Chelation bridging ligands

Compounds 1 and 2 are closely related to each other. Both exhibit linear chain structures in which the Cu2(hedp)2 dimers are connected by edge-shared CuOs square pyramids (Fig. la). Each hedp in the chains behaves as a bis(chelating) bridging ligand and links two copper ions in a c/s-bridging mode. This is different from the traw-bridging mode... 

First example of p(/), /) )-C104 as a bidentate bridging ligand (to Ag ) chelating /) -C104 identified in 197 4... 

Chromium, (ri6-benzene)tricarbonyl-stereochemistry nomenclature, 1,131 Chromium complexes, 3,699-948 acetylacetone complex formation, 2,386 exchange reactions, 2,380 amidines, 2,276 bridging ligands, 2,198 chelating ligands, 2,203 anionic oxo halides, 3,944 applications, 6,1014 azo dyes, 6,41 biological effects, 3,947 carbamic acid, 2,450 paddlewheel structure, 2, 451 carboxylic acids, 2,438 trinuclear, 2, 441 carcinogenicity, 3, 947 corroles, 2, 874 crystal structures, 3, 702 cyanides, 3, 703 1,4-diaza-1,3-butadiene, 2,209 1,3-diketones... 

Thiolates (RS ) represent an extensive family of ligands, and include chelating forms. Thiolates are known to act as monodentate donors, but often act in a bridging role. There is a clear biological interest, through participation of thiolates (cysteine residues) as donors in many metalloproteins both as terminal S donors and bridging ligands in, for example, Fe S clusters. 

The dithioacid family of ligands includes dithiocarbamates (R2N CS2 ), xanthates (RO-CS2 ), thioxanthates (RS CS2 ) and dithiocarboxylates (R CS2 ), which have been described in CCC(1987, Section 47.8.10).1 The ligands are prepared by addition of a suitable nucleophile to the carbon center in CS2, usually in the presence of a base. It has been established for some decades that they bind to Co almost exclusively as bidentate chelates, including S-donors acting as bridging ligands in dinuclear systems. 

The dark red Ir11 binuclear complex [Ir(CO)(P(/i-tolyl)3)(mnt)]2, formed via one-electron oxidation of [Ir(CO)(P(/ -tolyl)3(mnt)] by ferrocenium, contains chelating mnt ligands bridging the Ir—Ir bond.639 The X-ray crystal structure shows square-pyramidal geometry at each Ir, and an Ir—Ir bond length of 2.706(2) A. 

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