The Interplay between Various σ- and π-Hole Interactions of Trigonal Boron and Trigonal Pyramidal Arsenic Triiodides

Jindřich Fanfrlík, Petr Švec, Zdeňka Růžičková, Drahomír Hnyk, Aleš Růžička, Pavel Hobza
2017 Crystals  
Boron and arsenic triiodides (BI 3 and AsI 3 , respectively) are similar molecules that differ mainly in their geometries. BI 3 is a planar trigonal molecule with D 3h symmetry, while AsI 3 exhibits a trigonal pyramidal shape with C 3v symmetry. Consequently, the As atom of the AsI 3 molecule has three σ-holes, whereas the B atom of the BI 3 molecule has two symmetrical π-holes. Additionally, there are σ-holes on the iodine atoms in the molecules studied. In the first step, we have studied
more » ... e and π-hole interactions in the known monocrystals of BI 3 and AsI 3 . Quantum mechanical calculations have revealed that the crystal packing of BI 3 is dominated by π-hole interactions. In the case of AsI 3 , the overall contribution of dihalogen bonding is comparable to that of pnictogen bonding. Additionally, we have prepared the [Na(THF) 6 ] + [I(AsI 3 ) 6 ] − (AsI 3 ) 2 complex, which can be described as the inverse coordination compound where the iodine anion is the center of the aggregate surrounded by six AsI 3 molecules in the close octahedral environment and adjacent two molecules in remote distances. This complex is, besides expected dihalogen and pnictogen bonds, also stabilized by systematically attractive dispersion interactions.
doi:10.3390/cryst7070225 fatcat:zcgqwyzjyjfejextapianvacne