Copper(I)-organophosphine complexes of bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand

Article abstract of DOI:10.1016/j.ica.2007.09.017

Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR₃ (PR₃ = P(C₆H₅)₃; P(C₆H₅)₂(4-C₆H₄COOH); P(C₆H₅)₂(2-C₆H₄COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH₂OH)₃, tris(hydroxymethyl)phosphine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS₂]. Mono-nuclear complexes of the type [LCS₂]Cu[PR₃] have been obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (¹H, ¹³C and ³¹P) NMR spectral data; in these complexes the ligand behaves as a κ³-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex [LCS₂]Cu[P(CH₂OH)₃]₂, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure of [LCS₂]Cu[P(C₆H₅)₃] has been determined. The [LCS₂]Cu[P(C₆H₅)₃] complex has a pseudo tetrahedral copper site where the bis(3,5-dimethylpyrazolyl)dithioacetate ligand acts as a κ³-N,N,S donor.

Full text of DOI:10.1016/j.ica.2007.09.017

Available online at www.sciencedirect.com
Inorganica Chimica Acta 361 (2008) 1456–1462
www.elsevier.com/locate/ica
Copper(I)–organophosphine complexes of
bis(3,5-dimethylpyrazol-1-yl)dithioacetate ligand
a
a
b
b
Maura Pellei , Simone Alidori , Mercedes Camalli , Gaetano Campi ,
a
a
a
Giancarlo Gioia Lobbia , Marilena Mancini , Grazia Papini ,
b
a,
*
Riccardo Spagna , Carlo Santini
a
`
Dipartimento di Scienze Chimiche, Universita di Camerino, via S. Agostino 1, 62032 Camerino, Macerata, Italy
Istituto di Cristallografia, CNR, Sezione di Monterotondo, via Salaria Km 29.3, 00016 Monterotondo Stazione, Roma, Italy
b
Received 18 April 2007; received in revised form 7 September 2007; accepted 15 September 2007
Available online 21 September 2007
Abstract
Copper(I) complexes have been synthesized from the reaction of CuCl, monodentate tertiary phosphines PR3 (PR3 = P(C6H5)3;
P(C6H5)2(4-C6H4COOH); P(C6H5)2(2-C6H4COOH); PTA, 1,3,5-triaza-7-phosphaadamantane; P(CH2OH)3, tris(hydroxymethyl)phos-
phine) and lithium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS2]. Mono-nuclear complexes of the type [LCS2]Cu[PR3] have been
obtained and characterized by elemental analyses, FT-IR, ESI-MS and multinuclear (1H, 13C and 31P) NMR spectral data; in these com-
plexes the ligand behaves as a j3-N,N,S scorpionate system. One exception to this stoichiometry was observed in the complex
[LCS2]Cu[P(CH2OH)3]2, where two phosphine co-ligands are coordinated to the copper(I) centre. The solid-state X-ray crystal structure
of [LCS2]Cu[P(C6H5)3] has been determined. The [LCS2]Cu[P(C6H5)3] complex has a pseudo tetrahedral copper site where the bis(3,5-
dimethylpyrazolyl)dithioacetate ligand acts as a j3-N,N,S donor.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Copper(I); Scorpionates; X-ray; Phosphines; Spectroscopy
1. Introduction
have been extensively employed as anionic r-donor ligands
in a variety of metal complexes, and they have found wide
application in coordination, organometallic and bioinor-
ganic chemistry [11]. Modifications of poly(pyrazol-
yl)borates can be made by replacement of the boron
bridging atom by other elements such as carbon [12], sili-
con [13] or phosphorus [14,15]. Recent contributions are
related to the ligands derived from bis(pyrazol-1-yl)meth-
ane, with [RR0C(pz)2] as general structure and bearing a
coordinating moiety (R0) such as acetate [6,8,16–34] or
dithioacetate [21,23,26,33,35–37].
On this basis, in recent years, we have focused our
attention on the study of the coordinative ability of the
mono-anionic heteroscorpionate bis(pyrazol-1-yl)acetate
[6,8,16,22–24] and bis(pyrazol-1-yl)dithioacetate [23,37]
ligands, towards Cu(I), Re(V) and Sn(IV) acceptors. As
part of our investigations into the copper(I) coordination
It is known that copper is an essential trace metal for liv-
ing organisms [1]. This metal plays a crucial role in different
enzymes that catalyze oxidation/reduction reactions
involved with the antioxidant system of the organism [2].
