Carboranes: chemical concepts derived from the AIM study of the experimental and theoretical electron density distribution functions

Abstract

On the basis of high-resolution X-ray diffraction studies as well as quantum-chemical calculations of five carborane derivatives the peculiarities of electron density distribution functions have been analyzed. The data obtained permitted a deeper insight into the nature of unusual properties of the C-C bond in o-carborane and investigating intermolecular H ... H interactions in crystal. It was shown that such an approach allows estimating the values of lattice energy for the crystals of carboranes.

An unexpected cluster opening upon the formation of electronically unsaturated η3-(cyclooctenyl)metallacarboranes of rhodium(III) and iridium(III) with sterically reduced [(PhCH2)2C2B9H9]2− ligand

“…The topological characteristics of C(1)-C(2) bond in 6 (e.g. values of q(r), r 2 q(r) and E e (r)) are similar to those found in the 12-vertex C-phenylated ortho-carboranes [19]. In contrast to this, the critical point CP(3,-1) between the cage carbon atoms in 9 is absent, in agreement with the considerable distortion of closo geometry in this complex which adopts a typical pseudocloso structure with a cage C(1)Á Á ÁC(2) separation of 2.418 Å.…”

“…In order to study the electronic structure of 6 and 9 we have utilized R. F. Bader's theory ''Atoms in molecules" (AIM) [18] which is based on the topological analysis of electron density distribution function (q(r)). Previously, we successfully used this approach for investigations of the 12-vertex Ph-substituted ortho-carboranes [19]. In this paper, we have focused on analysis of occupancies of atomic basins (AIM charges), whose values, we believe, can be indicative of rearrangement of electron density in the Rh(III) atom coordination polyhedron area.…”

Experimental Charge Density Evidence for Pnicogen Bonding in a Crystal of Ammonium Chloride

“…[32]), including weak interactions, such as H···H and CÀH···O [57] or CÀH···N, [58] Mg···C, and Ca···C interactions, [59,60] strong and intermediate hydrogen bonds, [61] CaÀO(carbonate), [62] AuÀPPh 3 , and GdÀOH 2 bonds, [63,64] etc. [32] The interaction energies thus obtained were shown to accurately reproduce the energy of a crystal lattice, [57,58,62,65,66] the discrepancy between the crystal lattice energies estimated in such a manner from X-ray diffraction data and those measured experimentally can be as small as 0.2 kcal mol À1 . [57,67] PW-DFT calculations were carried out by using the VASP 5.3.3 program; [68][69][70][71] exchange and correlation parts of the total energy were described by means of PBE functional.…”

Synthesis and structure of halogen derivatives of 9-dimethylsulfonium-7,8-dicarba-nido-undecaborane [9-Me2S-7,8-C2B9H11]

“…At the first sight the formation of such intermolecular interactions seems unlikely as both interacting atoms have negative charges. However, recent investigations of crystal packages of carboranes have shown that similar B-HÁ Á ÁH-B interactions do exist and contribute significantly to the overall lattice energy [26]. The similar type of intermolecular interaction was found recently in structure of [9-Py-11-I-7, 8-C 2 B 9 H 10 ] [16].…”