Complex heteronuclear

Carriedo, G.A., Riera, V., Sanchez, G. and Solans, X. (1988) Synthesis of new heteronuclear complexes with bridging... 

Run/Nin heteronuclear complexes such as (653), in which a photosensitizer [Ru(bpy)3]2+ or [Ru(phen)3]2+ is covalently attached to the Ni1 cyclam complex, have been synthesized in order to improve the efficiency of electron transfer from the photoexcited photosensitizer to the catalytic site.1 44-1646 However, these complexes did not perform particularly well, either due to unfavorable configuration of the Nin-cyclam subunit and the resulting steric hindrance or due to short lifetime of the excited states of the Ru photosensitizer moieties. A stable catalytic system has been prepared by immobilizing macrocyclic Ni11 complexes and [Ru(bipy)3]2+ in a nafion membrane.164... 

The hexakis(methyl isocyanide) dimers, [Pt2(CNMe)6], undergo photolytic cleavage of the Pt—Pt bond to give 15-electron radicals, Pt(CNMe)3.94 Mixtures of platinum and palladium dimers give rise to heteronuclear complexes under photolytic conditions. Mixtures of normal and deuterium-labeled methyl isocyanide complexes reveal that the metal-ligand bonds undergo thermal redistribution.94... 

Other heteronuclear complexes are those of the bis(diphenylphosphino)methanide and the group 6 metals, [M(C04) (PPh2)2CHAu(PPh3) ] (M = Cr, Mo, W).2641... 

The reaction of [LnM-SiR3]" with transition metal halides or halogeno complexes L mM Xx gives silyl-substituted heteronuclear complexes [Ln(R3Si)M]xM L m [2,5,18]. Stable complexes are usually only obtained if the metal complex fragment M L m is not too sterically demanding and if the resulting M-M bond is not too polar. A few examples are shown in Scheme 3. 

Deliberate and stepwise increase of the nuclearity of polynuclear complexes is possible by condensation reactions between silyl-substituted heteronuclear complexes [Ln(R3Si)M]xM L m and metal halides. Two such examples are shown in Scheme 3 (reaction of MeCp(CO)2(MePh2Si)Mn-HgPh with PhHgCl, and reaction of [MeCp(CO)2(MePh2Si)Mn]2Hg with HgBr2) [18]. 

Heteronuclear species may also be prepared - the nmr studies indicate that a heteronuclear Ag(i)/Pb(n) species is produced in solution when a 1 1 mixture of the respective dinuclear Ag(i) and Pb(n) complexes is dissolved. However, the reaction is not quantitative and the heteronuclear complex exists in equilibrium with both of its homonuclear precursors. 

This field has developed at a rapid pace since 1968, and a wide range of heteronuclear complexes of the tri- and tetranuclear variety has been established. It will be convenient to discuss the compounds in the first instance on the basis of nuclearity and, for the tetranuclear species, to subdivide the discussion on the basis of the carbonyl stoichiometry and cluster electron count. We have excluded from the discussion the interaction with nontransition elements, such as Hg, Tl, and Cd, which form a wide range of compounds. 

Even the basic properties of mixed metal or heteronuclear complexes and mixed valence metal complexes have not been studied, so that their catalytic effects are far from dearly understood. 

In contrast to the unsuccessful early attempts to produce [W2(02CR)4], the heteronuclear compound [MoW(02CCMe3)4] was obtained by reacting a 3 1 mixture of W(CO)6 and vlo(CO)6 in refluxing dichlorobenzene.334 The heteronuclear complex was freed from Mo2(02CCMe3)4] by careful oxidation with I2. Structure analysis of MoW(02CCMe3)4]I-MeCN shows the expected idealized Dih symmetry with a short W—Mo separation of 2.194 A. The iodide ion is coordinated to the W atom and the MeCN molecule is coordinated to the molybdenum atom. 

Recently, heteronuclear complexes containing cir-Pt(NH3)2+, Ag(I) and either 1-methylthymine97 or 1-methyluradl98 have been isolated. These studies were initiated due to the interest in the binding of platinum(II) antitumour agents to DNA. 

The larger-ringed macrocycles of (53a-d) form binuclear complexes with alkali metal, alkaline earth, silver(I) and lead(II) cations.68,192 The two 18-membered rings are large enough to allow for cations as large as Rb+ to be incorporated within their cavity, with a net result of increasing the metal-metal separation. Thus, crystal structure data for the disodium complex of (53a) indicate the sodium ions to be 6.40 A apart,193,194 compared to a 3.88 A separation found for the aforementioned disilver complex of (52a). Heteronuclear complex formation has also been observed, e.g. with both Ag+ and Pb2+ incorporated in the same cryptand.192... 

The most common strategy in the synthesis of heteronuclear complexes is the use of bidentate donor ligands bearing different donor centers. In that way both donor atoms can be coordinated selectively to two different metal centers in a consecutive way. If the space between the donor atoms of the ligands is short, interactions between both metals usually appear, normally intramolecular. Sometimes, albeit not very often, the bidentate units bind to one another, leading to extended structures through metallophilic interactions. As we have commented, in the case of gold-silver derivatives the number of luminescent studies of these derivatives is very scarce. 

Among heteronuclear complexes, the binuclear compound 88 with the moiety Fe — C = N—Cu is interesting as a biomimetic model of cytochrome C-oxidaze [121] ... 

Use of coordinated azole and azine system containing donor-active nitrogen atoms as metal ligands open wide possibilities for obtaining homo- and heteronuclear complexes. Thus, such reactions are known where the complexes of coordinatively unsaturated pyrazole (3.221) [490] and triazole (3.222) [491] take part ... 

In relation to the discussed syntheses, we emphasize the systematic study of the kinetics of metal dissolution [202,657-659]. Also, the oxidation of Cu—Zn alloy was studied [658], which opens a route to simple preparation of heteronuclear complexes. 

The ammonia syntheses of heteronuclear complexes with use of elemental copper, lead halides, and aminoalcohols (3.273) [679-681] are significant, since... 

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