Revealing the Role of the Cyaphide Ion as a Bridging Ligand in Heterometallic Complexes

The synthesis of heterometallic transition metal complexes featuring bridging cyaphide ions (C P-) is reported. These are synthesized from reactions of Au(IDipp)(CP) (IDipp=1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene) with electron-rich, nucleophilic transition metal reagents, affording Au(IDipp)(mu(2)-C P)Ni((IPr)-I-Me-Pr-i)(2) ((IPr)-I-Me-Pr-i=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) and Au(IDipp)(mu(2)-C P)Rh(Cp*)(PMe3). These studies reveal that, in contrast to the cyanide ion, bimetallic cyaphido complexes strongly favor a eta(1) : eta(2) coordination mode that maximizes the interaction of the second metal (Ni, Rh) with the pi-manifold of the ion (and not the phosphorus atom lone pair). End-on bridging can be effectively unlocked by blocking the pi-manifold, as demonstrated by reaction of Au(IDipp)(mu(2)-C P)Rh(Cp*)(PMe3) with an electrophilic transition metal reagent, W(CO)(5)(THF), which affords the heterotrimetallic compound Au(IDipp)(mu(3)-C P)[Rh(Cp*)(PMe3)][W(CO)(5)].

Automated summary

The synthesis of heterometallic transition metal complexes featuring bridging cyaphide ions has been reported. These complexes were synthesized from reactions of Au(IDipp)(CP) with electron-rich, nucleophilic transition metal reagents. The studies reveal that these cyaphido complexes strongly favor a specific coordination mode that maximizes their interaction with the ion.