%0 Journal Article %1 Maurer.2006 %A Maurer, Joerg %A Sarkar, Biprajit %A Schwederski, Brigitte %A Kaim, Wolfgang %A Winter, Rainer F. %A Zalis, Stanislav. %D 2006 %J Organometallics %K DFT;DFT addn bridged bridging cation;divinylphenylene complex complex;diethynylbenzene complex;diruthenium diruthenium divinylphenylene electrochem hydro ligand oxidn prepn;electrochem radical ruthenium stereoselective %N 15 %P 3701--3712 %R 10.1021/om0602660 %T Divinylphenylene-Bridged Diruthenium Complexes Bearing Ru(CO)Cl(PiPr3)2 Entities %V 25 %X The divinylphenylene-bridged diruthenium complexes (E,E)-(PiPr3)2(CO)ClRu2(m-HC:CHC6H4CH:CH-1,3) (m-2) and (E,E)-(PiPr3)2(CO)ClRu2(m-HC:CHC6H4CH:CH-1,4) (p-2) have been prepd. and compared to their PPh3-contg. analogs m-1 and p-1. The higher electron d. at the metal atoms increases the contribution of the metal end groups to the bridge-dominated occupied frontier orbitals and stabilizes the various oxidized forms with respect to those of m-1 and p-1. This has been confirmed and quantified electrochem., because the two reversible oxidn. waves were obsd. at considerably lower potentials than for the PPh3 complexes. Owing to their greater stability, the one- and two-electron-oxidized forms m-2n+ and p-2n+ of both complexes could be generated and spectroscopically characterized inside an optically transparent thin layer electrolysis cell. UV/vis/near-IR and ESR spectroelectrochem. indicates that the oxidn. processes are centered at the org. bridging ligand. s-Bonded divinylphenylenes thus constitute an unusual class of \dqnoninnocent\dq ligands for organometallic compds. Electronic transitions obsd. for the mono- and dioxidized forms closely resemble those of donor-substituted phenylenevinylene compds., including oligo(phenylenevinylenes) (OPVs) and poly(phenylenevinylene) (PPV) in the resp. oxidn. states. Strong ESR signals and nearly isotropic g tensors are obsd. for the monocations in fluid and frozen solns. The metal contribution to the redox orbitals is illustrated by a shift of the CO stretching bands to notably higher energies upon stepwise oxidn. The shifts strongly exceed those obsd. for the PPh3 contg., six-coordinated species (E,E)-(PPh3)2(CO)Cl(L)Ru2(m-HC:CHC6H4CH:CH)n+ (L = substituted pyridine). IR spectroelectrochem. reveals the presence of two electronically different transition-metal moieties in m-2+, while they resemble each other more closely in p-2+. Differences in electronic coupling are illustrated by the charge distribution parameters calcd. from the spectra. Bulk electrolysis expts. confirm the results from the in situ spectroelectrochem. and the overall stoichiometry of the redox processes. Quantum-chem. calcns. were performed in order to provide insight into the nature and compn. of the frontier orbitals. The electronic transitions obsd. for the neutral forms were assigned by TD DFT. IR frequencies calcd. for m-2 and p-2 in their various oxidn. states retrace the exptl. observations. They fail, however, in the case of m-2+, where a sym. structure is calcd., as opposed to the distinctly asym. electron distribution obsd. by IR spectroscopy. Geometry-optimized structures were calcd. for all accessible oxidn. states. The structural changes following stepwise oxidn. agree well with the exptl. findings: e.g., a successive low-energy shift of the C:C stretching vibration of the bridge. The radical cation m-2+ displays a broad composite electronic absorption band at low energy that extends into the mid-IR region. on SciFinder(R)

