Complexation chlorine bridge

In general, the dimers have three chlorine bridges, and Ru3C18(PBu3)4 resembles the mixed-valence chloro complex Ru3Cl 2. A similar, but less extensively studied, pattern of behaviour has been found with other alkyl phosphines. 

FABMS has shown that the bulky Pr PCEhCHhPPr forms the dimeric [ TcNCl2(P-P) 2]. The 3,PNMR spectrum indicates a chlorine bridged structure [57]. The reaction of MePhNNH2/dppe/[TcOCl4] in MeOH, however, yields a cationic complex formulated as the oxo-imido tra .v-[TcO(NH)(dppe)2]+. Few details are available, but the crystal structure determination showed marked asymmetry in the bonding of the two axial ligands [74]. A distinction between the [HN=Tc=OJ+ core and the tautomeric [N=Tc-OH]+ core should be possible... 

A chiral diphosphine ligand was bound to silica via carbamate links and was used for enantioselective hydrogenation.178 The activity of the neutral catalyst decreased when the loading was increased. It clearly indicates the formation of catalytically inactive chlorine-bridged dimers. At the same time, the cationic diphosphine-Rh catalysts had no tendency to interact with each other (site isolation).179 New cross-linked chiral transition-metal-complexing polymers were used for the chemo- and enantioselective epoxidation of olefins.180... 

Reaction of 3 with 1 equivalent of a phosphine results in formation of "phosphine-modified catalysts (4). The complex formed from 7r-allyl-nickel chloride, tricyclohexylphosphine, and methylaluminum dichloride (4a) has been isolated and its structure determined crystallographically (see Fig. 1) (57) The phosphine is bonded to the nickel atom, and interaction with the Lewis acid takes place via a chlorine bridge. The bridging chlorine atom is almost symmetrically bound to both the nickel... 

As yet, with regard to both ligands C(NHC)2 and C[C(NMe2)2 2. each is only represented by one transition metal complex. The two complexes are confirmed by X-ray analyses. The carbodicarbene C(NHC)2 was allowed to react with [Rh(p-Cl) (CO)2l2 to afford complex 70 in benzene solution. The carbon is able to split the chlorine bridge in the starting Rh complex and the vacant coordination site is occupied by the ligand, a very common synthetic route [10, 11]. 

Slade and Jonassen (192) treated ethyleneplatinous chloride, [Pt2Cl4-(C2H4)2], with butadiene, and obtained an unstable complex to which they ascribed the chlorine-bridged structure (XXXIV), on the evidence that its infrared spectrum showed a weak absorption at 1608 cm-1 due to the free double bond of each butadiene molecule. 

The bridging chlorine atoms in these ir-allylicpalladium complexes are readily replaced by bromine, iodine, or the thiocyanate group by treatment with the corresponding alkali metal salt in a suitable solvent such as acetone 105, 194). The chlorine bridge is split by amines for example, the ir-allyl complex [PdCl(7r-CsH6)]2, with p-toluidine, gives [PdCl(7r-C3H6) (p-tolui-dine)] as stable, pale yellow crystals (105). 

The complex is dimeric and has a chlorine-bridged structure in which each tetramethylcyclobutadiene molecule is bound to a nickel atom by its four 7r-electrons (71). The nuclear magnetic resonance spectrum of the complex... 

Only a small number of zirconium(III) and hafnium(III) complexes are known. Nearly all of these are metal trihalide adducts with simple Lewis bases, and few are well characterized. Just one zirconium(III) complex has been characterized structurally by X-ray diffraction, the chlorine-bridged dimer [ ZrCl PBu,) ]- Although a number of reduced halides and organometallic compounds are known in which zirconium or hafnium exhibits an oxidation state less than III, coordination compounds of these metals in the II, I or 0 oxidation states are unknown, except for a few rather poorly characterized Zr° and Hf° compounds, viz. [M(bipy)3], [M(phen)3] and M Zr(CN)5 (M = Zr or Hf M = K or Rb). 

Halides. Gold(III) chloride [13453-07-1] can be prepared directly from the elements at 200°C (167). It exists as the chlorine-bridged dimer, Au2Q6 in both the solid and gas phases under an atmospheric pressure of chlorine at temperatures below 254°C. Above this temperature in a chlorine atmosphere or at lower temperatures in an inert atmosphere, it decomposes first to AuCl [10294-29-8] and then to gold. The monochloride is only metastable at room temperature and slowly disproportionates to gold(0) and gold(III) chloride. The disproportionation is much more rapid in water both for AuQ and the complex chloride, [AuClJ, formed by interaction with metal chlorides in solution. 

An almost unique variation on the -peroxo coordination mode is exhibited by a rhodium dimer, [RhCl(02)(PPh3)2]2,60 which is composed of two identical subunits which have the dioxygen moiety coordinated in the -peroxo mode. These subunits are linked, not by a chlorine bridge as in other rhodium complexes such as [RhCl(CO)2]2, but via the coordinated dioxygen group as shown in (3). 

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