Stille Cross-Coupling Reaction with Cationic [(η5‑Cp)(η6‑C6H6–xIx)Ru]+ Complexes as Key for Ethynyl-Bridged Homo- and Heteronuclear Sandwich Compounds

The cationic homo- and heteronuclear sandwich complexes (η5-cyclopentadienyl)­(ferrocenylethynyl-η6-benzene)­ruthenium­(II) hexafluoridophosphate (3a), (η5-cyclopentadienyl)­(ruthenocenyl­ethynyl-η6-benzene)­ruthenium­(II) hexafluoridophosphate (3b), (η5-cyclopentadienyl)­[1,4-bis­(ferrocenylethynyl)-η6-benzene]­ruthenium­(II) hexafluoridophosphate (4a), (η5-cyclopentadienyl)­[1,4-bis­(ruthenocenylethynyl)-η6-benzene]­ruthenium­(II) hexafluoridophosphate (4b), and (η5-cyclopentadienyl)­[1,3,5-tris­(ferrocenylethynyl)-η6-benzene]­ruthenium­(II) hexafluoridophosphate (5) were synthesized by means of Stille cross-coupling reaction using tri-n-butyl­(metallocenylethynyl)­stannane as nucleophile and the appropriate (η5-cyclopentadienyl)­(η6-iodobenzene)­ruthenium­(II) cations as electrophiles. As a catalyst, a Pd(0) complex, furnished with AsPh3 ligands, was applied. The hitherto unknown iodobenzene complexes (η5-cyclopentadienyl)­(1,4-η6-diiodobenzene)­ruthenium­(II) hexafluoridophosphate (1b) and (η5-cyclopentadienyl)­(η6-1,3,5-triiodobenzene)­ruthenium­(II) hexafluoridophosphate (1c) as well as the described cationic homo- and heteronuclear sandwich complexes 3–5 were fully characterized and investigated with respect to the second-harmonic generation by hyper-Rayleigh scattering. For complexes 1b, 1c, 3a, and 5 X-ray structure determinations were performed.