Rhenium hydride complexes structure

In contrast, spectroscopic and crystal structure analysis indicates that nucleophilic attack of hydride on 72 occurs on the face of the ligand which is coordinated to the metal (Scheme 17). No intermediate species could be detected for this latter reaction. Monitoring of the reduction of the rhenium analog 74 with sodium borohydride indicated the intermediacy of a rhenium formyl complex 75, presumably formed by attack on a coordinated carbon monoxide. Signals for 75 eventually disappear and are replaced by those of the (diene)rhenium product 76 (Scheme 18)95. 

Treatment of an ethereal solution of lithiated bis(7r-cyclopenta-dienyl)rhenium hydride, (C5H4Li)oReH, with an excess of methyl iodide yields a rather unstable yellow compound of composition CisHmRe (125). The infrared and NMR spectra indicate that the complex is (methylcyclopentadiene)(cyclopentadienyl)dimethylrhenium for which the structure (48) has been deduced by X-ray analysis (5). The methyl-... 

Evidence for rc(-l) in complex compounds appears in the synthesis of the carbonyl anion 1Tc(CO)5], the carbonyl hydride [HTc(CO)s]°, and the heteronuclcar carbonyl anion TcFe2(CO)i2] . Their existence was suggested by a comparison of their TR absorption bands with those of the corresponding compounds of manganese and rhenium, however, no structural determinations or magnetic measurements were reported. 

Hydridotris(3,5-dimethyl-l-pyrazolyl)borate]molybdenum-(i72-acyl) complexes, such as 1, are deprotonated by butyllithium or potassium hydride to generate enolate species, such as 488.8> jjie overa]] structure of these chiral complexes is similar to that of the iron and rhenium complexes discussed earlier the hydridotris(3,5-dimethyl-l-pyrazolyl)borate ligand is iso valent to the cyclopentadienyl ligand, occupying three metal coordination sites. However, several important differences must be taken into account when a detailed examination of the stereochemical outcome of deprotonation-alkylation processes is undertaken. 

---