Halogen-induced core structural evolution of four dinuclear copper(I) luminescent coordination compounds

The reactions of [Cu(CH3CN)(4)]ClO4 and 2-(diphenylphosphino)pyridine (dppy) with different halogen reagents NH4X (X = Cl-, Br- and l(-)) and four luminescent di-copper(i) coordination compounds, namely [Cu-2(mu-dppy)(3)Cl]ClO4 center dot H2O (1a), [Cu-2(mu-dppy)(3)Br]ClO4 (2a), Cu-2(mu-Br)(2)(mu-dppy)(eta-dppy)(2) (2b) and [Cu-2(mu-l)(2)(mu-dppy)(eta-dppy)(2)] (3b), were isolated. Intriguingly, X-ray crystallographic studies reveal that there were two kinds of Cue-core structural configuration induced by the differently sized halogen anions. With Cl--acting as a co-ligand, 1a featured a trefoil-like Cu-2-core with three mu(2)-dppy in a head-to-head orientation bridging two Cu(I) and one terminal Cl- occupying one axial position. On replacing Cl- with l(-), 3b comprised a butterfly-like Cue-core, being bridged by two I- anions and one mu(2)-dppy along with two terminal dppy. When Br- was employed, both the above types of Cu-2-cores were obtained in 2a and 2b, respectively. All these four di-copper(I) compounds exhibit intense green photoluminescence with microsecond lifetimes.

Automated summary

Four luminescent di-copper(I) coordination compounds were synthesized and characterized in this study. X-ray crystallographic studies revealed two different Cue-core structural configurations induced by different sized halogen anions.