Halide bridges

It appears that a modified mechanism operates when tr .s-(o-tolyl)phosphine is used as the ligand,133 and this phosphine has been found to form a palladacycle. Much more stable than noncyclic Pd(0) complexes, this compound is also more reactive toward oxidative addition. As with the other mechanisms, various halide adducts or halide-bridged compounds may enter into the overall mechanism. 

Halide bridged nickel(II)/platinum(IV) and palladium(II)/platinum(IV) complexes with onedimensional linear-chain structures have been studied extensively.556-559 These are analogous to the linear-chain platinum(II)/platinum(IV) systems described in Section 6.5.13 and have similar broad and intense intervalence bands.556-559 However, they have weaker metal-metal interactions resulting in more localized valences than the all platinum analogues.556-559... 

The presence of halides in the coordination sphere with aldehydes is important as zinc halides are typically used in organic synthesis as organic carbonyl activators. Large excesses of aldehydes and anhydrous zinc halides were necessary. Both monomeric and polymeric structures with halide bridges were observed. Tetrahedral geometries were observed for mixed ligand, aldehyde, and halide complexes.353... 

Subtle changes may influence the outcome of such reactions. Thus, the formation of a binuclear, halide bridged Fe-Cd complex was observed exclusively when starting from CdBr2 whereas only trinuclear Fe-Cd-Fe chains where found in the case of CdCl2 13c, d]. 

In contrast, Fe-Hg-X complexes show little tendency to form halide bridged species and less is known about complexes containing Zn. We first reported the formation of Fe-Si-O-M four membered ring systems with soft metals M = Ag, Rh, Pd, and Pt, and then prepared bimetallic complexes with more oxophilic metals in order to better understand the conditions for the occurrence of this unusual (t-alkoxy-silyl bridging mode. We have expanded our studies on Cd-containing complexes [3b-d] to Group 13 elements and we report here about the synthesis and reactivity of new, stable heterometallic Fe-M (M =... 

As mentioned above (Section 2.1), inorganic and organic halides of TeIV are generally exhibiting halide-bridged supramolecular structures.1 3,6,7 Both Te X and X- X contacts are occurring, depending on the substitution patterns of compounds R4 TeX (n = 3, 2, 1). 

In the reaction of group 13 element halides with metal carbonyl dianions, the analysis is more complex than observed for the reactions with metal monoanions. Upon addition of metal dianions to EX3 or REX3, either one or two halide ions may be eliminated. When only one halide ion is eliminated per added metal dianion, the complexes may still be viewed as E3+ derivatives (Equations (33)-(36)).19 This may be controlled to some extent by the stoichiometry of the reaction. Comparison of Equations (33)19 and (34)19 shows that the electron demand at the main group element can be satisfied by coordination either to an electron-rich metal center 26 or formation of a halide bridge 27. Ligand-stabilized forms may also be prepared in this fashion (Equation (36)).19... 

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]. 

Fe(tmen)l2] to be tetrahedral the Fe in [Fe(dienm)Cl2] (dienm = bis(2-dimethylaminoethyl)-methylamine) is five-coordinated. Both complexes are mononuclear with no halide bridging in the solid state." " ... 

The re-allyl complexes can be isolated as halide-bridged dimers. 

Formula HfCR MW 320.30 tetrahedral and mononuclear structure in gas phase, halide bridging polymeric structure in solid phase. 

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