Cooperative bimetallic oxidative addition reactions

Qin, C. Jin; Gavrilova, Anna L.; Bosnich,

doi:10.1351/pac200173020221

Cited by 18 publications

(3 citation statements)

References 1 publication

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“…These particular features of the present type of bimetallic complexesin combination with the possibility of accommodating various different metal ions in the N 4 pocket and the obvious ease of oxidation of the organometallic part of the bimetallic system -suggests to use the CpMn(COh subunit as an electron reservoir for redox reactions occurring at the adjacent Werner-type site, i.e. for so-called one-site addition two-metal oxidation pro cesses [27].…”

Section: Resultsmentioning

confidence: 93%

Combining organometallic and Werner-type coordination sites in highly preorganized heterobimetallic systems

Röder¹,

Meyer²,

Winter³

et al. 2002

Journal of Organometallic Chemistry

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A first example of a novel class of preorganized bimetallic complexes is reported, in which both an organometallic CpMn(COh fragment and a classical Werner-type coordination site are arranged in close proximity by means of a bridging pyrazolate. The synthetic route starts from N-protected bis(chloromethyl)pyrazole and involves sequential attachment of the manganese part and the chelating N-donor compartment, bis(pyridylmethyl)amine, at the different sides of the ligand backbone. Pyrazole binding to the manganese(I) is achieved by photoinduced substitution of CO, and the adjacent N4-coordination pocket is suited to accommodate a second metal ion. The heterodinuclear MnZn complex 4 is characterized crystallographically and its redox chemistry investigated by spectroelectrochemical methods.

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Section: Resultsmentioning

confidence: 93%

Combining organometallic and Werner-type coordination sites in highly preorganized heterobimetallic systems

Röder¹,

Meyer²,

Winter³

et al. 2002

Journal of Organometallic Chemistry

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“…In the case of redox-active metal ions in the {N 4 } site, this approach may lead to well-defined systems capable of novel "one-site-addition-two-metal-oxidation" reactions. [8] Two characteristics of type D complexes are noteworthy in this regard: firstly, the rigid chelate arrangement precludes dissociation of the organometallic fragment from the bridging pyrazolate, and secondly, the π plane of the heterocycle roughly coincides with the mirror plane of the Mn(CO) 2 moiety. The latter situation is most favorable for Mn-pyrazolate π-interactions and hence for electronic communication between the Mn site and the second metal ion.…”

Section: Introductionmentioning

confidence: 99%

Heterobimetallic Systems Containing Organometallic and Classical Coordination Sites: Effects of Subtle Changes in the Werner‐Type Site

et al. 2005

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Several highly unsymmetrical heterodinuclear Mn/Zn complexes are reported, in which an organometallic CpMn-(CO) 2 fragment and a classical Werner-type zinc coordination unit are arranged in close proximity by means of a bridging pyrazolate. Ligand scaffolds differing in the chelate size of the tripodal tetradentate {N 4 } binding site, and different coligands for zinc are employed. Both the zinc-devoid precursor compounds and the bimetallic complexes with zinc(II) nested in the tris(pyridylalkyl)amine type {N 4 } compartment

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“…A prominent case is the respiratory protein hemerythrin that contains in its active site both a five-coordinate iron where the O 2 substrate binds and an adjacent six-coordinate iron that provides the second electron for dioxygen-to-hydroperoxide reduction . Such intriguing metal ion cooperativity, sometimes referred to as one-site addition two-metal oxidation, has recently triggered the search for suitably designed unsymmetric bimetallic complexes that could lead to similar reactivity patterns in a synthetic system . Asymmetry in bridged binuclear metalloenzymes has also provided lessons for the synthetic chemist in a much broader sense, and a variety of unsymmetric compartmental ligand scaffolds have been designed to study the mutual effects of the two metals. , One strategy to achieve coordination site distinction is the attachment of two different chelating sidearms to an endogenenous bridging moiety such as phenolate, , pyrazolate, or oxadiazole .…”

Section: Introductionmentioning

confidence: 99%

Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes

et al. 2005

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A set of highly preorganized pyrazolate-bridged dimanganese complexes L(Mn)MnX have been prepared and structurally characterized. They can be described as hybrid organometallic/Werner-type systems that consist of a low-spin CpMn(I)(CO)2 subunit (Mn1) and a proximate tripodal tetradentate {N4} binding pocket accommodating a high-spin Mn(II) ion (Mn2), with Mn...Mn distances of approximately 4.3 A and different coligands bound to Mn2. Density functional theory (DFT) calculations (both the hybrid B3LYP and the pure BP86 functionals and the all-electron basis sets 6-311G and 6-311G*) confirm that the valence alpha and beta Kohn-Sham molecular orbitals (MOs) of these mixed-valent Mn(I)Mn(II) compounds have predominant Mn(3d) character and an almost perfectly localized nature: all five unpaired electrons are essentially localized at the Werner-type Mn2, whereas Mn1 possesses an effective closed-shell structure with the MOs of highest energy centered there. One-electron oxidation occurs in a clean process at approximately E(1/2) = -0.6 V (versus ferrocene/ferrocinium), giving the low-spin/high-spin Mn(II)Mn(II) species. UV/vis and IR spectroelectrochemistry as well as a detailed theoretical analysis reveal that the redox process takes place with strict site control at the organometallic subunit, while it does not significantly influence the spin and charge distribution on the Werner-type site. Positions and shifts of the nu(C[triple bond]O) absorptions are largely reproduced by the DFT calculations. These systems thus represent an exceptional example of the effect the unsymmetry of a dinucleating ligand scaffold has on the spin and charge distribution in homobimetallic complexes and might offer interesting prospects for the study of the cooperative effects of bimetallic arrays.

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Cooperative bimetallic oxidative addition reactions

Cited by 18 publications

References 1 publication

Combining organometallic and Werner-type coordination sites in highly preorganized heterobimetallic systems

Combining organometallic and Werner-type coordination sites in highly preorganized heterobimetallic systems

Heterobimetallic Systems Containing Organometallic and Classical Coordination Sites: Effects of Subtle Changes in the Werner‐Type Site

Redox Site Confinement in Highly Unsymmetric Dimanganese Complexes

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