Dimeric chloride bridges

In contrast to the lithium acetylide reaction, addition of copper(I) phenylacetylide to (i75-C5H5)(PPh3)2RuCl (1) affords the monomeric ruthenium acetylide-copper chloride adduct (62) as the major product. An X-ray crystal structure of this complex reveals an tj1, -bridging acetylide between the ruthenium and copper centers, respectively (62). A small amount of the dimeric chloride bridged complex 61 was also isolated. The copper chloride can be removed from the monomeric complex by the... 

When a deficit of the lithium alkylamide is used, dimeric chloride-bridged silylamides are obtained which are useful synthetic intermediates (Figure 4.10). 

When a deficit of the lithium alkylamide is used, dimeric chloride-bridged silylamides are obtained which are useful synthetic intermediates (Figure 27) they can also be prepared by redistribution reactions between LnCb and [Ln(N(SiMc3)2)3 some bromo- and iodo- analogues have been reported. 

The dichloride 8.21a forms fragile, lamellar crystals with a golden colour. The X-ray structure reveals a layered arrangement of hexameric units formed by linking three ( BuNTeCl2)2 dimers by chloride bridges. The reaction of 8.21a with potassium tert-butoxide yields... 

Ph3TeCl is a chloride-bridged dimer with 5-coordinate square-pyramidal Te (Fig. 16.13c). 

The a,a,a,a-tetraaryl-l,3-dioxolane-4,5-dimethanol (TADDOL) chiral ligands have also been the basis of enantioselective catalysis of the D-A reaction. In a study using 2-methoxy-6-methylquinone as the dienophile, evidence was found that the chloride-ligated form of the catalysts was more active than the dimeric oxy-bridged form.117... 

Scheme 3 shows the details of the synthetic strategy adopted for the preparation of heteroleptic cis- and trans-complexes. Reaction of dichloro(p-cymene)ruthenium(II) dimer in ethanol solution at reflux temperature with 4,4,-dicarboxy-2.2 -bipyridine (L) resulted the pure mononuclear complex [Ru(cymene)ClL]Cl. In this step, the coordination of substituted bipyridine ligand to the ruthenium center takes place with cleavage of the doubly chloride-bridged structure of the dimeric starting material. The presence of three pyridine proton environments in the NMR spectrum is consistent with the symmetry seen in the solid-state crystal structure (Figure 24). 

ZrC. CCliCN and ZrCl4.,CH2ClCN have been prepared from ZrCl and the corresponding chlorinated nitrile the former has been shown to be iso-morphous with TiCl4,CCl3CN, and is thus a chloride-bridged dimer, with each Zr"" octahedrally co-ordinated. ... 

Recently similar complexes of neodymium have been prepared by Karraker 48) containing bromide and iodide in place of chloride. While their chemical properties are similar to the dimeric chloride compound their powder patterns suggest they may have different structures. Since they also have increasing amounts of solvent, the bromide containing three THF molecules and the iodide four, these may be complexes in which the halide bridge is broken by addition of another solvent molecule to give a monomer such as [Ln(COT)X 3 THF]. 

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