Cadmium phenylphosphonates: preparation, characterisation and in situ investigation

Abstract

The crystalline cadmium phenylphosphonates Cd(O 3 PPh) · H 2 O (1), Cd(HO 3 PPh) 2 (2), and Cd(HO 3 PPh) 2 (H 2 O 3 PPh) (3) can be synthesized in solid state reactions by grinding together cadmium acetate with respective equivalents of phenylphosphonic acid. The phosphonates (2) and (3) were not obtained by any other synthesis method so far. The determination of the crystal structure of the new compounds (2) and (3) based on the powder X-ray diffraction (PXRD) data is reported. The milling reactions were investigated using in situ synchrotron PXRD. Based on these data, an identification of intermediates and a detailed analysis of the underlying mechanisms was possible.Unlike for the related class of metal organic frameworks (MOFs) the use of alternative synthetic routes like mechanochemistry is scarce. [18][19][20] Recently, in situ methods were developed to investigate milling syntheses to provide the necessary data for a thorough mechanistic study. 21-24 Fig. 1 Reaction scheme for the syntheses of the products (1), (2) and (3); OAc = (O 2 CCH 3 ) -·Here, we present the mechanochemical synthesis of three cadmium phenylphosphonates; the cadmium monophenylphosphonate Cd(O 3 PPh) · H 2 O (1) (Ph = C 6 H 5 ) 25 and two novel structures (1:2 and 1:3) (Figure 1). The structures of the new compounds Cd(HO 3 PPh) 2 (2) and Cd(HO 3 PPh) 2 (H 2 O 3 PPh) (3) were determined from powder X-ray diffraction (PXRD) data. Compound (2) contains two monodeprotonated phenylphosphonate ligands. The compound (3) contains a further neutral J o u r n a l N a me , [ y e a r ] , [ v o l . ] , 1-9 | 1

The structure and in situ synthesis investigation of isomorphic mononuclear molecular metal phenylphosphonates

“…The control of the product of mechanochemical reactions by varying the stoichiometric ratio is a known strategy. 18,[31][32][33][34] The interaction of both factors, the thermodynamic stability and the ratio of the starting material, leads to the obtained reaction paths. Reflections of one unknown intermediate could be detected and all other compounds could be identified.…”

Quantitative determination of activation energies in mechanochemical reactions

“…Fundamental information such as reaction mechanisms and pathways were available using the in situ methodology. [35][36][37][38][39][40] This methodology paves the way for kinetic investigations of mechanochemical reactions. Previous studies state that the kinetics of mechanochemically activated processes is governed not by time (as in classical kinetics) but by the total number of collisions.…”

New Directions in Metal Phosphonate and Phosphinate Chemistry

“…In 2016, a synthesis was reported using a vibration ball mill, in which cadmium acetate dihydrate and phenylphosphonic acid were combined inside a reaction vessel in various ratios (1:1, 1:2, and 1:4) and then milled for 15 min along with two 4.0-g stainless steel balls. One known and two novel cadmium phenylphosphonates were obtained: Cd(O3PPh)•H2O ( Figure 9a,d), Cd(HO3PPh)2 (Figure 9b,e), and Cd(HO3PPh)2(H2O3PPh) (Figure 9c,f) [56]. Each of the products obtained after milling were damp, which was caused by the release of water and acetic acid during the reaction, which in turn, means that each section of the synthesis was in fact liquid-assisted.…”

“…Colour code: yellow: cadmium, orange: phosphorus, red: oxygen, grey: carbon, light grey: hydrogen. Adapted with permission from reference [56]. Copyright 2016, Royal Society of Chemistry.…”

“…These do not include any MPs, but the SynRAC could easily find employment for this class of materials as well. Section 3.2 has already suggested that in situ studies can be very informative for mechanochemical syntheses [56][57][58][59]97]. The two techniques used in each of the in situ studies reported so far were XRD and Raman spectroscopy, which allow the reaction to be monitored at both molecular and crystalline levels [97].…”