High Pressure Coordination Chemistry: The Search for New Phenomena Alexander J. Blake School of...

High Pressure Coordination Chemistry: The Search for New

Phenomena

Alexander J. BlakeSchool of ChemistryThe University of Nottingham

PACCON2014

Introduction

Experimental

Initial results for [PdCl2([9]aneS3)]

High pressure facilities

HP studies

[MX2([9]aneS3)] complexes

[Pd([9]aneS3)(PPh3)2][PF6]2

[Pt([9]aneS3)(PPh3)2][PF6]2

Multi-phase [PdCl2([9]aneS2O)]

Current and future work

Acknowledgements

Outline of Talk

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Pressure in the solar system

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Location Pressure/bar

Interplanetary space 10-9

Surface of Mars 10-2

Surface of the Earth 1

Surface of Venus 90

Marianas Trench 1,100

Centre of Jupiter 40,000,000

Centre of the sun 150,000,000,000

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Under our feet:pressure increases with depth

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Depth /km Pressure/bar

3 (crust) 1,000

400 (upper mantle ends) 133,000

2900 (mantle/core boundary) 1,300,000

6371 (centre of the earth) 3,500,000

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Pressure around us

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System Pressure/bar

Car tyre 2

Bicycle tyre 8

Pressure washer 100

Stiletto heel 50-110

Rifle chamber 4,000

Synthesis of diamonds 55,000

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Pressure in chemistry

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Application Pressure/bar

A hydrogenation reaction 3

Ethene polymerisation 10-40

Critical pressure for CO2 73

Haber process 200

KBr press for IR disks 10,000

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Very high pressures

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Pressure/kbar

Possible processes

up to 100 van der Waals space compressed

30-200 coordination, packing changes

100 melting point of ice = 400ºC

300-600 deformation of covalent bonds

400 organic solid-state reactions

1,000 nearly all elements become metallic

“very high” electrons move off atoms

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High pressure crystallography

from 1950’s onward

• initial interest from geophysics and astrophysics

• rocks, minerals, seismology, phase transitions

• planetary interiors

from early 1990’s

• work on molecular compounds

• compressed liquids: acetone, phenol, alcohols

• solvates, pharmaceuticals, energetic materials

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High pressure crystallography

Very few metal-organic compounds reported, e.g.

• bis(dimethylglyoximato)platinum(II) O…O proton transfer

• spin-crossover in Fe(II) complexes

• resistivity in BEDT-TTF salts as a function of pressure

• pressure-dependence of structure in LiCp and KCp

• pressure-induced metal-to-insulator transitions in Pt(dmg)2

• metal-organic networks: (4-chloropyridinium)2[CoX4])

• some recent studies of copper complexes, MOFs, etc

• typically a few structures a year, but growing steadily J. P. Tidey, H. L. S. Wong, M. Schröder and A. J. Blake, Coord. Chem. Rev. 2014, submitted

Experimental – the Technology

• pressure = force/area• 1 Nm-2 = 1 Pa = 10-5 bar• diamond anvil cell (~100 kbar)• small sample compartment• pressure-transmitting medium• measure pressure by ruby

fluorescence

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Diamond Anvil Cell

5 cm

fully assembled

metal cell body

Allen screws

aperture (200 μm)

support

(goniometer head)

Fits easily into the palm of a handFits a ‘standard’ X-ray diffractometer

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Experimental issues

limited extent of data

limited quality of data

diamond reflection

gasketsample reflection

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Results for [PdCl2([9]aneS3)]

Pd1 Cl1

S4

C3

C2S1C9

C8

S7

Cl2

C6

C5

D.R. Allan, A.J. Blake, D. Huang, T.J. Prior, M. Schröder, Chem. Commun. 2006, 4081-4083

Square planar +

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Response of [PdCl2([9]aneS3)]

Between ambient pressure and 76.8 kbar

• axial Pd…S 3.159(10) 2.771(13) Å • intermolecular Pd…S 3.525(8) 3.006(10) Å• intense colour change at 44 kbar• ligand conformation [234] → [1233]• unit cell volume contracts by 23%• density increases from 2.105 to 2.732 g cm-3

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[PdCl2([9]aneS3)]

- axial Pd…S1 distance contracts

3.009(5) Å 2.846(7) Å

42.5 kbar 46 kbar

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[PdCl2([9]aneS3)]

3.204(5) Å 3.117(8) Å

42.5 kbar 46 kbar

- intermolecular Pd…S contracts- distorted octahedral coordination- chain polymer formed

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[PdCl2([9]aneS3)]

42.5 kbar 46 kbar

[234] [1233]

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- ligand changes conformation

[PdCl2([9]aneS3)]

42.5 kbar 46 kbar

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- dramatic, reversible colour change

A short movie

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Increasing pressure now …

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Now decreasing pressure …

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“Based on a true story …”

The film you have just seen is based on real results, but does not represent an actual sequence of experiments.

