Salts based on perchlorinated closo-dodecaborate anion: First Cl-35 NQR studies and crystal structure

Three salts based on perchlorinated closo-dodecaborate anion, Cs-2[B12Cl12]*2MeCN (1), K-2[B12Cl12]*7MeCN (2), and (Ph4P)(2)[B12Cl12] (3) were synthesized and characterized using B-11, H-1, C-13 NMR, X-ray diffraction and 35Cl nuclear quadrupole resonsnce (NQR) spectroscopy. The latter was for the first time applied for identification of noncovalent interactions Cl...X in closo-dodecaborate clusters. Subtle perturbations of the cluster electron density caused by weak noncovalent Cl...X interactions were detected hence selecting from the whole totality of measured interatomic << short >> contacts those which really participated in noncovalent interactions. It has been shown that X-ray structural information based on measuring the distances between atomic nuclei can be substantially sup-plemented with the Cl-35 NQR data on the features of the electronic distribution in these compounds. According to the Cl-35 NQR results, the alkali cations in 2*7MeCN, unlike in 1*2MeCN, do not participate in noncovalent in-teractions with Cl atoms whereas the X-ray diffraction analysis found a number of K...Cl distances shorter than the sum of vdW radii.

Automated summary

Three new salts based on perchlorinated closo-dodecaborate anion were synthesized and characterized using various techniques, with the application of 35Cl nuclear quadrupole resonance for the identification of noncovalent interactions being a notable first. The results revealed subtle perturbations in cluster electron density caused by weak noncovalent Cl...X interactions, and demonstrated the complementarity of X-ray structural information and Cl-35 NQR data.