title: Dipyridinium diaqua-bis-(pyrazole-3,5-di-carboxyl-ato-κ(2) N,O)cuprate(II) dihydrate.
abstract: In the mononuclear title salt, (C5H6N)2[Cu(C5H2N2O4)2(H2O)2]·2H2O, the Cu(II) ion is located on an inversion centre and is coordinated by two chelating pyrazole-3,5-dicarboxyl-ate anions and two water mol-ecules, forming a Jahn-Teller-distorted CuN2O4 octa-hedron. O-H⋯O and N-H⋯O hydrogen bonds are formed between water mol-ecules, complex anions and the pyridine counter-cations, leading to the formation of layers parallel to (100). The layers are held together by weak C-H⋯O hydrogen bonds.
authors.affiliation: State Key Laboratory Breeding Base of Humid Subtropical Mountain Ecology, College of Geographical Sciences, Fujian Normal University, Fuzhou 350007, People's Republic of China ; Université Européenne de Bretagne, Université de Bretagne Occidentale, CS 93837, 29238 Brest Cedex 3, France.
authors.forename: Youtao
authors.initials: Y
authors.lastname: Si