Functionalized ruthenatricarbadecaboranes via selective cage iodination and Sonogashira coupling reactions

Selective iodination of the cyclopentadienylruthenium tricarbadecaboranyl complexes 1-(η5-C5H5)–2-Ph–closo-1,2,3,4-RuC3B7H9 (1) and 1-(η5-C5(CH3)5)–2-Ph–closo-1,2,3,4-RuC3B7H8 (2) to form their mono-iodo derivatives, 1-(η5-C5H5)–2-Ph–6-I–closo-1,2,3,4-RuC3B7H9 (3) and 1-(η5-C5(CH3)5)–2-Ph–6-I–closo-1,2,3,4-RuC3B7H8 (4), was achieved in 90% yields by their reactions with ICl in CH2Cl2 solutions. Also isolated in trace amounts from the reaction with 2 was the di-iodo 1-(η5-C5(CH3)5)–2-Ph–6,11-I2–closo-1,2,3,4-RuC3B7H7, (5) complex. The sonication-promoted Sonogashira coupling reaction of 3 with terminal acetylenes catalyzed by Pd(dppf)Cl2/CuI yielded the functionalized ruthenatricarbadecaboranyl complexes 1-(η5-C5H5)–2-Ph–6-(Ph-C≡C)–closo-1,2,3,4-RuC3B7H8 (6), 1-(η5-C5H5)–2-Ph–6-[CH3CH2C(O)OCH2-C≡C]–closo-1,2,3,4-RuC3B7H8 (7), 1-(η5-C5H5)–2-Ph–6-[(η5-C5H5)Fe(η5-C5H4)-C≡C]–closo-1,2,3,4-RuC3B7H8 (8) and 1-(η5-C5H5)–2-Ph–6-[(CH3)3Si-C≡C]–closo-1,2,3,4-RuC3B7H8 (9). These reactions thus provide a versatile, systematic pathway for the syntheses of a wide variety of new types of functionalized ruthenatricarbadecaboranyl complexes.

A versatile, systematic pathway for the syntheses of a wide variety of new types of functionalized ruthenatricarbadecaboranes has been developed based on selective B-iodination followed by palladium catalyzed Sonogashira coupling reactions.Figure optionsDownload as PowerPoint slideHighlights
► New B-iodination/Sonogashira pathways to functional ruthenatricarbadecaboranes.
► Selective B-iodination of ruthenatricarbadecaboranes in 90% yields with ICl.
► Sonogashira couplings provide routes to alkynyl-linked ruthenatricarbadecaboranes.