The Influence of Halogenated Hypercarbon on Crystal Packing in the Series of 1-Ph-2-X-1,2-dicarba-closo-dodecaboranes (X = F, Cl, Br, I)

Abstract

Although 1-Ph-2-X-closo-1,2-C2B10H10 (X = F, Cl, Br, I) derivatives had been computed to have positive values of the heat of formation, it was possible to prepare them. The corresponding solid-state structures were computationally analyzed. Electrostatic potential computations indicated the presence of highly positive σ-holes in the case of heavy halogens. Surprisingly, the halogen•••π interaction formed by the Br atom was found to be more favorable than that of I.

Electrophilic Methylation of Decaborane(14): Selective Synthesis of Tetramethylated and Heptamethylated Decaboranes and Their Conjugated Bases

“… The hydrogen atoms of the methyl groups in 2 have a positive ESP surface, while the carbon atom has a negative ESP surface, which makes the methyl groups typical amphiphilic partners . Conceivably, the most positive values of the ESP molecular surfaces of 1 and 2 are 44.2 and 40.2 kcal mol –1 , respectively, which are among the most positive values so far computed in the area of boron clusters. − This prevents this part of the molecule from electrophilic attack, which agrees with the positions attacked by the methyl groups. It also corresponds to the possible structures of the aforementioned 1 -based nonlinear optical devices.…”

1,12-Diiodo-Ortho-Carborane: A Classic Textbook Example of the Dihalogen Bond

“…As mentioned in the Introduction, no Br• • • Br halogen bond was observed in the crystal structure of 1,12-dibromo-ortho-carborane 1,12-Br 2 -1,2-C 2 B 10 H 10 [28]. It should be noted that similarities and differences between bonding preferences of the bromine atom in comparison to iodine atom, on the one hand, and chlorine atom, on the other hand, was the subject of extensive studies [58][59][60][61]. Based on comparison of the crystal packing of 1-Ph-2-X-ortho-carboranes (X = F, Cl, Br, I), it was shown that both Br and I form Hal• • • π interactions, while neither Cl or F participate in such interactions [58].…”

“…It should be noted that similarities and differences between bonding preferences of the bromine atom in comparison to iodine atom, on the one hand, and chlorine atom, on the other hand, was the subject of extensive studies [58][59][60][61]. Based on comparison of the crystal packing of 1-Ph-2-X-ortho-carboranes (X = F, Cl, Br, I), it was shown that both Br and I form Hal• • • π interactions, while neither Cl or F participate in such interactions [58]. Study of N-(2-halo-2,2-dinitroethyl)pyrrolidine-2,5-diones (Hal = F, Cl, Br) [59] has revealed that both Cl and Br participate in halogen bonding, but bromine interacts with the carbonyl oxygen atom (the strongest donor site), while chlorine prefers to connect to much weaker donors, namely, oxygen atoms of the nitro group.…”

Beyond the Limits of Perbromo‐Substituted Octahedral Pnictogenaboranes: A Spectroscopic and Computational Study

“…Solid-state stereochemistry of heteroboranes has recently relied on the formation of special kinds of noncovalent interactions such as chalcogen bonding, [1][2][3] pnictogen bonding [4] and halogen bonding. [5] These kinds of interactions arise from the σhole concept, which has recently received considerable attention in boron-cluster chemistry. The latter interactions defy the classical understanding of electronegativity; for instance, although sulfur is more electronegative than boron, it has five significantly positively charged σ-holes in an icosahedral thiaborane, [1] also as a result of the fivefold bonding capacity of sulfur toward boron atoms in the corresponding pentagonalpyramidal moiety of the icosahedron.…”

“…Solid‐state stereochemistry of heteroboranes has recently relied on the formation of special kinds of noncovalent interactions such as chalcogen bonding, [1–3] pnictogen bonding [4] and halogen bonding [5] . These kinds of interactions arise from the σ‐ hole concept, which has recently received considerable attention in boron‐cluster chemistry.…”