Double Complex Salts [Ln(C6H5NO2)3(H2O)2][Cr(NCS)6] · 2H2O (Ln = Lu, Ce, Y): Synthesis and Crystal Structure

Abstract

Double complex salts [Ln(C₆H₅NO₂)₃(H₂O)₂][Cr(NCS)₆] · 2H₂O, Ln = Lu (I), Ce (II), Y (III), have been synthesized by the reaction between aqueous solutions of Ln(NO₃)₃ (Ln = Lu, Ce, Y), K₃[Cr(NCS)₆], and nicotinic acid (C₅H₅NCOO). The salts representing light lilac crystalline powders have been studied by chemical analysis, IR spectroscopy, and single-crystal X-ray diffraction. The salts crystallize in monoclinic system, space group P2₁/n, Z = 4: a = 9.4969(15) Å, b = 25.606(4) Å, c = 15.541(2) Å, β = 107.126(4)°, V = 3624.34 ų, ρ_calcd = 1.864 g/cm³ for I; a = 9.6559(2) Å, b = 25.8492(5) Å, c = 15.5303(3) Å, β = 106.586(1)°, V = 3715.0(1) ų, ρ_calcd = 1.756 g/cm³ for II; and a = 9.5662(7) Å, b = 25.756(2) Å, c = 15.541(1) Å, β = 107.122(2)°, V = 3659.3(4) ų, ρ_calcd = 1.690 g/cm³ for III. The cations in the crystal structures of complexes I–III have a chain polymer structure, and the coordination polyhedron of chromium(III) represents a slightly distorted octahedron. The steric factor has no appreciable effect on the specific features of the crystal structures in the series of lanthanide hexa(isothiocyanato)chromate(III) complexes with nicotinic acid, and the content of crystallization water molecules is varied alone in their composition.