Cyclopalladation of 2-acetylthiophene acetylhydrazone

INORG. NUCL. CHEM. LETTERS Vol. 14, pp. 337-340. ©Pergamon Press Ltd. 1978. Printed in Great Britain

CYCLOPALLADATION

OF 2-ACETYLTHIOPHENE

0020-1650/78/1001-0337502.00/0

ACETYLHYDRAZONE

Matsuo Nonoyama Department

of Chemistry,

Nagoya University,

Faculty

Chikusa,

of Science,

Nagoya,

464 Japan

(Received 1 May 1978; revised 22 May 1978; received for publication 3 August 1978)

Numerous benzene

studies of cyclometallation

derivatives(l)

pyridine,

metallated

similar

derivatives.

to benzene,

derivative

so far(~).

~

as Hata),

2-phenyl-

to be cyclo-

Thiophene

is

2-(2-

example of a thiophene

We have found another

which can be cyclopalladated,

ace~ylbyflra:~one(~bbrev[~ted

for

Recently

but surprisingly

alone appears as a unique

cyclometallated

etc.

have been reported

like the above benzene

pyridyl)thiophene

thiophene

N,N-dimethylhydrazone,

derivatives(2-4)

also an aromatic

derivative

such as N,N-dimethylbenzylamine,

acetophenone

some ferrocene

have been made

the complex

acetylthiophene formed being I.

CH3 S.

C/

\ /N~N'H Pd

i

X/ \o~C~cH3 (1)

Acetylhydrazones (~bbreviated

of acetylferrocene

as Hafa and Hpma,

cyclopalladated

and p-methylacetophenone

respectively)

are similarly

to give the complexes II and III, respectively.

337

338

Cylopalladation of Acetylhydrazones

~H3

~

/ ~

C~N-NHCOCH

H3C--~, /~'--C,,

3

/

,,,CH3

~Q~pd/N"N'H I Ct/ "o~C~cH3

Fe --"/Pd---i (IT)

(III)

The acetylhydrazone(HL)(1 chloropalladate(1 acetate(1 mmol) [PdCiL](L=ata,

mmol)

in methanol

in the presence

for a few days at room temperature afa, and pma)(6).

prepared by using lithium infrared

mmol) reacted with lithium tetra-

[PdBr(ata)]

in Table.

to give

was similarly

tetrabromopalladate.

spectra of Hata and [PdX(ata)](X=C1

of sodium

The pmr and and Br) are shown

The pmr spectra of Hata and [PdBr(ata)]

of importance

are shown in Fig.

of the three thiophene

The spectra reveal

ring protons

pattern turns to an AB quartet. spectrum but is less soluble

TABLE

in the region that one

is lost and the spectral

[PdC1(ata)]

gives a similar

in dmso-d 6 .

INFRARED AND PMR SPECTRA

Infrared

spectra a, cm -1

PMR spectra b,

ppm c

Compound

~(N-H) ~C=O) ~Pd-X)

N-H

CH3

Hata

3165

1666

10.47

2.32, 2.22

[PdCl(ata)]

3240

1585

363, 287 d

lO.5vbr e

2.30, 2.05

[PdBr(ata)]

3238

1581

217

lO.Svbr

2.28, 2.02

a) KBr discs and Nnjol mulls,

b) DMSO-d 6 solutions,

2,2-dimethyl-2-silapentanesulfonate(DSS) standard,

upon complexation is suggested

is used as an internal

d) These may be coupled bands,

The band of ~(C=O)

for [PdX(ata)].

cm -1 disappear

e)vbr=very

of free Hata shifts to a lower

and coordination

c) Sodium

broad. frequency

of the carbonyl-oxygen

atom

Two strong bands at 363 and 287

upon substitution

of C1 with Br and the bromide

Cylopalladation of Acetylhydrazones

"t

339

,.

|

8

7

7

8 6' ppm

60MHz PM~ SPECTRA

FIGURE (b):

[PdBr(ata)]

OF (a): Hata AND

IN DMSO-d 6 AGAINST DSS

shows a strong band at 217 cm -I

The band ~(Pd-CI)

may be

coupled with other vibrations. In the region of aromatic vibrations(7),

ring C-H out-of-plane

Hata shows bands at 863, 852, and 8~0 cm -I,

which are replaced by a band at 878(CI) complexes.

deformation

This may suggest

substituted(~).

Structure

or 877(Br)

that the thiophene I is, therefore,

cm -I in the

ring is di-

the most reasonable

one.

The pmr s p e c t r a

o f Hafa a n d [ P d C l ( a f a ) ]

cyclopentadienyl

ring

those

reported

previously

infrared

spectra

atom.

report

resonances

for related

are very similar systems(2,4).

show n o n - c o o r d i n a t i o n

Structure

[PdCl(pma)]

proton

II is presumed.

reveal

in the region

of the

of this study will be presented

III.

to

The

carbonyl-oxygen

The spectral

that it has Structure

of

data of A more detailed

subsequently.

REFERENCES I.

M. I. BRUCE,

2.

S.S.

~.

T. IZUMI, K. ENDO,

O. SAITO,

A. KAS&HARA,

Bull.

Chem.

M. NONOYAMA,

Inorg.

4.

Angew.

Chem.,

89, 7~(1977).

CRAWFORD and H. D. KAESZ,

Nucl.

Inorg.

Chem., 16, 3193(1977).

I. SHIMIZU,

Soc. Jpn.,

M. MAEMURA,

51, 663(1978).

Chem. Lett.,

12, 709(1976).

and

340

5.

Cylopalladation of Acetylhydrazones

T. J. GIORDAN0 and P. G. RASMUSSEN, Inorg. Chem., 14, 1628 (1975) •

6.

These complexes are insoluble in organic solvents suitable for recrystallization, so that the analytical results de~iate slightly from the calculated ~alues but mot seriously. Calcd. for I(X=CI): C, 29.74; H, 2.81; N, 8.67 %. 29.51; H, 3.11; N, 7.80 %. 2.47; N, 7.62 %.

Calcd. for I(X=Br): C, 26.14; H,

Found: C, 26.97; H, 2.58; N, 7.50 %.

Calcd. for I_!: C, 40.52; H, 3.64; N, 6.70 %. H, 3.51; N, 6.39 %. 8.40 %. 7.

Found: C,

Found: C, 39.77;

Caled. for III: C, 39.91; H, 3.96; N,

Found: C, 39.69; H, 3.96; N, 7.84 %.

A. R. KATRITZKY and A. J. BOULTON, J. Chem. Soc., 1959, 3500.