V. Tirkey et al. / Journal of Organometallic Chemistry 732 (2013) 122e129
123
In view of their enormous opportunity, we became interested to
synthesize some Schiff base compounds containing [(
5-C5H4R)M]
under stirring condition and the reaction was continued for 3e4 h.
After the reaction, the solution was filtered and the pale yellow
precipitate was washed with cold ethanol and vacuum dried. The
product was purified by preparative TLC in 5% ethanol:n-hexane
solvent mixture. (Yield ¼ 35 mg (92%) (4); 32 mg (88%) (5), 29 mg
(81%) (6); 31 mg (86%) (7)).
h
organometallic tags and investigate their biological and electro-
chemical properties. Our aim was to prepare hydrazone type Schiff
base compounds by the condensation of hydrazide derivative with
appropriate organometallic species especially ferrocenyl and
cymantrenyl derivatives. Some synthetic and biological studies on
mono- and di-ferrocenyl hydrazone compounds have been carried
out recently [7e13,27], but 1,10-unsymmetrically substituted fer-
rocenyl hydrozone compounds are not known. We selected cym-
antrenyl moieties as because these compounds contain metal
carbonyls, which show specific IR signals with intense absorption in
the range 1900e2200 cmꢀ1 and can be used as IR probes in various
biological samples. Moreover, to our knowledge cymantrenyl Schiff
base compounds have been rarely studied and one of the reports
show the synthesis of cymantrenyl-biotine compounds for their
use as tracer molecule [36], whereas cymantrenyl-hydrazone
compounds have been largely unexplored and are yet to be inves-
tigated for their possible antibacterial activities. In this report, we
describe the synthesis and characterization of four new cyman-
trenyl hydrazone Schiff base compounds (4e7) along with mono-
and di-substituted (8e10, 12) ferrocenyl hydrazones compounds.
We have also attempted to synthesize hydrazone derivative con-
taining unsymmetrically 1,10 disubstituted ferrocenyl fragment (11,
13). Compounds 4, 5, 8 and 9 have been characterized structurally
by single crystal X-ray diffraction techniques. Antibacterial activity
and electrochemical properties have been studied for some of the
ferrocenyl and cymantrenyl compounds.
4: Anal. Calcd. (found): C, 53.68 (53.45); H, 3.42 (3.37); N, 7.36
(7.45). IR (
(vs), 1630.4 (s), 1601.5 (m). 1H NMR (
(s, 2H,
5-C5H4), 5.38 (s, 2H, 5-C5H4), 6.90e6.94 (t,1H, C6H4), 7.04e
n
, cmꢀ1, CH2Cl2): 3278.7 (br), 3057.4 (br), 2010 (s), 1923.7
d, CDCl3): 2.15 (s, 3H, CH3), 4.84
h
h
7.06 (d,1H, C6H4), 7.45e7.49 (t,1H, C6H4), 9.01 (br,1H, NH),11.66 (br,
1H, OH). MS (ESI): m/z 381 (M)þ.
5: Anal. Calcd. (found): C, 52.60 (52.78); H, 3.28 (3.21); N, 11.50
(11.62). IR (
1669 (s), 1603 (w). 1H NMR (
5-C5H4), 5.11e5.40 (m, 2H,
2H, C6H4N), 8.95 (br, 1H, NH).
n
, cmꢀ1, CH2Cl2): 3210 (br), 2019 (vs), 1929.8 (vs, br),
d
, CDCl3): 2.09 (s, 3H, CH3), 4.79 (s, 2H,
h
h
5-C5H4), 7.67 (s, 2H, C6H4N), 8.78 (s,
6: IR (n
, cmꢀ1, CH2Cl2): 3213 (br), 2018 (vs), 1926 (vs, br), 1658
(br), 1604 (w). 1H NMR ( , CDCl3): 2.09 (s, 3H, CH3), 4.79 (s, 2H, h5
d -
C5H4), 5.17e5.34 (m, 2H, h
5-C5H4), 7.49e7.84 (m, 5H, C6H5), 8.83 (br,
1H, NH). MS (ESI): m/z 365 (M þ 1)þ.
7: IR (n
, cmꢀ1, CH2Cl2): 3195 (br), 2017 (vs), 1925.5 (vs, br), 1654
(br), 1590 (w). 1H NMR (
C5H4), 5.15e5.36 (m, 2H,
d
, CDCl3): 2.1 (s, 3H, CH3), 4.78 (s, 2H, h5
5-C5H4), 7.47 (s, 1H, C6H4N), 8.17 (s, 1H,
-
h
C6H4N), 8.89 (br, 2H, C6H4N), 9.16 (br, 1H, NH). MS (ESI): m/z 366
(M þ 1)þ.
2.3. Synthesis of [(
{R ¼ C6H4eOH (8), C6H4N-p (9)}
h h
5-C5H5)Fe{( 5-C5H4)C(CH3)]NeN(H)C(O)eR}]
2. Experimental sections
In a two necked round bottomed flask respective hydrazide
(0.1 mmol) was taken and 10 ml of ethanol solvent was added. To
the reaction mixture, 23 mg (0.1 mmol) of monoacetyl ferrocene
and two drops of acetic acid was added at room temperature under
stirring condition. The reaction was continued for 6e12 h under
nitrogen atmosphere and monitored using TLC. After the reaction,
the solution was filtered and the orange precipitate was washed
with cold ethanol and vacuum dried. The product was further pu-
rified by preparative TLC in 5% ethanol:n-hexane solvent mixture.
