Literature Seminar on Expansion of Pd chains through Beta-Carotene & Tetraphosphine ligands
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Transcript of Literature Seminar on Expansion of Pd chains through Beta-Carotene & Tetraphosphine ligands
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Literature Seminar
Expansion of Pd Chains through -Carotene & Tetraphosphine Ligands
Nina Saraei Nov 24.2015
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Outline Introduction The Chemistry of Pd(I) & other Low Valent Transition Metals Applications of Pd Chains(containing Pd(I)) Challenges Hetero metals in Pd(I) Chains
First paper: Stepwise Expansion of Pd Chains via Binuclear Pd(I) Complexes Supported by Tetraphosphine Ligands Previous Studies Results & Discussions Conclusion
Second paper: Multinuclear Metal-binding ability of a Carotene Previous Studies Results & DiscussionsConclusion Critics & New ideas 2
Introduction The Chemistry of Pd(I) & other Low Valent Transition MetalsPd: Group 10 Principal oxidation states II & IV Metal clusters (M-M bonds & -acidic ligands like PR) I & III
Pd(I) like [Pd(PMe)]: Coordination number 4 Square planar
Pd(I) complexes* : Pd(0) + Pd(II) 2 Pd(I) Pd(II) + Reducing conditions Pd(I) Pd(0) + Oxidizing conditions Pd(I)
* Cotton. F., Wilkinson. G., Murillo. C., Bochmann. M., Advanced Inorganic Chemistry, Sixth Edition, 1063-10703
Introduction The Chemistry of Pd(I) & other Low Valent Transition Metals Pd(I) Pd(I) clusters : non-bridged entities , SP environment for each metal center
[PdCl] + Pd(CO)
Bridged entities, ligands like chelating phosphines such as PhPCHPPh(dppm) , allenyl (Organopalladium complex)
* Cotton. F., Wilkinson. G., Murillo. C., Bochmann. M., Advanced Inorganic Chemistry, Sixth Edition, 1063-1070
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Introduction The Chemistry of Pd(I) & other Low Valent Transition Metals
Pt(I) : Behavior similar to Pd(I) Greater density & Higher melting point Less abundant , more expensive
Ni(I) : Mostly contain phosphine ligands Coordination number 4 Tetrahedral or tbp Less stable in air
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IntroductionApplications of Pd Chains(containing Pd(I))
Pd chains EMACs (Extended Metal Atom Chains) Mixed-valence compounds with delocalized unpaired electrons Conductivity along chain , Electronic devices , Quantum tunneling 6
Introduction Applications of Pd Chains(containing Pd(I))
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Introduction Challenges The longer metal chain > The more synthetic difficulties Lower yield Instability of EMAC due to high flexibility of large ligand 8
Solutions
I. Stepwise methodology rather than Template synthesis
II. Substitution of rigid & potentially redox active ligands
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Introduction Hetero metals in Pd(I) chains
Manipulation of the conductivity along chain Conformation control , Preference of M bonding , Avoiding regioisomers Different energy gap between d orbitals , Different current flow [CuCuPd(npa)Cl] (3d)(4d) [CuCuPt(npa)Cl] (3d)(5d)* Large energy gap , One-direction current flow , Rectifier-like behavior
* Liu. I., Wang. W., Peng. S., Chem. Commun, 2009, 29, 4323-4331.
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First paper: Stepwise Expansion of Pd Chains via Binuclear Pd(I) Complexes Supported by Tetraphosphine Ligands Previous Studies [Pt(RNC)](PF) + 2 dpmp
[Pt(XylNC)] NaBH/EtOH1a
* Goto. E., Begum. R., Hosokawa. A., Yamamoto. C., Kure. B. , Organometallics, 2012, 31, 8482.
