Manganese complexes with tripodal

In the titanosilicate system, cyclic voltametric measurements had indicated (Section III.D) that the electron density at the tripodal sites is higher than at the tetrapodal sites. Hence, by analogy with the chromium and manganese complexes, we may expect the tripodal sites to favor hydrogen abstraction and allylic CH oxidation, although electron transfer and epoxidation occur preferentially on the tetrapodal sites. 

To examine the chemical behavior of these new ligands 48-50 in coordination chemistry, tricarbonyl complexes with manganese and rhenium were synthesized from [MnBr(CO)s] and [ReBrCCOls] as described earlier for the other heteroscorpionate ligands (Scheme 28). The purpose of these tricarbonyl complexes was to verify tripodal binding of the solid-bound ligand. The protected OH linker in 50 acts as model for the solid phase bound ligand. 

Treatment of 5-thioxo-4,5-dihydro-3,4-dimethyl-l,2,4-triazole with sodium tetrahydroborate at 210 °C provides the new N3S3-donor tripod ligand Tt as its sodium complex salt [Na(H20)6] [Na(Tt)2]. Bailey also describes some Tt bismuth(III), tin(IV) and manganese complexes, which illustrated the flexible Tt offering a combination of the properties ot the Tp and Tm ligands.163... 

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