Argentophilic interactions in mono-, di-, and polymeric Ag(I) complexes with N, N ′-dimethyl-piperazine-2,3-dithione and iodide

A variety of silver(I) neutral complexes differing in stoichiometries and/or crystallographic arrangements have been obtained by reacting [HMe ₂pipdt]I₃ (1) (Me₂pipdt = N,N′-dimethyl- piperazine-2,3-dithione) with silver as a metal powder and as 1+ metal ion. Once dissolved in THF, 1 reacts with silver powder, affording complexes of different ligand/metal ratios: [Ag(Me₂pipdt)₂]I₃ (2a) and [Ag(Me₂pipdt)I]₂(3) (in the two different crystallographic arrangements 3a and 3b). The polymer [Ag₂(Me ₂pipdt)I₂]_n (4) and the monomer [Ag(Me ₂pipdt)₂]I₃ (2b) are instead obtained when 1 reacts with AgSbF₆ in CH₃CN. The short intermetallic distances found in the dimeric and polymeric structures [d _Ag-Ag(Å) = 3.3267(9) (3a), 3.0873(5) (3b), 2.8139(9)/3.1460(9)/ 3.2420(8) (4)] suggested possible argentophilic interactions in the complexes. These interactions have been investigated applying density functional theory (DFT) calculations and the atoms-in-molecules (AIM) analysis on 3a and 3b, on a fragment of 4, and on a Ag₂I₂ model. This model mimics the rhomboidal fragment which occurs in most of the described structures and provides the tools to ascertain the occurrence and the strength of the argentophilicity as a function of the intermetallic distance (2.7-3.5 Å) for the isolated Ag₂I₂ moiety. The obtained results highlight argentophilicity in 3b and 4.(Figure Presented)