Synthesis and characterisation of new Ni2Mn, Ni2Mn2 and Mn8 clusters by the use of 2-pyridyl oximes

The initial employment of methyl 2-pyridyl ketoxime, (py)C(Me)NOH, in mixed metal Ni/Mn cluster chemistry, provided access to complexes [(Ni2MnIII)-Mn-II(PY)C(Me)NO)(6)](ClO4) (1) and [(Ni2Mn2III)-Mn-II{(PY)C(Me) NO)(6)(OMe)(2)(MeOH)(2)](ClO4)(2) (2) that display a linear and a zig-zag metal arrangement, respectively. I and 2 are synthesized by reacting Ni(ClO4)(2)center dot 6H(2)O, (py)C(Me)NOH, Mn(ClO4)(2)center dot 6H(2)O and NaOMe in different molar ratios (2:6:1:6, 1; 1:3:1:3, 2) in Me0H, and they are the first examples of 3d-3d' mixed -metal clusters bearing (py)C(Me)NOH. The employment of phenyl 2-pyridyl ketoxime, (py)C(ph)NOH, instead of (py)C(Me) NOH, provided access to the octanuclear homometallic compound [(Mn4Mn4O4)-Mn-II-O-III(NO3)(2){(PY)C(ph) NO)(8)(HCO2)(2)(MeOH)(2)] (3) that possesses a double-butterfly {(Mn4Mn4III)-Mn-III(mu(4)-O)(2)(mu(3)-O)(2))(12+) core. 3 joins the small family of Mni(py)C(ph)NO- clusters. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on 1 and 2 and revealed the presence of antiferromagnetic exchange interactions between the metal ions (J(Mn-Ni) = -6.34 +/- 0.14 cm(-1) in 1; J(Mn-Ni) = -4.57 +/- 0.08 cm(-1), J(Mn-Mn) = -12.72 +/- 0.12 in 2) and a diamagnetic ground state for both compounds. (C) 2019 Elsevier Ltd. All rights reserved.