Dithiosquarate (dtsq) complexes of nickel(II). Syntheses and crystal structures of [Ni(phen)(2)(1,2-dtsq)]center dot 3.SH2O, [Ni(phen)(2)(1,3-dtsq)] and [Ni(tren)(1,2-dtsq)] [phen=1,10-phenanthroline; tren=tris(2-aminoethyl)amine]

摘要

The new nickel(II) complexes [Ni(phen)(2)(1,2-dtsq)].3.5H(2)O (1), [Ni(phen)(2)(1,3-dtsq)] (2) and [Ni(tren)(1,2-dtsq)] (3) [1,2-dtsq = dianion of 3,4-dimercapto-3-cyclobutene-1,2-dione, 1,3-dtsq = dianion of 3-hydroxy-4-mercapto-2-thioxo-3-cyclobuten-1-one, phen = 1,10-phenanthroline and tren = tris(2-aminoethyl)amine] have been synthesized and characterized by single-crystal X-ray diffraction. Their structures are made up of neutral [Ni(phen)(2)(1,n-dtsq)] [1 (n = 2) and 2 n = 3)] and [Ni(tren)(l,2-dtsq)] (3) mononuclear units. The nickel atom is six-coordinated in all three cases: four nitrogen atoms from two bidentate phen (1 and 2) or a tetradentate tren (3) groups and either two sulfur (1 and 3) or a sulfur and an oxygen atoms (2) atoms from the dithiosquarate (dtsq) ligands form a distorted octahedron around the metal atom. The Ni-N(phen) bond lengths [2.082(5)-2.103(5) Angstrom for 1 and 2.075(8)-2.124(9) Angstrom for 2] are very close to that of Ni-N(tren) [2.088(2)-2.140(2) Angstrom for 3]. The Ni-S bond distances are 2.4598(15) and 2.4817(15) Angstrom for 1, 2.497(3) Angstrom for 2 and 2.4362(6) and 2.6446(7) Angstrom for 3. The values of the angle subtended at the metal atom by the 1,2-dtsq [91.06(4) (1) and 89.61(2)degrees (3)] and 1,3-dtsq [88.4(2)degrees (2)] ligands are very close to the ideal value of 90degrees in spite of their asymmetric bidentate coordination. The influence of the number and position of sulfur atoms of these ligands on their coordination modes is analyzed and discussed in the light of the available structural data. (C) 2003 Elsevier B.V. All rights reserved. [References: 62]