A novel stibacarbaborane cluster with adjacent antimony atoms exhibiting unique pnictogen bond formation that dominates its crystal packing.

Authors :: Holub J
Melichar P
Růžičková Z
Vrána J
Wann DA
Fanfrlík J
Hnyk D
Růžička A
Source :: Dalton transactions (Cambridge, England : 2003) [Dalton Trans] 2017 Oct 17; Vol. 46 (40), pp. 13714-13719.
Publication Year :: 2017
Abstract: We have prepared nido-7,8,9,11-Sb <subscript>2</subscript> C <subscript>2</subscript> B <subscript>7</subscript> H <subscript>9</subscript> , the first cluster with simultaneous Sb-B, Sb-C and Sb-Sb atom pairs with interatomic separations with magnitudes that approach the respective sums of covalent radii. However, the length of the Sb-Sb separation in this cluster is slightly less than the sum of the covalent radii. Quantum chemical analysis has revealed that the crystal packing of nido-7,8,9,11-Sb <subscript>2</subscript> C <subscript>2</subscript> B <subscript>7</subscript> H <subscript>9</subscript> is predominantly dictated by pnictogen (Pn) bonding, an unconventional σ-hole interaction. Indeed, the interaction energy of a very strong Sb <subscript>2</subscript> H-B Pn-bond in the nido-7,8,9,11-Sb <subscript>2</subscript> C <subscript>2</subscript> B <subscript>7</subscript> H <subscript>9</subscript> dimer exceeds -6.0 kcal mol <superscript>-1</superscript> . This is a very large value and is comparable to the strengths of known Pn-bonds in Cl <subscript>3</subscript> Pnπ complexes (Pn = As, Sb).

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