Electronic coupling of two Cp*ClM+/Cp*M reaction centers via p conjugated bridging ligands: Similarities and differences between rhodium and iridium analogues
Dinuclear Cp*ClM(m-L)MClCp*(PF6)2, M = Rh or Ir, L = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) or 2,5-bis(phenyliminoethyl)pyrazine (bpip), are reduced in several chem. reversible steps by up to six electrons to Cp*M(m-L)MCp*n-. UV-visible/NIR spectroelectrochem. and EPR of the paramagnetic states were used to identify the various intermediates. The complexes clearly show a reversible, ligand-centered 1-electron redn. (E) preceding the 1st chloride-dissociative metal redn. step (EC). Metal-metal interaction via the bridging p acceptor ligand L causes a splitting of 310-710 mV between the potentials for the two Cl--dissociative steps. The 2nd chloride release occurs in EC+E fashion for L = bpip but in a two-electron process for L = bptz. The MIIMI mixed-valent species Cp*M(m-L)MCp*+ could be identified via long-wavelength bands from intervalence charge transfer (IVCT) transitions. All complexes contg. at least one chloride-free Cp*M group display intense long-wavelength absorption bands. The Ir complexes are distinguished by more neg. potentials of the Cp*Ir-contg. forms, by slower formation of the M2I,II mixed-valent intermediate, by larger g anisotropy of the paramagnetic forms, and by triplet absorption features in the UV-visible electronic spectra. on SciFinder(R)
%0 Journal Article
%1 Kaim.1999b
%A Kaim, Wolfgang
%A Berger, Sascha
%A Greulich, Stefan
%A Reinhardt, Ralf
%A Fiedler, Jan.
%D 1999
%J Journal of Organometallic Chemistry
%K bidentate binuclear bispyridinyltetrazine center;iridium complex coupling diiridium dirhodium electron intermediate iridium redn redox rhodium spectroelectrochem;mixed tetrazinebispyrinyl valent
%N 2
%P 153--159
%R 10.1016/S0022-328X(98)01027-4
%T Electronic coupling of two Cp*ClM+/Cp*M reaction centers via p conjugated bridging ligands: Similarities and differences between rhodium and iridium analogues
%V 582
%X Dinuclear Cp*ClM(m-L)MClCp*(PF6)2, M = Rh or Ir, L = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) or 2,5-bis(phenyliminoethyl)pyrazine (bpip), are reduced in several chem. reversible steps by up to six electrons to Cp*M(m-L)MCp*n-. UV-visible/NIR spectroelectrochem. and EPR of the paramagnetic states were used to identify the various intermediates. The complexes clearly show a reversible, ligand-centered 1-electron redn. (E) preceding the 1st chloride-dissociative metal redn. step (EC). Metal-metal interaction via the bridging p acceptor ligand L causes a splitting of 310-710 mV between the potentials for the two Cl--dissociative steps. The 2nd chloride release occurs in EC+E fashion for L = bpip but in a two-electron process for L = bptz. The MIIMI mixed-valent species Cp*M(m-L)MCp*+ could be identified via long-wavelength bands from intervalence charge transfer (IVCT) transitions. All complexes contg. at least one chloride-free Cp*M group display intense long-wavelength absorption bands. The Ir complexes are distinguished by more neg. potentials of the Cp*Ir-contg. forms, by slower formation of the M2I,II mixed-valent intermediate, by larger g anisotropy of the paramagnetic forms, and by triplet absorption features in the UV-visible electronic spectra. on SciFinder(R)
@article{Kaim.1999b,
abstract = {Dinuclear [Cp*ClM(\textgreek{m}-L)MClCp*](PF6)2, M = Rh or Ir, L = 3,6-bis(2-pyridyl)-1,2,4,5-tetrazine (bptz) or 2,5-bis(phenyliminoethyl)pyrazine (bpip), are reduced in several chem. reversible steps by up to six electrons to [Cp*M(\textgreek{m}-L)MCp*]n-. UV-visible/NIR spectroelectrochem. and EPR of the paramagnetic states were used to identify the various intermediates. The complexes clearly show a reversible, ligand-centered 1-electron redn. (E) preceding the 1st chloride-dissociative metal redn. step (EC). Metal-metal interaction via the bridging \textgreek{p} acceptor ligand L causes a splitting of 310-710 mV between the potentials for the two Cl--dissociative steps. The 2nd chloride release occurs in EC+E fashion for L = bpip but in a two-electron process for L = bptz. The MIIMI mixed-valent species [Cp*M(\textgreek{m}-L)MCp*]+ could be identified via long-wavelength bands from intervalence charge transfer (IVCT) transitions. All complexes contg. at least one chloride-free Cp*M group display intense long-wavelength absorption bands. The Ir complexes are distinguished by more neg. potentials of the [Cp*Ir]-contg. forms, by slower formation of the M2I,II mixed-valent intermediate, by larger g anisotropy of the paramagnetic forms, and by triplet absorption features in the UV-visible electronic spectra. [on SciFinder(R)]},
added-at = {2019-07-15T13:41:23.000+0200},
author = {Kaim, Wolfgang and Berger, Sascha and Greulich, Stefan and Reinhardt, Ralf and Fiedler, Jan.},
biburl = {https://puma.ub.uni-stuttgart.de/bibtex/2207a9db70fd4da839eefa50d88c2dc6b/b_schwederski},
doi = {10.1016/S0022-328X(98)01027-4},
interhash = {08213d42a7315c8f999a4336b09d45e5},
intrahash = {207a9db70fd4da839eefa50d88c2dc6b},
journal = {Journal of Organometallic Chemistry},
keywords = {bidentate binuclear bispyridinyltetrazine center;iridium complex coupling diiridium dirhodium electron intermediate iridium redn redox rhodium spectroelectrochem;mixed tetrazinebispyrinyl valent},
number = 2,
pages = {153--159},
timestamp = {2019-07-15T13:42:10.000+0200},
title = {Electronic coupling of two [Cp*ClM]+/[Cp*M] reaction centers via \textgreek{p} conjugated bridging ligands: Similarities and differences between rhodium and iridium analogues},
volume = 582,
year = 1999
}
