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) Å, α = 109.9320(10), β = 94.1250(10), γ = 105.0490(10)°, U = 1912.14(8) Å 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) Å, β = 92.4560(10)°, U = 3124.97(9) Å 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.