ORGANOMETAL CHEMISTRY OF TECHNETIUM .11. SYNTHESIS, CHARACTERIZATION AND X-RAY STRUCTURAL-ANALYSIS OF ETRAMETHYLAZACYCLOPENTADEINYLTECHNETIUMTRICARBONYL (ME4C4N)TC(CO)3-CENTER-DOT-HNC4ME4 AND ITS MN AND RE HOMOLOGS

The heterocyclic ''half-sandwich''-compounds eta5-(Me4C4N)M(CO)3.HNC4M e4 of manganese, technetium and rhenium have been synthesized by react ion of tetramethylpyrrolyl potassium, (Me4C4N)K, with BrM(Cb)5 (M = Mn , Tc, Re) in THF. The products were isolated and characterized by IR, UV/VIS, EI-MS and H-1-NMR spectroscopy. The crystal and molecular stru cture of the three compounds were determined by single-crystal X-ray d iffraction. The technetium and rhenium compounds crystallize orthorhom bic with four molecules per elementary cell. The manganese compound cr ystallizes monoclinic with eight molecules per elementary cell, which belong to two discrete types of molecules. A tetramethylpyrrolylring i s eta5-coordinated to the M(CO)3-fragment, and a free tetramethylpyrro le is bonded to the nitrogen atom of the eta5-bonded pyrrolylring by a hydrogen-bridged bond.