Center for Magnetic Resonance

A. Miroslavov, Y. Polotskii, V. Gurzhiy, A. Ivanov, A. Lumpov, M. Tyupina, G. Sidorenko, P. Tolstoy, D. Maltsev, D. Suglobov

“Technetium and Rhenium Pentacarbonyl Complexes with C2 and C11 ω-Isocyanocarboxylic Acid Esters”

Inorg. Chem. 2014, Article ASAP

Technetium(I) and rhenium(I) pentacarbonyl complexes with ethyl 2-isocyanoacetate and methyl 11-isocyanoundecanoate, [M(CO)₅(CNCH₂COOEt)]ClO₄ (M = Tc (1) and Re (2)) and [M(CO)₅(CN(CH₂)₁₀COOMe)]ClO₄ (M = Tc (3) and Re (4)), were prepared and characterized by IR, ¹H NMR, and ¹³C{¹H} NMR spectroscopy. The crystal structures of 1 and 2 were determined using single-crystal X-ray diffraction. The kinetics of thermal decarbonylation of technetium complexes 1 and 3 in ethylene glycol was studied by IR spectroscopy. The rate constants and activation parameters of this reaction were determined and compared with those for [Tc(CO)₆]⁺. It was found that rhenium complexes 2 and 4 were stable with respect to thermal decarbonylation. Histidine challenge reaction of complexes 1 and 2 in phosphate buffer was examined by IR spectroscopy. In the presence of histidine, the rhenium pentacarbonyl isocyanide complex partially decomposes to form an unidentified yellow precipitate. Technetium analogue 1 is more stable under these conditions.