Redox-Active Tetraruthenium Macrocycles Built from 1,4-Divinylphenylene-Bridged Diruthenium Complexes.
Metallamacrocylic tetraruthenium complexes were generated by treatment of 1,4-divinylphenylene-bridged diruthenium complexes with functionalized 1,3-benzene dicarboxylic acids and characterized by HR ESI-MS and multinuclear NMR spectroscopy. Every divinylphenylene diruthenium subunit is oxidized in two consecutive one-electron steps with half-wave potential splittings in the range of 250 to 330 mV. Additional, smaller redox-splittings between the +/2+ and 0/+ and the 3+/4+ and 2+/3+ redox processes, corresponding to the first and the second oxidations of every divinylphenylene diruthenium entity, are due to electrostatic effects. The lack of electronic coupling through bond or through space is explained by the nodal properties of the relevant molecular orbitals and the lateral side-by-side arrangement of the divinylphenylene linkers. The polyelectrochromic behavior of the divinylphenylene diruthenium precursors is retained and even amplified in these metallamacrocyclic structures. EPR studies down to T=4 K indicate that the dications 1-H(2+) and 1-OBu(2+) are paramagnetic. The dications and the tetracation of macrocycle 3-H display intense (dications) or weak (3-H(4+) ) EPR signals. Quantum chemical calculations indicate that the four most stable conformers of the macrocycles are largely devoid of strain. Bond parameters, energies as well as charge and spin density distributions of model macrocycle 5-H(Me) were calculated for the different charge and spin states.
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Stefan
S
Scheerer
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Michael
M
Linseis
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.|Boehringer Ingelheim Pharma GmbH & CO. KG, Birkendorfer Straße 65, 88397, Biberach a. d. Riß, Germany.
Evelyn
E
Wuttke
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Sabrina
S
Weickert
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Malte
M
Drescher
Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058, Erlangen, Germany.
Oliver
O
Tröppner
Department of Chemistry and Pharmacy, Friedrich-Alexander-Universität Erlangen-Nürnberg, Egerlandstraße 1, 91058, Erlangen, Germany.
Ivana
I
Ivanović-Burmazović
Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany.
Andreas
A
Irmler
Fachbereich Physik, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany. fabian.pauly@uni-konstanz.de.
Fabian
F
Pauly
Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, 78457, Konstanz, Germany. Rainer.Winter@uni-konstanz.de.
Rainer F
RF
Winter
(spectro)electrochemistry; density functional calculations; electrochromism; metallamacrocycle; paramagnetism