Preparation and characterization of arylantimony(III) aryloxyacetates ArnSbL3-n

Article abstract of DOI:10.1080/15533170500359562

A series of hitherto unreported arylantimony(III)aryloxyacetates of the general formula Ar_nSbL_3-n(n = 1: L = OCOCH ₂OC_6- H₃(CH₃)₂-2,3 (1); OCOCH(CH₃)O C₆H₄(CH₃)-p (2); OCOCH₂OC₆H₅ (3); OCOCH₂OC ₁₀H₇-β (4); OCOCH₂OC₆H ₄ (CH₃)-p (5); OCOCH₂OC₆H ₄ Cl-o (6); OCOCH₂OC₆H₄Cl-p (7); n = 2: L = OCOCH (CH₃) OC₆H₄(CH₃)-p (8); OCOCH₂O C₆H₃(CH₃) ₂-2,3 (9); OCOCH₂OC₆H₄Cl-o (10); have been prepared by the metathesis of Ar_nSbCl_3-n with aryloxyacetic acids. These have been characterized by elemental analysis, IR, ¹H NMR spectra and UV spectra. Molar conductance and molecular weight data show them to be nonelectrolyte and having covalent monomeric constitution. These complexes were found to possess moderate to significant antifungal and antibacterial activity. Copyright

Full text of DOI:10.1080/15533170500359562

Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry, 35:889–893, 2005
Copyright # 2005 Taylor & Francis, Inc.
ISSN: 1553-3174 print/1532-2440 online
DOI: 10.1080/15533170500359562
Preparation and Characterization of Arylantimony(III)
Aryloxyacetates ArnSbL32n
Kiran Singhal, Prem Raj, Rahul Mishra, and Om Prakash
Department of Chemistry, Lucknow University, Lucknow, India
may be noted that intramolecular coordination of etheral
A series of hitherto unreported arylantimony(III)aryloxyace- oxygen has been observed in the case of dialkyltin aryloxyace-
tates of the general formula Arn SbL32n (n 5 1: L 5 OCOCH2OC6-
C6H4(CH3)-p
OCOCH2OC6H5 (3); OCOCH2OC10H7-b (4); OCOCH2OC6H4
(CH3)-p (5); OCOCH2OC6H4 Cl-o (6); OCOCH2OC6H4Cl-p (7);
n 5 2: L 5 OCOCH (CH3) OC6H4(CH3)-p (8); OCOCH2O
tates (O: ! Sn) thereby raising coordination of tin from 4 to 5
Solid-state IR, UV, and 1H NMR spectra in addition to some
solution phase studies have been carried out to ascertain the
H3(CH3)2-2,3
(1);
OCOCH(CH3)O
(2);
(Chattopadhyay et al., 1984).
C6H3(CH3)2-2,3 (9); OCOCH2OC6H4Cl-o (10); have been mode of bonding of aryloxyacetate group to antimony.
prepared by the metathesis of ArnSbCl32n with aryloxyacetic
acids. These have been characterized by elemental analysis, IR,
1H NMR spectra and UV spectra. Molar conductance and molecu-
lar weight data show them to be nonelectrolyte and having covalent
monomeric constitution. These complexes were found to possess
moderate to significant antifungal and antibacterial activity.
RESULTS AND DISCUSSION
The aryloxyacetate derivatives can readily be obtained by
the metathesis of arylantimony(III)chlorides with an appropri-
ate aryloxyacetic acid in presence of triethylamine as hydrogen
halide acceptor in benzene.
Et3N
!
Ph2SbCl þ ROCH2COOH
Ph2Sb(OCOCH2-ORÞ
þ Et3N ꢀ HCl
Benzene
ð1Þ
ð2Þ
INTRODUCTION
Et3N
!
PhSbCl2 þ 2ROCH2COOH
PhSbðOCOCH2-ORÞ2
þ 2Et3N ꢀ HCl
In sharp contrast to extensive studies an organometal cor-
boxylates of group 15 elements corresponding aryloxyacetates
Benzene
having an additional donor site i.e.,
to functionality
in addition
have occasionally been
These complexes can also be prepared by the displacement
reaction of arylantimony(III)halide with the corresponding
sodium salt of aryloxyacetic acid.
studied. Only a few organoantimony(V) aryloxyacetates,
having monomeric constitution and pentacoordinate dispensa-
tion around antimony have been isolated till date (Shukla et al.,
2002; Ranjan et al., 1994).
Benzene
!
Ph2SbCl þ ROCH2COOM
PhSbCl2 þ 2ROCH2COOM
Ph2Sb(OCOCH2ORÞ
þ MCl
Here we report the synthesis and isolation of arylantimo-
ny(III) aryloxyacetates ArnSb(ArOCH2OCO)32n. Apart from
the synthesis of new compounds the object was to explore
the coordinating ability of etheral oxygen to the antimony. It
ð3Þ
ð4Þ
Benzene
!
PhSbðOCOCH2ORÞ2
þ MCl2
where M ¼ Na or Ag; R ¼ C6H3(CH3)2-2,3; C6H5; C6H4Cl-p;
C6H4Cl-o; C6H4CH3p; b-C10H7; p-CH3C6H4.
Received 12 May 2005; accepted 9 September 2005.
The authors are thankful to the Head of the Chemistry Department,
Lucknow University, Lucknow for providing necessary laboratory
facilities, and the Director R.S.I.C., Lucknow, for obtaining spectral
and micro-analytical data. Authors are thankful to CSIR for financial
assistance.
Address correspondence to Kiran Singhal, Department of
Chemistry, Lucknow University, Lucknow 226 007, India. E-mail:
kiransinghal@indiatimes.com
All the reactions were conducted at room temperature and
the product were recrystallised from petroleum ether (408–
608C) or benzene. The complexes are off-white to light
brown solids and are obtained as a sticky mass which on treat-
ment with sodium dried benzene, solidified and subsequently
crystallised with benzene/pet ether. The complexes are fairly
stable to air and moisture and have sharp melting point.
889

