New Diruthenium Bis-alkynyl Compounds as Potential Ditopic Linkers

The reaction between Ru2(ap)4-CC-4-C6H4-P­(O)­(OtBu)2 and LiC2X afforded trans-XC2-Ru2(ap)4-CC-4-C6H4–P­(O)­(OtBu)2, where X is −SiMe3 (1), −C2SiMe3 (2), −C4H
(3), or −4-C6H4C2SiMe3 (4). Compound 5, trans-(tBuO)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-4-C6H4SC2H4SiMe3 and excess LiCC-4-C6H4-P­(O)­(OtBu)2. Compounds 1–5 were characterized by elemental analysis,
HR-nESI-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.