774598-66-2Relevant academic research and scientific papers
Sulfur bridging interactions of cis-planar NiII-S 2N2 coordination units with nickel(II), copper(I,II), zinc(II), and mercury(II): A library of bridging modes, including Ni II(μ2-SR)2MI,II rhombs
Venkateswara Rao,Bhaduri, Sumit,Jiang, Jianfeng,Holm
, p. 5833 - 5849 (2004)
Sulfur bridging interactions between three cis-planar Ni II-S2N2 complexes and NiII, Cu I,II, ZnII, and HgII reactants were investigated by synthesis and X-ray crystal structures of some 24 complexes. This work was stimulated by recent crystallographic structures of the A-cluster of carbon monoxide dehydrogenase/acetylcoenzyme A synthase. This bridged biological assembly has the minimal formulation [Fe4S 4]-(μ2-SCys)-[M((μ2-S Cys)2Gly)Ni] with M = NiII, CuI, and ZnII at sites distal and proximal, respectively, to the iron-sulfur cluster. Bridges supported by representations of the distal nickel site were sought by reactions of the complexes [NiII(LH-S 2N2)]2- and [NiII(L R-S2N2)], with 5-5-5 chelate ring patterns. Reaction products implicate the bridges Ni-(μ2-S)1,2-M in a variety of molecular structures, some with previously unknown connectivities of bridge atoms. The most frequently encountered bridge units are the nonplanar rhombs Ni(μ2-S)2M involving both sulfur atoms of a given complex. Those with M = NiII are biologically relevant inasmuch as the catalytic metal at the proximal site is nickel. The complex [Ni(L-655)]2-, containing the 6-5-5 ring pattern and coordination sphere of the distal nickel site, was prepared and structurally characterized. It was shown to sustain Ni2(μ2-S) 2 rhombic interactions in the form of trinuclear [{Ni(L-655)} 2Ni]2- and [{Ni(L-655)}Ni(R2PCH 2CH2PR2)] (R = Et, Ph) in which the second NiII simulates the proximal site. Bridging interactions of Ni II-S2N2 complexes are summarized, and geometrical features of Ni2(μ2-S)2 rhombs in these complexes, as dependent on ring patterns, are considered (L H-S2N2 = N,N′-ethylenebis(2- mercaptoisobutyramide)(4-); LR-S2N2 = trans-rac-N,N′-bis(2-mercapto-2-methylprop-1-yl)-1,2-cyclohexanediamine(2- ); L-655 = N-(2-mercaptopropyl)-N′-(2′-mercaptoethyl)glycinamide(4-) ).
