Synthesis and characterization of copper(I) complexes of N-carboethoxy-4-chlorobenzene and N-carboethoxy-4-bromobenzene thioamides (Hcct and Hcbt)

Article abstract of DOI:10.1081/SIM-120016465

Reactions of [Cu(EPh₃)₃X] with the title ligands yield [Cu(EPh₃)₂(LH)X] (LH = Hcct and Hcbt). Twelve complexes have been prepared and characterized on the basis of analytical, IR, electronic and NMR spectral and magnetic measurements. These complexes have a tetrahedral structure with the aromatic ligand bonded to copper(I) through sulfur.

Full text of DOI:10.1081/SIM-120016465

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SYNTHESIS AND CHARACTERIZATION OF COPPER(I)
COMPLEXES OF N-CARBOETHOXY-4-CHLOROBENZENE
AND N-CARBOETHOXY-4-BROMOBENZENE THIOAMIDES
(Hcct AND Hcbt)
Sunil K. Misra a & U. C. Tewari a
a Department of Chemistry , Dayanand Anglo-Vedic College, Chatrapati Shahu Ji Maharaj
University , Kanpur, U. P., 208001, India
Published online: 15 Feb 2007.
To cite this article: Sunil K. Misra & U. C. Tewari (2002) SYNTHESIS AND CHARACTERIZATION OF COPPER(I) COMPLEXES OF
N-CARBOETHOXY-4-CHLOROBENZENE AND N-CARBOETHOXY-4-BROMOBENZENE THIOAMIDES (Hcct AND Hcbt), Synthesis and
