pd or Pt complexes, we developed synthetie procedures for the preparation of square-planar Pt(II) or Pd(II) anionic complexes i.e. palladate or platinate complexes) containing from one to four perhalophenyl groups per metal center. The study of the reactivity of these complexes revealed that because of their anionic nature, they have an excess of electron density around the metal center (probably located on the d orbital) and they can react with Lewis acids giving rise to neutral reaction products. When the Lewis acid is a metal complex or a metal salt, polynuclear derivatives with metal-metal bonds of a donor-acceptor nature are obtained. Most of the work presented in this account has been carried out by reacting the platinate substrates with silver derivatives, which afford polynuclear complexes containing Pt Ag bonds. Our first paper in this field ap-... 

We can see so many lanthanide clusters behave as efficient SMMs in those p -O-fixed complexes. Especially, the energy barrier record (530 K) for polynuclear lanthanide SMMs, held by the p5-0-fixed Dy5 with a square-based pyramid, has not been broken by the end of 2013. Such a structural characteristic should support the isolation of a robust SMM to a great extent, which provides a change to explore new methods for achieving SMMs with high barriers. 

Numerous d cobalt(III) complexes are known and have been studied extensively. Most of these complexes are octahedral in shape. Tetrahedral, planar and square antiprismatic complexes of cobalt(lII) are also known, but there are very few. The most common ligands are ammonia, ethylenediamine and water. Halide ions, nitro (NO2) groups, hydroxide (OH ), cyanide (CN ), and isothiocyanate (NCS ) ions also form Co(lII) complexes readily. Numerous complexes have been synthesized with several other ions and neutral molecular hgands, including carbonate, oxalate, trifluoroacetate and neutral ligands, such as pyridine, acetylacetone, ethylenediaminetetraacetic acid (EDTA), dimethylformamide, tetrahydrofuran, and trialkyl or arylphosphines. Also, several polynuclear bridging complexes of amido (NHO, imido (NH ), hydroxo (OH ), and peroxo (02 ) functional groups are known. Some typical Co(lll) complexes are tabulated below ... 

Polynuclear square planar complexes wereprepared with the bifunctional dithiophosphinate ligand [S2P(R)(CH2) P(R)S2]2- (n = 4-10).207 ... 

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