Organic metals from chiral BEDT-TTF donors

Synthetic Metals, 41--43 (1991) 2101-2105

2101

O R G A N I C M E T A L S F R O M CHIRAL B E D T - T T F DONORS

CHEN Benming +, F. DEILACHER, Anorganisch-Chemisches berg

M. HOCH, H.J. KELLER,

Institut der Universit~t

WU Peiji +

Heidelberg,

Heidel-

(F.R.G.)

P. ARMBRUSTER,

R. GEIGER,

3. Physikalisches

S. KAHLICH,

D. SCHWEITZER

Institut der Universit~t

Stuttgart,

Stuttgart

80,

(F.R.G.)

ABSTRACT We have recently described our project to prepare methylated BEDT-TTF derivatives

in order to obtain different

salts of these donors thyI-BEDT-TTF

("DIET"),

7,8'-DimethyI-BEDT-TTF

7,7',8,8'-Tetramethyl-BEDT-TTF some of them in an "optically have been prepared "classical"

starting

and 2,3-butanediol

ion

7,7'-Dime-

("DIET")

and

as isomeric mixtures

and

pure" form. The isomeric mixtures

of BEDT-TTF

pounds have been obtained propanediol

("TMET")

as reported earlier

synthesis

radical

(I). Meanwhile we have obtained

(I) corresponding

to the

(2). The optically pure comfrom the optically

respectively,

pure 1,2-

depicted on page 4.

RESULTS The different donors were electrocrystallized conditions.

under varying

The following results have been obtained:

(i) DIET-salts

could be crystallized with the counter ions FSO~, J

CLO4, HSO4, I04, Re04, BF4, CF3SO3, NO~, Br3, I~, [AuI2]- and PF 6. The salts (DIET) (BF 4) and (DIET) (FSO3)have been prepared starting

from an isomeric mixture and from the optically pure S,S

and R,R-derivatives preparations Monoclinic, 14.20(I)~, +Guests

of

respectively.

The crystals of the different

(DIET) (BF 4) show the same structural

space group C 2/m, a = 5,240(9),

features:

b = 12,13(I),

C =

B = 95.39(9) ° . The symmetry of the unit cell and the

from Academia

0379-6779/91/$3.50

Sinica, Institute of Chemistry,

Beijing

(China)

© Elsevier Sequoia/Printed in The Netherlands

2102

position of the methyl groups show that only an average of the possible m o l e c u l a r orientations investigations. Figures

in the lattice is found by X-ray

This means that the crystals are highly disordered.

I and 2 show the temperature d e p e n d e n c e of the electrical

conductivity

for

(DIET) (BF 4) o b t a i n e d from the isomeric mixture

and from the pure S , S - d e r i v a t i v e

(I)

(fig. 2).

(O IET)(BF4) 400~I

I

I

I

350-I .

I

+++++f+

400 350

+ +÷ ~ ~+~++÷÷++÷+ ++ %+ i

300-~ ~-

i

250-[

® oo o

+ ~.

200

300 "

C oo cP

250

200

150

~50

100

100 + = decreasing

50-]

temperature

50

= increasing temperature

0-4, 0

0 50

100

150

200

250

300

Temperotur~ [K]

Fig. I. T e m p e r a t u r e d e p e n d e n c e of the electrical c o n d u c t i v i t y of DIET-BF 4 from isomeric mixture of the donor

[(S, S)(-)-D I ET] [BF4] 150 J

i

:

i

i

14°I 120

150

++~,+o~o ~ ~ I ~ f÷ oo0090~eo~m~

r~

110 100

~-~

9o~

>',

80"1.~

~

i

120 110

+÷ QS ÷+

:l

/°

50

÷+÷o

100

~~

9O

÷+oo#

80

7(?

6o

4~

40

,~++

40

30

30

oolJ

20

+ = decreasing

I

o = increasing mmperature

0

50

100

~50

Temperoture

200 [K]

"

temperature

250

20 lo

300

~5

Fig. 2. Temperature dependence of the electrical conductivity of DIET-BF4 from the S,S-derivative of DIET (crosses are data during cooling, circles during heating of the sample).

2103

(ii) T M E T - s a l t s could be o b t a i n e d with the counter ions PF6, AsF6, SbF6,

I3, FSO3, CF3SO~,

mixtures

Re04, CIO4, BF4. S t a r t i n g from isomeric

and using PF~ as counter ion results

s e m i c o n d u c t i n g phase. TMET/PF 6 system

in a m e t a l l i c and a

In contrast to earlier i n v e s t i g a t i o n s of the

(3) we were able to isolate a m e t a l l i c solid. X-

ray i n v e s t i g a t i o n s

suggest that compounds of at least two diffe-

rent compositions

(TMET) 2PF 6 and

are obtained.

(TMET)2PF 6 phase contains the achiral R,S,R,S-

The

(TMET) (PF6) (C6H5C1)respectively

7,8,7',8'-Tetramethyl-BEDT-TTF molecules

solely.

(Crystal data: M o n o c l i n i c space group P2 I, a = 5,057(3), b = 6,823(4),

c = 33,44(2)~,

y = 107,72(5) ° , Z = I). Figure 3 gives an

i m p r e s s i o n of the a r r a n g e m e n t of the molecules

in the lattice.

This

s t r u c t u r e is totally d i f f e r e n t compared to the earlier reported semiconducting

(TMET) 2PF 6 phase

(3).

.

.

Fig.

.

.

.

.

.

.

,

3

A d d i t i o n a l l y we could characterize a 1:1 phase, which contains 2+ (TMET) 2 dimers. The m o l e c u l a r ions of a pair are related to each other by a center of symmetry.

So the crystal contains only the

R , R , S , R - 7 , 8 , 7 ' , 8 ' - T M E T m o l e c u l e s paired directly with its enantio2+ Figure 4 presents the c o n f o r m a t i o n of one (TMET) 2 pair in

mer.

this solid. F u r t h e r m o r e we could isolate an isostructural A s F ~ - p h a b

2104 Cn

Si

C;

C J~.

Ce

S 3.

""

C

S

---" -

-

~

~ Ss

,~-.J Cs

cJ.

C

,c n

,Co

se

(composition

a = 8,478(8),

(C14HI6S8)AsF6"C6H5CI:

b = 19,O6(2),

Fig.

monoclinic

c = 17,89(I)~,

space

S ~

~ [

S-C-CsH6

/S--O

NaOEt

S~ / S-Na÷

0

Xs/~'~S

S

S

DIET: X:=CH s Xs=H TUET: X: =Xs=CHs

P2 I,

B = 91,O2(7) ° , Z = 4).

Xl\ •

6HOH + SOCI,

groups

4

Sf~xz (*)

2105 REFERENCES

I

Chen Benming, Armbruster,

F. Deilacher, M. Hoch,

R. Geiger,

S. Kahlich,

H.J. Keller, Wu Peiji, P.

D. Schweitzer,

in Procee-

dings of the N A T O - A S I on " L o w e r - D i m e n s i o n a l Systems and Molecular Devices",

Spetses,

Greece,

1989.

2

M. Mizuno,

A. Garito, A. Cava, Chem. Commun.

3

A. Karrer,

J.D. Wallis, J.D. Dunitz,

B~rkle,

J. Pfeiffer,

Helv.

1978,

B. Hilti,

Chim. Acta,

70, 942

18

(1978).

C.W. Mayer, M. (1987).