Reactivity in Inorganic and Metal-Organic Chemistry, 32:10, 1789-1798, DOI: 10.1081/SIM-120016465
To link to this article: http://dx.doi.org/10.1081/SIM-120016465
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ꢘꣂꢶꢳꢱꢪꢘꢦꢘ ꢒꢶꢁ ꢧꢪꢒꢋꢳꢦꢖꢦꢳꣂ ꢦꢶ ꢦꢶꢺꢧꣃꢒꢶꢦꢋ ꢒꢶꢁ ꢛꢪꢳꢒꢰꢕꢺꢧꣃꢒꢶꢦꢋ ꢋꢱꢪꢛꢦꢘꢳꢧꣂ
ꢖꢉꢔꢤ ꢫꢠꢐ ꢶꢉꢤ ꢣꢡꢐ ꢃꢃꢤ ꢣꢿꢢꢾ꣄ꢣꢿꢾꢢꢐ ꢠꢡꢡꢠ
ꢀꢁꢂꢃꢄꢅꢀꢆꢀ ꢇꢂꢈ ꢉꢄꢇꢊꢇꢉꢃꢅꢊꢆꢋꢇꢃꢆꢌꢂ
ꢌꢍ ꢉꢌꢎꢎꢅꢊꢏꢆꢐ ꢉꢌꢑꢎꢒꢅꢓꢅꢀ ꢌꢍ
ꢂꢔꢉꢇꢊꢕꢌꢅꢃꢄꢌꢓꢁꢔꢖꢔꢉꢄꢒꢌꢊꢌꢕꢅꢂꢋꢅꢂꢅ
ꢇꢂꢈ ꢂꢔꢉꢇꢊꢕꢌꢅꢃꢄꢌꢓꢁꢔ
ꢖꢔꢕꢊꢌꢑꢌꢕꢅꢂꢋꢅꢂꢅ ꢃꢄꢆꢌꢇꢑꢆꢈꢅꢀ
ꢏꢄꢗꢗꢘ ꢇꢂꢈ ꢄꢗꢙꢘꢐ
ꢀꢚꢛꢜꢝ ꢞꢟꢑꢜꢠꢡꢢ ꢀ ꢢꢛꢣ ꢤꢟꢉꢟꢃꢥꢦꢢꢡꢜ
ꢁꢂꢃꢄꢅꢆꢇꢂꢈꢆ ꢉꢊ ꢋꢌꢂꢇꢍꢎꢆꢅꢏꢐ ꢁꢄꢏꢄꢈꢄꢈꢑ ꢒꢈꢓꢔꢉꢕꢖꢂꢑꢍꢗ
ꢋꢉꢔꢔꢂꢓꢂꢐ ꢋꢌꢄꢆꢅꢄꢃꢄꢆꢍ ꢘꢌꢄꢌꢙ ꢚꢍ ꢛꢄꢌꢄꢅꢄꢜ ꢝꢈꢍꢞꢂꢅꢎꢍꢆꢏꢐ
ꢟꢄꢈꢃꢙꢅ ꢠꢡꢢꢡꢡꢣꢐ ꢝꢤ ꢥꢤꢐ ꢦꢈꢑꢍꢄ
ꢇꢕꢀꢃꢊꢇꢉꢃ
ꢧꢂꢄꢗꢆꢍꢉꢈꢎ ꢉꢊ ꢨꢋꢙꢩꢪꢥꢌꢫꢬꢫꢭꢮ ꢯꢍꢆꢌ ꢆꢌꢂ ꢆꢍꢆꢔꢂ ꢔꢍꢓꢄꢈꢑꢎ ꢏꢍꢂꢔꢑ
ꢨꢋꢙꢩꢪꢥꢌꢫꢬꢠꢩꢰꢱꢬꢭꢮ ꢩꢰꢱ ꢀ ꢱꢗꢗꢆ ꢄꢈꢑ ꢱꢗꢲꢆꢬꢤ ꢳꢯꢂꢔꢞꢂ ꢗꢉꢇꢃꢔꢂꢴꢂꢎ
ꢌꢄꢞꢂ ꢲꢂꢂꢈ ꢃꢅꢂꢃꢄꢅꢂꢑ ꢄꢈꢑ ꢗꢌꢄꢅꢄꢗꢆꢂꢅꢍꢵꢂꢑ ꢉꢈ ꢆꢌꢂ ꢲꢄꢎꢍꢎ ꢉꢊ ꢄꢈꢄꢔꢏꢕ
ꢆꢍꢗꢄꢔꢐ ꢦꢧꢐ ꢂꢔꢂꢗꢆꢅꢉꢈꢍꢗ ꢄꢈꢑ ꢶꢛꢧ ꢎꢃꢂꢗꢆꢅꢄꢔ ꢄꢈꢑ ꢇꢄꢓꢈꢂꢆꢍꢗ ꢇꢂꢄꢕ
ꢎꢙꢅꢂꢇꢂꢈꢆꢎꢤ ꢳꢌꢂꢎꢂ ꢗꢉꢇꢃꢔꢂꢴꢂꢎ ꢌꢄꢞꢂ ꢄ ꢆꢂꢆꢅꢄꢌꢂꢑꢅꢄꢔ ꢎꢆꢅꢙꢗꢆꢙꢅꢂ ꢯꢍꢆꢌ
ꢆꢌꢂ ꢄꢅꢉꢇꢄꢆꢍꢗ ꢔꢍꢓꢄꢈꢑ ꢲꢉꢈꢑꢂꢑ ꢆꢉ ꢗꢉꢃꢃꢂꢅꢩꢦꢬ ꢆꢌꢅꢉꢙꢓꢌ ꢎꢙꢔꢊꢙꢅꢤ
ꢀꢋꢉꢅꢅꢂꢎꢃꢉꢈꢑꢍꢈꢓ ꢄꢙꢆꢌꢉꢅꢤ ꢪꢕꢇꢄꢍꢔꢷ ꢞꢍꢜꢈꢄꢈꢲꢸꢅꢂꢑꢍꢹꢇꢄꢍꢔꢤꢗꢉꢇ
ꢧꢨꢩꢪ
ꢁꢺꢦꢷ ꢣꢡꢤꢣꢡꢢꢣꢀꢘꢦꢛꢕꢣꢠꢡꢡꢣꢻꢼꢻꢽ
ꢋꢉꢃꢏꢅꢍꢓꢌꢆ # ꢠꢡꢡꢠ ꢲꢏ ꢛꢄꢅꢗꢂꢔ ꢁꢂꣁꣁꢂꢅꢐ ꢦꢈꢗꢤ
ꢡꢡꢾꢼꢕꢽꢿꢣꢼ ꢩꢥꢅꢍꢈꢆꢬꣀ ꢣꢽꢫꢠꢕꢠꢼꢼꢡ ꢩꢺꢈꢔꢍꢈꢂꢬ
ꢯꢯꢯꢤꢑꢂꣁꣁꢂꢅꢤꢗꢉꢇ

