Benzophenoneimine Complexes of Copper(I)

The reactions of [(MeCN)₄Cu]BF₄ with two or three equivalents of benzophenoneimine lead to the formation of [(Ph₂C= NH)₂Cu]BR, (1) and [(Ph₂C=NH)₃Cu]BF₄ (2), respectively. A further equivalent of the ligand does not coordinate to the cation of complex 2. The crystal structures of both compounds were determined. 1 shows a linearly two-coordinated copper(I) center with a Cu-N distance of 1.877(2) Å. In compound 2 a distorted trigonal planar coordination of copper is observed with N-Cu-N angles of 114.5(2), 112.9(2) and 132.4(2)°, corresponding to two nearly ecrual Cu-N distances [Cu-N2 1.947(5) and Cu-N3 1.934(5) Å] and a significantly longer third one [Cu-Nl 2.011(5) Å]. A comparison of these data with recently determined structures of bis(benzophenoneimine)silver(I) and -gold(I) complexes shows that the covalent radii of the monovalent coinage metals decrease in the order Ag(I) > Au(I) > Cu(I).