Halides Held by Bifurcated Chalcogen-Hydrogen Bonds. Effect of μ(S,N-H)Cl Contacts on Dimerization of Cl(carbene)PdII Species

The reaction of cis-[PdCl2(CNCy)(2)] (1) with thiazol-2-amines (2-10) leads to the C,N-chelated diaminocarbene-like complexes [PdCl{C(N(H)4,5-R-2-thiazol-2-yl)NHCy](CNCy)] (11-14; 82-91%) in the case of 4,S-R-2-thiazol-2-amines (R, R = H, H (2), Me, Me (3),-(CH2)(4)- (4)) and benzothiazol-2-amine (5) or gives the diaminocarbene species cis[PdCl2{C(N(H)Cy)N(H)4-R-thiazol-2-yl}(CNCy)] (15-19; 73-93%) for the reaction with 4-aryl-substituted thiazol-2-amines (R = Ph (6), 4-MeC6H4 (7), 4-FC6H4 (8), 4-ClC6H4 (9), 3,4-F2C6H3 (10)). Inspection of the single-crystal X-ray diffraction data for 15-17 and 19 suggests that the structures of all these species exhibit previously unrecognized bifurcated chalcogen-hydrogen bonding mu Cl-(S,Cl-N-H) and also Pd-II center dot center dot center dot Pd-II metallophilic interactions. These noncovalent interactions collectively connect two symmetrically located molecules of 15-17 and 19, resulting in their solid-state dimerization. The existence of the mu Cl-(S,Cl-N-H) system and its strength (6-9 kcal/mol) were additionally verified/estimated by a Hirshfeld surface analysis and DFT calculations combined with a topological analysis of the electron density distribution within the formalism of Bader's theory (AIM method) and NBO analysis. The observed noncovalent interactions are jointly responsible for the dimerization of 15-19 not only in the solid phase but also in CHCl3 solutions, as predicted theoretically by DFT calculations and confirmed experimentally by FTIR, HRESI-MS, H-1 NMR, and diffusion coefficient NMR measurements. Available CCDC data were processed under the new moiety angle, and the observed mu Cl-(S,Cl-N-H) systems were classified accordingly to E (E = N, O, C) type atoms.