Copper tetrafluoroborate complexes of the potentially binucleating ligand 1,4-di(2′-pyridyl)aminophthalazine. Mononuclear and polynuclear derivatives

Three different copper tetrafluoroborate complexes are obtained from the reaction of copper tetrafluoroborate and the title ligand (PAP) in water. Two crystalline modifications of a six-coordinate mononuclear protonated derivative, [Cu(PAPH)2(H2O)2](BF4)4, a triclinic brown form (I) and a monoclinic green form (II), and a dark green polynuclear complex containing neutral ligand and formulated as [Cu3(PAP)2(OH)2](BF4)(BF3OH)3•5H2O (III), are obtained from the same reaction mixture. The hydrolysis of BF4− in water is thought to be responsible for the formation of protonated PAP. In methanol a four-coordinate protonated derivative, [Cu(PAPH)2](BF4)4 (IV) and a binuclear complex [Cu2(PAP)2(H2O)2](BF4)4•0.5MeOH (V), containing neutral ligand, are obtained. The molecular structures of both forms of [Cu(PAPH)2(H2O)2](BF4)4 have been determined by single crystal X-ray diffraction. The brown triclinic form (I) belongs to space group with a = 9.856(1), b = 12.724(1), c = 9.401(1) A, α = 101.691(8), β = 96.717(9), γ...