Aminoallenylidene complexes of ruthenium(<scp>ii</scp>) from the regioselective addition of secondary amines to butatrienylidene intermediates: a combined experimental and theoretical study of the hindered rotation around the CN-bond

Winter, Rainer F.; Hartmann, Stephan; Záliš, Stanislav; Klinkhammer, K. W.

doi:10.1039/b211774f

Cited by 30 publications

(33 citation statements)

References 45 publications

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“…The most likely explanation is provided by reference to our earlier work on amino-substituted allenylidene complexes of the trans-[Cl(dppm) 2 Ru] fragment. [48] Here we found that the electron density on the phosphane ligands was quite small for both occupied frontier levels, and this may also hold for the mixed Tp/diphosphane complexes described here. Our experimental observations can then be accommodated by the assumption that the HOMO level has some contribution from the phosphane ligands while there is only a negligible one to the lower-lying HOMO-1 orbital.…”

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confidence: 56%

(Allenylidene)ruthenium Complexes with Redox‐Active Substituents and Ligands

et al. 2003

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, L 2 = 2 PPh 3 or 1,1Ј-bis(diphenylphosphanyl)ferrocene (dppf), R = Ph or ferrocenyl] and their spectroscopic and electrochemical characteristics. Three of these compounds possess redox-active, ferrocenebased substituents or ligands − that are oxidized at lower potentials than the ruthenium center itself − attached either to the terminal carbon atom of the allenylidene ligand or to the ruthenium atom. The Fc/Ph-substituted complexes 3a and 3b provide unique examples of hindered rotation of the allenylidene substituent around the M=C bond. For 3a (L 2 = 2 PPh 3 ), two isomers differing in the orientation of the vertically aligned, unsymmetrically substituted allenylidene ligand are discernible even at 388 K. The dppf-substituted congener 3b has the allenylidene ligand in a horizontal orientation and exhibits a rotational barrier, as determined by dynamic 31 P NMR spectroscopy, of ∆G ϶ = 47 kJ/mol at T C = 238 K. The changes in the spectroscopic and electrochemical properties upon replacement of the PPh 3 by a dppf ligand and the Ph by an Fc moiety can be explained in terms of the bonding within these systems. These effects are attenuated when the ferrocene-based redox tags are oxidized, as shown by IR and

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confidence: 56%

(Allenylidene)ruthenium Complexes with Redox‐Active Substituents and Ligands

et al. 2003

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“…The main absorption band in the visible regime of the electronic spectra is centered at 390-408 nm for complexes ta -e and 3a-e, but shifted to significantly lower energies (432 and 522 nm, respectively) for the iminostil bene (14] and the 2,5-dimethylpyrrole derived complexes 2a,b. The latter derivative may be viewed as a vinylogous aminoallenylidene complex.…”

Section: Resultsmentioning

confidence: 92%

“…13 MHz) and I3C_ (62.90 MHz) NMR spectra were recorded on a Bruker AC 250 spectrometer at 303 K. The spectra were referenced to the residual protonated solvent (' H) or the solvent signal itself (13C). For complexes Ie, 2a [14] and 3a-e, the assignment of 13C_NMR spectra wa s aided by a DEPT-135 measurement. UV -vis experiments were performed on an Omega 10 spectrometer by Bruins Instruments in HELMA quartz cuvettes whith I cm optical path lengths.…”

Section: Instrumentationmentioning

confidence: 99%

Long-lived higher excited state luminescence from new ruthenium(II)–allenylidene complexes

Slageren

Winter

Klein

et al. 2003

Journal of Organometallic Chemistry

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Resonance Raman spectra of heteroatom substituted ruthenium(II)-allenylidene complexes, obtained by irradiation into the second electronic absorption band, clearly prove the d(Ru)-> 1t*(CCC) MLCT character of the corresponding electronic transition. The complexes are not significantly luminescent at room temperature, but in solvent glasses at 77 K, emission is observed. Only some of the complexes studied are luminescent upon irradiation into their lowest-energy absorption band. The striking finding of this study is that a lmost a ll complexes are luminescent on irrad iation into their second absorption band. The emission was shown to originate from a higher lying 3MLCT state, which shows that internal conversion to the lowest excited state is very inefficient in these complexes.

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“…This can be accounted for [95] by the lower basicity of the N atom of the unsaturated heterocycles, rather than by the involvement in the oxidation of the expected electroactive heterocycles.…”

Section: Allenylidenesmentioning

confidence: 98%

“…Most of the electrochemical studies of allenylidene complexes have been performed with the trans-{RuCl(dppm) 2 } + center [92][93][94][95][96] (in a few cases with the analogous dppe [86,94] or depe [94] sites) which has allowed to establish the following order of net electron acceptance: arylallenylidenes @C@C@CRR 0 (P L = À0.15 to À0.31 V, E L = 0.61-0.47 V vs. NHE) > selenoallenylidenes @C@C@C(SeR) (alkyl) (P L = À0.22 to À0.26 V, E L = 0.55-0.51 V vs. NHE) > thioallenylidenes @C@C@C(SR)(alkyl) (P L = À0.26 to À0.31 V, E L = 0.51-0.47 V vs. NHE) > aminoallenylidenes (P L = À0.39 to À0.84 V, E L = 0.41-0.0 V vs. NHE), pyrollyl or indolyl substituted allenylidenes (P L = À0.53 to À0.65 V, E L = 0.28-0.18 V vs. NHE). This order reflects the electronic effects of the groups at the C c which are transmitted to the binding metal center through the allenylidene unsaturated carbon chain.…”

Section: Allenylidenesmentioning

confidence: 99%