Rhenium complexes, mixed

Schiff bases provide useful mixed donor sets. The carbonyl function of the most frequently used ligands is derived from either 1,3-dicarbonyl compounds or salicylaldehyde. Favourable combinations involve O-, N- and S-donor atoms. A range of technetium and rhenium complexes exist with bi-, tri-, tetra- and pentadentate ligands. The geometry of these complexes depends on the number and type of coordinating atoms as well as on the chain length between the donor atoms in the SchifF-base ligands. 

Another type of mixed ligand technetium or rhenium complexes in the above sense contains two or more monodentate ligands (Fig. 26b). The six-coordinated polypyridyl-thiolato complexes of rhenium(V) [ReO(terpy)(SR)2] + [186] are an example. Further representatives are a variety of mixed-ligand complexes, combining tetramethylthiourea with dimethyldithiocarbamate [TcO(tu)2-((CH3)2NCSS)]2+ [194],... 

Attempts to prepare fluoro derivatives of (102) failed and resulted in the formation of the unusual /i-pyrazolyl fi-oxo dimer [ ReO HBF(pz)2-A,A 2(/i-pz)2(M-0)] (105)." An X-ray structural analysis shows that one pyrazolyl residue of each tridentate ligand has been substituted by fluoride. With the analogous complex containing hydridotris(3,5-dimethyl-l-pyrazolylborate), however, mixed Cl/F, I/F, or OSO2CF3/F derivatives of (102) are readily formed. The different reactivity of the hydridotris(pyrazolyl)borato rhenium complexes has been attributed to the greater steric protection of the boron atom afforded by the dimethyl-substituted ligand. 

It was recently shown [435] that the mixed-valent complex compounds with N-coordinated bridge fragment can be obtained on the basis of the nitride rhenium complex as a result of the transformation (3.202) ... 

Tetrahedral [Mn(NCSe)4] and octahedral [Mn(NCSe)g] anions are known (162, 295, 6i7, 655, 656), and [Re2(NCSe)8] has been tentatively identified (377). There seem to be no reports of similar Tc compounds, nor indeed of any mixed-ligand selenocyanate complexes of either technetium or rhenium. Some mixed-ligand complexes of manganese(II) selenocyanate have been prepared, and in every case so far described the selenocyanate is N-bonded. Analogous to the thio-... 

Earlier, Herrmann et al. (1976 a, 1976 b) found that the mononuclear (pentacar-bonyl)(hydrido)manganese complex 10.74 forms a 10 1 mixture of the di- and trinuclear complexes 10.75 and 10.76 with diazomethane, if the reagents are mixed in THF at - 85 °C and the system is allowed to reach room temperature (10-34). In the same reaction with the analogous rhenium complex, only the binuclear complex... 

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... 

Other work involving complexation of ferrocenylphosphines include the preparation of silver complexes of diferrocenylphosphine a trinuclear dirhenium complex dppf as a spacer ligand between rhenium centres dppf in gold complexes palladium and platinum complexes from the carboxylation of [(dppf)MCl2], M = Pd, Pt complexes technetium and rhenium heterometallic complexes mixed silver/nickel complexes ... 

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

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