Rigid Bis(tetrathiafulvalenes) Doubly Bridged by Phosphino Groups and Derivatives: Synthesis and Intramolecular Mixed Valence State

Danila, Ion; Biaso, Frédéric; Sidorenkova Cruz Gonzalez, Elena; Geoffroy, Michel; Fourmigué, Marc; Levillain, E.; Avarvari, Narcis

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Title		Rigid Bis(tetrathiafulvalenes) Doubly Bridged by Phosphino Groups and Derivatives: Synthesis and Intramolecular Mixed Valence State
Authors		Danila, Ion Biaso, Frédéric Sidorenkova Cruz Gonzalez, Elena Geoffroy, Michel Fourmigué, Marc Levillain, E. Avarvari, Narcis
Published in		Organometallics. 2009, vol. 28, no. 13, p. 3691-3699
Abstract		The synthesis and structural characterization of the λ5-bis(phosphine sulfide) and the bimetallic complexes bis[phosphino-M(CO)5] (M = Mo, W) of the 3,4-dimethyltetrathiafulvalene (ortho-DMTTF)-based rigid dimer (PPh)2(o-DMTTF)2, containing a central 1,4-dihydro-1,4-diphosphinine ring, are described. Single-crystal X-ray analyses have been performed for the trans isomers (PhPX)2(o-DMTTF)2 (X = S, Mo(CO)5, and W(CO)5) and for the cis isomer [PhPW(CO)5]2(o-DMTTF)2. Planar or slightly folded boat-type conformations are observed for the central six-membered ring, together with different packings characterized by short intermolecular S···S contacts. The optical signature of the oxidized species in the case of the free ligand (PPh)2(o-DMTTF)2 has been evidenced by UV−vis spectroelectrochemistry measurements. Solution EPR measurements on the radical cation species of (PPh)2(o-DMTTF)2 definitely assess the full delocalization of the unpaired electron over both electroactive TTF units, with an associated coupling of 0.48 G with 12 equivalent protons. The EPR signal of the dication proves the radical nature of this species, in favor of a triplet ground state. The radical cation of the cis-[PhPW(CO)5]2(o-DMTTF)2 isomer was also investigated by EPR, for which the observed hyperfine structure demonstrates the extended delocalization of the electron, together with a larger coupling constant with the phosphorus nuclei. DFT calculations for the radical cation of (PPh)2(o-DMTTF)2 afford a boat-type conformation for the central ring and a SOMO consistent with a full delocalization of the electron over both TTF units. Moreover, the calculations indicate that in the case of the dication of (PPh)2(o-DMTTF)2 the triplet state is more stable by 11.7 kcal mol−1 than the singlet state.
Identifiers		DOI: 10.1021/om900107y
Full text		Article (Published version) - Free access Other version: http://pubs.acs.org/doi/pdf/10.1021/om900107y
Structures		Faculté des sciences / Section de chimie et biochimie / Département de chimie physique
Research group		Groupe Geoffroy
Citation (ISO format)		DANILA, Ion et al. Rigid Bis(tetrathiafulvalenes) Doubly Bridged by Phosphino Groups and Derivatives: Synthesis and Intramolecular Mixed Valence State. In: Organometallics, 2009, vol. 28, n° 13, p. 3691-3699. https://archive-ouverte.unige.ch/unige:3551