It has been reported that certain copper-complexes catalyze
radical formation while others seem to have efficacy as
antioxidants [3]. The different behaviour depends upon
the chemical environment and nature of the chelating
agent. In this field, our attention has been focused on cop-
per(I) complexes containing ‘‘scorpionate’’ ligands [4–8].
Poly(pyrazolyl)borates [9] and related scorpionates [10]
*
Corresponding author. Tel./fax: +39 (0) 737 402213.
E-mail address: carlo.santini@unicam.it (C. Santini).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.09.017

M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
1457
chemistry [4–8], here we describe the synthesis and struc-
2.1. Synthesis
tural characterization of new pyrazole-based scorpionate
copper(I) complexes containing monodentate tertiary
phosphine co-ligands.
2.1.1. [LCS2]Cu[P(C6H5)3] (1)
To a methanol/acetonitrile (1:5) solution (50 ml) of
CuCl (0.099 g, 1.0 mmol) and P(C6H5)3 (0.262 g,
1.0 mmol), the ligand lithium bis(3,5-dimethylpyrazol-
yl)dithioacetate, Li[LCS2], (0.286 g, 1.0 mmol) was added
at room-temperature. After addition, the reaction mixture
was stirred for 12 h, and the solvent was removed under
vacuum. The resulting solid was treated with chloroform
(50 ml) and the salt (LiCl) removed by filtration. The fil-
trate was concentrated under vacuum and an orange solid
was filtered off, washed with diethyl ether and re-crystal-
lized from CHCl3/n-hexane (1:3) to give complex 1 in
2. Experimental
All reagents were purchased from Alfa (Karlsruhe) and
Aldrich (Milwaukee) and used as received. The ligand lith-
ium bis(3,5-dimethylpyrazolyl)dithioacetate, Li[LCS2]
(Fig. 1), was prepared according to the literature methods
[35]. All syntheses and handling were carried out under
an atmosphere of dry, oxygen-free dinitrogen, using stan-
dard Schlenk techniques or a glove box. All solvents were
dried, degassed and distilled prior to use. Elemental analy-
ses (C, H, N, S) were performed in house with a Fisons
Instruments 1108 CHNS–O Elemental Analyser. Melting
points were taken on an SMP3 Stuart Scientific Instru-
ment. IR spectra were recorded from 4000 to 100 cmꢀ1
with a Perkin–Elmer System 2000 FT-IR Instrument. IR
annotations used: m = medium, mbr = medium broad,
s = strong, sbr = strong broad, sh = shoulder, w = weak.
1H and 31P NMR spectra were recorded on a Oxford-400
1
86% yield. M.p. 187 ꢁC dec. H NMR (CDCl3, 293 K): d
1.73 (s, 6H, 3-CH3), 2.50 (s, 6H, 5-CH3), 5.87 (s, 2H, 4-
CH), 7.30–7.64 (m, 16H, CH). 1H NMR (DMSO,
293 K): d 1.69 (s, 6H, 3-CH3), 2.45 (s, 6H, 5-CH3), 6.09
(s, 2H, 4-CH), 7.35–7.52 (m, 15H, CH), 7.41 (m, 1H,
CHCS2). 13C{1H} NMR (CDCl3, 293 K): d 11.90 (5-
CH3), 13.91 (3-CH3), 79.36 (CHCS2), 106.67 (4-CH),
128.71–134.33 (C6H5), 140.82 (5-CCH3), 148.82 (3-
CCH3). 31P{1H} NMR (CDCl3, 293 K): d 7.08 (s).
31P{1H} NMR (CDCl3, 218 K): d 6.91 (sbr). IR (nujol,
cmꢀ1): 3052w (CH); 1557s (C@N, C@C); 1094s, 1060s
ðmasymCS2ꢀÞ; 876s, 850s, 814m, 791m ðmsymCS2ꢀÞ; 529s,
509s, 491s (R3P); 447m, 435m, 428m, 418m, 379w, 340w;
299w (Cu–N). ESIMS (major positive-ions, CH3OH), m/z
(%): 931 (100) [{(LCS2)Cu[P(C6H5)3]2 + Cu}] +. ESIMS
(major negative-ions, CH3OH), m/z (%): 279 (100)
[LCS2]ꢀ. Anal. Calc. for C30H30CuN4PS2: C, 59.54; H,
5.00; N, 9.26; S, 10.59. Found: C, 59.39; H, 5.08; N, 9.08;
S, 10.36%.
