E.G. Afonin – Ph.D.(Chem.), Senior Research Scientist, 

JSC «Kaluga Scientifically Research Institute of Telemechanical Devices»

E-mail: afonineg.chem@gmail.com

G.G. Aleksandrov – Ph.D.(Chem.), Senior Research Scientist, 

Kurnakov Institute of General and Inorganic Chemistry (Moscow)

E-mail: info@igic.ras.ru

Structure of complex K2Cu(H2P2O7)2·2H2O is determined by single crystal X-ray diffraction analysis. The complex crystallizes in the orthorhombic system (space group Pnma) with the cell parameters: a = 9,901(2) Å, b = 10,781(2) Å, c = 13,395(3) Å, z = 4. The structural units of the crystal are anions [Cu(H2O)2(H2P2O7)2]2− and cations K+ wich are linked together by interionic and hydrogen bonds. The Cu cation has a distorted tetragonal-bipyramidal coordination (4+2) because to four O(P) atoms of the two bidentatechelate H2P2O72− ligands lying in the equatorial plane (Cu–O(P) 1,978 and 1,983 Å) and the two O atoms of water molecules occupying axial positions (Cu–O(w) 2,319 and 2,404 Å). The average P–O, P–O(H), P–Obridge distances in the complex K2[Cu(H2O)2(H2P2O7)2] (1,499 Å, 1,550 Å and 1,607 Å) are in good agreement with the average distances in the complexes M+12[M+2(H2O)2(H2P2O7)2]·nH2O, M+1 = NH4, Na, K, Rb, Cs, organic ammonium cation, M+2 = Mg, Zn, Co, Ni (1,498 Å, 1,551 Å, 1,606 Å). The complex anions [Cu(H2O)2(H2P2O7)2]2− are joined together by the hydrogen (P)O–H···O(P) and O(w)–H···O(P) bonds. The K+ cations (c. n. 7 and 7, K–O 2,75…2,96 и 2,73…3,07 Å) are located between the anion chains.

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