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1a
Previous Studies dpmppm *
L = dmf , T >100 C
* Nakamae. K., Takemura. Y., Kure. B., Nakajima. T., Kitagawa. Y., Tanase. T., Angew. Chem., Int. Ed. 2015, 54, 1016. 13
L=CH3CN,DMF,XylNC
Results and Discussions - (Homonuclear complex) Preparation of [Pd(-dpmppm)]X (X= PF ,BF) [Pd(XylNC)]X + 2 dpmppm
XylNC : . Pd(I)-Pd(I) : 2.7379 . Asymmetrical fashion , 5 & 6-membered rings , 4 types P . UV-Vis : 458 nm for * . ESI MS : (m/z(=2))= 735.082 for [Pd(dpmppm)]14CHCl , 2hrs, rt
Results and Discussions - (Homonuclear complex) Preparation of [Pd(-dpmppm)(L)n]X (X= PF ,BF), (n=2 , 3), (L=XylNC ,L= BuNC)
15SymmetricalAsymmetricallow Thigh T
[Pd(db2]V+ L
Results and Discussions - (Homonuclear complex) Temperature-dependent NMR spectra of [Pd(-dpmppm)(XylNC)n]X in CDCN 16H{P} NMR
P{H} NMR
PPd
P
Pd
Pd
Pd
P
P
P
P
P
P
L
L
X2
Results and Discussions - (Homonuclear complex) Temperature-dependent NMR spectra of [Pd(-dpmppm)(BuNC)n]X in CDCN
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P{H} NMR
PPd
P
Pd
Pd
Pd
P
P
P
P
P
P
L
L
X2
Results and Discussions - (Homonuclear complex) Variable-temperature UV-Vis changes in CHCN for [Pd(-dpmppm)(XylNC)n]X(reversible upon changing ratio of [L]/[Pd])
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Results and Discussions - (Homonuclear complex) Variable-temperature UV-Vis changes in CHCN for [Pd(-dpmppm)(BuNC)n]X(reversible upon changing ratio of [L]/[Pd])
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Results and Discussions - (Homonuclear complex) Preparation of [Pd(-dpmppm)(CHCN)]X (X= PF ,BF)
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P{H} NMR
68%
Results and Discussions[Pd(-dpmppm)(CHCN)]X (X= PF ,BF)
21H{P} NMR
Pd1-Pd2 < Pd2-Pd3 < Pd3-Pd4 > Pd4-Pd5 Pd Pd distance range : (2.6249 2.7921 ) Space group : P-1 22
1. Results proved that [Pd(-dpmppm)].(BF) or (PF) is a good precursor for Pd chains , either extension to [Pd] in acetonitrile or termination to [Pd] in the presence of isocyanides .
2. All spectroscopic features of octanuclear complex for both (PF) and (BF) are identical ,indicating that the counteranions have no influence on the [Pd] structure.
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Results and Discussions - (Heteronuclear complex) Preparation of PdM Complexes, [PdCl(Cp*MCl)(Cp*MCl)(-dpmppm)](PF)(M= Rh, Ir)
M= Rh (Pd(I)-Pd(I) = 2.6932 )M= Ir (Pd(I)-Pd(I) = 2.710 )
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Conclusion
Results demonstrating that the binuclear palladium(I) complexes with two dpmppm ligands are viable precursors to extend low-valent Palladium chains and Pd-involved mixed-metal multinuclear systems in stepwise procedures. 26
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Second paper: Multinuclear metal-binding ability of a carotene Previous studies :
Carotenoids > Naturally abundant pigments , extended -conjugated C=C arrays Large (M-M)-bonded arrangement Poly-nucleating multidentate ligands , controlling metal assembly* Light-harvesting, photo-protective, antioxidative & conductive properties **
* Sunada, Y., Haige, R., Otsuka, K., Kyushin, S., Nagashima, H., Nat. Commun., 2013, 4, 2014. ** Polvika, T., Frank, H. A., Acc. Chem. Res., 2010, 43, 1125.28
Previous studies :
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Sunada, Y., Haige, R., Otsuka, K., Kyushin, S., Nagashima, H., Nat. Commun., 2013, 4, 2014
(excess)
Results and Discussions : Synthesis & structure of bis-(-Carotene) decanuclear Pd complexes :
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Results and Discussions :
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Results and Discussions : . HNMR & C{H} NMR : Olefinic protons & carbons , high-field region = 2.6- 3.5 ppm = 69- 111 ppm
