Synthesis and structural characterization of layered metal phosphonates, metal phosphites, and their intercalation compounds

Abstract

Two types of layered lanthanum phosphonates have been prepared and characterized by XRD, TGA, NMR and ER. The one form ed at pH< 3 has a composition of LaH(C>3 PR)2 (R= CH3, C2H 5 , C^Hs) and the other prepared at pH > 8 has the composition of La2 (0 3 PR)3 3 H2 O. Single crystals of lanthanum phenylphosphonate, L aH tO sP C ^H s^ were obtained and its structure determ ined. The structure is a layered one in which the La atoms are 8 -coordinate. The phenyl rings protrude into the interlam ellar space. Two copper phosphonates, Cu(0 3 PCH3 ) H 2O and CufC^PC^Hs) H 2O, have been synthesized and their structures determ ined. Cu(0 3 PC H 3 ) H 2O is layered with a interlayer distance of 8.5 A. Each Cu atom is 5-coordinated in a distorted tetragonal pyram idal configuration. Cu((>jPC6 H 5 ) H2O is also a layered com pound w ith an interlayer distance of 13.99 A. The coordination about the copper atoms and the layer structure are identical to those of the m ethvlphosphonate com pound. D ehydration of layered copper phosphonates Cu(0 3 PR)*H2 0 (R=CH3 , C6 H 5, CH 2C6H 5 ) yields layered anhydrous salts Cu(C>3PR) which show an increase of m ore than 1 A in interlayer spacing com pared to its monohydrate. Prim ary amines CnH 2 n+iN H 2 (n=3-8) were intercalated into Cu(0 3 PCH3> and Cu(0 3 PC6 H 5 ). The copper m ethylphosphonate takes up 1 mole of am ine form ing Cu(C>3 PC H 3 ) (RNH2 ), while 2 moles of amine were absorbed by copper phenylphosphonate. The alkyl chains of the am ine are packed as double layers w ith a tilt angle of 53° w ith respect to the mean plane of the layer. Both dehydrated and hydrated zinc phenylphsophonates are reactive towards prim ary amines. 1 mole of amine is intercalated forming layered com pound w ith composition of Zn(0 3 PC6 Hs) (RN H 2 ) in both cases. Two lanthanide phosphites, CeH(C>3 PH)2 2 H 2O and LaH(C>3PH)2 3 H 2O were prepared and their structures determined. Both of the structures are layered. Each lanthanide atom is 8 -coordinated by 7 phosphite oxygen atoms and 1 w ater molecule. The rest of water molecules reside between the layers.