“No animals …”

Unfortunately, several crystals were quite definitely harmed during the making of this film.

Disclaimers

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High Pressure Crystallography Laboratory in Nottingham

Oxford Diffraction (Agilent) SuperMovaII CCD diffractometer[Ancillary equipment for pressure measurement, etc.] 41

Diamond Light Source Oxfordshire, UK

Very high intensity synchrotron X-ray source on Beamline I19 (EH1 and EH2)

2008–date

HP work at SRS and Diamond

Synchrotron Radiation Source Daresbury Laboratory, Warrington, UK

High intensity synchrotron X-ray source on Stations 9.8 and 16.2SMX

2005–2008

[MX2([9]aneS3)] complexes studied at high pressure

Compound Shortaxial contact

Chain polymer formed

Ligand conformationchanges

Marked colourchange

Catenationinduced

[PdCl2([9]aneS3)]

[PtCl2([9]aneS3)]

[PdBr2([9]aneS3)] At 58 kbar

PtBr2([9]aneS3)] At 58 kbar

[PdI2([9]aneS3)] At 19 kbar

[PtI2([9]aneS3)] At 19 kbar

D. R. Allan, D. Bailey, N. Bird, A. J. Blake, N. R. Champness, D Huang, C. P. Keane, J. McMaster, T. J. Prior, J. P. Tidey & M. Schröder, Acta Crystallogr., Sect. B 2014, 70, 469−486.

Daniel Bailey

Cation at 0.001 kbar

Pressure-induced stacking and molecular deformation in [Pd([9]aneS3)(PPh3)2][PF6]2

… stacking

Pyramidalisation at C11 at 65.5 kbar

α = 149.3(8)⁰

Henry Wong

H. L. S. Wong, D. R. Allan, N. R. Champness, J. McMaster,M. Schröder & A. J. Blake, Angew. Chem. 2013, 52, 5093–5095.

Current work: [Pt([9]aneS3)(PPh3)2][PF6]2

• does not behave anything like the Pd analogue • pressure does not induce … stacking• no pyramidalisation at C11 under compression• edge-to-face interactions are more important• have preliminary results but need higher

precisionJeremiah Tidey

Current work: [PdCl2([9]aneS2O)]

α-[PdCl2([9]aneS2O)] - known phase:facially bound, endo macrocycleforms alternating sheets of Pd2 dimersHP study complete

γ-[PdCl2([9]aneS2O)] - new phase:equatorially bound, exo macrocycleproto-chains via intermolecular Pd···O HP study complete

2.985(16) Å

3.768(4) Å

3.213(15) Å

3.39(2) Å

3.405(4) Å

3.4937(8) Å

β-[PdCl2([9]aneS2O)] - new phase:equatorially bound, exo macrocyclesimilar Pd2 dimers as in the α formbut different packing of thesecutting transforms crystals to α form

Jeremiah Tidey

Current work: [PdCl2([9]aneS2O)]

β-[PdCl2([9]aneS2O)] is a possible “disappearing polymorph”see J. D. Dunitz & J. Bernstein, Acc. Chem. Res. 1995, 28, 193–200formation of the β form may be kinetically favouredthe γ polymorph may be more thermodynamically stableit may now be impossible to obtain the β form

Jeremiah Tidey

Multiple attempts over a year to regrow β-[PdCl2([9]aneS2O)]different solvents and solvent mixturesdifferent methods, techniques and variationsall such efforts were uniformly unsuccessful

Obtained stable crystals of β-[PtCl2([9]aneS2O)]isomorphous with β-[PdCl2([9]aneS2O)]

used as a seed for epitaxial growth of β-[PdCl2([9]aneS2O)]the disappearing polymorph has been recoveredhigh pressure studies are underway on both complexes

Future work

• Central facilitiesBeamline I19 at Diamond Light Source– for any difficult cases– for structures near pressure limits

• In-house high pressure laboratoryall preliminary studies will be done herealso most of the complete studies

• Main areas of investigation

[M([9]aneS3)1-2]x+ [M([9]aneS3)PP]x+

[MX2([9]aneS2O)] MOFs48

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Future work at Diamond

• Require the capabilities of EH2• Intensity, focussed beam, sample centring

• High pressure studies on our new flexible MOFs

• Focus on MOFs with interesting properties

• Working at the limits of sample quality

• Need to optimise experimental conditions

• Develop the best experimental approaches

Acknowledgements

Dr Dave AllanProfessor Martin SchröderProfessor Neil ChampnessDr Jon McMaster

Daniel BaileyHenry Wong

Alice O’ConnorJeremiah Tidey

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Dr Deguang HuangDr Tim Prior (Daresbury)

Tom McDonnellConal KeaneNigel BirdJoe Cavan

Dr John Warren (Daresbury)The Diamond I19 TeamProfessor Geoff Lawrance (Newcastle, AU)