Relativistic modulation of supramolecular halogen/copper interactions and phosphorescence in Cu(I) pyrazolate cyclotrimers.

Described herein are the synthesis, structure, and photophysics of the iodo-substituted cyclic trinuclear copper(I) complex, Cu 3 [4-I-3,5-(CF 3 ) 2 Pz] 3 supported by a highly-fluorinated pyrazolate in comparison with its previously reported 4-Br/4-Cl analogues. The crystal structure is stabilised by multiple supramolecular interactions of Cu 3 ⋯I and hydrogen/halogen bonding. The photophysical properties and supramolecular interactions are investigated experimentally/computationally for all three 4-halo complexes vis-à-vis relativistic effects.