1790
MISRA AND TEWARI
INTRODUCTION
The important feature of the chemistry of [Cu(EPh3)3X] (E ¼ P or As;
X ¼ Cl, Br or I) is the facile replacement of one or two phosphine=arsine
groups by neutral ligands,[1] and that of halides by mono-anionic ligands.[2,3]
A number of copper(I) triarylphosphine and triarylarsine complexes having
sulfur donor ligands have been reported.[477] These were either synthesized
by the reaction of [Cu(EPh3)3X] and the sulfur ligands or by the reaction
of copper(I) halide with sulfur donor ligands and triphenylphosphine or
triphenylarsine. The synthesis, reactivity and ligating behaviour of N-
carboethoxy-4-chlorobenzene thioamide (Hcct) and N-carboethoxy-4-
bromobenzene thioamide (Hcbt) (Fig. 1) have been reported earlier.[8] In
continuation of these studies, we report here the reactivity of these ligands
with [Cu(EPh3)3X] to produce new complexes.
RESULTS AND DISCUSSION
The analytical data (Table I) are in good agreement with the stoi-
chiometry in which one molecule of ligand displaces one EPh3 in
[Cu(EPh3)3X] (E ¼ P or As); (X ¼ Cl, Br or I) when allowed to react in
benzene.
Â
Ã
Â
Ã
CuðEPh3Þ3X þ HL ! CuðEPh3Þ2ðHLÞX þ EPh3
ðE ¼ P or As; X ¼ C1; Br or I; HL ¼ Hcct or HcbtÞ
All of the prepared complexes are diamagnetic at room temperature
and are, in general air-stable and soluble in most of the organic solvents.
In all of the cases tetrahedral coordination with the thioamide ligands
to copper(I) via the thiocarbonyl sulfur may be assigned. The diamagnetic
nature and the stoichiometry confirm the oxidation state of copper as þ1.
Thus, these complexes may be represented as shown in Fig. 2.
Figure 1. The ligands Hcct (X ¼ C1) and Hcbt (X ¼ Br).

COPPER(I) COMPLEXES
1791

1792
MISRA AND TEWARI

COPPER(I) COMPLEXES
1793
Figure 2. Copper(I) complexes of Hcct or Hcbt.
The major IR bands of interest in the spectra of the ligands and
complexes are given in Table II. All complexes exhibit the characteristic
bands of PPh3 or AsPh3. The vibrations are mainly due to the phenyl groups
of the PPh3 or AsPh3 ligands for which the characteristic bands are at 1088
and 1075 cmꢂ1, respectively.[9,10]
The band at ꢃ3225 cmꢂ1 in the ligands and assigned to u(N7H), could
not be used reliably for ascertaining the bonding through nitrogen because
of unsystematic shifts after complexation. The presence of NH in the
1
complexes was confirmed by the H NMR spectrum in CDCl3 which dis-
played a signal at d ¼ 11.3 ppm (singlet, intensity 1H) [for the uncomplexed
ligand, d ¼ 11.8 ppm (s, 1H, NH)].[11] The position of the band at around
1765 cmꢂ1 assigned to u(C›O) either remains stationary or shifts towards
higher wave number (ca. 5 cmꢂ1) in the complexes, ruling out coordination
through the carbonyl group. The band around 1585 cmꢂ1 assigned to
uðCꢄ ꢄ ꢄ ꢄNÞ, shifts to higher wave number (Du ca. 25735 cmꢂ1). This indicates
non-involvement of nitrogen in bonding. The thioamide band
I
[uðCꢄ ꢄ ꢄ ꢄNÞ þ dðNHÞ] shifts to lower wave numbers (ca. 10730 cmꢂ1). The
thioamide band II around 1360 cmꢂ1 either remains stationary or shifts to
higher energy by 5710 cmꢂ1. The position of thioamide band IV
(8507830) cmꢂ1 is invariant but the band at 830 cmꢂ1 appears with appre-
ciable reduced intensity in the complexes. The band around 1130 cmꢂ1
assigned to u(C›S) systematically shifts to lower energy to an extent of
5720 cmꢂ1. This observation supports involvement of sulfur as the
donor site.
The electronic spectra of the complexes formed with the ligand Hcct
were taken in dichloromethane and assigned on the basis of earlier
reports.[9,12714] The values of lmax and their assignments are given in
Table III.
The spectra of the ligand, Hcct, exhibit bands at 445 nm, 305 nm and
265 nm. The higher energy band at 265 nm has been assigned to intraligand