(Yields: 8: 31 mg (85%); 9: 30 mg (87%)).
2.1. General procedures
All reactions and manipulations were carried out under an inert
atmosphere of dry, pre-purified argon using standard schlenk line
techniques. Solvents were purified, dried and distilled under argon
atmosphere prior to use. Infrared spectra were recorded on a Perkin
Elmer Spectrum RX-I spectrometer as KBr pellet or CH2Cl2 solution
and NMR spectra on a 400 MHz Bruker spectrometer in CDCl3 or
DMSO-d6 solvent. Elemental analyzes were performed on a Vario El
Cube analyzer. Mass spectra were obtained on a SQ-300 MS in-
strument operating in ESI mode. Cyclic voltammetric and differ-
ential pulse voltammetric measurements were carried out using a
CH Instruments model 600D electrochemistry system. A platinum
working electrode, a platinum wire auxiliary electrode and a silver/
silver chloride reference electrode were used in a three-electrode
configuration. The supporting electrolyte was 0.1 M [NEt4]ClO4 and
the solute concentration was w10ꢀ3 M. The scan rate used was
50 mV sꢀ1. All electrochemical experiments were carried out under
a nitrogen atmosphere and are uncorrected for junction potentials.
TLC plates (20 ꢁ 20 cm, Silica gel 60 F254) were purchased from
8: Anal. Calcd. (found): C, 62.98 (63.39); H, 4.97 (4.92); N, 7.73
(7.85). IR (
1607 (s), 1542 (s). 1H NMR (
5H, h
5-C5H5), 4.42 (t, 2H, 5-C5H4), 4.69 (t, 2H,
n
cmꢀ1, KBr): 3446 (br), 2667.7 (m), 2577.7 (m), 1628 (s),
d
, DMSO-d6): 2.23 (s, 3H, CH3) 4.23 (s,
h
h
5-C5H4), 6.94e7.01
(m, 2H, C6H4), 7.39e7.42 (t, 1H, C6H4), 7.95e7.97 (d, 1H, C6H4), 11.16
(s, 1H, NH), 11.84 (br, 1H, OH). MS (ESI): m/z 363 (M þ 1)þ.
9: Anal. Calcd. (found): C, 62.24 (62.68); H, 4.89 (4.81); N, 12.10
(12.26). IR (nCO, cmꢀ1, CH2Cl2): 3412 (br), 3146 (m), 1600 (vs), 1578
(vs). 1H NMR (
4.50 (s, 2H,
d, DMSO-d6): 2.30 (s, 3H, CH3), 4.29 (s, 5H, h
5-C5H5),
h
5-C5H4), 4.78 (s, 2H, 5-C5H4), 7.85 (br, 2H, C5H4N), 8.82
h
(br, 2H, C5H4N), 10.95 (s, 1H, NH). MS (ESI): m/z 348 (M þ 1)þ.
Merck.
[(CO)3Mn(
[(
h
h
5-C5H5)Fe(
h
5-C5H4COCH3)],
[Fe(h
5-C5H4COCH3)2],
eC6H4eOH,
5-C5H4COCH3)], [H2NN(H)C(O)R], (R
¼
2.4. Synthesisof[Fe{(h
5-C5H4)C(CH3)]NeN(H)C(O)C6H4eOH}2](10)
C6H4N-p, C6H5, C6H4N-o) were prepared following reported pro-
cedures [37,38,39].
Ethanol solution of salicyloyl hydrazide (31 mg, 0.2 mmol) was
taken in a two necked flask and 27 mg (0.1 mmol) of 1,10-dicetyl
ferrocene and one drop of HCl was added at room temperature
under stirring condition. The reaction was continued for 3 h and
monitored using TLC. After the reaction, the solution was filtered
and the orange precipitate was washed with cold ethanol and dried
under vacuum. The product was purified by preparative TLC in 20%
ethanol:n-hexane solvent mixture. Yield: 50 mg (92%).
2.2. Synthesis of [(CO)3Mn{(
{R ¼ C6H4eOH (4), C6H4N-p (5), C6H5 (6), C6H4N-o (7)}
h
5-C5H4)C(CH3)]NeN(H)C(O)eR}]
In typical synthetic procedure, respective hydrazide
a
(0.1 mmol) was taken in a two neck round bottomed flask and
ethanol (10 ml) solvent was added. The solution was stirred under
nitrogen atmosphere to obtain a clear solution. To the reaction
mixture 0.1 mmol of monoacetyl cymantrene (25 mg, 0.1 mmol)
and two drops of acetic acid was added at room temperature and
10: Anal. Calcd. (found): C, 62.45 (62.17); H, 4.83 (4.62); N, 10.41
(10.58). IR (
n
, cmꢀ1, KBr): 3284 (m), 3078.3 (br), 1633.5 (vs), 1605.8
(s), 1558.7 (vs). 1H NMR (
d, DMSO-d6): 2.17 (s, 6H, CH3) 4.46 (s, 4H,