Niobium(I) and tantalum(I) tetracarbonyl derivatives containing nitrogen ligands

Abstract

Diamino derivatives of niobium(l) and tantalum(l) of general formula MX(CO) 4(NN), M=Nb, Ta; X=Cl, 1; NN=ethylendiamine (en), N, N′dimethylethylendiamine (dmen), N, N, N′, N′-tetramethylethylendiamine (tmen), 2,2-dipyridyl (2,2′-dipy), 4,4′-dipyridyl (4,4′-dipy), have been prepared by oxidation of the [M(CO) 6] − anions with either 1,1′-dimethyl-4,4′-dipyridilium diiodide (methylviologen, mvI 2) in the presence of the diamine or the diprotonated salt of the corresponding diamine, [(NN)H 2]Cl 2. Alternatively, these derivatives have been obtained by amine exchange reactions on [MCl(CO) 4(4,4-dipy)] n or by chloride substitution on the dinuclear anion [Nb 2( μ-Cl) 3(CO) 8] −. The MX(CO) 4(NN) derivatives have been characterized by analytical, spectroscopic and, in the case of TaI(CO) 4 (tmen), also by single crystal diffractometry. Crystal data. TaI(CO) 4(tmen), monoclinic, space group P2 1/c (No. 14); a=16.222 (5); b=12.855 (3); c=16.452 (6) Å, β=117.67 (2)°, M=536.10 g mol −1; V=3038.4 (1) Å 3; Z=8; D c =2.344 g cm −3; λ=0.7107 Å; T=203 K; μ=91.71 cm −1; F(000)=1984; R=0.045; Rw=0.048.