A study of the effect of ammonia gas on the solid mono- and dinuclear oxorhenium(V) complexes

Abstract

The reaction of ammonia gas with the solid oxorhenium(V) complexes [Re2 O3L2Cl4].2H2O, [Re2O2L3Cl6].2H2O, [ReOLCl(OH2)3]Cl2, [ReOL2(OH2)3]Cl3, [ReOLCl3(OH2)], [ReOL(SCN)2Cl(OH2)].H2O and [ReOL(SCN)Cl2(OH2)] (where L = 2-benzimadazolethione), yielded the corresponding ammine and/or amine complexes, [Re2O3L2(NH3)2(NH2)2]Cl2 (I), [Re2O2L3(NH3)2(NH2)4]Cl2(II), [Re2O3L2(NH3)2 (NH2)4].H2O (III), [Re2O3L4(NH2)4] (IV), [Re2O3L2(NH3)2(NH2)4] (V), [Re2O3L2 (SCN)4(NH3)2] (VI) and [Re2O3L2(Thio)2(NH2)4] (VII), respectively, (Thio = thiourea) where ammonia gas has replaced other ligands such as chlorine and water. In complex VII thiourea replaced the thiocyanate group in the start complex through its reaction with ammonia gas. The obtained ammine and/or amine of rhenium(V) complexes have been observed to decompose through several isolatable, as well as non-isolatable complex species as intermediates during heating. [Re2O3L4], [Re2O3 L2(NH2)4] and [Re2O3L2(SCN)4], were synthesized pyrolytically in the solid state from the corresponding parent oxorhenium complexes. The electronic absorption spectra and magnetic moments of the complexes show that the Re(V) cation has an octahedral configuration. IR, 1 H-NMR spectroscopy, conductivity measurements and thermal analysies show that ammonia and thiourea behave as neutral monodentate ligands, SCN- and NH2- as monodentate monoanionic ligands, the organic ligand (L) as a neutral monodentate or bidentate ligand towards the metal cation.