1794
MISRA AND TEWARI

COPPER(I) COMPLEXES
1795
Table III. Electronic Spectra of the Ligand Hcct and the Complexes [CuX(Hcct)-
(Eph3)2] in Dichloromethane (conc. ¼ 10ꢂ4 M) (E ¼ P or As; X ¼ Cl, Br or I)
Band Position
lmax (nm)
a
Compounds
ðeÞ
Assignments
Ligand [Hcct]
445
305
265
280
265
390
278
265
280
265
270
260
275
265
300
275
(1498)
(2667)
(2954)
(952)
n ! pꢅ
p ! pꢅ
CT
CT
CT
[CuCl(Hcct)(PPh3)2]
[CuBr(Hcct)(PPh3)2]
(721)
M ! L CT
(615)
(527)
(767)
(652)
(733)
(891)
(761)
(531)
(373)
(306)
CT
CT
[CuI(Hcct)(PPh3)2]
[CuCl(Hcct)(AsPh3)2]
[CuCl(Hcct)(AsPh3)2]
[CuI(Hcct)(AsPh3)2]
CT
CT
CT
CT
CT
CT
p ! pꢅ
CT
ae, L molꢂ1 cmꢂ1
.
charge transfer (IL-CT) while the bands at 445 nm and 305 nm are assigned
to n ! pꢅ and p ! pꢅ intraligand (IL) bands, respectively. The n ! pꢅ
transition usually occurs at the low-energy side and is less intense in com-
parison with p ! pꢅ in the system involving nitrogen and sulfur atoms.[15]
The spectra of the copper(I) complexes exhibit only intraligand transitions.
The d-d transitions for Cu(I) (d10) are not observed.
EXPERIMENTAL
The ligands, Hcct and Hcbt, were synthesized as reported.[8] The
complexes [Cu(EPh3)3X] (E ¼ P or As; X ¼ Cl, Br or I) were prepared by
literature methods.[1,9,16,17] Cuprous halides were freshly prepared just prior
to use for the preparation of the phosphine and arsine complexes.
A benzene solution (25 mL) containing an equivalent amount of ligand
(1 mmol) was mixed slowly with a benzene solution (25 mL) of [Cu(EPh3)3X]
(1 mmol) at room temperature. The colour of the solution intensified and it
was then heated under reflux for 0.5 to 1 h and concentrated to ca. half of its
ꢁ
volume under reduced pressure. Addition of petroleum ether (60780 C)

1796
MISRA AND TEWARI
(10 mL) and allowing the mixture to stand for 273 h produced coloured
crystals. These were filtered, washed several times with petroleum ether and
dried in vacuo.
Copper, halide, phosphorus and sulfur were determined gravime-
trically. Analyses of C, H and N were done at the Microanalytical
Laboratory, Indian Institute of Technology, Kanpur. The IR spectra of the
ligands and complexes were recorded in KBr pellets in the range
40007250 cmꢂ1. The electronic spectra were recorded on a Cary model 17D
UV-Visible spectrophotometer using dichloromethane as solvent. Magnetic
susceptibilities of the complexes at room temperature (298 K) were deter-
mined by using a model 150A parallel field vibrating sample magnetometer
(VSM).
ACKNOWLEDGMENTS
The authors thank Professor S. K. Dikshit, Department of Chemistry,
Indian Institute of Technology, Kanpur, for providing spectral analysis
facilities and the University Grants Commission, New Delhi, for financial
assistance.
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Received October 27, 1999
Accepted July 18, 2002
Referee I: K. Moedritzer
Referee II: J. D. Zubkowski