화학공학소재연구정보센터
Materials Research Bulletin, Vol.39, No.11, 1717-1722, 2004
One-dimensional lone electron pair micelles in the crystal structure of Pb-5(SiO4)(VO4)(2)
The structure of Pb-5(SiO4)(VO4)(2) (hexagonal, P6(3)/m, a = 9.9865(11), c = 7.3599(12) Angstrom, V = 635.67(14) Angstrom(3), Z = 2) has been solved by direct methods and refined to R-1 = 0.051 on the basis of 440 unique observed reflections with \F-o\ greater than or equal to 4sigma(F). The compound belongs to the apatite structure type. The Pb coordination polyhedra are distorted due to the presence of stereoactive lone electron pairs Psi. The structure contains channels running along the c axis and centered at (00z). The channels are most probably occupied by the lone electron pairs of the Pb2+ cations and thus represent lone electron pair micelles. The existence of such micelles in the structure may well be the reason for the electrogyratory effect and protonic conductivity observed in crystals of the title compound. (C) 2004 Published by Elsevier Ltd.