Toward Supramolecular Assembly of 10-Vertex {closo-2,1,10-FeC2B7} Clusters: Intramolecular Imidate Formation and Polymetallic, Polycluster Species

Addition of Me3NO to CH2Cl2 solutions of [1-OH-2,2,2-(CO)3-closo-2,1,10-FeC2B7H8] (1a) affords [2,2-(CO)2-1,2-μ-{OCH2NMe2}-closo-2,1,10-FeC2B7H8] (2), which contains a five-membered FeNCOC unit. The same reaction in MeCN as solvent gives [2,2-(CO)2-1,2-μ-{OC(R)NH}-closo-2,1,10-FeC2B7H8] (3a, R = Me). Analogous derivatives [R = CH═C(H)Me (3c), p-C6H4NO2 (3d), p-C6H4Br (3f), p-C6H4C(H)O (3g), p-C6H4C≡CH (3h), p-C5H4N (3i), or NH2 (3j)] are obtained from treatment of CH2Cl2 solutions of 1a with other cyano-containing substrates and Me3NO. The μ-imidate species 3 undergo a variety of subsequent reactions. Thus, oxidative coupling of compound 3h in CH2Cl2, in the presence of CuCl−TMEDA (TMEDA = Me2NCH2CH2NMe2), affords dimeric [2,2-(CO)2-closo-2,1,10-FeC2B7H8-1,2-μ-{OC(NFeH)-p-C6H4-C≡C}]2 (4), which reacts with [Co2(CO)8] in CH2Cl2 to give the tetracluster species [2,2-(CO)2-closo-2,1,10-FeC2B7H8-1,2-μ-{OC(NFeH)-p-C6H4-{(μ-η2:η2-C≡C)Co2(CO)6}}]2 (5). Conversely, 3f forms a bis(cluster) species, [2,2′-dppb-{2-C...