Synthesis and unusual crystal structure of the Eu(III) complex with 1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluorobutane-1,3-dione

The reaction of Eu(NO3)3 · 6H2O with 1-(1,5-dimethyl-1H-pyrazol-4-yl)-4,4,4-trifluorobutane-1,3-dione (HL) in the presence of NaOH in aqueous ethanol gave neutral complex [EuL3(H2O)] (I). The unstable adduct [EuL3(H2O)] · 1.3MeCN (Ia) was obtained from an acetonitrile solution and studied by X-ray diffraction. The crystals of Ia at 100 K are monoclinic, a = 17.551(3) Å, b = 11.532(2) Å, c = 20.371(3) Å, β = 110.886(3)°, V = 3852(1) Å3, space group P21/c, Z = 4, R = 0.0505. The molecules are connected into chains by strong interactions between the europium atom of one molecule and the pyrazole N(2) atom of another molecule and additionally stabilized by strong hydrogen bonds O(1w)-H(1w1)…N(4)*. The chains are combined into layers by the hydrogen bonds (1w)-H(2w1)…N(2)*.