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Syntheses of Functionalized Ferratricarbadecaboranyl Complexes

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posted on 31.05.2004, 00:00 by Bhaskar M. Ramachandran, Patrick J. Carroll, Larry G. Sneddon
The reactions of nitriles (RCN) with arachno-4,6-C2B7H12- provide a general route to functionalized tricarbadecaboranyl anions, 6-R-nido-5,6,9-C3B7H9-, R = C6H5 (2-), NC(CH2)4 (4-), (p-BrC6H4)(Me3SiO)CH (6-), C14H11 (8-), and H3BNMe2(CH2)2 (10-). Further reaction of these anions with (η5-C5H5)Fe(CO)2I yields the functionalized ferratricarbadecaboranyl complexes 1-(η5-C5H5)-2-C6H5-closo-1,2,3,4-FeC3B7H9 (3), 1-(η5-C5H5)-2-NC(CH2)4-closo-1,2,3,4-FeC3B7H9 (5), 1-(η5-C5H5)-2-[(p-BrC6H4)(Me3SiO)CH]-closo-1,2,3,4-FeC3B7H9 (7), 1-(η5-C5H5)-2-C14H11-closo-1,2,3,4-FeC3B7H9 (9), and 1-(η5-C5H5)-2-H3BNMe2(CH2)2-closo-1,2,3,4-FeC3B7H9 (11). Reaction of 11 with DABCO (triethylenediamine) resulted in removal of the BH3 group coordinated to the nitrogen of the side chain, giving 1-(η5-C5H5)-2-NMe2(CH2)2-closo-1,2,3,4-FeC3B7H9 (12). Crystallographic studies of complexes 3, 5, 7, 9, and 11 confirmed that these complexes are ferrocene analogues in which a formal Fe2+ ion is sandwiched between the cyclopentadienyl and tricarbadecaboranyl monoanionic ligands. The metals are η6-coordinated to the puckered six-membered face of the tricarbadecaboranyl cage, with the exopolyhedral substituents bonded to the low-coordinate carbon adjacent to the iron.