Conducting and insulating salts of phosphiniminium cations with 7,7,8,8-tetracyano-p-quinodimethane (TCNQ)

Tetrahedron Letters,Vo1.28,No.38,pp Printed in Great Britain

CONDUCTING

AND

4465-4468,1987

INSULATING

SALTS

0040-4039/87 $3.00 + .OO Pergamon Journals Ltd.

OF PHOSPHINIMINIUM

7,7,8,8-TETRACYANO-p-QUINODIMETHANE

Martin

R. Bryce*a,

a Department b Department Barbara,

Abstract: cations

Adrian

of Chemistry, of Physics CA 93106,

(art 0.05-0.15 variable

University

Kimb,

of Durham,

and Institute

(TCNQ)

Z-X. LiuIb

Durham,

for Polymers

of cation-TCNQ

(2) form

salts

1:2 salts with

S cm-l) whereas

temperature

Y.H.

WITH

and M.J.

Nowakb

DHl 3LE, U.K.

and Organic

Solids,

Santa

U.S.A.

A new series (1) and

J. Moorea,

CATIONS

cations

conductivity,

is described:

phosphiniminium

TCNQ that are organic (3) and

magnetic

conductors

(4) form insulating

susceptibility

1:l salts;

and FTir data

are

described.

A large have

been

TCNQ

salts

thoroughly

of complexes studied:

and they provide

[Ph3P=N=PPh3]'

recently

been

communication

cations4

characterised we describe

a new class

that form both

and ethyl-derivatives, contrast,

IPermanent

address:

under

of segregated

of organic

(1) and

state

of cations,

conducting

metals,

semiconducting

of solid

China.

4465

have In this

viz. phosphiniminium

propyl-

Chinese

semi-

salts of TCNQ

techniques.

(2), form conducting

of Physics,

cations

stack

dications5

and insulating

the same conditions,

Institute

and phosphonium

[Ph2(Me)PCH2P(Me)Ph212+

by a range

Methyl-

in marked

examples

For example,

and

(l)-(4),

ammonium

they are the prototypes

classical

cations

Beijing,

of TCNQ with

and insulators. 1,2,3

conductors with

number

salts with

TCNQ.

1:2 salts,

while,

and butyl-derivatives,

Academy

of Sciences,

4466

(41, form

(3) and

insulating

a change

in properties

a series

of cation-TCNQ

by variable

Room

temperature

band

present

Both

Pressure

(l)-(4)

four salts

the paramagnetic

range with

Infrared

K, with

have

obtained

a well-defined

data

and

signal Curie

electrons

(l)-(4).

spectra

value increase

this value,

absorption

with

by a strong

(I):

increasing

phenomenon

has recently

been

correlated

with

distortions

a broad

is characteristic

of

at 1.5 kBar. dependence

of

spectroscopy;

for salts

(l)-(4)

implying

spectra

absorption

provide

at xmax

of conducting

range salt

300-15

the

over

the

a major

for other

absorption conductor:

(1) and

(2) below

at frequencies

conducting

this

in

absorption

decreasing

band,

anion

At frequencies

(2) 2268 cm-l]

with

structural

840 nm in the U.V. salts

K.

in these materials.7

of an organic

for needles

of the TCNQ radical

increase

charge-transfer

over

E, 0.047 and 0.050

by e.s.r.

temperature,while

reported

(2)

salts

behaviour

studied

law behaviour,

samples

1975;

coefficients

Peierls

or phosphonium-TCNQ

was

intensity

(1) and

on the TCNQ molecules.

the temperature

[salt

of art for salts

The temperature

studied

The presence

of powdered

over

of the partially-filled

energies

of conductivity

are shown

than the 1:l

(2) show semiconductor

activation

has been

(l)-(4)

conducting

ammonium-

are paramagnetic.

localised

coefficients

which

in

characterised

susceptibility

art 0.32 S cm-l, was reached

K obeys

is confirmed

FTir

exhibit

The values

(1) and

integrated

300-90

on salts

spectra.

both

for such

substitution

has been

(or-t_)for salts

and solid state ultraviolet-visible

(l)-(4)

been

of salts

are more

for most

salts

susceptibility

of the total

information

unusual

of alkyl

as a consequence

dependence

All

contribution

the 1:2 salts

300-80

value,

temperature

variation

of conductivity

end of the range

(1); a maximum

variation

It is most

magnetic

data,

in the 1:2 salts.1

range

respectively.

salts

conductivity

values

s crn-l).l

the temperature

salt

simple

This new series

is well-established

are at the upper (10-2-10-5

salts.

Predictably,

this

congeners;

upon

TCNQ.6

techniques.

in the Table.

energy

to occur

temperature

spectroscopic

1:l salts with

above

temperature. TCNQ

Salts

centred

salts

This

and

(i! and

(2)

at 3400 cm-l,

is absent

in the

4467

Ph3P=&PhR

Cation

R

Complex

Stoichiometry Cation : TCNQ

art (S cm-l)

(1)

Me

1 :2

0.15a

(2)

Et

1 :2

0.05a

(3)

n-Pr

1 : 1

1 x 10-B b

(4)

n-Bu

1:l

2 x 10-7 b

a single

crystal,

b compressed

4 probe

pellet,

measurement

2 probe

measurement

Table

insulating salts

salts

(l)-(4)

reported, charge

transfer

moderate

particular,

A noteworthy

salts,

and to occur metal-TCNQ

or strong

between

of the i.r. spectra

of the nitrile

absorptions;

correlated

that of neutral

(2185 cm-l).8

with

TCNQ

However,

at significantly

of 2149 and 2160 cm-l

We thank

grant

feature

to be linearly

intensity

and for helpful

SERC for a travel

frequency

salts

are remarkably

Acknowledgements. equipment

TCNQ

the values

respectively,

(4).

is the stretching

for many

of fully-ionic with

(3) and

lower

(l)-(4)

frequencies;

for the 1:l salts

this

the degree

(2227 cm-l)

salts

of

(3) and

is

of

and that all absorb6 in (4)

low.

Professors

A.J.

Heeger

discussions:

NATO

for financial

(to MRB)

and the award

and F. Wudl

for the use of

support

of a studentship

(to MRB);

(to AJM).

4468

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Torrance,

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Bryce

3.

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M. Lequan,

Ahmad,

1984, 25,

6.

M.R.

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Bryce,

Res.,

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were

P. Batail,

J.F. Halet

by cooling

acetonitrile

obtained

iodide

satisfactory

microanalytical

(dec), urnax 2168(s),

mp 207-208°C

(dec) urnax 2176(s),

data

(dec), vrnax 2149(m),

vrnax 2160(s), 7.

E.M. Conwell

8.

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Chappell,

D.O.

Cowan,

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2196(m)

Tetrahedron

D.B.

Tanner,

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Salts

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2176(s)

Mol.

Salt

2191(m)

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cm-l.

Bloch, Chem.

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(11, (48%)

cm-l.

Salt Salt

gave

Salt

(21, (45%)

(?), (36%) mp

(41, mp 1566158'C

cm-l.

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R.P. McCall,

and L. Ouahab,

3107.

mp 184-187°C

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79.

1984, 309,

Conference

1987,

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183-185°C

1979, 12,

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4275.

1983, 3,

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Chem.

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4.

E.,

Rccts.

and L.C. Murphy,

W.A. Sot.,

1987)

Liq. Cryst.,

R.J.

Epstein

1985, E,

51;

and E.M. Conwell,

59.

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M. Maxfield,

1981, 103,

2442.

T-0.

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and

(dec)