Showing papers by "Wiktor Zierkiewicz published in 2016"

Thiocyanate copper complexes with pyrazole-derived ligands – synthesis, crystal structures, DFT calculations and magnetic properties

Abstract: This paper presents the synthesis, X-ray studies, spectroscopic characterization and variable temperature magnetic investigations and DFT calculation of four novel thiocyanato Cu(II) compounds [Cu(mpz)2(NCS)2]n·nH2O (1), {[Cu2(dmpz)4(NCS)4][Cu(dmpz)(NCS)2]}n·2nMeOH (2) [(bdmpzm)CuII(SCN)2(μ1,3-SCN)CuI(bdmpzm)]n (3) and [Cu(bpzpy)(NCS)2] (4) Three of them (1, 2 and 3) display one-dimensional coordination structures while complex (4), incorporating a tridentate N-donor ligand, possesses a 0D molecular structure Complex 3 belongs to a relatively rare group of mixed-valence CuII/CuI coordination polymers

Ab initio and DFT studies of the interaction between carbonyl and thiocarbonyl groups: the role of S···O chalcogen bonds

Abstract: The chalcogen bonds formed between carbonyl bases (H2C=O and CH3- and Cl-derivatives) and carbon disulfide have been studied by density functional BLYP-D3 and ab initio CCSD(T) methods. The CCSD(T)/CBS calculated interaction energies between these molecules are moderate, ranging from −1.45 to −2.29 kcal mol−1. The charge transfer occurs from the carbonyl base to CS2 and is small. According to the AIM analysis, the molecules are bonded by S···O chalcogen bonds. In addition, weak van der Waals S···Cl and S···H interactions stabilize most of the systems. The same results can be extracted from the NBO calculations which reveal the nature of the interacting bonding and antibonding orbitals. For some of the carbonyl derivatives, other stable structures characterized by S···Cl bonds or CH···C hydrogen bonds are also predicted. A SAPT decomposition of the interaction energies allows to conclude that the electrostatic energy is the predominant component in the stronger complexes and that the dispersion energy becomes more important in the weaker van der Waals complexes.

1–D Framework l-arginine zinc(II) units bridged by oxalate: synthesis, structure, properties, and theoretical studies

Abstract: We synthesized a l-arginine containing Zn2+ complex and oxalate ions. {[Zn2(l-Arg)2(ox)2]·8H2O}n (1) (l-Arg =l-arginine, ox = oxalate) crystallize in the monoclinic space group P21 with a = 8.979(2), b = 9.840(2) (A), c = 18.509(3) (A), β = 95.58(3) (A), V = 1627.6(6) A3, and Z = 2. The zinc centers are six-coordinate via one l-arginine zwitterion and two bridging oxalates. The binuclear [Zn2(l-Arg)2(ox)2] units are linked via oxalate and form 1-D “stair-like” linear chains. The complex was characterized using FT-IR, FT-Raman, UV–vis spectroscopy, and thermal analysis techniques, as well as DFT methods. Electronic bands above 31,000 cm−1 originate in 1,3Au (n→π*) transitions within oxalate ions. Theoretical studies were performed for the model compound {[Zn(l-Arg)(Hox)2]·4H2O} using the fragment of the crystallographic structure of 1. The interaction energy (ΔE) values for l-arginine and two oxalate ions are comparable at -145 kcal mol−1. Natural bond orbital (NBO) analysis of the e...