title: Synthesis, structural and magnetic characterisation of iron(II/III), cobalt(II) and copper(II) cluster complexes of the polytopic ligand: N-(2-pyridyl)-3-carboxypropanamide.
abstract: Herein we describe the synthesis, structural and magnetic characterisation of three transition metal cluster complexes that feature the polytopic ligand N-(2-pyridyl)-3-carboxypropanamide (H2L): [Fe3(III)Fe2(II)(HL)6(O)(H2O)3][ClO4]5·3MeCN·4H2O, 1, [Co8(HL)8(O)(OH)4(MeOH)3(H2O)]-[ClO4]3·5MeOH·2H2O, 2, and [Cu6(L(ox))4(MeOH)(H2O)3]·MeOH, 3. Complex 1 is a mixed valence penta-nuclear iron cluster containing the archetypal {Fe3(III)O} triangular basic carboxylate cluster at its core, with two Fe(II) ions above and below the core coordinated to three bidentate pyridyl-amide groups. The structure of the octanuclear Co(II) complex, 2, is based upon a central Co4 square with the remaining four Co(II) centres at the 'wing-tips' of the complex. The cluster core is replete with bridging oxide, hydroxide and carboxylate groups. Cluster 3 contains an oxidised derivative of the ligand, L(ox), generated in situ through hydroxylation of an α-carbon atom. This hexanuclear cluster has a 'barrel-like' core and contains Cu(II) ions in both square planar and square-based pyramidal geometries. Bridging between Cu(II) centres is furnished by alkoxide and carboxylate groups. Magnetic studies on 1-3 reveals dominant antiferro-magnetic interactions for 1 and 2, leading to small non-zero spin ground states, while 3 shows ferro-magnetic exchange between the Cu(II) centres to give an S = 3 spin ground state.
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Department of Chemistry, University of Canterbury, Private Bag 4800, Christchurch, 8041, New Zealand. paul.kruger@canterbury.ac.nz.
authors.forename: Mark E
authors.initials: ME
authors.lastname: Russell
authors.forename: Chris S
authors.initials: CS
authors.lastname: Hawes
authors.forename: Alan
authors.initials: A
authors.lastname: Ferguson
authors.forename: Matthew I J
authors.initials: MI
authors.lastname: Polson
authors.forename: Nicholas F
authors.initials: NF
authors.lastname: Chilton
authors.forename: Boujemaa
authors.initials: B
authors.lastname: Moubaraki
authors.forename: Keith S
authors.initials: KS
authors.lastname: Murray
authors.forename: Paul E
authors.initials: PE
authors.lastname: Kruger
mesh_terms: D003035:Cobalt / Q000737:chemistry*; D003300:Copper / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D060328:Magnetic Phenomena; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry*
chemical_list: C587382:N-(2-pyridyl)-3-carboxypropanamide; D009942:Organometallic Compounds; D011725:Pyridines; D003035:Cobalt; D003300:Copper; D007501:Iron