Spectroscopy, photophysics and photochemistry of zerovalent transition metal α-diimine complexes

Stufkens, Derk J.

doi:10.1016/0010-8545(90)80040-z

Cited by 189 publications

(136 citation statements)

References 165 publications

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“…The lowest energy absorption band showed negative solvatochromism (see Table 3) which is characteristic for metal-to-ligand charge-transfer (MLCT) transitions, as has been shown for a series of a-diimine complexes such as M(CO)4(a-diimine) (M = Cr, Mo, W) [1]. The solvatochromism decreased as the 7r-acceptor ability of the ligand increased (ipr-PyCa > tBu-DAB > ipr-DAB…”

Section: Uv-vis Spectroscopymentioning

confidence: 73%

“…The maxima of these latter transitions could not be reached because of the restricted wavelength region of hexc(> 450 nm). Such transitions have, however, been observed for other a-diimine complexes such as M(CO)a(a-diimine) [1], and they always give rise to a stronger rR effect for v~ (CO) because of an increase in MLCT character with respect to the lower-energy transition. The EP of Re(Me)(CO)3(pAn-DAB) showed a much stronger rR effect for vs(CN) upon excitation into the second, higher-energy band, which belongs to an IL transition.…”

Section: Resonance Raman Spectroscopymentioning

confidence: 93%

“…undergo efficient homolysis of the M --Re bond upon irradiation into their lowest-energy absorption band [1][2][3][4][5]. This was rather unexpected, since visible excitation leads to occupation of a non-reactive MLCT state.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and spectroscopic properties of Re(R)(CO)3(α-diimine) (R  alkyl; α-diimine  R′-pyCa, R′-DAB) complexes. Crystal structure of Re(Me) (CO)3 (iPr-DAB)

Rossenaar

Kleverlaan

Ven

et al. 1995

Journal of Organometallic Chemistry

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Section: Uv-vis Spectroscopymentioning

confidence: 73%

Section: Resonance Raman Spectroscopymentioning

confidence: 93%

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Synthesis and spectroscopic properties of Re(R)(CO)3(α-diimine) (R  alkyl; α-diimine  R′-pyCa, R′-DAB) complexes. Crystal structure of Re(Me) (CO)3 (iPr-DAB)

Rossenaar

Kleverlaan

Ven

et al. 1995

Journal of Organometallic Chemistry

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“…complexes can lead to the formation of radicals if the metal-a-diimine moiety is covalently bonded to another metal fragment or an alkyl group; examples are the complexes [LnM-M'(CO)3(a-diimine)] (LnM = (CO)5Mn , (CO)5Re , (CO)4C0, Ph3Sn ' etc. ; M' = Mn, Re) [1][2][3][4][5][6][7][8], [Re(R)(CO)3(a-diimine)] [9], [RuI(ipr)(CO)2(iPr-DAB)] [10] and [Zn(R)2(R'-DAB) ] [11]. With exception of the Zn compounds, all these complexes are characterized by strongly allowed metalto-o~-diimine (MLCT) transitions in the visible region.…”

Section: Introductionmentioning

confidence: 99%

Photochemistry of the metal-metal-bonded complexes [(CO)5MnRu(Me)(CO)2(α-diimine)]. Crystal structure of the photoproduct [(CO)4Mn-μ-(σ(N),σ(N′),ν2(CN)-iPr-PyCa)Ru(Me)(CO)2]

Nieuwenhuis

Loon

Moraal

et al. 1995

Journal of Organometallic Chemistry

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Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The photochemical quantum yield for the disappearance of the ipr-DAB complex was ca. 0.30, but only 0.05 for the iPr-PyCa complex. Low-temperature measurements and flash photolysis data showed that this difference in behaviour is due to the thermal instability of the dimer [Ru(Me)(CO)2(ipr-PyCa)]2, which leads to partial regeneration of the parent complex at room temperature. At temperatures below 163 K, the photodecomposition into radicals was followed by electron transfer, leading to formation of the ions [(CO)sMn]-and [Ru(Me)(SXCO)z(a-diimine)] + in 2-MeTHF and the contact ion-pair [(CO)sMn-... Ru(Me)(CO)z(a-diimine) +] in 2-chlorobutane. Similar photodisproportionation products were formed upon irradiation of thc complexes at room temperature in the presence of N-or P-donor ligands.

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“…Owing to the d 10 configuration at the metal LF states do not exist. The photoreactivity of Ni(CO) 4 was attributed to 3d -> 4s [4] [135,136]. MLCT excitation leads to the breakage of Ni-N or Ni-CO bonds.…”

Section: Ligand Dissociation/substitutionmentioning

confidence: 99%

Charge Transfer Excitation of Coordination Compounds. Generation of Reactive Intermediates

Vogler

Kunkely

1993

Catalysis by Metal Complexes

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Reactive compounds exhibit frequently catalytic properties. Particularly, many reactive metal complexes are characterized by their catalytic activity. Photochemistry presents one of the most important and versatile methods for the generation of reactive compounds. The design of photochemically generated catalysts requires a deeper insight in the photochemistry in general. The choice of appropriate light-sensitive precursors can be guided by several considerations. A straight-forward approach involves the selection of compounds according to the type of electronic excitation which often predetermines the nature of the photoproducts.In a metal complex the metal-ligand bonds are generally polar. The molecular orbitals are then not equally delocalized between metal and ligands but predominantly located at the metal or the ligands. The electronic transitions are classified according to this localization [1]. In simple homoleptic mononuclear complexes three types of electronic excitations can be distinguished. Electronic transitions are localized at the metal (metalcentered, MC), at the ligand (ligand-centered, LC or intraligand, IL) or they take place between MOs at the metal and the ligand. The latter transitions are associated with a spatial redistribution of electrons and therefore are termed charge transfer (CT) transitions. While this review deals with CT excited states let us first have a short look at MC and LC states and their significance for the generation of reactive species which might be catalytically active.Since the valence orbitals of metals may be of the s, p, d, and f type all these orbitals can be involved in MC transitions. Ligand field (LF) or dd excited states have been investigated in great detail [2][3][4][5][6]. In many cases LF (or dd) excitation leads to a weakening of metal-ligand bonds. As a result a ligand may be released without any change of the oxidation state of the metal. This process is very important for the generation of catalysts because the product is a coordinatively unsaturated complex which provides an

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Spectroscopy, photophysics and photochemistry of zerovalent transition metal α-diimine complexes

Cited by 189 publications

References 165 publications

Synthesis and spectroscopic properties of Re(R)(CO)3(α-diimine) (R  alkyl; α-diimine  R′-pyCa, R′-DAB) complexes. Crystal structure of Re(Me) (CO)3 (iPr-DAB)

Synthesis and spectroscopic properties of Re(R)(CO)3(α-diimine) (R  alkyl; α-diimine  R′-pyCa, R′-DAB) complexes. Crystal structure of Re(Me) (CO)3 (iPr-DAB)

Photochemistry of the metal-metal-bonded complexes [(CO)5MnRu(Me)(CO)2(α-diimine)]. Crystal structure of the photoproduct [(CO)4Mn-μ-(σ(N),σ(N′),ν2(CN)-iPr-PyCa)Ru(Me)(CO)2]

Charge Transfer Excitation of Coordination Compounds. Generation of Reactive Intermediates

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