Crystal and molecular structure and magnetism of (.mu.-terephthalato)bis[(N-(2-diethylamino)ethyl)salicylidenaminato)copper(II)]-water-methanol

Abstract

The crystal and molecular structure of (p-terephthalato)bis[ (N-(2-(diethylamino)ethyl)salicylidenaminato)copper-(11)-water-methanol, [ C U~( S~~N E~~)~( C~H~~~) ]~H~~~C H~~H ,where SalNEtz = N-(2-(diethylamino)ethyl)-salicylidenaminate, has been determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P21/c, with a = 7.379(1) A, b = 7.546(2) A, c = 33.783(6) A, and 8-100.40(1)0. In the molecular structure of this centrosymmetric compound the two equivalent copper(I1) ions are bridged by the terephthalato ligand coordinated in an amphimonodentate mode. The local geometry around both copper(I1) ions is square planar, whereas two noncoordinated molecules, namely a water and a methanol molecule, are also present.The fitting of the variable-temperature magnetic susceptibilitiy data to the HDVV (H = 2&$), S1 = Sz = spin exchange model yields a 2Jvalue of 0.6 cm-l. The results of extended Huckel calculations on a model compound are consistent with the existense of accidental orthogonality between the magnetic orbitals.

μ‐1,3‐ (trans) and μ‐1,2‐ (cis) Bonding in Squarato‐Bridged Dinuclear Copper(II) and Nickel(II) Complexes Derived from Polypyridyl Amines

“…This was attributed to the large delocalization in the SOMOs of µ-1,2-squarato compounds compared to those of µ-1,3-squarato compounds. [16] Aside from this trend, very weak ferromagnetic interaction has been reported in [Cu 2 (bpcam) 2 …”

“…In general, the dinuclear copper(II) complexes with the µ-1,3-squarato bonding are usually antiferrromagnetically coupled with |J| values in the range of 0-8.6 cm -1 . [2,5,10,14,18] The µ-1,2-squarato-bridged compounds show higher |J| values [2,16,10,14,18] in the range Scheme 1. of 10.3-26.4 cm -1 . This was attributed to the large delocalization in the SOMOs of µ-1,2-squarato compounds compared to those of µ-1,3-squarato compounds.…”

“…The presence of four donor oxygen atoms and the richness of the electron density on the squarate dianion enhance its capability to simultaneously bind more than one metal ion, hence acting as a bridging ligand. The bridging squarato ligand affords three types of coordination modes known as µ-1,3-(trans), [2][3][4]6,16,22] µ-1,2-(cis), [2,5,8,9,13,14,16,18] and µ- ronment in 2 is achieved by the three N-atoms of the MeDPA ligand, by an oxygen atom of a bridging squarato ligand and, at longest distances, by two oxygen atoms from coordinated water molecules. In the nickel complex 3, the geometry is attained by the four N-atoms of TPA and by two oxygen atoms supplied by a coordinated water molecule and by a bridging squarato ligand.…”

A Structural and Magnetic Investigation of Ferromagnetically Coupled Copper(II) Isophthalates

“…[3][4][5][6] Alhough magnetic interactions transmitted through phenyldicarboxylate bridges are usually weak, [2,[6][7][8] the magnitude and nature of the coupling interactions can be influenced by a series of factors, such as the separation of the metal centers, bridging modes, degree of coplanarity between the coordination basal planes and the ligand, the dihedral angles between the carboxylato planes and the phenyl ring, and the angle between the planes of the two carboxylato groups of each phthalato bridge. [9][10][11][12] In copper phthalates, magnetic systems with terephthalate as bridges are the most abundant, whereas those with isophthalate have been less widely re-isophthalate anion acts as a bis(monodentate) ligand bridging copper(II) centers. The variable temperature magnetic behavior reveals the existence of ferromagnetic interactions in 1-3.…”

Syntheses, Crystal Structures, and Magnetic Properties of Carboxylate-Bridged Copper(II) Complexes with Bis(2-Pyridylmethyl)Amino Acids

“…Similar results are also reported through the carboxylate-bridged copper(II) complexes Table V, the values of the ferromagnetic coupling constant (J) for compounds 1 and 2 are considerably smaller than for {[Cu(µ-papa)(H 2 O)](ClO 4 )·2H 2 O} n . The weak magnetic interaction may be due to the long intramolecular Cu···Cu distance [13,29]. However, the J value for compound 2 is slightly larger than that of 1, even though 2 has the long intrachain Cu···Cu distance compared with 1.…”