Five-coordinate iron and manganese dinitrosyl complexes incorporating tridentate chelating dimethyl(N,N-dimethylethanolamino)(pyrazolyl)gallate ligands: crystal and molecular structure of [Me2Ga(N2C5H7)(OCH2CH2NMe2)]Fe(NO)2

Abstract

Novel neutral monomeric five-coordinate manganese and iron dinitrosyl compounds incorporating asymmetric tridentate anionic gallate ligands are described. The crystal structure of the formally "19-electron" iron complex [Me2Ga(N2C5H7)(OCH2CH 2NMe2)]Fe(NO)2 has been determined. Crystals of [dimethyl(N,N-dimethylethanolamino)(3,5-dimethylpyrazolyl)gallato (N(2),N(3),O)]dinitrosyliron(I) are monoclinic, a = 7.3079(6), b = 14.274(1), c = 17.076(1) Å, β = 91.709(4)°, Z = 4, space group P21/c. The structure was solved by Patterson and Fourier syntheses and was refined by full-matrix least-squares procedures to R = 0.034 and Rw = 0.046 for 2848 reflections with I ≥ 3σ(I). The crystal structure consists of discrete monomeric units. The coordination geometry about the iron atom is distorted trigonal-bipyramidal with the tridentate gallate ligand acting in a meridional fashion, occupying one equatorial and both axial positions. The two nitrosyl groups occupy the other two equatorial sites and both Fe—N—O groupings are considerably bent toward one another in the equatorial plane. Important mean molecular dimensions (distances corrected for libration) are: Fe—O, 2.037(3), Fe—N(pyrazolyl), 2.112(3), Fe—N(amino), 2.279(3), Fe—NO, 1.710(3), N—O, 1.153(5), Ga—O, 1.916(3), Ga—N, 1.975(3), Ga—C, 1.972(6) Å, and Fe—N—O, 158.6(7)°.