Transition-Metal Complexes Containing Alkynylsilyl Functionalized η6‑Arene Ligands

Six transition-metal arene complexes containing alkynylsilyl groups have been synthesized. Direct complexation of the corresponding arenes yielded the alkynylsilylarene complexes PhCCMe2SiPhCr­(CO)3 (1), n-PrCCMe2SiPhCr­(CO)3 (2), n-PrCCMe2Si–SiMe2–SiMe2PhCr­(CO)3 (4), and PhCCMe2SiPhMo­(CO)3 (6), while PhCCMe2Si–SiMe2PhCr­(CO)3 (3) and (PhCCMe2SiPh)2Cr (7) were synthesized by modification of precomplexed arenes. The reactivity of the CC triple bonds of the synthesized alkynylsilyl compounds toward complexation and carbon–carbon bond-forming reactions was studied. The alkynyl groups of 1 and 6 underwent intermolecular complexation to yield the trinuclear compounds 1·Ni2Cp2 (8) and 6·Cp2Mo2(CO)4 (9), respectively, while reaction of 7 with CpCo­(PPh3)2 led to intramolecular [2 + 2] cycloaddition of its two alkynyl groups with formation of the dinuclear cyclobutadiene complex CpCo­(PhCCSiMe2Ph)2Cr (10). All of these complexes were characterized by NMR, IR, and mostly also UV/vis (1, 2, 6–10) spectroscopy. The molecular and crystal structures of compounds 1, 2, and 6–10 were determined by single-crystal X-ray diffraction.