Studies on the Effect of Various Anions and Pyridine on the Stereochemistry of Lanthanide(III) Coordination Compounds of 4[N-(2′-Hydroxy-1′-Naphthalidene)Amino] Antipyrine Thiosemicarbazone

Abstract

In the present studies, the effect of pyridine on stereochemistry of the coordination compounds of lanthanide(III) derived from 4[N-(2′-hydroxy-1′-naphthalidene)amino] antipyrine thiosemicarbazone (HNAAPTS) has been studied. The general composition of the present complexes is LnX3·n(HNAAPTS)·Py (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy, or Ho; X = NO3, n = 1, x = Cl, NCS or ClO4, n = 2, Py = pyridine). All the complexes were characterized by elemental analyses, molecular weight, molar conductance, magnetic susceptibilities, infrared and electronic spectral studies. The infrared studies reveal that the HNAAPTS behaves as a neutral tridentate (N, N, S), while pyridine is coordinated to metal ions via its nitrogen atom. Nitrates are bicovalently bonded, while thiocyanate is coordinated through a strong N-atom. Perchlorate ions are not coordinating in coordination sphere. From electronic spectral data, nephelauxetic effect (β), covalence factor (b½), Sinha parameter (δ%), and the covalence angular overlap parameter (η) have been calculated. Thermal stabilities of these complexes were studied by thermogravimetric analysis. In conclusion, the coordination number of lanthanides(III) in the present compounds is either seven or ten depending on the coordinating anions. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.