title: Synthesis, structure and magnetic properties of tetrakis-mu-carboxylato-bis(dodecylnicotinato)dicopper(II) complexes; crystal and molecular structure of the decyl carboxylate derivative.
abstract: Dodecylnicotinate bis-adducts of binuclear copper carboxylates, of the general formula Cu2(O2CC(n-1)H(2n-1))4(C5H4NCOOC12H25)2, were synthesized for n = 10, 12, 14, 16, 18 and 20, and their crystal structure, thermal behavior and magnetic properties studied. The molecular structure of the decyl derivative has been determined from single-crystal X-ray diffraction data. The dimer is centrosymmetric with the CuII ions in a square-pyramidal coordination with four O-alkyl O atoms [average d(Cu-O) 1.960 (6) A] in the basal plane and the nicotine N atom at apical positions [d(Cu-N) 2.183 (3) A]. The copper ions, 2.615 (1) A apart, are bridged by four O-alkyl carboxylate groups. Both the n = 20 and n = 18 homologues exhibit lamellar phases, which can be related to the supramolecular arrangement found in the n = 10 derivative. The magnetic behavior of the decyl and octadecyl dimers was studied in the 2-300 K temperature range. They exhibit a strong intramolecular antiferromagnetic interaction (Cu-Cu superexchange coupling constant J = -347 cm(-1) for the decyl derivative), which can be attributed to a large overlap of the metal 3d orbitals and the oxygen lone pair orbitals of the linking carboxylate groups.
authors.affiliation: INQUIMAE, Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Rusjan
authors.forename: Z
authors.initials: Z
authors.lastname: Chaia
authors.forename: O E
authors.initials: OE
authors.lastname: Piro
authors.forename: D
authors.initials: D
authors.lastname: Guillon
authors.forename: F D
authors.initials: FD
authors.lastname: Cukiernik
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D003460:Crystallization; D018360:Crystallography, X-Ray; D008280:Magnetics; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D044367:Phase Transition
chemical_list: D002264:Carboxylic Acids; D009942:Organometallic Compounds; D003300:Copper