Synthesis and structures of isopropyl-β-diketiminato copper(I) complexes

The reaction of N,N'-diisopropyl-2-amino-4-iminopent-2-ene (nacnac(i-Pr)H, 1) either with CuOt-Bu or with a mixture of mesityl copper and 10% CuOt-Bu afforded, in the presence of PPh3, CN(C6Me2H3), or MeCN, the Lewis base co-ordinated complexes nacnac(i-Pr)CuPPh(3)center dot 0.5 C6H14 (2), nacnac(i-Pr)CuCN(C6Me2H3) (3), and nacnac(i-Pr)Cu(NCMe) (4). Compounds 2, 3, and 4 were characterized by single-crystal X-ray diffraction studies. Compound 4 afforded two species in deuterated benzene in a 2:1 ratio, which were assigned to {nacnac(i-Pr)Cu}(2)(mu-NCMe) and nacnac(i-Pr)CuNCMe (4). Upon addition of 5 equiv. of MeCN, the two sets collapsed into that of 4. No copper complexes were formed in the presence of styrene, stilbene, or diphenylacetylene.