Crystal structure of bis(isocyanato-κ1N)-bis(2-(pyridin-4-ylthio)pyrazine- κ1N) zinc(II), C20H14N8S4Zn

Abstract

Source of materialAll reagents and solvents from commercial sources were used withoutfurther purification.With the sodium pyridine-4-thiolate (0.67 g, 5m mol) and 2-chloropyrazine (0.6 g, 5.2m mol), 4-pyridyl-2-pyrazinyl sulfide was obtained through the synthetic procedure reported in [1]. Zn(NCS) 2 (18.1 mg, 0.1 mmol) and 2-(pyridine-4-ylthio)pyrazine (19 mg,0.1 mmol) were dissolved in 1mlmethanol followed by the addition of 3mLofmixed solvent of methanol and acetonitrile, then stirred at room temperature for 3hours. The colourless solution was filtered and left to stand in air to slowly evaporate the solvent. Colourless block-shaped crystals of the title compound suitable for X-ray diffraction were deposited after aweek. 12.6 g, 45% yield. Experimental detailsAll hydrogen atomswere identified in difference Fourier syntheses. The U iso values of the hydrogen atomsofmethyl groups were set to 1.5U eq (C) and the U iso values of all other hydrogen atoms were setto1.2U eq (C, N). DiscussionThe semi-rigid dipyridylsulfideand its N-positionalisomers are totally different from thel inear 4,4'-bipyridine ligand, as they showmore flexiblecoordination modesincoordinationsupramolecular assembly on accountofthe rotatableC(sp2)-S bonds and the variable C(sp2)-S-C(sp2) angle [2].Sofar,the coordination supramolecular architectureso fv arious isomeric dipyridyls ulfide ligands have beenreported [3].But, studies dealing with the unsymmetrically bent-shapedl igands containing pyridyla nd pyrazinyl moieties are rare [1,4]. Herein, we report the structure of ac omplex with theu nsymmetrical bent-shaped ligand 2-(pyridine-4-ylthio)pyrazine, am ultidentate ligand bearing a C(sp2)-S-C(sp2) fragment. In the mononuclearc omplex, each zinc(II) center is surrounded by two Natoms from two independent 2-(pyridine-4-ylthio)pyrazine ligands (Zn1-N1 =2.032(19) Å) and two independent isocyanato ligands (Zn1-N4 =1.912(3) Å). Each 2-(pyridine-4-ylthio)pyrazine ligand exhibits aterminal ligand with one pyridine nitrogen atom linking to one zinc(II) atom,which combines the apair of isocyanato anions to yield a the mononuclear complex (Fig.). Herein, the C3-S1-C6 angles of the 2-(pyridine-4-ylthio)pyrazine is 103.47(11)°. Along the b direction, the mononuclearunits are arranged and stacked to form an infinite one-dimensional columnmotif, which form contacts with adjacent ones through S(isocyanato)×××p(pyrazine ring) = 3.711(3) Å) interactions [5].