title: Cyano-bridged pentanuclear Fe(III)3M(II)2 (M = Ni, Co, Fe) clusters: synthesis, structures, and magnetic properties.
abstract: The reactions of [M(II)(Tpm(Me))(H2O)3]2+ (M = Ni, Co, Fe; Tpm(Me) = tris(3,5-dimethyl-1-pyrazoyl)methane) with [Bu4N][(Tp)Fe(III)(CN)3] (Bu4N+ = tetrabutylammonium cation; Tp = tris(pyrazolyl)hydroborate) in MeCN-Et2O afford three pentanuclear cyano-bridged clusters, [(Tp)3(Tpm(Me))2Fe(III)3M(II)2(CN)9]ClO4.15H2O (M = Ni, 1; M = Co, 2) and [(Tp)3(Tpm(Me))2Fe(III)3Fe(II)2(CN)9]BF4.15H2O (3). Single-crystal X-ray analyses reveal that they show the same trigonal bipyramidal structure featuring a D3h-symmetry core, in which two opposing Tpm(Me)-ligated M(II) ions situated in the two apical positions are linked through cyanide bridges to an equatorial triangle of three Tp-ligated Fe(III) (S = 1/2) centers. Magnetic studies for complex 1 show ferromagnetic coupling giving an S = 7/2 ground state and an appreciable magnetic anisotropy with a negative D(7/2) value equal to -0.79 cm(-1). Complex 2 shows zero-field splitting parameters deducted from the magnetization data with D = -1.33 cm(-1) and g = 2.81. Antiferromagnetic interaction was observed in complex 3.
authors.affiliation: Coordination Chemistry Institute and the State Key Laboratory of Coordination Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, P. R. China.
authors.forename: Zhi-Guo
authors.initials: ZG
authors.lastname: Gu
authors.forename: Qiao-Fang
authors.initials: QF
authors.lastname: Yang
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: You
authors.initials: Y
authors.lastname: Song
authors.forename: Yi-Zhi
authors.initials: YZ
authors.lastname: Li
authors.forename: Jing-Lin
authors.initials: JL
authors.lastname: Zuo
authors.forename: Xiao-Zeng
authors.initials: XZ
authors.lastname: You