@article{Maurer.2006, abstract = {The divinylphenylene-bridged diruthenium complexes (E,E)-[{(PiPr3)2(CO)ClRu}2(\textgreek{m}-HC:CHC6H4CH:CH-1,3)] (m-2) and (E,E)-[{(PiPr3)2(CO)ClRu}2(\textgreek{m}-HC:CHC6H4CH:CH-1,4)] (p-2) have been prepd. and compared to their PPh3-contg. analogs m-1 and p-1. The higher electron d. at the metal atoms increases the contribution of the metal end groups to the bridge-dominated occupied frontier orbitals and stabilizes the various oxidized forms with respect to those of m-1 and p-1. This has been confirmed and quantified electrochem., because the two reversible oxidn. waves were obsd. at considerably lower potentials than for the PPh3 complexes. Owing to their greater stability, the one- and two-electron-oxidized forms m-2n+ and p-2n+ of both complexes could be generated and spectroscopically characterized inside an optically transparent thin layer electrolysis cell. UV/vis/near-IR and ESR spectroelectrochem. indicates that the oxidn. processes are centered at the org. bridging ligand. \textgreek{s}-Bonded divinylphenylenes thus constitute an unusual class of {\dq}noninnocent{\dq} ligands for organometallic compds. Electronic transitions obsd. for the mono- and dioxidized forms closely resemble those of donor-substituted phenylenevinylene compds., including oligo(phenylenevinylenes) (OPVs) and poly(phenylenevinylene) (PPV) in the resp. oxidn. states. Strong ESR signals and nearly isotropic g tensors are obsd. for the monocations in fluid and frozen solns. The metal contribution to the redox orbitals is illustrated by a shift of the CO stretching bands to notably higher energies upon stepwise oxidn. The shifts strongly exceed those obsd. for the PPh3 contg., six-coordinated species (E,E)-[{(PPh3)2(CO)Cl(L)Ru}2(\textgreek{m}-HC:CHC6H4CH:CH)]n+ (L = substituted pyridine). IR spectroelectrochem. reveals the presence of two electronically different transition-metal moieties in m-2+, while they resemble each other more closely in p-2+. Differences in electronic coupling are illustrated by the charge distribution parameters calcd. from the spectra. Bulk electrolysis expts. confirm the results from the in situ spectroelectrochem. and the overall stoichiometry of the redox processes. Quantum-chem. calcns. were performed in order to provide insight into the nature and compn. of the frontier orbitals. The electronic transitions obsd. for the neutral forms were assigned by TD DFT. IR frequencies calcd. for m-2 and p-2 in their various oxidn. states retrace the exptl. observations. They fail, however, in the case of m-2+, where a sym. structure is calcd., as opposed to the distinctly asym. electron distribution obsd. by IR spectroscopy. Geometry-optimized structures were calcd. for all accessible oxidn. states. The structural changes following stepwise oxidn. agree well with the exptl. findings: e.g., a successive low-energy shift of the C:C stretching vibration of the bridge. The radical cation m-2+ displays a broad composite electronic absorption band at low energy that extends into the mid-IR region. [on SciFinder(R)]}, added-at = {2022-06-15T11:26:56.000+0200}, author = {Maurer, Joerg and Sarkar, Biprajit and Schwederski, Brigitte and Kaim, Wolfgang and Winter, Rainer F. and Zalis, Stanislav.}, biburl = {https://puma.ub.uni-stuttgart.de/bibtex/27f2f29937149d1945d0964925b49fe3a/huebleriac}, doi = {10.1021/om0602660}, interhash = {0afa12ecbfb5b8b4380646cd5a724114}, intrahash = {7f2f29937149d1945d0964925b49fe3a}, issn = {0276-7333}, journal = {Organometallics}, keywords = {DFT;DFT addn bridged bridging cation;divinylphenylene complex complex;diethynylbenzene complex;diruthenium diruthenium divinylphenylene electrochem hydro ligand oxidn prepn;electrochem radical ruthenium stereoselective}, number = 15, pages = {3701--3712}, timestamp = {2022-06-15T09:26:56.000+0200}, title = {Divinylphenylene-Bridged Diruthenium Complexes Bearing Ru(CO)Cl(PiPr3)2 Entities}, volume = 25, year = 2006 }