Hydrogen and halogen bonds are important anisotropic attractive interactions in the molecular crystalline state. 2,6dibromophenol (1) was analyzed by single-crystal X-ray diffraction for the first time. The intermolecular interaction pattern was studied by Hirshfeld surface analysis along with 2D fingerprint diagrams. The characteristic interactions that dominate the crystal packing are electrostatic type-II Br⋅⋅⋅Br interactions, OÀ H⋅⋅⋅O hydrogen bonds, and an offset parallel πstacking arrangement. Compound 1 was compared with 2,6difluoro-(2) and 2-bromo-6-chlorophenol (3) in terms of their interplay between hydrogen and halogen bonding. Whereas the OÀ H⋅⋅⋅O hydrogen bond is more pronounced in the lighter homologues, the halogen⋅⋅⋅halogen interaction becomes a particularly important directional, attractive interaction in the crystal structure of 2,6-dibromophenol.

The functionalization of the arsenic transfer reagent [Cp″2Zr(η1:1-As4)] (1) focuses on modifying its properties and enabling a broader scope of reactivity. The coordination behavior of 1 towards different Lewis-acidic transition metal complexes and main group compounds is investigated by experimental and computational studies. Depending on the steric requirements of the Lewis acids and the reaction temperature, a variety of new complexes with different coordination modes and coordination numbers could be synthesized. Depending on the Lewis acid (LA) used, a mono-substitution in [Cp″2Zr(µ,η1:1:1:1-As4)(LA)] (LA = Fe(CO)4 (4); B(C6F5)3 (7)) and [Cp″2Zr(µ,η3:1:1-As4)(Fe(CO)3)] (5) or a di-substitution [Cp″2Zr(µ3,η1:1:1:1-As4)(LA)2] (LA = W(CO)5 (2); CpMn(CO)2 (3); AlR3 (6, R = Me, Et, iBu)) are monitored. In contrast to other coordination products, 5 shows an η3 coordination in which the butterfly As4 ligand is rearranged to a cyclo-As4 ligand. The reported complexes are rationalized in terms of inverse coordination.