Olefin Metathesis as an Inorganic Synthetic Tool: Cross and Ring Closing Metathesis Reactions of Diruthenium-Bound ω-Alkene-α-carboxylates

Diruthenium compounds containing one ω-alkene-α-carboxylate ligand, Ru2Cl(D(3,5-Cl2Ph)F)3(O2C(CH2)nCHCH2)
(n = 1 (1a) and 2 (1b)), were prepared from the reaction between Ru2Cl(D(3,5-Cl2Ph)F)3(O2CCH3) (D(3,5-Cl2Ph)F
= N,N‘-bis(3,5-dicholorophenyl)formamidinate) and the corresponding ω-alkene-α-carboxylic acid. Compounds 1a
and 1b both underwent olefin cross metathesis reactions catalyzed by (Cy3P)2Cl2Ru(CHPh) to afford the dimerized
compounds [Ru2Cl(D(3,5-Cl2Ph)F)3]2(μ-O2C(CH2)nCHCH(CH2)nCO2) (n = 1 (2a) and 2 (2b)). Similarly, diruthenium
compounds containing two ω-alkene-α-carboxylate ligands, cis-Ru2Cl(D(3,5-Cl2Ph)F)2(O2C(CH2)nCHCH2)2 (n =
1 (3a), 2 (3b), and 3 (3c)), were prepared by substituting the acetate ligands in cis-Ru2Cl(D(3,5-Cl2Ph)F)2(O2CCH3)2 with the corresponding ω-alkene-α-carboxylate ligands. Compounds 3 exhibited different reactivity under
olefin metathesis conditions:  both 3b and 3c underwent the intramolecular ring closing reaction quantitatively to
afford compounds cis-Ru2(D(3,5-Cl2Ph)F)2(μ-O2C(CH2)nCHCH2(CH2)nCO2)Cl with n = 2 (4b) and 3 (4c),
respectively, but 3a displayed no metathesis reactivity. Molecular structures of compounds 1a/1b, 2a/2b, 3a/3b,
and 4b were established via X-ray diffraction studies, confirming the formation of cross and ring closing metathesis
products. Voltammograms of compounds 2 are nearly identical to those of compounds 1, indicating the absence
of electronic interactions mediated by the tether derived from olefin metathesis.