890
K. SINGHAL ET AL.
Complexes are soluble in chloroform and acetonitrile and can 1H NMR Spectra
1H NMR spectra of the compound C6H5Sb(OCOCH2OC6-
be stored at room temperature without decomposition for
H3(CH3)2-2,3) (1) and C6H5Sb(OCOCH3OC6H4CH23 p)2 (5)
was recorded in CDCl3 using TMS as an internal reference at
258C. The disappearance of OH proton signals (d 9.1 ppm)
present in the ligand indicates the formation of aryloxyacetates
derivatives. The appearance of a singlet for –CH2 protons in
(1) and (5) at d 4.80 ppm and d 4.85 ppm respectively,
showed that both the ligands are equivalent and seemed to be
in one plane. The phenyl proton for both the derivatives
appears as multiplets in the range d 7.80–7.20 ppm. For
compound (1) a singlet appearing at d 1.98 is assigned to
–CH3 protons while for compound (5) methylprotons
(–CH3) were observed as a singlet at d 2.30 ppm.
several weeks. The constancy in melting points after repeated
crystallisation as well as TLC run in chloroform-hexane
mixture (1 : 1), with the observation of a single spot excluded
the presence of mixture of reactants. The molar conductance
of 1023 M solutions were recorded in methanol and were in
the range of 15–25 ohm21 mole21 cm2 indicating the absence
of ionic species in solution (Geary, 1971). The complexes
were found to be monomeric in nitrobenzene.
Infrared Spectra
Diagnostic infrared absorption for phenylantimony arylox-
yacetate and those related to the ligands have been identified,
which at preliminary stage indicate mode of bonding of arylox-
yligand. The data are given in Table 3 (Maslowsky, 1974).
The characteristic n(OH) absorption band of the ligand
which appear around 3400 cm21 in the free ligand was found
missing in the newly synthesized complexes. A medium
strong intensity band appearing at 1690–1700 cm21 can
confidently be assigned to nasy(OCO) mode while the compara-
tively weaker band in the range 1380–1400 cm21 can be attrib-
uted to nsym(OCO) band (Raj and Aggarwal, 1992; Raj et al.,
1985; Singhal et al., 1987). The deformation mode as a
medium intensity band was found in the range 780–
815 cm21. The absorption associated with the antimony-
oxygen band, n(Sb-O) appears in the range between
400–430 cm21 and the absorption due to antimony-carbon
bond n(Sb-C), corresponding to Y-mode occurs in the range
450–470 cm21 (Shukla et al., 2002; Ranjan et al., 1994;
Maslowsky, 1974). These values clearly indicate the formation
of phenylantimony(III)aryloxyacetates. The comparison of IR
spectra of the compounds with those of respective ligands in
solid and solution did not show any significant shift in nasy
(C55O), nsym(C–O) and n(C–O–C) deformation bands,
which in turn showed the lack of coordination around
Ultraviolet Spectra
Electronic spectra were obtained for representative compound
(1,3,4 and 7) and were recorded in chloroform in the range 200–
400 nm. The UV absorption due to COO group appears at l
260 + 4 in all the cases and the two absorptions in the range l
274 + 6 and l 294 + 2 are due to aryloxy moieties. As there is
no significant change in absorption peaks of the ligands it
appeared that
and
centre of aryloxy acetates are
not coordinated to antimony in any of the compounds. This also
lends support to the fact that aryloxyacetate behave as monoden-
tateligandstowardsantimonyinþ3oxidationstate(Shuklaetal.,
2002; Ranjan et al., 1994; Maslowsky, 1974).
Based on IR, UV, and NMR spectral data as discussed pre-
vioulsy, it may tentatively be concluded that aryloxyacetate,
under the present study, behave as unidentate ligands. Conduc-
tance measurement and molecular weight data showed that
these aryloxyacetate possesses monomeric constitution and
are non-conducting. The experimental data are thus consistent
with three coordinate pyramidal structure as has been
previously assigned to RnSbX3-n (2,6,9).
antimony through
Y centre of the legands.
Further, it has been reported earlier that separation between
[n(nasy(OCO)–nsym(OCO)] is smaller, around 150 cm21 in the
case of linear polymeric moieties and is considerably larger
(around 250–350 cm21) for monomeric compounds (6–9).
Since the separation observed in the present compounds is
fairly large (230 cm21), monomolecular constitution seems to
be most plausible where antimony would be having a coordi-
EXPERIMENTAL
Arylantimony chlorides ArnSbCl32n were prepared by the
nation number three. This observation is in sharp contrast to reported method (Raj and Aggarwal, 1992). Aryloxyacetic
organotin complexes of aryloxyacetates that have been found acids were obtained by literature method and dried before
to be polymeric involving carboxylic bridges (Chattopadhyay use. All manipulation were carried out in dry solvents in
et al., 1984). In addition to this intramolecular interaction absence of oxygen and moisture.
involving the etheral oxygen has also been demonstrated,
IR data were recorded in the range of 4000–200 cm21 on
particularly in case of phenyl substituted tin compounds of FTIR RX-1 Perkin-Elmer spectrophotometer. 1H NMR in
aryloxyacetate that have been found to be monomeric in CDCl3 and UV spectra were obtained/recorded in chloroform
nitrobenzene (Chattopadhyay et al., 1984).
in the range of 200–400 nm.

