A Monometallic Bis(cyaphido) Complex.

The first example of a bis(cyaphido) complex, trans-[Ru(dppe) 2 (C≡P) 2 ], 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) 2 (C≡P)] + via sequential coordination and desilylation of the phosphaalkyne Me 3 SiC≡P. The heteroleptic analogue trans-[Ru(dppe) 2 (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.