ESR of homo- and heteroleptic mono- and dinuclear tris(.alpha.-diimine)ruthenium radical complexes

Abstract

of the osmium and ruthenium complexes and allowed for two (28) The maximum solubility of (Os)(Ru)DPB in benzene is approximately 3 mg/mL so the concentration range investigated was 0.2-0.7 mM. convergent steps. The syntheses for more interesting combintions, such as early-late transition metals (i.e., Mo^Ru), will probably not be as straightforward. The disparity between low oxidation state stabilities and the coordination chemistry of the two metalloporphyrins may still frustrate the synthesis. However, we nevertheless view this general synthetic procedure as an important step in the preparation of complexes with heteronuclear metalmetal multiple bonds.We also anticipate benefits from these results in the area of electrocatalysis. The ability to prepare heterodinuclear DPB complexes with a 4d or 5d metal known to bind dinitrogen and another metal to activate it toward multielectron reduction should facilitate the survey of possible catalysts for this challenging catalytic reaction.

Variable Structure of the Cu2S2 Core in Doubly Thiolate-Bridged Dicopper(I) Complexes. An X-Ray Crystallographic, Electrochemical and EPR Study of (dmp)2(o-CH3C6H4S)2Cu2, dmp = 2,9-Dimethyl-1,10-phenanthroline, and a Comment on the Nature of Phenanthroline-Containing “Cu(0)” Complexes

“…However, the total width of about 2.4 mT of the spectrum does not point to a delocalized or interm ediate situation which would rather lead to unusually broad or very narrow signals, as has been discussed for com plexes (L)3 R u+ = [(L_I)(L)2R uH]+, L = a-diim ine ligands [15]. We attribute this difference between (L)3 R u+ and (L)2Cu° radical complexes to the vir tually orthogonal arrangement of the ligand n sys tems in the latter compounds with their approxi mately tetrahedral configuration at the metal [1 2 ].…”

“…Reversible one-electron reduction of complex 1 was carried out inside an EPR cavity using a twoelectrode cell [15], The EPR spectrum of I -* is centered at g = 2.0019 and could be simulated with the coupling param eters a(63'65Cu) = 0.53 mT (1 Cu), a(14N) = 0.29 mT (2N ) and a (!H ) = 0.29 mT (4H; H 3A7'8) (Fig. 4).…”

“…UV-VIS absorption measurem ents were car ried out in benzonitrile solutions using a Shimadzu UV 160 spectrophotom eter. EPR spectra were taken on a Bruker ESP 300 system using sealed tubes (potassium reduction) or two-electrode cells [15] for radical generation, g Factors were deter mined with the help of an E R 035 M Gaussm eter (Bruker) and a HP 5350 B microwave counter.…”

Characterization of excited electronic and vibronic states of platinum metal compounds with chelate ligands by highly frequency-resolved and time-resolved spectra

“…The data are summarized in Table 7. In particular, for [Ru(bpy)2(bpz)] 2+ and [Ru-(bpy)2(bpdz)] ~+, the lowest excited states are -in general agreement [85,196,198,210,[248][249][250][251][252][253] -localized on the (Ru-bpz) and the (Ru-bpdz) subunit, respectively. Interestingly, in these situations the values of zfs zlE~_i1 and AEI_ m are ~100% and ~70% larger, respectively, than those for the related tris compounds [Ru(bpz)3] 2+ and [Ru(bpdz)3]2+.…”

Isomeric Diruthenium Complexes Bridged by Deprotonated Indigo in cis and trans Configuration

“…The scan rate used was 100 mVs À1 .A ll electrochemical experiments were carried out under dinitrogen atmosphere. The half wave potential E8 298 was set equal to 0.5(E pa + E pc ), where E pa and E pc are anodic and cathodic cyclic voltammetry peak potentials, respectively.T he EPR measurements were made in at wo electrode capillary tube [20] with an X-band (9.5 GHz) Bruker system ESP300 spectrometer.U V-vis-NIR spectroelectrochemical studies were performed in CH 2 Cl 2 /0.1 m Bu 4 NPF 6 at 298 Ku sing an optically transparent thin-layer electrode (OTTLE) cell [21] mounted in the sample compartment of aJ &M TIDAS spectrophotometer.A ll spectroelectrochemical experiments were carried out under ad initrogen atmosphere. …”