Electronic structures of [Ru(II)(cyclam)(Et(2)dtc)](+), [Ru(cyclam)(tdt)](+), and [Ru(cyclam)(tdt)](2+): an X-ray absorption spectroscopic and computational study (tdt = toluene-3,4-dithiolate; Et(2)dtc = N,N-diethyldithiocarbamate(1-)).
The reaction of [Ru(III)(cyclam)Cl(2)]Cl with 2 equiv of sodium N,N-diethyldithiocarbamate in methanol afforded [Ru(II)(cyclam)(Et(2)dtc)](BPh(4)) (1(BPh(4))). The same reaction with only 1 equiv of toluene-3,4-dithiol and a base yielded [Ru(cyclam)(tdt)](PF(6)) (2(PF(6))) which was oxidized by 1 equiv of ferrocenium hexafluorophosphate generating [Ru(cyclam)(tdt)](PF(6))(2) (2(ox)(PF(6))(2)). The crystal structures of 1 and 2 have been determined by X-ray crystallography at 100 K. The electronic structures of diamagnetic 1(BPh(4)), paramagnetic 2(PF(6)) (S = (1)/(2)), and diamagnetic 2(ox)(PF(6))(2) have been studied by magnetochemistry, spectroelectrochemistry, electron paramagnetic resonance spectroscopy, and (1)H NMR spectroscopy. X-ray absorption spectroscopy on Ru K- and L-edges as well as S K-edges has been employed. Finally, the molecular and electronic structures of all three species have been calculated by using density functional theory (B3LYP). It is shown that 2(ox) comprises an electronic structure which is best described by three resonance structures {[Ru(II)(cyclam)(tdt(0))](2+) <--> [Ru(III)(cyclam)(tdt(*))](2+) <--> [Ru(IV)(cyclam)(tdt(2-))](2+)} with a closed-shell singlet ground state. This is in stark contrast to the isoelectronic iron species, namely, [Fe(III)(cyclam)(tdt(*))](2+) which is a singlet diradical with a low-spin ferric ion coupled intramolecularly antiferromagnetically to a ligand pi radical monoanion (tdt(*))(-).
Milsmann
Carsten
C
Max-Planck-Institut für Bioanorganische Chemie, Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany.
Bill
Eckhard
E
Weyhermüller
Thomas
T
DeBeer George
Serena
S
Wieghardt
Karl
K
D018360:Crystallography, X-Ray; D004583:Electrons; D000431:Ethanol / Q000138:chemical synthesis / Q000737:chemistry; D006571:Heterocyclic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D017975:Ruthenium Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013859:Thiocarbamates / Q000138:chemical synthesis / Q000737:chemistry*; D014050:Toluene / Q000031:analogs & derivatives / Q000138:chemical synthesis / Q000737:chemistry
D006571:Heterocyclic Compounds; D017975:Ruthenium Compounds; D013859:Thiocarbamates; C024560:cyclam; D014050:Toluene; D000431:Ethanol; C004848:dithiol