Mixed metal complexes

The red tetrathiomolybdate ion appears to be a principal participant in the biological Cu—Mo antagonism and is reactive toward other transition-metal ions to produce a wide variety of heteronuclear transition-metal sulfide complexes and clusters (13,14). For example, tetrathiomolybdate serves as a bidentate ligand for Co, forming Co(MoSTetrathiomolybdates and their mixed metal complexes are of interest as catalyst precursors for the hydrotreating of petroleum (qv) (15) and the hydroHquefaction of coal (see Coal conversion processes) (16). The intermediate forms MoOS Mo02S 2> MoO S have also been prepared (17). 

By judicious choice of reaction conditions an acyclic Ni11 complex (784) could be isolated, which serves as a valuable starting material for the preparation of unsymmetrical and mixed metal complexes by subsequent reaction with various amines. Also, a symmetrical Schiff base macrocycle of larger size has been obtained as a minor byproduct upon condensation of (784) with 1,3-diaminopropane. The resulting Ni11 complex (785) is again bimetallic, although room to bind four metal ions is in principle available.1367... 

Pt Pt bond to give A-frame complexes.108 The related mixed-metal complex [PtCl(p-dppm)2Pd(C6F5)] also reacts with R2N+, S02, and alkynes to give A-frame complexes. 

Multinuclear mixed-metal complexes can be formed with carboxylate ligands. 

Other first-generation dendrimers built around multichelating ligands are the trinuclear complexes 29 - 38 [50-52] and several hexanuclear complexes (for representative examples, see 39 and 40) [53]. In all of these compounds, the photophysical properties are equivalent to those of their building blocks. In the mixed-metal complexes 31 and 34 [50b] the Ru(II)- and Os(II)-based chromo-phores are only weakly-coupled and a dual luminescence is observed. 

This section surveys the rapid development which has occurred in the synthesis and structural analyses of mixed metal complexes in the 12 years since the publication of COMC (1995). The limited information which was available then on ate complexes has expanded into a more sophisticated understanding of how different metals gathered in a single complex influence the adopted structure and observed reactivity. 

D. Dolphin For reasons that are at present unclear both the rates of insertion, or removal, of metals within the cofacial systems are different so that mixed metal complexes can be con-viently prepared. We have, as yet, not looked at the unsymmet-rically linked systems. 

Figure 29 Crystal structure of the mixed metal complex, [RuPt(/i-HH/i-o- rj5-7,8-C2B9H-n)(CO)2(PEt3)2]. Reproduced by permission of the American Chemical Society from Organometallics 1995, 14, 3516.

Mixed Metal Complexes. In contrast to the reaction producing [Fe5C(CO)j4 ] discussed above, treatment of Fe2(CO)g with [(jr-Cp)Mo(CO)3] at room temperature in THF yields [(7r-Cp)2Mo2Fe2(CO),Q] , for which structure (17) is suggested on the basis of i.r. data. The analogous tungsten compound has also been isolated, but no hydrides were isolated upon acidification. ... 

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