title: Synthesis and Electrochemical Properties of cis- and trans-[Mo2(O2C-Fc)2(DArF)2] (O2C-Fc = Ferrocenecarboxylate; DArF = N,N'-Diarylformamidinate).
abstract: The reaction of cis-[Mo2(O2C-Fc)2(NCCH3)4][BF4]2 (cis-1) with three electronically different N,N'-diarylformamidinate (DArF) ligands [DArF = N,N'-diphenylformamidinate (DPhF), N,N'-di(p-trifluoromethylphenyl)formamidinate (DTfmpF), and N,N'-di(p-anisyl)formamidinate (DAniF)] results in products of the general composition [Mo2(O2C-Fc)2(DArF)2]. Even though the trans-[Mo2(O2C-Fc)2(DArF)2] isomers were originally expected to be the sole products, the corresponding cis-[Mo2(O2C-Fc)2(DArF)2] complexes were isolated as well via crystallization and verified unambiguously by X-ray crystallography. All novel complexes, namely, cis-[Mo2(O2C-Fc)2(DPhF)2] (cis-2a), cis-[Mo2(O2C-Fc)2(DTfmpF)2] (cis-2b), and trans-[Mo2(O2C-Fc)2(DAniF)2] (trans-2c), were studied regarding their electrochemical properties with respect to electrolyte, solvent, and ligand. The electron-donating ligand DArF(-) enables the oxidation of the [Mo2](4+) unit prior to that of Fc, while the oxidation sequence is reversed when acetonitrile or diphosphine ligands are coordinated instead of formamidinate. In the case of trans-[Mo2(O2C-Fc)2(DAniF)2], interactions were found between the two redox-active ferrocenecarboxylate ligands, with a clear ΔE1/2 value originating from the peak-to-peak separation in DPV of around 100 mV with CH2Cl2 as solvent. Furthermore, the second oxidation of the Mo2-handle [Mo2](5+)/[Mo2](6+) was exclusively observed with DAniF(-) as the ligand. Similar absorption patterns in UV-vis spectra were found within the series 2a-2c, corresponding to similar structural and electronic features of the complexes.
authors.affiliation: †Molecular Catalysis, Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München (TUM), Lichtenbergstrasse 4, 85747 Garching bei München, Germany.
authors.forename: Xu-Min
authors.initials: XM
authors.lastname: Cai
authors.affiliation: †Molecular Catalysis, Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München (TUM), Lichtenbergstrasse 4, 85747 Garching bei München, Germany.
authors.forename: Teresa K
authors.initials: TK
authors.lastname: Zimmermann
authors.affiliation: ‡CRC, Ernst-Otto-Fischer-Straße 1, 85747 Garching bei München, Germany.
authors.forename: Alexander
authors.initials: A
authors.lastname: Pöthig
authors.affiliation: †Molecular Catalysis, Department of Chemistry and Catalysis Research Center (CRC), Technische Universität München (TUM), Lichtenbergstrasse 4, 85747 Garching bei München, Germany.
authors.forename: Fritz E
authors.initials: FE
authors.lastname: Kühn