Symmetry-based magnetic anisotropy in the trigonal bipyramidal cluster [Tp2(Me3tacn)3Cu3Fe2(CN)6]4+.

Coordination Chemistry Institute and State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing 210093, China.
Journal of the American Chemical Society (Impact Factor: 11.44). 07/2006; 128(22):7162-3. DOI: 10.1021/ja061788+
Source: PubMed

ABSTRACT Reaction of [(Me3tacn)Cu(H2O)2]2+ (Me3tacn = N,N',N' '-trimethyl-1,4,7-triazacyclononane) with [TpFe(CN)3]- (Tp- = hydrotris(pyrazolyl)borate) in a mixture of ethanol and acetonitrile affords the pentanuclear cluster [Tp2(Me3tacn)3Cu3Fe2(CN)6]4+. Single-crystal X-ray analysis reveals a trigonal bipyramidal structure featuring a D3h-symmetry core in which two opposing FeIII (S = 1/2) centers are linked through cyanide bridges to an equatorial triangle of three CuII (S = 1/2) centers. Fits to variable-temperature dc magnetic susceptibility data are consistent with ferromagnetic coupling to give an S = 5/2 ground state, while fits to low-temperature magnetization data indicate the presence of a large axial zero-field splitting (D = -5.7 cm-1). Frequency dependence observed in the ac magnetic susceptibility data confirms single-molecule magnet behavior, with an effective spin reversal barrier of Ueff = 16 cm-1. When compared with the much lower anisotropy barrier previously observed for the face-centered cubic cluster [Tp8(H2O)6Cu6Fe8(CN)6]4+, the results demonstrate the enormous influence of the geometry in which a given set of metal ions are arranged.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The reaction of tricyanometallate precursor, (Bu4N)[(pzTp)Fe(CN)3] with Cu(ClO4)2·6H2O in the presence of the tetradentate ligand tris(2-pyridylmethyl)amine (TPyA) afford the dinuclear compound fac-{[FeIII(pzTp)(CN)2(μ-CN)]CuII(TPA)}·Et2O·ClO4 (1) (pzTp = tetrakis(pyrazolyl)borate). The molecular structure was determined by single-crystal X-ray diffraction. In compound 1, the FeIII ion is coordinated by three cyanide carbon atoms and three nitrogen atoms of pzTp anions. Whereas, the CuII ion is surrounded by one cyanide nitrogen atom and four nitrogen atoms from the TPyA ligand. Magnetic measurements indicate the intramolecular ferromagnetic coupling is observed for compound 1, and it has S = 1 ground states.
    Zeitschrift für anorganische Chemie 02/2009; 635(2). · 1.25 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tailoring the specific magnetic properties of any material relies on the topological control of the constituent metal ion building blocks. Although this general approach does not seem to be easily applied to traditional inorganic bulk magnets, coordination chemistry offers a unique tool to delicately tune, for instance, the properties of molecules that behave as "magnets", the so-called single-molecule magnets (SMMs). Although many interesting SMMs have been prepared by a more or less serendipitous approach, the assembly of predesigned, isolatable molecular entities into higher nuclearity complexes constitutes an elegant and fascinating strategy. This Feature article focuses on the use of building blocks or modules (both terms being used indiscriminately) to direct the structure, and therefore also the magnetic properties, of metal ion complexes exhibiting SMM behaviour.
    Chemical Communications 03/2014; · 6.38 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Treatment of [Mn(dpop)(H2O)2]Cl2 (dpop = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo-[12.3.1]octadeca-1(18),2,12,14,16-pentaene) with K4[Mo(CN)7]·2H2O under varied synthetic conditions afforded four different compounds: {[Mn(dpop)]4[(dpop)Mn(H2O)]2[Mo(III)(CN)7]3·27H2O}n (), {[(dpop)Mn(H2O)][Mo(III)(CN)7][Mn(dpop)]3[Mo(IV)(CN)8]·29H2O}n (), {[(dpop)Mn(H2O)]2[Mo(IV)(CN)8]2[Mn(dpop)]4[Mo(III)(CN)7]·12H2O}n (), and [(dpop)Mn(H2O)]2[Mo(IV)(CN)8]·9H2O (). Compound contains only [Mo(III)(CN)7](4-) anions and exhibits a corrugated two-dimensional layered architecture. The structure of with a 1 : 1 ratio of Mo(III) : Mo(IV) is best described as a ladder-like chain composed of [Mo(III)(CN)7](4-)-based pentanuclear [Mo(III)Mn(II)4] fragments which are further linked by in situ produced [Mo(IV)(CN)8](4-) anions. In the case of , [Mn8Mo8] rings containing bent [Mo(III)Mn(II)2] fragments are extended into a two-dimensional layer with the ratio of [Mo(CN)7](4-) : [Mo(CN)8](4-) being 1 : 2. Compound exhibits a bent trinuclear structure in which two CN(-) groups of [Mo(CN)8](4-) function as μ2-bridges to [Mn(dpop)(H2O)](2+) fragments. Magnetic studies suggest significant antiferromagnetic coupling interactions occur between Mo(iii) and Mn(ii) ions while, not surprisingly, interactions between the Mn(ii) ions through diamagnetic [Mo(IV)(CN)8](4-) anions are negligible. Compound exhibits ferrimagnetic ordering below 3.0 K whereas shows the signature of single molecule magnet behavior with slow relaxation of the magnetization and an effective energy barrier (Ueff) of 8.1 K.
    Dalton Transactions 03/2014; · 4.10 Impact Factor

Full-text (2 Sources)

Available from
May 27, 2014