Reverse Sandwich Structures from Interplay between Lone pair–π-hole Atom-directed C•••dz2[M] and Halogen Bond Interactions

4-Bromo- and 4-iodo-5-nitrophthalonitriles (BNPN and INPN, respectively) were co-crystallized with the metal acetylacetonates [M(acac)2] (M = Pd 1, Pt 2) to give three adducts 1•2BNPN, 2•2BNPN, and 1•2INPN exhibiting reverse arene sandwich solid-state structures. The inspection of the XRD data for the adducts revealed new type of (lone pair)[M]•••π-hole noncovalent interactions, namely atom-directed C•••dz2[M] noncovalent contact. In addition, C–X•••(O,O) (X = I, Br) bifurcated halogen bonds (XBs) along with some other types of short contacts were recognized. The XRD experiments were supported by Hirshfeld surface analysis and DFT calculations, i.e. topological analysis of the electron density distribution within the framework of QTAIM method at the ωB97XD/DZP-DKH level of theory. Estimated energies of all studied noncovalent contacts vary from 0.6 to 3.8 kcal/mol.