TRANSITION-METAL COMPLEXES WITH SULFUR LIGANDS .55. NICKEL-COMPLEXES WITH THIOLATO-THIOETHER LIGANDS INCLUDING NITROGEN AND OXYGEN DONORS IN S6, S5, OS4, NS4, AND S4 DONOR SETS - SYNTHESES, PROPERTIES, AND X-RAY STRUCTURE DETERMINATION OF [NI(S6)], [NI(S5)], [NI(OS4)]2, [NI(S4-C5)]2, AND [NI(S4-C3)]

In order to investigate specific properties of nickel-sulfur complexes, a series of novel compounds with multidentate thioether-thiolate ligands were synthesized and characterized by spectroscopic methods and X-ray structure analyses. The ligands derive from two benzenedithiol units linked by bridges of different length and nature. The reactions of [Ni(acac)2] (acac = acetyl-acetonate) with ‘S6'2−(=l,2-bis((2-((2-mercaptophenyl)thio)ethyl)thio)ethanato(2−)) and ‘OS4'2−(=bis(2-((2-mercapto-phenyl)thio)ethyl)etherato(2−)) yield [Ni(‘S6')] (1) and [Ni(‘OS4')]2-3THF (2). In [Ni(‘S6')] (monoclinic space group P21/n, Z = 4,a = 693.6 (2) pm, b = 2001.2 (5) pm, c = 1459.3 (2) pm, β = 100.33 (1)°, R/Rw= 0.037/0.029), the C2H4SC2H4SC2H4linkage spans like a handle diagonally over a square-planar [Ni(S2C6H4)2] unit. The two thioether atoms in the linkage do not coordinate. The binuclear [Ni(‘OS4')]2·3THF (triclinic space group Pl, Z = 2, a = 1146.5 (3) pm, b = 1360.2 (4) pm, c = 1613.6 (6) pm, α = 92.79 (2)°, β = 107.04 (3)°, γ = 93.86 (2)°, R/Rw= 0.094/0.082) contains two cofacial square-planar [NiS4] centers connected by the O(C2H4)2linkages of both ligands, the thiolate sulfurs being trans to each other. The Ni-Ni distance is 770 pm, producing a cagelike cavity between the [NiS4] entities. [Ni(‘S5‘)] (3), [Ni(‘S4-Cx')] (x = 1 (4), 3 (5), 5 (6), 7 (7)), and [Ni(‘NHS4')] (8) (‘S5'2−= bis(2-((2-mercaptophenyl)thio)ethyl)sulfidato(2−), ‘S4-C,'2- = bis((2-mercaptophenyl)thio)-methanato(2−), ‘S4-C3'2−= l,3-bis((2-mercaptophenyl)thio)propanato(2-), ‘S4-C5'2−= l,5-bis((2-mercaptophenyl)thio)pentana-to(2−), ‘S4-C7'2−= l,7-bis((2-mercaptophenyl)thio)heptanato(2−), ‘NHS4'2−= bis(2-((2-mercaptophenyl)thio)ethyl)aminato(2−)) were synthesized by template alkylation of Na2[Ni(S2C6H4)2] with bis(2-bromoethyl) sulfide, CH2I2, 1, 3-dibromopropane, 1, 5-dibromopentane, 1,7-dibromoheptane, and bis(2-bromoethyl)amine, respectively. In the mononuclear [Ni(‘S5')] (monoclinic space group P21/c, Z = 4, a = 1071.2 (5) pm, b = 1119.7 (5) pm, c = 1416.5 (5) pm, β = 91.11 (3)°, R/Rw= 0.085/0.071), the Ni center is five-coordinate and has a square-pyramidal geometry. This is the first five-coordinate Ni complex that is surrounded by sulfur donors only. The thiolate sulfur atoms lie cis to each other in the basal plane, and the linkage thioether atom occupies the apical position. [Ni(‘S4-C3')] (monoclinic space group P21/c, Z = 4, a = 1065.2 (4) pm, b = 813.5 (3) pm, c = 1758.2 (6) pm, β = 98.85 (3)°, R/Rw= 0.054/0.048) is mononuclear and has a slightly distorted square-planar structure with cis thiolate atoms. [Ni(‘S4-C5')]2·2THF (monoclinic space group P21/c, Z = 2, a = 938.7 (4) pm, b = 1230.9 (5) pm, c = 1872.5 (5) pm, β = 97.11 (2)°, R/Rw= 0.075/0.061) adopts the same binuclear bridged structure as [Ni(‘OS4')]2·3THF. The structural differences of the complexes are discussed in terms of the nature of the linkage between the C6H4S2units. Important factors are the preferred conformation of the uncoordinated ligand, the “hard” or “soft” character of the donor atom within the linkage, and the formation of five- and six-membered chelate rings. © 1990, American Chemical Society. All rights reserved.