A Novel Cadmium Aminophosphonate:  X-ray Powder Diffraction Structure, Solid-State IR and NMR Spectroscopic Determination of the Fine Structure of the Organic Moieties

Abstract

A new divalent cadmium phosphonate, Cd2Cl2(H2O)4(H2L), has been synthesized from the ethylenediamine-N,N'-bis(methylenephosphonic acid) (H4L). The obtained microcrystalline compound has been characterized by solid-state IR spectra and 13C, 31P, and 113Cd CP MAS NMR. The static 13P NMR spectra have been also recorded to give the delta11, delta22, and delta33 chemical shift parameters for both compounds. The spectral data, collected for Cd2Cl2(H2O)4(H2L), are in an agreement with its X-ray powder diffraction structure solved with the cell dimensions a = 16.6105(10), b = 7.1572(4), and c = 6.8171(4) A and beta = 98.327(4) degrees. The octahedral coordination sphere of the cadmium atoms consists of two phosphonate oxygen atoms, two water oxygen atoms, and the two chlorine atoms. Cadmium atoms are bridged by the chlorine atoms forming four-membered rings. The phosphorus atoms exhibit a tetrahedral coordination with two oxygen atoms bonded to the cadmium atoms with P-O distances of 1.503(10) and 1.504(10) A. The third oxygen atom, showing a longer P-O distance (1.546(9) A), is not bonded to the metal center, nor is it bonded to a proton. The combined IR and NMR proton-phosphorus cross-polarization kinetic data together with the X-ray data confirm that the cadmium phosphonate has the zwitterionic structure (NH2(+)CH2P(O2Cd2)O-) similar to the initial aminophosphonic acid H4L.

Ab‐initio Powder Structure Determination of Dichloro[1,2‐ethanediylbis(iminomethylene)bis(phosphonato)]trizinc Dihydrate

“…This led to the formation of Zn 3 Cl 2 (H 2 L) 2 ·2 H 2 O, whose structure, quite different from the previous cadmium structure, [9] is presented here as characterized by its X-ray structure derived from powder data and FTIR.…”

“…The zwitterionic structure of the compound could also be observed, in the region 3400-2500 cm -1 of the spectrum. In fact the NH stretching vibrations band is high-frequency shifted with much higher ∆ν (91 cm -1 ) value than the CdL 2 H 2 O [9] compound. At the same time, the ν(NH 2 + ) band belonging to acid H 4 L is still present in the spectrum.…”

“…The Cd complex is octahedrally coordinated [9] by two Cl, two phosphonate oxygen atoms and two water molecules. The chloride ions bridge across two cadmiums while the phosphonate groups connect these dimers into double-stranded chains.…”

“…The ligand employed was H 2 O 3 PCH 2 NHCH 2 CH 2 NHCH 2 PO 3 H 2 (H 4 L) which exists in solution as a di-zwitterion. In a previous paper [9] we described the synthesis and characterization of chloro(amino)-(phosphonato) cadmium which crystallizes in a monoclinic system and has a layered type structure, the layers being held together by hydrogen bonding. In the cadmium compound the Cd atoms form dimers through bridging chlorides.…”

Strontium Methylphosphonate Trihydrate: An Example of a New Class of Host Materials for Intercalation Reactions – Synthesis, Structure and Intercalation Behavior

“…The absence of water in SrCH 3 PO 3 also causes an internal stress leading to a deformation of the phosphonate group, which results in some changes to the PO 3 stretching vibrations. [15] The infrared spectra of all three strontium methylphosphonates exhibit several strong bands at 1103, 1057, and 1007 cm -1 , that can be assigned to asymmetric and symmetric PO 2 stretching vibrations, and the peaks at 986 cm -1 are assigned to an asymmetric stretching P-O -vibration [23] ( Figure 7a). To help explain the presence of the bands at 1302 cm -1 , the spectra of hydrogen methylphosphonate Sr(CH 3 PO 3 H) 2 and methylphosphonic acid, CH 3 PO 3 H 2 , www.eurjic.orgare included in Figure 7.…”