Dihalomethanes as Bent Bifunctional XB/XB-Donating Building Blocks for Construction of Metal-involving Halogen Bonded Hexagons.

The dihalomethanes CH2 X2 (X=Cl, Br, I) were co-crystallized with the isocyanide complexes trans-[MXM 2 (CNC6 H4 -4-XC )2 ] (M=Pd, Pt; XM =Br, I; XC =F, Cl, Br) to give an extended series comprising 15 X-ray structures of isostructural adducts featuring 1D metal-involving hexagon-like arrays. In these structures, CH2 X2 behave as bent bifunctional XB/XB-donating building blocks, whereas trans-[MXM 2 (CNC6 H4 -4-XC )2 ] act as a linear XB/XB acceptors. Results of DFT calculations indicate that all XCH2 -X⋅⋅⋅XM -M contacts are typical noncovalent interactions with estimated strengths in the range of 1.3-3.2 kcal mol-1 . A CCDC search reveals that hexagon-like arrays are rather common but previously overlooked structural motives for adducts of trans-bis(halide) complexes and halomethanes.