Novel linear transition metal clusters of a heptadentate bis-beta-diketone ligand.
The synthesis and the structure of the new potentially heptadentate ligand 1,3-bis-(3-oxo-3-(2-hydroxyphenyl)-propionyl)-2-methoxybenzene (H5L) is described. The reaction in pyridine or DMF of this ligand with various M(AcO)2 salts (M = NiII, CoII, MnII) leads to very different products depending on the metal. Thus, the dinuclear complexes [M2(H3L)2(py)4] (M = NiII, 1; CoII, 2) or the linear zigzag tetranuclear clusters [Mn4(H2L)2(AcO)2(py)5] (3) and [Mn4(H2L)2(AcO)2(dmf)4] (4) have been synthesized and characterized crystallographically. Slow oxidation of complex 3 leads to the formation of the novel mixed-valence linear complex [Mn3(HL)2(py)6] (5), displaying an unprecedented asymmetric MnIIIMnIIIMnII topology. The coordination geometry of complexes 1 to 5 has been analyzed and discussed by means of continuous shape measures. Magnetic measurements of 3 and 5 demonstrate that the metals within these complexes weakly interact magnetically with coupling constants of J1 = -1.13 cm-1 and J2 = -0.43 cm-1 (S = 0) for complex 3 and J1 = -5.4 cm-1 and J2 = -0.4 cm-1 (S = 5/2) for complex 5 (using the H = -Sigma2JijSiSj convention). These results are consistent with X-band EPR measurements on these compounds.
Aromí
Guillem
G
Departament de Química Inorgànica, Universitat de Barcelona, Diagonal 647, 08028 Barcelona, Spain. guillem.aromi@qi.ub.es
Gamez
Patrick
P
Krzystek
J
J
Kooijman
Huub
H
Spek
Anthony L
AL
MacLean
Elizabeth J
EJ
Teat
Simon J
SJ
Nowell
Harriott
H
D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D007659:Ketones / Q000737:chemistry*; D008024:Ligands; D008968:Molecular Conformation; D015394:Molecular Structure; D028561:Transition Elements / Q000737:chemistry*
D007659:Ketones; D008024:Ligands; D028561:Transition Elements