The reactions of some σ-alkynylnickel complexes with 7,7,8,8-tetracyanoquinodimethane

The CC bonds of Ni(η-C5H5)(PPh3)-CC-R (1), insert into the CC(CN)2 of TCNQ to give Ni(η-C5H5)(PPh3)-C{C6H4C(CN)2}-C{C(CN)2}-R (4), which have UV-Vis spectra that are independent of the group R; similar reactions of Ni(η-C5H5)(PPh3)-CC-X-CCH take place only at the Ni-CC and not at the H-CC.