Structural similarities in 1D coordination polymers of alkaline earth diphosphinates

The coordination polymers [Sr(Hpcp)2(H2O)]n, 1, and [Ba(Hpcp)2(H2O)]n, 2, (H2pcp = p,p′-diphenylmethylenediphosphinic acid) are isomorphous and consist of 1D chains. The solid compounds were characterized by X-ray diffraction, solid state NMR spectroscopy and thermogravimetric analysis. The photophysical properties of 1 and 2 were also investigated. The refinement of the crystal structures was based on laboratory X-ray powder diffraction data using the Rietveld method. An analysis of the effect of the size of the alkaline earth cation on the network dimensionality was based on a series of coordination polymers bearing ligands comparable to pcp in shape. We found that, as expected, the size of the metal atoms has a minor role in determining the dimensionality of the network, whereas other factors such as steric requirements of the ancillary groups bonded to the phosphorus atoms or the strong tendency of this type of ligand to chelate metal atoms revealed to be important.

Graphical abstractIn the analyzed coordination polymer of the group II atoms, the size of the metals has a minor role in determining the dimensionality of the network, while other factors such as steric requirements of the ancillary groups and the strong tendency of the ligand used to chelate metal atoms revealed to be important.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► How to control the dimensionality of the networks in coordination polymer. ► The size of the metal cation versus the steric requirements of the ligand. ► How the structural disorder is revealed by the solid state NMR spectra.