TABLE 1
Preparation and properties of phenyl and diphenyl antimony(III) aryloxyacetates
Molar conductance
(in methanol)
(ohm21 mole21 cm2)
Molecular
weight found
(Calcd.)
Yield
Recrystallisation
solvent
M.P.
(8C)
Sl. no.
Complex
Color
%
g
1
2
C6H5Sb[OCOCH2OC6H3(CH3)2-2,3]2 Petroleum ether
C6H5Sb[OCOCH(CH3)OC6H4(CH3)-p]2 Hexane Petroleum
124
Light brown
Light brown
15.01
16.7
548 (557)
544 (557)
52
59.21
0.53
0.54
202
202
190
ether (408–608C)
3
4
C6H5Sb(OCOCH2OC6H5)2
Petroleum ether
(408–608C)
Petroleum ether
(408–608C)
Benzene
White
18.01
23.06
493 (501)
594 (601)
73
0.51
0.58
C6H5Sb(OCOCH2OC10H7-b)2
Light brown
48.3
5
6
7
8
C6H5Sb[OCOCH2OC6H4(CH3)-p]2
C6H5Sb(OCOCH2OC6H4-H4-Cl-o)2
C6H5Sb(OCOCH2OC6H4Cl-p)2
95
180
114
190
White
24.19
17.61
16.07
20.14
520 (529)
565 (570)
563 (570)
448 (455)
63
0.62
0.70
0.64
0.48
Benzene
Benzene
Light brown
Dirty white
White
61.5
56.3
52.8
(C6H5)2SbOCOCH(CH3)OC6H4(CH3)-p Petroleum ether
(408–608C)
9
(C6H5)2SbOCOCH2OC6H3(CH3)2-2,3
Petroleum ether
(408–608C)
Hexane–Benzene
156–157
214
Light brown
Light brown
21.16
22.19
441 (455)
67.1
65.8
0.61
0.56
10
(C6H5)2SbOCOCH2OC6H4Cl-o
450 (461.5)

