Cyanometalate Cages with Exchangeable Terminal Ligands

The coordination chemistry of the unusual metallo‐ligand Cs⊂[CpCo(CN) 3 ] 4 [Cp*Ru] 3 (Cs⊂Co 4 Ru 3 ) is described with attention to the behavior of the ligand itself, its binding to Lewis‐acidic metal cations, and its ability to stabilize catalytically relevant Ru–PPh 3 fragments. A series of tests demonstrate that the “rim” [CpCo(CN) 3 ] – groups in Cs⊂Co 4 Ru 3 are exchangeable. Upon treatment with [(MeC 5 H 4 )Co(CN) 3 ] – (Co′) Cs⊂Co 4 Ru 3 undergoes vertex exchange to give Cs⊂Co 4– x Co′ x Ru 3 . Similarly the cage is degraded by CO. Most convincing, Cs⊂Co 4 Ru 3 reacts with PhNH 3 OTf to precipitate the polymer PhNH 3 CpCo(CN) 3 and form the molecular box [Cs⊂Co 4 Ru 4 ] + . Treatment of Cs⊂Co 4 Ru 3 with [M(NCMe) x ]PF 6 (M = Cu, Ag) gave the Lewis acidic cages {Cs⊂[CpCo(CN) 3 ] 4 [Cp*Ru] 3 M(NCMe)}PF 6 , which reacted with tertiary phosphane ligands to give adducts [Cs⊂Co 4 Ru 3 M(PPh 3 )]PF 6 . Lewis acidic octahedral vertices were installed using Fe, Ni, and Ru reagents. The boxes [Cs⊂Co 4 Ru 3 M(NCMe) 3 ] 2+ (M = Ni, Fe) formed readily from the reaction Cs⊂Co 4 Ru 3 with [Ni(NCMe) 6 ](BF 4 ) 2 and [Fe(NCMe) 6 ](PF 6 ) 2 . Displacement of the MeCN ligands gives [Cs⊂Co 4 Ru 3 Ni(9‐ane‐S3)](BF 4 ) 2 . A series of boxes were prepared by the reaction of Cs⊂Co 4 Ru 3 and RuCl 2 (PPh 3 ) 3 , RuHCl(PPh 3 ) 3 , and [(C 6 H 6 )Ru(NCMe) 3 ](PF 6 ) 2 . The derivative of the hydride, [Cs⊂Co 4 Ru 3 Ru(NCMe)(PPh 3 ) 2 ](PF 6 ) 2 , was characterized crystallographically.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)