1
Varian spectrometer (400.4 MHz for H and 162.1 MHz
for 31P). NMR annotations used: d = doublet, dd = double
doublet, dbr = broad doublet, m = multiplet, m = broad
multiplet, s = singlet, sbr = broad singlet, t = triplet. Elec-
trospray ionization mass spectra (ESIMS) were obtained in
positive- or negative-ion mode on a Series 1100 MSD
detector HP spectrometer using a methanol mobile phase.
The compounds were added to the reagent grade methanol
to give solutions of approximate concentration 0.1 mM.
These solutions were injected (1 ll) into the spectrometer
via a HPLC HP 1090 Series II fitted with an autosampler.
The pump delivered the solutions to the mass spectrometer
source at a flow rate of 300 ll minꢀ1, and nitrogen was
employed both as a drying and nebulizing gas. Capillary
voltages were typically 4000 V and 3500 V for the positive-
and negative-ion mode, respectively. Confirmation of all
major species in this ESIMS study was aided by compari-
son of the observed and predicted isotope distribution pat-
terns, the latter calculated using the ISOPRO 3.0 computer
program.
2.1.2. [LCS2]Cu[P(C6H5)2(4-C6H4COOH)] (2)
Complex 2 was prepared analogously to compound 1 by
using CuCl (0.099 g, 1.0 mmol), [P(C6H5)2(4-C6H4COOH)]
(0.306 g, 1.0 mmol) and Li[LCS2] (0.286 g, 1.0 mmol) in
methanol/acetonitrile (1:5) solution (50 ml). The orange
product was re-crystallized from chloroform/n-hexane
1
(1/3), in 80% yield. M.p. 164 ꢁC dec. H NMR (CDCl3,
293 K): d 1.71 (s, 6H, 3-CH3), 2.49 (s, 6H, 5-CH3), 5.93
(s, 2H, 4-CH), 7.25–8.05 (m, 15H, CH). 1H NMR (DMSO,
293 K): d 1.69 (s, 6H, 3-CH3), 2.45 (s, 6H, 5-CH3), 6.09 (s,
2H, 4-CH), 7.31–8.00 (m, 14H, CH), 7.41 (m, 1H, CHCS2).
31P{1H} NMR (CDCl3, 293 K): d 7.18 (sbr). 31P{1H}
NMR (CDCl3, 218 K): d 7.16 (sbr). IR (nujol, cmꢀ1):
3405br (OH); 3048w (CH); 1694sbr (C@O); 1560s (C@N,
C@C); 1094s, 1019s ðmasymCS2ꢀÞ; 873s, 850s ðmsymCS2ꢀÞ;
567w, 540sbr, 516sbr (R3P); 441br, 398w, 375w, 352w,
326w; 303w (Cu–N). ESIMS (major positive-ions,
CH3OH), m/z (%): 650 (20) [{(LCS2)Cu[P(C6H5)2(4-C6
H4COOH)] + H}]+, 1019 (100) [{(LCS2)Cu[P(C6H5)2(4-
C6H4COOH)]2 + Cu}]+. ESIMS (major negative-ions,
CH3OH), m/z (%): 378 (100) [{(LCS2)Cu + Cl}]ꢀ. Anal.
Calc. for C31H30CuN4O2PS2: C, 57.35; H, 4.66; N, 8.63;
S, 9.88. Found: C, 57.19; H, 4.54; N, 8.78; S, 10.02%.
Fig. 1. Schematic representation of the ligand Li[LCS2].