. X-ray structure : infinite intermolecular - stacking columns/dimers , typical property of the planar -conjugated system
Both of above results show that bis--Carotene -framework can accommodate 10 Pd atoms array through remarkable multidentate bridging -coordination32
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Pd Pd : 2.5827- 2.7172 Pd Pd : 2.6010 2.7111 Pd1-Pd2 > Pd2-Pd3 > Pd3-Pd4 > Pd4-Pd5 > Pd5-Pd5* Pd1-Pd2 > Pd2-Pd3 > Pd3-Pd4 > Pd4-Pd5
1-meso1-rac
Results and Discussions : Synthesis & structure of bis-(-carotene) decanuclear PdPt complexes :
metal-deficient dications [Pd(-carotene)]34
Results and Discussions : Synthesis & structure of bis-(-carotene) decanuclear PdPt complexes : 35
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Pd Pd : 2.6546-2.7501 Pd Pd : 2.6285-2.7359 Pd1-Pd2 > Pd2-Pd3 > Pd3-Pd4 < Pd4-Pd5 Pd1-Pd2 > Pd2-Pd3 > Pd3-Pd4 < Pd4-Pd5 < Pd5-Pd6 < Pd6-Pd7
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2-meso3-meso
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Pd Pd : 2.6290 2.7305 Pt Pt : 2.6569 2.6864
Pd1-Pd2 > Pd2-Pd3 > Pd3-Pd4 < Pd4-Pd5 < Pd5-Pt6 < Pt6-Pt7 < Pt7-Pt8 39
4-meso
HNMR CNMR , confirmation of Pt-Pt-Pt >, upfield shifted Pt-bounded carbons ESI MS for [CHPdPt] : 1201.555340
Conclusion :
. -Carotene , Binding homometallic & heterometallic decanuclear chain , Stepwise demetalation/metalation , Controlling the bimetal arrangement . -Carotene , multidentate -scaffolds , giant metal clusters 41
Critics & new ideas : . In both articles, only synthetic pathways were investigated . Although successful, no computational studies were done to consider how charge is delocalized along the chain. . No studies on physical & chemical properties of EMACs were reported.
* Computational studies deeply investigating charge delocalization along chain * Studies on conductivity of homo & heterometallic chains. * Comparison among different functional groups on ligands & physical properties of produced EMACs.
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Thanks
Advisor : Dr. Grapperhaus Lab mates & friends
Committee : Dr. Buchanan Dr. Liu Dr. Li
Seminar coordinator : Dr. Kozlowski 43
Introduction explanation slide 8 Applications of Pd(I) Chains (EMAC) EMACs Mixed-valence compounds with delocalized unpaired electrons (symmetric coordination sphere > indistinguishable valence) Quantitatively explored conductance
Different arrangement of metal ions > Various interactions > Change in extent of charge delocalization > Different ET efficiency
The stronger M-M interaction > The better conductivity
Longer chain > greater electron mobility > higher conductance
Less anionic ligand > Low valent MV > greater electron mobility
Heteronuclear EMAC > Charge disproportional framework > Rectifier
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Introduction explanation slide 8 Applications of Pd Chains(containing Pd(I)) Properties :Linearly ordered, high-nuclearity, electron rich Electron-transporting along metal string based on quantum conducting phenomena (quantum tunneling)
An electron wavepacket directed at a potential barrier. The dim spot atright represents tunnelling electrons
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Previous Studies explanation slide 13 & 14 Linear tetraphosphine ligand (dpmppm) :
1 . dpmp (linear triphosphine ligand) effective in stabilizing PtPd centers in EMACs* 2 . dpmp leading to reductive coupling to generate low valent EMACs Pd :
1 . Relatively weak Pd-L & Pd-Pd bonds > easier formation of Pd-M(hetero metal) chains 2 . More feasible to undergo convergent metal assembly **
* Goto. E., Begum. R., Ueno. C., Hosokawa. A., Yamamoto. C., Nakamae. K., Kure. B., Organometallics, 2014, 33, 1893. ** Mednikov. E., Dahl. L., J. Chem. Edu., 2009, 86, 1135.46
Reference to slide 18:
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