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The synthesis and magnetic characterisation of a new series of 1D {MnIII2 LnIII2}[sub n] (Ln = Pr, Nd, Gd, Tb, Dy) coordination polymers are described. The repeating unit consists of a tetranuclear fragment made up of two MnIII and two Ln[sup III] ions exhibiting a butterfly/planar-diamond motif. The MnIII ions are situated in the body of the butterfly, with the LnIII ions occupying the outer wing sites. Each tetranuclear unit is linked by two bridging sulfonate ligands resulting in a 1D coordination polymer. Direct current (dc) magnetic measurements reveal the presence of weak magnetic interactions which are quantified for the {MnIII2 GdIII2}[sub n] complex, with exchange J values for the Mn[sup III]-Gd[sup III] and MnIII-MnIII pairwise interactions of 0.04 and 1.69 cm[sup -1], respectively. Alternating current (ac) susceptibility measurements reveal an absence of out-of-phase (χM") signals at all temperatures and frequencies utilising a 3.5 Oe oscillating ac field and a zero static dc field. Application of a bias dc field (2000 Oe), however, reveals field induced slow relaxation of the magnetisation for the DyIII complex. The structures and magnetism of a new family of 1D heterometallic complexes {MnIII2 LnIII2}[sub n] (Ln = Pr, Nd, Gd, Tb, Dy) are described with the exchange parameters deduced for the Gd complex. Slow magnetisation reversal was noted for the Dy complex in the alternating current susceptibility data when measured in an applied direct current field. [ABSTRACT FROM AUTHOR]

The synthesis and magnetic characterisation of four new heterometallic {CrIII2 DyIII2} complexes 2-5 are described. The present work follows on from a recently isolated complex CrIII2 DyIII2 (OMe)2 (O[sub 2]CPh)4 (mdea)2 (NO3)2] (1) (mdeaH2 = N-methyldiethanolamine), which displayed impressive single molecule magnet (SMM) properties, notably highly coercive magnetic hysteresis loops below 3.5 K. Compounds 1-5 all display a planar butterfly type metallic core arrangement, with the DyIII ions occupying the central body positions and the CrIII ion the outer wing positions. The core is stabilized by the amine-diolate, and carboxylate bridging ligands. Variation of the amine-diolate ligand resulted in several structural analogues which maintain the same metallic core, but differ from the parent 1 in the outer ligand coordination environment. Magnetic studies reveal complexes 2-5 also display SMM behaviour, unambiguously confirmed via low temperature magnetic hysteresis loops, each displaying wide coercive fields, a rare occurrence for lanthanoid-based SMMs. The detailed structural and magnetic properties of a family of {CrIII2 DyIII2}-alcoholamine cluster complexes reveal single molecule magnetism properties with strongly coercive hysteresis loops at temperatures up to 3.5 K, the strong intra-cluster magnetic exchange being responsible for these features. [ABSTRACT FROM AUTHOR]

Two novel trinuclear Cu[sup II] complexes have been synthesised from the nucleophilic addition derivatives of the small cyano anion, dicyanonitrosomethanide (dcnm). The reaction of Cu[sup II] with the water adduct ligand, carbamoylcyanonitrosomethanide (ccnm) and teaH[sub 3] (triethanolamine) in a basic MeOH/MeCN solution results in the formation of [Cu[sub 3](acnm)[sub 2](teaH[sub 2])[sub 2]] * 2MeOH (1) (acnm = amidocarbonyl(cyano)nitrosomethanide and teaH[sub 2][sup -] = singly deprotonated triethanolamine). The reaction of Cu[sup II] with dicyanonitrosomethanide (dcnm) and m-xylenediamine in a basic MeOH/MeCN solution results in the formation of [Cu[sub 3](cimm)[sub 2](a3acnm)[sub 2]] * 6MeCN (2) (cimm = cyano(imido(methoxy)methyl)nitrosomethanide and a3acnm = {amino(3-aminomethylphenyl)methylimino}methyl(cyanonitrosomethanide)). Both complexes display linear trinuclear Cu[sup II] metallic cores. Solid state DC magnetic susceptibility studies were performed on 1 and 2. Compound 1 revealed very strong antiferromagnetic interactions between central and terminal Cu atoms, while compound 2 displayed ferromagnetic interactions because of the orthogonal relationship of the terminal CH12100_IE1.gif and the central CH12100_IE2.gif 'magnetic' orbitals, which contrasts with these orbitals being coplanar in 1 thus providing strong superexchange pathways involving Cu-N-O-Cu moieties. Two novel trinuclear Cu[sup II] complexes have been synthesised from the nucleophilic addition derivatives of the small nitrile anion, dicyanonitrosomethanide (dcnm). [ABSTRACT FROM AUTHOR]