Rhenium complexes mixed metal

Scheme 10.35. A rhenium-iron mixed-metal complex with electro-switchable photoluminescence activity.

Seifert S, Syhre R, Gupta A, Spies H, Johannsen B (1999) Stability studies on 3+1 mixed-ligand technetium and rhenium complexes. In Nicolini M, Mazzi U (eds) Technetium, rhenium and other metals in chemistry and nudear medicine, vol 5. SGE Editoriali, Padova, p 687... 

The bimetalhc rhenium thiolato complex Re2(p-S2NC7H4)2(CO)e has been reacted with trimetallic group 8 carbonyl clusters M3(CO)i2 (M = Fe, Ru) and Os3(CO)io(NCMe) to give the mixed-metal clusters 49-51. Reaction of 50 (M = Os) with PPhs results in mono- and bis-substitution,... 

Catalytic and photochemical processes using mixed metal carbonyls are also represented. Tin-cobalt carbonyl compounds have been used as catalysts for ring-opening of oxiranes by secondary and tertiary alcohols 121 and the photochemical reactions of Pt2M4(CO)jg (M=Os, Ru) with cycloocta-1,5-diene under UV irradiation 122,123,124 jjgve been reported. A new rhenium-cobalt complex has been characterised 126 and Pt(cod)2 has been used to prepare new complexes via its reaction with 0 3(CO) jQ(FlCMe)2 26. 

The robustness of the rhenium(i) diimine alkynyl systems and rich photophysical behavior have rendered them suitable as metalloligands for the synthesis of mixed-metal complexes. It is well-known that organometallic alkynes exhibit rich coordination chemistry with Cu(i), Ag(i) and Au(i) [214-218], however, photophysical properties of these r-coordinated compounds are rare. Recent work by Yam and coworkers has shown that luminescent mixed-metal alkynyl complexes could be synthesized by the metalloligand approach using the rhenium(i) diimine alkynyl complexes as the z -ligand. Reaction of the rhenium(i) diimine alkynyl complex [Re(bpy)(CO)3C=CPh] with [M(MeCN)4]PF6 in THF at room temperature in an inert atmosphere afforded mixed-metal Re(i)-Cu(i) or -Ag(i) alkynyl complexes (Scheme 10.31) [89]. Their photophysical properties have also been studied. These luminescent mixed-metal complexes were found to emit from their MLCT[d7i(Re) —> 7i (N N)] manifolds with emission bands blue-shifted relative to their mononuclear precursors (Table 10.5). This has been attributed to the stabilization of the dTi(Re) orbital as a consequence of the weaker t-donating ability of the alkynyl unit upon coordination to the d metal centers. 

Exploration of the constmction of mixed-metal luminescent materials using rhenium(i) diimine alkynyl complexes in a terminal mode has also been of interest... 

Scheme 10.36. Mixed-metal branched complexes of rhenium i)-palladium(ii) - potential building blocks for heterometal lie metal lodendrimers.

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