[(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O – A Coordination Polymer with the Chain-like Polyanion

What is it about?

Triclinic single crystals of [(C6H10)(NH3)2][Ni(H2O)4C6H2(COO)4]·4H2O have been prepared in aqueous solution at 55 °C. Space group P1¯ (Nr. 2), a = 691.23(6), b = 924.84(5), c = 1082.43(7) pm, alpha= 74.208(6)°, beta= 75.558(7)°, gamma= 68.251(6)°, V = 0.60985(7) nm3, Z = 1. The Nickel(II) species, located on a crystallographic inversion centre, is coordinated in a trans-octahedral fashion by two oxygen atoms stemming from the centrosymmetric pyromellitate anions and four from water molecules (Ni-O 205.82(12) - 208.11(13) pm). The onnection between Ni2+ and [C6H2(COO)4)]4- leads to infinite chain-like polyanions extending parallel to [10-1] with {Ni(H2O)4[C6H2(COO)4]2+}n composition. [(C6H10)(NH3)2]2-cations are accomodated between the chains, compensating for the negative charge of the polyanions. Thermogravimetric analysis in air showed that the loss of water of crystallisation occurs in two steps between 102 and 206 °C, corresponding to the loss of 6 and 2 water molecules per formula unit, respectively. The dehydrated sample was stable between 206 and 353 °C. Further decomposition yielded nickel(II) oxide (NiO).

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