A new unconventional halogen bond CX···HM between HCCX (X = Cl and Br) and HMH (M = Be and Mg): An ab initio study

Abstract

In this article, a new type of halogen-bonded complex YCCX...HMY (X = Cl, Br; M = Be, Mg; Y = H, F, CH(3)) has been predicted and characterized at the MP2/aug-cc-pVTZ level. We named it as halogen-hydride halogen bonding. In each YCCX...HMY complex, a halogen bond is formed between the positively charged X atom and the negatively charged H atom. This new kind of halogen bond has similar characteristics to the conventional halogen bond, such as the elongation of the C-X bond and the red shift of the C-X stretch frequency upon complexation. The interaction strength of this type of halogen bond is in a range of 3.34-10.52 kJ/mol, which is smaller than that of dihydrogen bond and conventional halogen bond. The nature of the electrostatic interaction in this type of halogen bond has also been unveiled by means of the natural bond orbital, atoms in molecules, and energy decomposition analyses.

Nature of a Hydride–Halogen Bond. A SAPT-, QTAIM-, and NBO-Based Study

“…The same effect has been obtained for all systems investigated earlier by Li et al 33 A small decrease of the IR intensity of the R−H mode has only been obtained in the case where FCF 3 is the halogen donor molecule. This, however, is not regarded as the representative one.…”

“…32,33 These are Li−H···ClCF 3 and HBe−H···ClCF 3 analyzed by Grabowski et al 32 and HBeH···ClCCH and HBeH···BrCCH analyzed by Li et al 33 Thus the present studies are to widen the already known set of hydride−halogen bonded systems.…”

Binuclear Copper(I) Borohydride Complex Containing Bridging Bis(diphenylphosphino) Methane Ligands: Polymorphic Structures of [(µ2-dppm)2Cu2(η2-BH4)2] Dichloromethane Solvate

“…The angles (∠C-H···Cl) for these interactions vary from 145.9 to 149.6 • and H···Cl distances are in the range 2.659-2.679 Å that is less than the sum of van der Waals radii for these two atoms (2.95 Å). There is also a short B-H···Cl-C distance 2.755 Å between BH and DCM with angle ∠C-Cl···H(B) = 158.2 • that resembles a halogen bonding [106,107] and was referred to as a hydride-halogen bond [108][109][110][111][112][113]. This interaction has a donor-acceptor nature, where B-H δ− acts as a donor of electron density and interacts with an electron deficient area (σ-hole) located on the halogen atom +δ Hal-R.…”

Halogen Bonding in Crystal Engineering

“…The results indicate that H δ-is a potential electron donor for halogen bonds. [51][52][53] The halogen bonding interaction between LiH or HBeH and either XCF3 or XCCH (X= F, Cl, Br, I) has been studied with high-level quantum mechanical calculations, quantum theory of atoms in molecules (QTAIM), and natural bond orbital (NBO) methods. The most important finding of these studies has been that the hydride-halogen bond formation causes the elongation of R δ+ -H δ-bond due to the involvement of hydride in the halogen bond.…”