The synthesis and characterization of technetium and rhenium hydrazinopyrimidine chelate complexes

Abstract

Organohydrazide chelate complexes of rhenium and technetium, which are defined as complexes containing a metal–nitrogen–nitrogen linkage, have been synthesized using 2-hydrazino-4-(trifluoromethyl)pyrimidine. The complexes all contain a chelating organohydrazide that forms a five-membered ring with the metal center. The chelate ring forms a delocalized π system and contributes to the unique electronic characteristics of these d 4 , octahedral complexes, which all have 1 H NMR spectra characteristic of diamagnetic complexes. An X-ray structural analysis of Tc III (NNC 4 H 2 N 2 CF 3 )(PPh 3 ) 2 Cl 2 1 was obtained. Complex 1, C 41 H 32 Cl 2 F 3 N 4 P 2 Tc, crystallizes in the triclinic space group P with a = 11.9193(3), b = 12.7026(3), c = 14.1335(3) A, α = 109.9320(10), β = 94.1250(10), γ = 105.0490(10)°, U = 1912.14(8) A 3 , Z = 2 and R = 0.0737 based on 3528 unique reflections. The complex Re III (NNC 4 H 2 N 2 CF 3 )(PPh 3 ) 2 Cl 2 2 was prepared and characterized. Both 1 and 2 contain a uninegative, chelating diazenido ligand. An X-ray structural analysis of Re III (NNC 4 H 2 N 2 CF 3 )(HNNC 4 H 2 N 2 CF 3 )(PPh 3 )Cl 2 3 was obtained. Complex 3, C 28 H 20 Cl 2 F 6 N 8 PRe, crystallizes in the monoclinic space group P2 1 /c with a = 10.1292(2), b = 14.92310(10), c = 20.6924(4) A, β = 92.4560(10)°, U = 3124.97(9) A 3 , Z = 4 and R = 0.0807 based on 4472 unique reflections. Complex 3 contains a monodentate, uninegative diazenido ligand and a chelating, α-nitrogen protonated, neutral diazene ligand.