Heterotrimetallic complexes

A related unprecedented double insertion of electron-deficient alkynes has also been reported in the reactions of the linear Pt2Pd heterotrimetallic complex 64 with 65 (RO2CCSCR) (Scheme 24) [95,96]. A series of unsymmetri-cal A-frame clusters 68 has thus been obtained in which a first insertion of the alkyne takes place site-selectively into the Pt-Pd bond vs the Pt-Pt bond (66). After a zwitter-ionic polar activation of the resulting inserted alkene (67), a subsequent reaction with the phosphine unit of the dpmp allows one to obtain the products 68 via the nucleophilic migration of the terminal P atom from the Pd center to the CH terminal carbon (formation of the P-C bond). 

Tanase, T., Inukai, FI., Onaka, T., Kato, M., Yano, S., and Lippard, S.J., Trinuclear Zn(II) and Cu(II) homo and heterotrimetallic complexes involving D-glucopyranosyl and biscarboxylate bridging ligands. A substrate binding model of Xylose isomerases, Inorg. Chem. 40 (2001) 3943-3953. 

This compound was prepared in a higher yield by using Cp 2ZrMe (OH) and Hf(NMe2)4 in a 2 1 stoichiometric ratio, yielding almost quantitatively the heterotrimetallic complex 27, as indicated by the NMR spectrum of the reaction mixture. 

A classic example of square antiprismatic geometry is solid-state Na7Zr6F3i, which features square antiprismatic ZrFg units arranged in the crystal. A noteworthy recent square antiprismatic W(V) complex is [W(bipy)(CN)5] (Figure 9.34b), used to prepare 3d-4f-5d heterotrimetallic complexes for magnetic applications. [Yb(NH3)gf is also square antiprismatic. ... 

It was speculated that the catalyhc achvity was a result of the reduction of one palladium(ll) center under the reaction conditions. This palladium center was stabilized as a mixed-valence complex, and entered the catalytic cycle via oxidative addihon of the aryl halide. It was also shown that heterotrimetallic complexes, bearing additional bridging Zn atoms, gave poor conversions and led to the formation of palladium black. A maximum TON of 490 was observed in the reaction of 4-bromoacetophenone with phenylacetylene at 0.2mol% catalyst loading in NEts at 90 °C. An important observahon here was that the addition of Cul did not improve the catalyhc activity rather, the use of this additive caused an overall decrease in the chemical yield. 

Mn-Mn 2. 6745(5)A Scheme 7.9 Synthesis of heterotrimetallic complexes with Mn-Mn bonds. 

Another heterotrimetallic complex with a gold(I) acetylide imit is Ph3PAu-C=C-NCN-Pt-C=C-Fc (91), which can be obtained by combining PhsPAu-C C-NCN-PtCl (90) with FcC CSnMcs [74k]. Complex 91 represents a rigid-rod shaped molecular wire molecule in which the transition metals Au, Pt, and Fe are spanned by acetylide, cyclopentadienyl and phenylene imits. 

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