The crystal structure of a dithiophosphate-bridged binuclear cobalt(II) complex of a macrocyclic ligand

Abstract

The crystal and molecular structure of LCO2 [S2P(OEt)2]2 (where L is a binucleating ligand derived from the macrocycle LH2 formed by condensation of two molecules each of propane-1,3-diamine and 2-hydroxy-5-methylisophthalaldehyde) has been determined by single-crystal X-ray diffraction techniques at 295 K. The compound crystallizes in the triclinic space group Pī with two molecules in a cell of dimensions a 18.644(6), b 11.694(4), c 9.487(4) �, α 84.99(3), β 82.61(3), γ 73.48(2)�. Automatic diffractometry has provided significant Bragg intensities for 2799 independent reflections and the structure has been refined by least-squares methods to R 0.054. The structure is molecular, consisting of discrete binuclear units LCo2[S2P(OEt)2]2. The two centrosymmetric molecules in the unit cell are crystallographically unique but essentially chemically similar. The two cobalt(11) atoms in each molecule are separated by 3.075(2) and 3.072(2) �. Each cobalt atom is in an octahedral environment, with an N2O2 equatorial plane and two sulfur atoms of bridging dithiophosphate ligands in the axial positions. The Co-S bonds are the longest yet observed [2,680(3), 2.652(3), 2.642(3), 2.623(3) �]. The cobalt(11) centres are high spin, with �eff 4.53 BM per cobalt atom. The macrocyclic ligand deviates slightly from planarity. The forces exerted both by the ligand L on associated metal atoms, and by axial ligands on the macrocycle, are discussed.