Single crystal X-ray diffraction

Dr Georgina Rosair

Lab: G.06/7 Ground floor below crush area

Power of crystallography

• Crystals <1mm long

• Complete 3D structure

Crystal growing tips– PURIFY your compound as much as is practically possible. – FILTER the solution you will grow the crystals from– TEST THE CRYSTALS are they the RIGHT compound– Remove a few crystals to see if they lose solvent and

examine them by infrared, nmr etc. – Grow the crystals SLOWLY and with the MINIMUM of

vibration - a fridge is a good place.– PERSEVERE - you may need to try several methods

Crystal growing methods

• Solvent diffusion – Dissolve your compound in a solvent in which

it is soluble and layer slowly on top a second solvent in which it is almost insoluble.

– The two solvents must be miscible. CH2Cl2/hexane is a common combination.

– Nmr samples have been used successfully

SAMPLES FOR SINGLE CRYSTAL X-RAY DIFFRACTION

NAME :

Email:

LAB NO. PHONE

NO.

DATE Sample Ref. No.

Project code Supervisor/grant holder

signature

Please return completed forms to Dr. Georgina Rosair in G.07 Put your labeled sample in the analytical services fridge The BOLD Sections below MUST be filled out please!

Empirical FORMULA

Has the structure of

related compounds and

/or starting materials

been determined?

Filename(s)

C:H:N Analysis Experimental : :

Theoretical : :

OTHER ANALYTICAL

TECHNIQUES USED

AND INFORMATION

GAINED

(e.g. CO from infrared)

Solvent(s) of crystallisation

Is solvent present in crystal? (e.g.

seen in an nmr spectrum of crystals

from this batch). If yes what is it?

Hazards associated

with this sample

IS THE

SAMPLE

STABLE?

In air?

In light? At room

temperature?

Without mother liquor

vapour?

*Please draw a diagram of the expected structure on the other side of this sheet Reasons why crystal structure analysis is required and chemical background (e.g. refs.) PLANS FOR PUBLICATION:

When you have crystals, what do you do?

• Completed forms into the pocket on the X-ray notice board outside G.07

• Contact number – lab phone no & HW email

• LABELLED Samples in the analytical services fridge/freezer in the 200mHz NMR room

X-ray crystallography and your research

• Structure solution and refinement• Access to databases• Pictures and tables for reports and papers• X-seed software you can download and use on

your laptop• Advice and training from me

Crystallographic resultsTable 1. Crystal data and structure refinement for X82720_0m.

Identification code x82720_0m

Empirical formula C20 H26 B10 Co2

Formula weight 492.37

Temperature 100(2) K

Wavelength 0.71073 Å

Crystal system Triclinic

Space group P-1

Unit cell dimensions a = 7.0221(11) Å = 78.819(8)°.

b = 9.8594(15) Å = 84.528(9)°.

c = 15.571(2) Å = 76.945(9)°.

Volume 1028.8(3) Å3

Z 2

Density (calculated) 1.589 Mg/m3

Absorption coefficient 1.620 mm-1

F(000) 500

Crystal size 0.74 x 0.24 x 0.18 mm3

Theta range for data collection 2.32 to 30.77°.

Index ranges -10<=h<=10, -14<=k<=13, -21<=l<=22

Reflections collected 23875

Independent reflections 5934 [R(int) = 0.0424]

Completeness to theta = 25.00° 97.0 %

Absorption correction Semi-empirical from equivalents

Max. and min. transmission 0.7586 and 0.6549

Refinement method Full-matrix least-squares on F2

Data / restraints / parameters 5934 / 0 / 326

Goodness-of-fit on F2 1.004

Final R indices [I>2sigma(I)] R1 = 0.0380, wR2 = 0.0885

R indices (all data) R1 = 0.0623, wR2 = 0.0980

Largest diff. peak and hole 0.547 and -0.633 e.Å-3