Crystal structure of bis(O,O'-tetraisopropylmethylenediphosphonate) trinitrate neodymium(III), Nd(NO3)3[(iPrO)2POCH2PO(OiPr)2]2

Abstract

Source of materialNd(NO 3)3 ·n H 2 O( 0.1797 g, 0.4 mmol) was dissolved in 5m l pyridine. Then tetrakis(O-isopropyl)-methylenediphosphonate (L =( i PrO) 2 P(O)CH 2 P(O)( i PrO) 2 ;0 .0689 g, 0.2 mmol) which was dissolved in 5m lm ethylene dichloride was added under stiring. After three hours stiring, phen(1,10-phen-anthroline; 0.0793 g, 0.4 mmol) was added as the second ligand, the clear pink solution was stirred for another 6hours at room temperature. Pink crystals [Nd(NO 3 ) 3 (L) 2 )] were obtained by chance through slowly evaporation of the solvent in the refrigerator. DiscussionLanthanide diphosphonate complexes have been widely studied in recent years and resulted in variety of structure types for the diphosphonate, which may be coordinated simultaneously to lanthanide ions in three different modes [1]. But the diphosphonate ligands in the compounds reported with crystal structure show only the chelating mode by now. As ac onsequence, the complexes form often dinuclear dimers, polymeric chain or network structures which are directed by the choice of metal and reaction conditions. If another ligand containing aromatic ring is added as an auxiliary one, the complexes obtained enhance the fluorescent properties and control the dimensionality. We have been interested in lanthanide with methylenediphosphonate complexes [2]. By attempt to synthesize Nd complex with mixed ligands tetrakis(O-isopropyl)methylene-diphosphonate (= L) and phen in am ild condition, an unexpected compound [Nd(NO 3 ) 3 (L) 2 )] is obtained. The single crystal X-ray study shows that there are two kind of crystals mixed equally in one pot, one is [Nd(NO 3)3(L)2)], the other is made up of phen Nd 3+ and (] is a mononuclear complex. The neodymium ion is coordinated by ten oxygen atoms, four from two Lligands, the other six from three nitrate ions. The NdO 10 coordination motif is best described as a distorted bi-capped square antiprism. The average neodymiumoxygen(P) bond distances of 2.473 Å in the title compound is slightly longer than the average value of 2.438 Å reported for the complexe . The bidentate nitrate ion shows neodymium-oxygen(N) bond distances of 2.580 Å which is almost equal to the average value of 2.588 Å [4]. The ∠O7−Nd1−O8 (47.92°) in the title compound is ab it wider than the ∠O3−Nd1−O4 (48.21°), and ∠O10−Nd1− O10' (49.53°) is almost equal to ∠O1−Nd1−O1' (49.40°) [4]. The ligands are disposed in afacial arrangement with ∠N−Nd−Nbeing slightly narrower than90°, with an average of 87.25°, whilst the ∠(P)O−Nd−O(P) display anarrow angle of 74.32°. This appear to be an electrostatic rather than steric effect, with the repulsions from two negative oxygen atoms per nitrate ion dominating the increased repulsions from the bulky diphosphonate groups. There is no hydrogen bond observed in the title compound. The high Riscaused by the crystal internal factors. Because the isopropyl group from the phosphate is bounded, thermal vibration of the carbon atoms from isopropyl group is severe.