Filling the gap with a bulky diaryl boron group: fluorinated and non-fluorinated copper pyrazolates fitted with a dimesityl boron moiety on the backbone.

Successful synthesis has been reported of 4-MesB-3,5-(CF)PzH and 4-MesB-3,5-(CF)PzH bearing sterically demanding diarylboron moieties at the pyrazole ring 4-position, and their corresponding copper(I) pyrazolate complexes. They show visible blue photoluminescence in solution. The X-ray crystal structures revealed that the fluorinated {[4-BMes-3,5-(CF)Pz]Cu} crystallizes as discrete trinuclear molecules whereas as the non-fluorinated {[4-BMes-3,5-(CH)Pz]Cu} forms dimers of trimers with two close inter-trimer Cu⋯Cu separations.