A Monometallic Bis(cyaphido) Complex.

The first example of a bis(cyaphido) complex, trans-[Ru(dppe)(C≡P)], is described, unequivocally demonstrating the synthetic accessibility and stability of complexes that feature more than one cyaphido ligand. Synthesis is achieved from the precedent cation [Ru(dppe)(C≡P)] via sequential coordination and desilylation of the phosphaalkyne MeSiC≡P. The heteroleptic analogue trans-[Ru(dppe)(C≡N)(C≡P)] is also prepared from the same cation and NaCN; both cyaphido complexes are structurally characterized, enabling the first direct comparison of cyaphide with cyanide, its isoelectronic and isolobal counterpart. This demonstrates an enhanced π-acidity for C≡P over C≡N, while computational studies reveal also a higher π-donor character for the cyaphido ligand.