Employment of methyl 2-pyridyl ketone oxime in manganese non-carboxylate chemistry: MnII2MnIV and MnII2MnIII6 complexes

Abstract

The employment of the anion of methyl 2-pyridyl ketone oxime (mpko(-)) as a tridentate chelating/bridging ligand in manganese chemistry is described. The inorganic anion (Br(-), ClO(4)(-)) used in the reaction affects the identity of the product. The reaction of MnBr(2) and one equivalent of mpkoH in the presence of a base affords [Mn(3)(OMe)(2)(mpko)(4)Br(2)] (3), which is mixed-valence (2Mn(II), Mn(IV)). The central Mn(IV) atom in each of the two, crystallographically independent, centrosymmetric molecules is coordinated by four oximate oxygen atoms belonging to the eta(1):eta(1):eta(1):mu mpko(-) ligands, and two eta(1):mu MeO(-) groups, while six coordination at each terminal Mn(II) atom is completed by four nitrogen atoms belonging to the 'chelating' part of two mpko(-) ligands, and one Br(-) ion. The Mn(II) atoms have trigonal prismatic coordination geometry. The reaction of Mn(ClO(4))(2).6H(2)O, mpkoH and OH(-) (1:2:1) in MeOH gives [Mn(8)O(4)(OMe)(mpko)(9)(mpkoH)](ClO(4))(4) (4), which is also mixed-valence (2Mn(II), 6Mn(III)) and possesses the novel [Mn(8)(mu(3)-O)(4)(mu-OMe)(mu-OR'')(2)](11+) core. The latter possesses a U-shaped sequence of four fused {Mn(II)Mn(III)(2)(mu(3)-O)}(6+) triangular units, with a Mn(III)-Mn(III) edge being shared between the central triangles. Variable-temperature, solid-state dc and ac magnetic susceptibility studies were carried out on complexes 3 and 4 . The dc susceptibility data for 3 in the 5.0-300 K range have been fit to a model with two J values, revealing weak ferromagnetic Mn(II)Mn(IV) (J = +3.4 cm(-1)) and Mn(II)Mn(II) (J' = +0.3 cm(-1)) exchange interactions. Fitting of the magnetization vs. H/T data by matrix diagonalization and including only axial anisotropy (ZFS, D) gave ground state spin (S) and D values of S = 13/2, D = +0.17 cm(-1) for and S = 3, D = -0.09 cm(-1) for 4 . The combined work demonstrates the usefulness of mpko(-) in the preparation of interesting Mn clusters, without requiring the co-presence of carboxylate ligands.

Employment of methyl 2-pyridyl ketone oxime in 3d/4f-metal chemistry: dinuclear nickel(ii)/lanthanide(iii) species and complexes containing the metals in separate ions

“…This shift to higher wavenumbers has been 75 discussed, and is in accord with the concept that upon deprotonation and oximate-O coordination there is a higher contribution of N=O to the electronic structure of the oximate group; consequently the v(NO) vibration shifts to a higher wavenumber in the complexes containing mpkorelative to 80 mpkoH. 34 The spectra of 1-15 (Fig. S4) exhibit a strong band at ~1100 cm -1 and a medium band at ~625 cm -1 , due to the v 3 …”

“…In the spectra of dried 1-10 the v(OH) band (resulting from the neutral oxime groups of the mpkoH ligands and the lattice H 2 O that is present in the analytically pure samples) appears at ~3415cm -1 . 34,35 The in-plane deformation of the 2pyridyl ring of free mpkoH at 632 cm -1 shifts upwards in the 65 complexes (~680 cm -1 ) confirming the involvement of the ring Natom in coordination. 36 Several bonds appear in the 1630-1400 cm -1 region in the spectra of the complexes.…”

Oxygen Atom Transfer and Oxidative Water Incorporation in Cuboidal Mn3MOn Complexes Based on Synthetic, Isotopic Labeling, and Computational Studies

“…Antiferromagnetically coupled manganese clusters in the literature have also shown significant deviation at 300 K from the expected spin-only value. [16][17][18][19][20] …”

Mononuclear and Dinuclear Manganese(II) Complexes from the Use of Methyl(2‐pyridyl)ketone Oxime

“…The structurally characterized Mn complexes of (py)C(Me)NOH and/or (py)C(Me)NO − [14, 31–33] are collected in Table 6, together with the cores of the polynuclear complexes and the ligands' coordination modes for convenient comparison. Closer inspection of Table 6 reveals that compound 1 is the first member of this subfamily in which the Mn II ions are linked by the SO 4 2− ion.…”