Complexes of nickel, and platinum

The difference in behaviour between the two olefins as ligands presumably arises from steric factors. The reaction of i-CsH5Mn(CO)3 with 

Finally, it is interesting that treatment of r-C5H5Mn(CO)3 with SbCls forms an unstable red precipitate which may contain the 17-electron cation [ r-C5H5Mn(CO)3]+ [184Z ]. 

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The chemistry of group 10 metallacyclopentanes is well established, with metalla-cyclic complexes of nickel and platinum having been extensively investigated, particularly by the groups of Grubbs74 79 and Whitesides80 82 in the 1970s. 

With the exception of a nickel -benzyne complex (13) [Eq. (5)],32,33 which is probably formed by trapping the free intermediate with the coordinatively unsaturated metal,34 all complexes of nickel and platinum have been prepared by reduction of preformed (2-haloaryl)halometal complexes, which in turn have been synthesized by oxidative addition of M(0) to o-diha-loarenes.2 35-37 Typical of this procedure is preparation of the bis(triethyl-phosphine)nickel-benzyne complexes 19 shown in Eq. (6). 

Third, n-allyl complexes are formed by palladium and cobalt analogous complexes of nickel and platinum are less stable, while ruthenium, rhodium, and iridium are not yet known to form them. In catalytic reactions the deuteration of cyclic paraffins over palladium has provided definite evidence for the existence of rr-bonded multiply unsaturated intermediates, while 7r-allylic species probably participate in the hydrogenation of 1,3-butadiene over palladium and cobalt, and of 1,2-cyclo-decadiene and 1,2-cyclononadiene over palladium. Here negative evidence is valuable platinum, for example does not form 7T-allylic complexes readily and the hydrogenation of 1,3-butadiene using platinum does not require the postulate that 7r-allylic intermediates are involved. Since both fields here are fairly well studied it is unlikely that this use of negative evidence will lead to contradiction in the light of future work. 

The triple bond in ortHo-benzyne can be stabilized by complexation with transition metals. Aryne-metal complexes were originally proposed as intermediates in the decomposition of various aryl derivatives of early transition metals, and the first fuUy characterized mononuclear ortho-benzyne complex, TaMe2(q -C5Me5) (q -CjH4), was prepared. Although this method does not appear general for all transition metals, various complexes of zirconium, rhenium, and niobium have been characterized. More recently, complexes of nickel and platinum have also been... 

P. T. Cheng, C. D. Cook, S. C. Nyburg, and K. Y. Wan, Inorg. Chem., 10, 2210 (1971). The Molecular Structures and Proton Magnetic Resonance Spectra of Ethylene Complexes of Nickel and Platinum. 

This procedure works well for tetraalkylammonium salts of nickel and platinum complexes, e.g.,... 

While apparently no metallasilsesquioxane complexes of nickel and palladium have yet been prepared, several literature reports have appeared on platinum compounds containing silsesquioxane ligands. Abbenhuis reported the synthesis and characterization of three platinum(II) complexes stabilized by the chelating diphosphine ligand dppe (= 1,2-bis(diphenylphosphino)ethane) as outlined in Scheme 63. ... 

As in the case of the reactions of the coordinated RS group, alkylation results in a weakening of the complexing ability of the ligand as evidenced by an expansion of the coordination number of the nickel ion. Similar reactions have been carried out with the complexes of palladium and platinum, and with all three metals and 2-pyridinaldoxime (POX). In the cases of palladium and platinum, one mole of coordinated ligand tends to be displaced by halide ions (Equation 48). 

In contrast to nickel, simple homoleptic Tpx or Bpx, and heteroleptic pyrazolylborate-halide complexes of palladium and platinum are largely unexplored. Indeed, while for 3d metals these are "standard" targets for each successive generation of poly(pyrazolyl)borate ligand, for the... 

Fourth, the complexes of acetylenes and diolefins react chiefly in polymerization, this tendency being most marked with the complexes of nickel and palladium. Platinum complexes are not generally active in polymerization. In the catalytic hydropolymerization of acetylene, nickel displays the greatest activity, palladium takes second place and platinum third place. The remaining noble metals are less active than platinum. Thus, again, a correlation between the two fields is observed to hold. 

E5.4 Formation of platinum and palladium clusters with carbonyl and phosphine ligands E5.5 Reactivity and flexibility in platinum metal clusters E5.6 Excited state properties of the low-valent bi- and trinuclear complexes of palladium and platinum E5.7 Interstitial nickel carbonyl clusters... 

Not only platinum forms carbene complexes by oxidative addition of 1,3-dialkylimidazolium salts. CaveU and coworkers also reported the formation of stable carbene complexes of nickel and palladium by reaction with imidazolium ionic liquids [53]. Even in cases where the imidazolium was protected with a methyl group in the 2-position of the imidazolium ring, carbene formation has been observed in the 4- or 5-position in some cases [54]. 

The synthesis of a tricarbonyl cobalt 1,3-diborolyl complex has been reported. The same ligand features in symmetrical and unsymmetrical multidecker complexes of platinum with iron, cobalt and nickel and in the first reported hexadecker sandwich complex. Thia-dlborole complexes of nickel and cobalt have also... 

Homoleptic fourteen electron bis(carbenes) of nickel and platinum Scheme 21) have been structurally characterised the compormds are linear with both planar ring. In the nickel compound the inter planar twist is 53° while the angle is 51° for the platinum complex.231... 

Mono-olefin and acetylene complexes of nickel, palladium and platinum... 

Several hydrido(phenoxo) complexes of nickel, trans-[NiH(OPh)L2] (6) (a L= P Prs b L = PCys c L = PBnj), have been prepared by the metathesis reaction of NaOPh with trans-[NiHClL2] (Eq. 6.6). The complex 6c was obtained as the phenol-solvated complex whose structure was determined by X-ray analysis [9]. An analogous platinum complex trans-[PtH(OPh)(PEt3)2] (7) was prepared by the reaction of trans-[PtH(N03)(PEt3)2] with NaOPh (Eq. 6.7). The complex 7 is air-stable but thermally sensitive and decomposes at room temperature. The structure was elucidated by X-ray analysis [10]. 

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