892
K. SINGHAL ET AL.
TABLE 2
Elemental analysis data of phenyl and diphenyl antimony(III) aryloxyacetates
Found (Calcd.) %
Empirical
formula
Sl. no.
Complex
C
H
1
2
C6H5Sb[OCOCH2OC6H3(CH3)2-2,3]2
C6H5Sb[OCOCH(CH3)OC6H4(CH3)-p]2
C6H5Sb(OCOCH2OC6H5)2
C26H27O6Sb
C26H27O6Sb
C22H19O6Sb
C30H23O6Sb
C24H23O6Sb
C22H17O6Cl2Sb
C22H17O6Cl2Sb
C22H21O3Sb
C22H21O3Sb
C20H16O3Sb
56.07 (56.11)
56.05 (56.11)
51.1 (51.8)
4.77 (4.85)
4.80 (4.85)
3.34 (3.79)
3.76 (3.82)
2.92 (4.35)
2.92 (2.98)
2.90 (2.98)
4.54 (4.16)
4.51 (4.16)
3.40 (3.46)
3
4
C6H5Sb(OCOCH2OC10H7-b)2
59.1 (60.0)
5
C6H5Sb[OCOCH2OC6H4(CH3)-p]2
C6H5Sb(OCOCH2OC6H4-H4-Cl-o)2
C6H5Sb(OCOCH2OC6H4Cl-p)2
54.38 (54.44)
46.27 (46.31)
46.22 (46.31)
52.93 (52.53)
52.93 (52.53)
51.4 (52.0)
6
7
8
(C6H5)2SbOCOCH(CH3)OC6H4(CH3)-p
(C6H5)2SbOCOCH2OC6H3(CH3)2-2,3
(C6H5)2SbOCOCH2OC6H4Cl-o
9
10
TABLE 3
IR absorption frequencies of phenyl and diphenyl antimony(III) aryloxyacetates (cm21
)
n(Sb-C)
y-mode
C. no.
Complex
n
asy(OCO)
n
sym(OCO)
n(Sb-O)
1
2
C6H5Sb[OCOCH2OC6H3(CH3)2-2,3]2
C6H5Sb[OCOCH(CH3)OC6H4(CH3)-p]2
C6H5Sb(OCOCH2OC6H5)2
1700
1695
1690
1696
1703
1698
1690
1695
1694
1694
1380
1393
1396
1390
1399
1400
1404
1395
1385
1382
430
425
429
419
400
425
429
411
415
417
450
455
456
451
470
465
467
458
468
464
3
4
C6H5Sb(OCOCH2OC10H7-b)2
5
C6H5Sb[OCOCH2OC6H4(CH3)-p]2
C6H5Sb(OCOCH2OC6H4-H4-Cl-o)2
C6H5Sb(OCOCH2OC6H4Cl-p)2
6
7
8
(C6H5)2SbOCOCH(CH3)OC6H4(CH3)-p
(C6H5)2SbOCOCH2OC6H3(CH3)2-2,3
(C6H5)2SbOCOCH2OC6H4Cl-o
9
10
Preparation of Complexes
Details of the typical experiments are discussed next.
Relevant IR, UV, analytical data, and molar conductance
values are listed in Tables 1–4.
TABLE 4
UV absorption data of aryloxy derivatives of
phenylantimony(III), PhnSbL32n (nm)
Reaction of Phenylantimony(III)dichloride with
2,3-Dimethylphenoxyacetic Acid (1)
Compound
number
Due to COO
¨
(–C55O)
x
(nm)
Due to aryloxy
group
In an anhydrous oxygen-free condition, a stirring solution of
phenylantimony(III)dichloride (0.270 g; 1 mmol) was added to
2,3-dimethylphenoxyacetic acid (0.360 g; 2 mmol) in the
presence of triethylamine (ꢀ1 mL) in benzene and was
stirred for 6 h, followed by refluxing for 2 h to ensure com-
pletion of reaction. A flocculent white precipitate of
1
3
4
7
260
264
262
264
280
274
268
280
292
294
296
294
.
Et3N HCl (m.p. 2408C) was formed that was filtered off.

NOVEL ARYLANTIMONY COMPLEXES AND THEIR ACTIVITY
893
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