Synthesis and magnetic properties of a binuclear copper(II) complex with a .mu.-1,2-squarato coordination mode. Crystal structure of (.mu.-1,2-squarato)bis[(N-(2-(diethylamino)ethyl]salicylidenaminato)aquacopper(II)] hydrate

Polynuclear and polymeric squarato-bridged coordination compounds

“…when the squarate is in the μ 1,2 -bisIJmonodentate) bonding mode. 81,[132][133][134] Another parameter which should be considered here is the intradimer M⋯M distance across the bridging squarato in the two coordination modes. Inspection of the data in Table 5 reveals that long separation is observed in the μ 1,3 -squarato complexes, where dIJM⋯M) > 7.4 Å compared to dIJM⋯M) < 6.7 Å, which were found in the corresponding μ 1,2 -squarato complexes.…”

Structural characterization of μ1,2- and μ1,3-bridged-squarato 1D metal(II) coordination polymers

“…The failure of the squarate to promote significant exchange interaction was attributed to the strong stabilization of the ligand orbitals by the large p-delocalization within the squarate ring [38][39][40]. The extended Hückel calculations performed on squarate dianion compounds on both delocalized (D 4h ) and localized (C 2m ) forms and on model complexes with squarate acting in l 1,3 -and l 1,2 -revealed that larger localization on the oxygen atoms of C 4 O 4 2À dianion (l 1,2 -bis(monodentate) bonding mode) enhances the exchange interaction [40][41][42][43].…”

Syntheses, Structures, and Magnetic Properties of Two 1D, Mixed‐Ligand, Metal Coordination Polymers, [M(C4O4)(dpa)(OH2)] (M = CoII, NiII, and ZnII; dpa = 2,2'‐dipyridylamine) and [Cu(C4O4)(dpa)(H2O)]2·(H2O)

“…In the equatorial plane, Cu(1) is bonded to two nitrogen atoms of dpa and two oxygen atoms of the two squarate ligands, while Cu(2) is bonded to two nitrogen atoms of dpa and two oxygen atoms, one from C 4 Table 3 are similar to those found in some other squarate-bridged Cu complexes. [22][23][24][25][26]32,37] Hydrogen bonds also play an important role in the helical chain of compound 4. These include three O-H···O hydrogen bonds [O(11)-H(11a)···O (8), O(10)-H(10b)···O (11), and O(9)-H(9b)···O (2)] between water molecules and squarate ligands, with O···O distances …”

“…[19][20][21][22] The inter-chain interactions are through hydrogen bonds between the dpa nitrogen atoms in one chain and uncoordinated squarate oxygen atoms in the adjacent chain, with hydrogen-bonding distances N(2)-H(2a)···O (3) …”