Synthesis, crystal structures, Hirshfeld surface analysis and physico-chemical characterization of two new ZnII and CdII halidometallates

Abstract

Two new organic–inorganic hybrid materials, based on 1,3-CycloHexaneBis-(Methyl Amine), abbreviated CHBMA, namely (H2CHBMA)ZnCl4·2H2O (CP1) and (H2CHBMA)CdI4·2H2O (CP2), have been synthesized under mild conditions in acidic media and characterized by single-crystal X-ray diffraction, spectroscopic techniques (13C NMR, FTIR, RAMAN) and thermal analysis. The crystal structures of the two compounds were solved by single-crystal X-ray diffraction methods. Both compounds show a 3-dimensional supramolecular structure directed by various interactions between tetrahalidometallate anions (ZnCl42−, CdI42−), water molecule and organic cations (H2CHBMA)2+. For both compounds, the cyclohexane ring of the template cation is in a chair conformation with the methylammonium substituent in the equatorial positions and the two terminal ammonium groups in a cis conformation but with two different orientations (upward for CP1 and downward for CP2) which influences the supramolecular architecture of the two structures. Hirshfeld surface analysis and the associated two-dimensional finger print plots were used to explore and quantify the intermolecular interactions in the crystals.

Single-Crystal-to-Single-Crystal Transformation and Catalytic Properties of New Hybrid Perhalidometallates

“…The Examination of the C-C, C-N distances and C-C-C, C-C-N angles in the (CHBMAH 2 ) 2+ dication shows that they are comparable to those found in other works [4,25] (Table S2).…”

“…It is important to note that the reaction of a mixture of cis and trans isomers of CHBMA with a suitable proportion of anhydrous zinc bromide and hydrobromic acid results in pure cis isomers in the synthesized crystal. This selectivity for the cis configuration in 1 has also been observed in the compounds (CHBMAH 2 )ZnCl 4 •2H 2 O 2 and (CHBMAH 2 )CdI 4 •2H 2 O 3 [25]. In contrast, in other compounds containing the same organic cation (CHBMAH 2 ) 2+ , such as (CHBMAH 2 )Zn 2.1 Co 0.9 (HPO 3 ) 4 [31] and (CHBMAH 2 )(NO 3 ) 2 [32], the trans configuration has also been found.…”

“…We report the chemical preparation and crystal structure of a new hybrid perhalidometallate (CHBMAH 2 )ZnBr 4 •3/2H 2 O 1, obtained in the presence of diprotonated 1,3-cyclohexanebis(methylammonium) (abbreviated: (CHBMAH 2 ) 2+ ). Additionally, the relationship with other similar structures recently reported by Rayes [25], is discussed in the present work. Interestingly, the compound (CHBMAH 2 )ZnCl 4 4 was obtained as a result of a solid state dehydration process of 2 by heating it up to 140 • C. Hence, it constitutes a new example of the uncommon single-crystal-to-single-crystal (SCSC) transition and has also been studied by single-crystal X-ray diffraction.…”

“…On the other hand, when comparing the fingerprint plots for 2 and 4 [25], the highest difference is regarding the O• • • H contact, which accounted for 5.5% of the total interactions in 2 but is absent in 4. This difference is relevant, confirming that compound 2 undergoes a dehydration reaction giving rise to the dehydrated compound 4.…”

“…It is important to note that comparable thermal behaviors have been observed for the two materials (CHB-MAH2)ZnCl4•2H2O 2 and (CHBMAH2)CdI4 . 2H2O 3 [25].…”