Diazoalkanes react with a bis(phosphino)borate copper(i) source to generate [Ph2BP(tBu)2]Cu(eta1-N2CR2), [Ph2BP(tBu)2]Cu(CPh2), and [Ph2BP(tBu)2]Cu-N(CPh2)(NCPh2).

[Ph2BP(tBu)2]Cu-L complexes react with diazoalkanes to generate structurally unusual eta1-diazoalkane adducts, a terminal carbene, and an eta1-azine adduct.