<b>Synthesis, crystal structure and magnetic properties of [Cu(mal)(abpt)(H₂O)].3/2H₂O and [Cu₂(sq)(abpt) ₂].2H₂O (mal = malonate, sq = squarate, abpt =4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole)</b>

Abstract

Two new mixed-ligand complexes of formula [Cu(mal)(abpt)(H2O)].3/2H2O (1) and [Cu2(sq)(abpt)2].2H2O (2) [mal = malonate, abpt = 4-amino-3,5-di-2-pyridyl-4H-1,2,4 triazole and sq = squarate], have been prepared and characterized by X-ray crystal structure determination and magnetic studies. Complex 1 crystallizes in the monoclinic system, space group C2/c, with a = 14.0086(2) Å, b = 10.0980(2) Å, c = 25.630(4) Å; β = 97.5900(10) o , and Z = 8. Complex 2 crystallizes in the triclinic system, space group P-1 with a = 7.5696(15) Å, b = 8.4697(17) Å, c = 11.049(2) Å; β = 93.00(3) o , α = 96.98(3), γ = 90.111(3) and Z = 1. Complex 1 consist of a neutral mononuclear [Cu(mal)(abpt)(H2O)] unit and water molecule of crystallization in a distorted square pyramidal coordination sphere, while complex 2 is viewed as being made up of [Cu(sq)(abpt)2] units with the squarato ligand bridging the two copper(II) cations. Variable temperature magnetic behaviour of the complexes reveals the existence of weak antiferromagnetic interaction for complex 1 and weak ferromagnetic intrachain interaction for complex 2.

Polynuclear and polymeric squarato-bridged coordination compounds

“…This category represents not only the major species for the bis-μ 1,3 but also for the rest of the bridging-squarato compounds. It includes mono-squarato catena -[M II (μ 1,3 -C 4 O 4 )(DMSO) 2 (H 2 O) 2 ] 37–65 {M = Mn, Co, Zn ( 18–20 )}, 37 catena -[Cu 2 ( 2 , 2 ′- bpy ) 2 (μ 1,3 -C 4 O 4 )(μ-OH) 2 ]·4H 2 O ( 21 ), 35 b [M II (L) x (μ 1,3 -C 4 O 4 )(H 2 O) y ] 37–65 where L = py, x = y = 2: M = Co, Ni, Cu, Zn ( 22–25 ); 38 L = H 2 O, x = y = 2: M = Mn, Fe, Co, Ni, Cu, Zn ( 26–30 ); 27,42 L = 4-Meim: M = Co, Ni, Cd, x = y = 2 ( 31–33 ); 44,46 L = 2-Meim, M = Co, x = y =2 ( 34 ); 46 L = 4-pyca, x = y =2: M = Co, Cu ( 35 , 36 ); 49 L = DMF: M = Mn, Co, Ni, Cu, Zn, x = y = 2 ( 37–41 ); 51,52 L = pz, M = Ni, x = y =2 ( 42 ); 51,52 L = 1-Meim, x = y =2: M = Zn, Cd ( 43 , 44 ); 53 L = bpp, x = y = 2: M = Mn, Fe, Co 45–47 ); 54,55 L = im, x = y = 2: M = Co, Cu, Zn ( 48–50 ); 27,56 L = DPA, M = Zn, x = y =1 ( 51 ); 11 L = Me 4 en, x = 1, y = 2, M = Ni ( 52 ); 45 L = 3-pypz, x = 2, y = 0, M = Cd ( 53 ); 48 L = L 1 , x = 2, y = 0, M = Cu ( 54 ); 57 L = L 2 , x = 2, y = 0, M = Ni ( 55 ); 44 L = L 3 , x = y = 1, M = Cu ( 56 ); 58 L = pic, x = 2, y = 0: M = Cu, Zn, Cd ( 57–59 ); 59 a L = ea, x = 2, y = 0, M = Cu ( 60 ); 60 L = 2-pEtOH, x = 2, y = 0, M = Cu ( 61 ); 61 L = bimam, x = 2, y = 0, M = Cu ( 62 ) 62 and catena -[Cu 2 (bimam) 2 (μ 1,3 -C 4 O 4 )Cl 2 ] ( 63 ), 63 as well as bis-squarato catena -[M II (μ 1,3 -C 4 O 4 ) 2 (H 2 O) 2 ] 2− (M = Ni, Cu, Zn, Mn and Cd ( 64–68 )) complexes. …”