Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-diacidooxophthalocyaninato( 2-)niobaten(V) und -tantalaten(V); Kristallstruktur von (nBu4N)CIS[Nb(F)2Opc2-]

Tetra(n-butyl)ammonium ds-diacidooxophthalocyaninato(2-)niobates(V) and -tantalates(V), (nBu4N)cis[M(X)2Opc2-] (M = Nb, Ta; X = F, Cl, NCS, N3), are obtained by the reaction of cis[M(Cl)3pc2-] or cis[M(Cl}Opc2-] (M = Nb, Ta) with the respective tetra(n-butyl)ammonium salt. (nBu4N)cis[Nb(F)2Opc2-] crystallizes in the monoclinic space group P21/n with cell parameters a = 13.460(5), b = 13.820(5), c = 23.360(5) Å, ß = 92.640(5)°, Z = 4. The heptacoordinated Nb(V) atom is surrounded by four isoindole nitrogen atoms (Niso) of the pc2- ligand, two fluorine atoms and one oxygen atom in a distorted square-base-trigonal-cap polyhedron. Nb(V) is displaced out of the centre of the (Niso)4 plane (Ct(Niso)) towards the acido ligands (d(Nb-Ct(Niso)) = 1.241 Å). The average (Nb-Niso), (Nb-F), and (Nb-O) distances are 2.300, 1.957, and 1.720(5) Å, the (F-Nb-F) and the average (O-Nb-F) angles are 79.8(2) and 91.8°, respectively. The pc2- ligand is concavely distorted. Typical π-π*-transitions of the pc2- ligand are observed in the UV/Vis spectra at ca. 14500 and 29300 cm-1 . Vibration frequencies υas,s(M-X), υ(M-O) and δ(X-M-0) have been assigned.