Synthesis and Characterization of Square Planar Nickel(II)−Arylthiolate Complexes with the Biphenyl-2,2‘-dithiolate Ligand

Abstract

Two new NiIIS4 complexes with the biphenyl-2,2'-dithiolate ligand (L) are reported. The dinuclear complex 1, [Ni2L3]2-, was formed in the reaction of 2-3 equiv of Na2L and [NiCl4]2- and the mononuclear complex [NiL2]2- (2) by using 4-10 equiv of Na2L. Complexes 1 and 2 have been crystallographically characterized. (Et4N)2[1].0.5S2Ph2, CH3CN: C60H71N3Ni2S7, triclinic, P1, a = 13.806(2) A, b = 14.267(2) A, c = 16.873(2) A, alpha = 69.263(10) degrees, beta = 69.267(8) degrees, gamma = 83.117(10) degrees, Z = 2, R1 = 0.0752 (wR2 = 0.2011). (Et4N)(Na.CH3CN)[2]: C34H39N2NaNiS4, triclinic, P1, a = 9.9570(10) A, b = 13.2670(10) A, c = 13.9560(10) A, alpha = 108.489(7) degrees, beta = 90.396(6) degrees, gamma = 103.570(4) degrees, Z = 2, R1 = 0.0390 (wR2 = 0.0995). Both complexes are square planar about the nickel ion in the solid state as well as in solution. Most Ni(II)-thiolate complexes are square planar except the tetrahedral mononuclear complexes with monodentate arylthiolate ligands that cannot force a square planar geometry. The ligand (L) has some flexibility to change its bite angle via the phenyl-phenyl bond and should not force a planar geometry on its complexes either. Therefore, it is interesting that 2 has adopted a square planar structure. Complex 2 readily converts to 1 in solution when not in the presence of excess L in a process that is presumably similar to that known for other mononuclear, bidentate ligated Ni(II) complexes. Both complexes, at least in the solid state, appear to have an inclination to bind another metal ion on one face of the complex (Ni2+ in 1, Na+ in 2). We hope to take advantage of this in future work to synthesize relevant model complexes for the active sites of the nickel-iron hydrogenases after suitable modifications are made to L.

A mononuclear molybdenum(V) mono-oxo biphenyl-2,2′-dithiolate complex in which the metal resides within a cleft formed by the ligands and that exhibits N-H...S hydrogen bonding in the solid state

“…As is typical for Mo(V) mono-oxo complexes, 1 is unreactive toward the oxygen atom acceptors DMS, PPh 3 , and PBu 3 for at least a week at ambient temperatures in solution. To the best of our knowledge, complexes with L are limited to 1, two square-planar nickel complexes [105], and a titanium system where the ligand was assembled on the metal center [106]. Malachowski and co-workers [107] have alkylated the thiolate sulfur atoms in L with imidazole-and pyridine-pendant groups to form tetradentate ligands.…”

Platinum Complexes of Dibenzo[1,2]Dithiin, Dibenzo[1,2]Dithiin Oxides and Related Polyaromatic Hydrocarbon Ligands

“…Mono-and dinuclear nickel complexes have also been reported. [9] Rauchfuss et al [10] reported the synthesis of titanocene 2,2'-dithiolatobiphenyl by ring opening of dibenzothiophene with lithium metal followed by addition of sulfur and titanocene dichloride giving the final product from a salt-elimination reaction. Recently, our group has shown [11] that this complex can also be produced by oxidative addition of dibenzo [1,2]dithiin with titanocene dicarbonyl (Ti II ).…”

Synthesis, structure and properties of two bimetallic compounds [Co(bpy)2 (NiL)] (ClO4)2 and {[Co(phen)3](NiL)}(ClO4)2 containing a macrocyclic oxamide ligand

“…Considering that there are two kinds of metal ions in these two compounds, it is difficult to identify each transition here. We deduced that the former transition may be assigned to the d-d transition of nickel(II) ions, according to similar compounds in the literature [17,18].…”