Copper(I) chloride and copper(I) perchlorate π-complexes with 2-allylthio-5-methyl-1,3,4-thiadiazole: synthesis and crystal structure

Abstract

By means of the alternating-current electrochemical technique two copper(I) π,σ-compounds [Cu 4 Cl 4 ( Almethia ) 2 ] ( 1 ) and [Cu 2 ( Almethia ) 3 ](ClO 4 ) 2 ( 2 ) with 2-allylthio-5-methyl-1,3,4-thiadiazole ( Almethia ) were obtained in a single crystal form and structurally characterized by X-ray diffraction. Diffraction data for 1 and 2 crystals were collected on an Kuma KM-4-CCD and Agilent Gemini A (with an Atlas CCD detector) diffractometers using Mo K a radiation (λ = 0.71073 Å). The collected diffraction data were processed using CrysAlis PRO program. The structures were solved by ShelXT and refined by least squares method on F 2 by ShelXL with the following graphical user interface of OLEX 2 . π-Complexes crystallize in the centrosymmetric space group P 2 1 /n : ( 1 ) a = 12.032(4), b = 8.289(3), c = 12.053(4) Å, b = 111.11(3)°, V = 1121.4(7) Å 3 , Z = 2; ( 2 ) a = 10.221(4), b = 22.777(6), c = 12.974(4) Å, b = 90.41(3)°, V = 3020.3(17) Å 3 , Z = 4. Оrganic ligand Almethia possesses a chelate-bridging function, being coordinated to the metal by means of unsaturated C=C bond and by the two nitrogen atoms of heterocyclic ring. Two crystallographically different copper(I) atoms in 1 possess different coordination environment: Cu(1) has distorted tetrahedral surrounding, arranged by allylic C=C bond, thiadiazole N atom of Almethia molecule and by two bridging halogen atoms; Cu(1) possesses the trigonal pyramidal environment arranged by N atom of the thiadiazole core and three chlorine atoms. Cu(1) deviates from a base of the trigonal pyramid (N4, Cl1 and Сl2) all-in-all by 0.13Å, while the apical Cl1 i (Symmetry code: ( і ) 1– x ; 1– y ; 1– z ) is removed from the metal center by 2.900(2)Å. Despite the last Cu2–Cl1 i distance is remarkably longer than the other analogue distances in the structure, this value still significantly shorter than the sum of van-der-Vaals radii of copper and chlorine. Thus, Almethia molecule causes a formation of stepped cubane tetramer Cu 4 Cl 4 . In contrast to 1 , in structure 2 two crystallographically independent copper(I) have distorted tetrahedral environment, arranged by allylic C=C bond and three N atoms of three different 1,3,4-thiadiazole molecules. Two of this molecules are π,σ-bonded to the metals and the third one is only σ-coordinated by two nitrogen atoms. Cationic [Cu 2 ( Almethia ) 3 ] 2+ fragments and ClO 4 – anions are only electrostatically bound. Keywords: copper(I), π-complex, 1,3,4-thiadiazole, crystal structure.