title: One-dimensional polymers containing strictly collinear metal ions: synthesis and XRPD characterization of homoleptic binary metal pyrazolates.
abstract: The synthesis of a number of 3d transition metal binary pyrazolates in microcrystalline form, thus suitable for a full XRPD characterization, has been pursued. The crystal and molecular structures of the Fe(pz)3, Co(pz)2, Co(pz)3, and Ni(pz)2 polymers, together with the few congeners reported in the recent literature, show that these species tend to afford highly crystalline materials where strictly collinear chains of metal atoms are present. Depending on the synthetic strategy used, Ni(pz)2 has been found to crystallize as two different alpha (orthorhombic) and beta (monoclinic) phases, possessing nearly identical intramolecular features. Data for each compound follow. Fe(pz)3: C9H9FeN6, hexagonal, P63/m, a = 9.1745(3) A, c = 7.2191(4) A, Z = 2. Co(pz)2: C6H6CoN4, orthorhombic, Ibam, a = 7.5239(5) A, b = 14.3461(9) A, c = 7.4331(5) A, Z = 4. Co(pz)3: C9H9CoN6, hexagonal, P63/m, a = 9.1966(3) A, c = 7.1051(3) A, Z = 2. Alpha-Ni(pz)2: C6H6N4Ni, orthorhombic, Cmcm, a = 16.6758(11) A, b = 6.4872(4) A, c = 6.9423(6) A, Z = 4. Beta-Ni(pz)2: C6H6N4Ni, monoclinic, P21/m, a = 9.967(2) A, b = 6.975(1) A, c = 6.016(1), A, beta = 98.50(1)degrees, Z = 2. The thermal stability and the detailed structural properties of these model compounds have been evaluated, in the light of the technologically relevant crystal phases (the well-known metal-diazolates showing reversible spin-crossover or spin-transition behavior) obtainable upon doping, magnetic dilution, and ring substitution (in the 4-position).
authors.affiliation: Dipartimento di Scienze Chimiche, Fisiche e Matematiche, Università dell'Insubria, Via Valleggio 11, 22100 Como, Italy. norberto. masciocchi@uninsubria.it
authors.forename: Norberto
authors.initials: N
authors.lastname: Masciocchi
authors.forename: G Attilio
authors.initials: GA
authors.lastname: Ardizzoia
authors.forename: Stefano
authors.initials: S
authors.lastname: Brenna
authors.forename: Girolamo
authors.initials: G
authors.lastname: LaMonica
authors.forename: Angelo
authors.initials: A
authors.lastname: Maspero
authors.forename: Simona
authors.initials: S
authors.lastname: Galli
authors.forename: Angelo
authors.initials: A
authors.lastname: Sironi