Linear Tetranuclear Copper(II) Complexes with Bridging Methoxide and a Schiff-Base Ligand: The Preparation and Magnetic Study of the [Cu(salpd-μ-O,O′)(μ-L)Cu(μ-CH3O)2Cu(μ-L)(sapd-μ-O,O′)Cu] Complexes (and L=Acetate or Formate Ions) and the Structure Determination of the Complex with L=Acetate

Abstract

The title complexes have been synthesized in quantitative yield from [Cu(salpd)] and copper(II) acetate or copper(II) formate , where H2salpd represents N,N′-disalicylidene-1,3-propanediamine. [Cu(salpd-μ-O,O′)(μ-L)Cu(μ-CH3O)2Cu(μ-L)(salpd-μ-O,O′)Cu] crystallizes in the monoclinic space group P21/n with formula=Cu4C40H44N4O10, F.W.=995.0, a=11.826(2) Å, b=17.192(4) Å, c=9.836(2) Å, β=94.08(2)°, V=1994.8(7) Å3 and Z=2 (R=3.83%), where L=CH3COO. The complex forms a centrosymmetric molecule made up of two units of [Cu(salpd-μ-O,O′)(μ-CH3COO)Cu] bound by a pair of methoxo bridges; each terminal copper(II) ion forms four short bonds with N and O atoms of salpd and a slightly longer (2.235(4) Å) axial bond with one of the oxygens of the acetato group, whereas each inner copper(II) ion is also pyramidally coordinated by two methoxo oxygens, one of the acetato oxygens, and one of the bridging salpd oxygens, the distant axial position being occupied (Cu–O=2.323(3) Å) by the remaining bridging salpd oxygen. The magnetic susceptibilities of the complexes in the 86.8–299.0 K range have been analyzed on the basis of a four-spin model for the linear copper(II) complexes, and the values of g and Jij, based on the Heisenberg-type Hamiltonian H=−2ΣJijSi·Sj, have been estimated as g (average)=2.13, J12=−390 cm−1, J13=67 cm−1 and J14=34 cm−1 in the complex with acetate bridges, and as g (average)=2.20, J12=−263 cm−1, and J13=39 cm−1 and J14=J34=0 cm−1 in the complex with formate bridges, where the numbering refers to the 3–1–2–4 arrangement of the Cu2+ ions.

Syntheses, structures and magnetism of linear tri- and tetra-copper chains containing anions of N,N′-bis(pyrimidine-2-yl)formamidine

“…for 2 and 2.732(1) and 2.827 with the N(10)-Cu(1)-N(24) angles of 128.19(2) for 1, 127.54 (12) for 2 and 128.17(15) • for 3, which deviate significantly from linearity. The Cu(1)-N distances to the nitrogen atoms located in the basal planes [1.972(5)-2.116(6) A ˚for 1; 1.989(4)-2.086(4) A for 2; 1.983(4)-2.127(4) A ˚for 3] are shorter than those to the axial nitrogen atoms [2.429(5) and 2.564(3) A ˚for 1; 2.461(3) and 2.545(4) A ˚for 2; 2.413(4) and 2.586( 4 3)-N distances to the nitrogen atoms located in the basal planes [2.005(6)-2.040(6) A ˚for 1; 2.011(4)-2.030(4) A ˚for 2; 1.997(4)-2.054(4) A ˚for 3] are shorter than those to the apical nitrogen atoms [2.462(6) A ˚for 1; 2.512(4) A ˚for 2; 2.473(4) A ˚for 3].…”

“…While one pmf − ligand adopts the new coordination mode Fig.2(b), with the two amine nitrogen atoms chelating to the central copper atom, the other three feature chelation by one pyrimidyl and one adjacent amine nitrogen atoms, Fig.2(c). The Cu(1) atom has a distorted octahedral geometry and the trans angles of the basal planes [formed by N(6), N(12), N(18) and N(22)] are 162.7(2) and 172.4(2) for 1,163.13(14) and 170.21(14) for 2 and 160.93(15) and 173.07(15) • for The axial positions are occupied by N(10) andN(24)…”

“…(d) adopted by the pmf − ligands in 5, resulting in better coupling of the spins. For the linear tetranuclear Cu(II) complex [Cu(salpd-l-O,O )(l-O 2 CMe)Cu(l-CH 3 O) 2 Cu(l-O 2 CMe)(salpd-l-O,O )Cu] (H 2 salpd = N,N -disalicylidene-1,3propanediamine),12 the calculation yielded g = 2.13, J 12 (inner copper pair) = −390 and J 13 (outer adjacent copper pairs) = 67 cm −1 ,…”

Syntheses, Crystal Structures, Magnetic Properties, and EPR Spectra of Tetranuclear Copper(II) Complexes Featuring Pairs of “Roof-Shaped” Cu2X2 Dimers with Hydroxide, Methoxide, and Azide Bridges

“…Hydroxo-and alkoxo-bridged Cu(II) complexes exhibit magnetic behavior ranging from ferromagnetic to antiferromagnetic depending on the geometry of the Cu 2 (OR) 2 (R ) H, alkyl, aryl) bridging units. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] These studies have established that the type and magnitude of the interaction is influenced by the M‚‚‚M separation, the M-O(bridge) distance, the M-O-M angle (θ), the dihedral angle between the planes formed by the two adjoining CuO units in a Cu 2 O 2 core, the out-of-plane displacement of substituents on the bridging groups, and the Cu(II) center geometry. Recently, Ruiz et al 10 have applied density functional (DFT) methods 10 angle and the out-of-plane displacement.…”

Metal complexes formed by metal-assisted solvolysis of di-pyridylketone azine: structures and magnetic properties

“…Hydroxoand alkoxo-bridged Cu(II) complexes exhibit magnetic behaviour ranging from the antiferromagnetic to ferromagnetic depending on the geometry of Cu 2 (OR) n (n = 1 and 2, R = H, alkyl, aryl) binding units. [16][17][18][19][20][21][22][23][24][25][26][27][28] The well-studied hydration reaction of the di-pyridylketone (dpk) ligand has been implemented to construct several metal clusters, in which the two pyridyl N atoms and the gem-diol obtained from metal-promoted hydration act as four potential donor sites and the resulting M(II)-dpk-azide (M = Co, Ni) compounds have been characterized so far to be isomorphous. 14c, 29 Herein, an analogous hydration reaction would be expected using di-pyridylketone azine (dpka) (Scheme 1) for the assembly of metal clusters and the hydration or solvolysis reaction will occur at the imino group to widen the range of structural arrangements.…”