New Diruthenium Bis-alkynyl Compounds as Potential Ditopic Linkers

The reaction between Ru-2(ap)4-C = C-4-C6H4-P(O)(O'Bu)(2) and LiC2X afforded trans-XC2-Ru-2(ap)(4)-CC-4C(6)H(4) P(O)(O'Bu)(2), where X is SiMe3 (1), C2SiMe3 (2), C4H (3), or 4-C6H4C2SiMe3 (4). Compound 5, trans(1BuO)(2)(O)P-C6H4-4-C=:-C-Ru2(ap)4-C=C-4-C6H4SC2H4SiMe3, was obtained from the reaction between Ru2(ap)4-C--=-C-4C6H4SC2H4SiMe3 and excess LiC = C-4-C6H4-P(0)((OBu)-Bu-t)2. Compounds 1-5 were characterized by elemental analysis, HRnESI-MS, voltammetric and spectroscopic techniques, and the X-ray diffraction study of 2. The electronic structures of the homologous series 1-3 were investigated using DFT calculations, which revealed both the retention of key features of Ru2 electronic structure upon the introduction of phosphonate capping and subtle dependence on the number of acetylene units (n) across the series.