Vibrational Signature of Metallophilic Interactions in [Pt(terpy)Cl][Au(CN)2]

Metallophilic interactions, weak interactions between closed-shell metal atoms, have been recently utilized to create unique nanostructures with anisotropy of electronic properties along the direction of the interaction. The strength of the metallophilic interaction is an important factor for the design of these nanostructures. Recently, Doerrer and co-workers presented a general metathesis route to create extended chains of metallophilic double salts with two modular opposite-charge ions with Au­(I) and Pt­(II) centers without bridging ligands. Here, we apply theoretical and experimental angle-resolved Raman spectroscopy to identify the vibrational signature associated with the Au­(I)–Pt­(II) interaction in the double salt wire, [Pt­(terpy)­Cl]­[Au­(CN)2)]. Our study reveals six Raman-active low-energy phonon modes below 75 cm–1 that are anisotropic, as shown by their polarization dependence. By analysis of the low-energy Raman spectrum and the nature of the associated phonon modes, we identify one mode to be associated with the intrachain Pt–Au interactions with a frequency of 57 cm–1. We show that the polarization dependence of the Raman spectrum is the key to elucidating directional metallophilic modes.