Influence of the counter anion and solvent in the structure of copper derivatives with the 2,3-bis(2-pyridyl)pyrazine ligand

摘要: Abstract Several compounds have been isolated from the reaction between different copper bis(acetylacetonato) derivatives and potentially bridging ligand 2,3-bis(2-pyridyl)pyrazine (bppz). A compound of formula [Cu(tfacac)2(bppz)] (1) is obtained when substituted trifluoromethylacetylacetonato used. The use anions unsubstituted acetylacetonato give rise to new general [{Cu(acac)}2(μ-bppz)2]X2 (X− = BF4−, 2; PF6−, 3; BPh4−, 4). In these bppz acting as a bridge by chelating one atom bonding monodentate second atom. presence with coordination abilities introduces variations in environment geometry. When non-coordinating tetraphenylborate used depending on nature solvent are obtained. dimer 4 was methanol/chloroform mixture, while absence chloroform monomeric [Cu(acac)(bppz)(ROH)](BPh4)·ROH (ROH = MeOH, 5) ethanol instead methanol analogous derivative 6 (R = EtOH) isolated. Both species show mononuclear structure five-coordinated acac ligands hydroxo group occupying apical position. similar for appears [Cu(tfacac)(bppz)(MeOH)](BPh4), 7, which shows dimeric through hydrogen bonds interactions. magnetic susceptibility data very weak antiferromagnetic interactions atoms, an expected fact since not planar but pyridine more or less perpendicular other two aromatic rings, precluding spin exchange via π electrons.