Tetra(n-butyl)ammonium ds-diacidooxophthalocyaninato(2-)niobates(V) and -tantalates(V), ( n Bu 4 N) cis [M(X) 2 Opc 2- ] (M = Nb, Ta; X = F, Cl, NCS, N 3 ), are obtained by the reaction of cis [M(Cl) 3 pc 2- ] or cis [M(Cl}Opc 2- ] (M = Nb, Ta) with the respective tetra(n-butyl)ammonium salt. ( n Bu 4 N) cis [Nb(F) 2 Opc 2- ] crystallizes in the monoclinic space group P2 1/ 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 (N iso ) of the pc 2- 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 (N iso ) 4 plane (Ct(N iso )) towards the acido ligands (d(Nb-Ct(N iso )) = 1.241 Å). The average (Nb-N iso ), (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 pc 2- ligand is concavely distorted. Typical π-π*-transitions of the pc 2- ligand are observed in the UV/Vis spectra at ca. 14500 and 29300 cm -1 . Vibration frequencies υ as,s (M-X), υ(M-O) and δ(X-M-0) have been assigned.