1458
M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
2.1.3. [LCS2]Cu[P(C6H5)2(2-C6H4COOH)] (3)
(0.248 g, 2.0 mmol), Li[LCS2] (0.286 g, 1.0 mmol) was
added at room temperature. After addition, the reaction
mixture was stirred for 6 h and solvent removed under vac-
uum. The resulting solid was treated with chloroform
(50 ml) and salt removed by filtration. The solution was
concentrated under vacuum and a brown solid was filtered
off and re-crystallized from CHCl3/acetone (1:1) to give
complex 5 in 81% yield. M.p. 222 ꢁC dec. 1H NMR
(DMSO, 293 K): d 2.23 (s, 6H, 3-CH3), 2.41 (s, 6H, 5-
CH3), 4.00 (d, 12H, CH2), 6.07 (s, 2H, 4-CH), 7.30 (s,
1H, CHCS2). 13C{1H} NMR (DMSO, 293 K): d 10.85 (5-
CH3), 13.65 (3-CH3), 55.40 (CH2), 78.59 (CHCS2), 106.01
(4-CH), 140.37 (5-CCH3), 147.78 (3-CCH3). 31P{1H}
NMR (DMSO, 293 K): d ꢀ8.20 (sbr). IR (nujol, cmꢀ1):
3300br, 3180br (OH); 3060w (CH); 1555s (C@N, C@C);
1066m, 1038s, 1021s ðmasymCS2ꢀÞ; 870s, 851s, 806m, 794s
ðmsymCS2ꢀÞ; 547w, 503s (R3P); 465m, 453br, 431s, 396s,
341w, 321m; 296w (Cu–N). ESIMS (major positive-ions,
CH3OH), m/z (%): 312 (100) {Cu[P(CH2OH)3]2}+. ESIMS
(major negative-ions, CH3OH), m/z (%): 279 (100)
[LCS2]ꢀ. Anal. Calc. for C18H33CuN4P2O6S2: C, 36.57;
H, 5.63; N, 9.48; S, 10.85. Found: C, 36.29; H, 5.48; N,
9.28; S, 10.66%.
Complex 3 was prepared analogously to compound 1 by
using CuCl (0.099 g, 1.0 mmol), [P(C6H5)2(2-C6H4COOH)]
(0.306 g, 1.0 mmol) and Li[LCS2] (0.286 g, 1.0 mmol) in
methanol/acetonitrile (1:5) solution (50 ml). The orange
product was re-crystallized from chloroform/n-hexane (1/
3), in 75% yield. M.p. 192 ꢁC dec. 1H NMR (CDCl3,
293 K): d 1.68 (s, 6H, 3-CH3), 2.47 (s, 6H, 5-CH3), 5.93 (s,
1
2H, 4-CH), 7.25–8.05 (m, 15H, CH). H NMR (DMSO,
293 K): d 1.67 (s, 6H, 3-CH3), 2.44 (s, 6H, 5-CH3), 6.08 (s,
2H, 4-CH), 7.29–8.00 (m, 14H, CH), 7.40 (m, 1H, CHCS2).
31P{1H} NMR (CDCl3, 293 K): d 0.78 (br). 31P{1H} NMR
(CDCl3, 218 K): d 0.91 (s). IR (nujol, cmꢀ1): 3451br (OH);
3124w, 3053w (CH); 1658sbr (C@O); 1558s (C@N, C@C);
1080m, 1039w ðmasymCS2ꢀÞ; 874s, 849m, 812m ðmsymCS2ꢀÞ;
556m, 536m, 523s, 502sbr (R3P); 467m, 430br, 368m,
326br; 301m (Cu–N). ESIMS (major positive-ions, CH3OH),
m/z (%): 676 (100) [{Cu[P(C6H5)2(2-C6H4COOH)]2}]+.
ESIMS (major negative-ions, CH3OH), m/z (%): 279 (20)
[LCS2]ꢀ, 305 (100) [P(C6H5)2(2-C6H4COOH)-H]ꢀ, 674 (40)
[{Cu[P(C6H5)2(2-C6H4COOH)]2-2H}]ꢀ. Anal. Calc. for
C31H30CuN4O2PS2: C, 57.35; H, 4.66; N, 8.63; S, 9.88.
Found: C, 57.19; H, 4.54; N, 8.78; S, 10.02%.
2.1.4. [LCS2]Cu[PTA] (4)
2.2. X-ray measurements and structure determination for
complex 1
To an acetonitrile solution (40 ml) of [Cu(CH3CN)4][PF6]
(0.373 g, 1.0 mmol) a methanol solution (10 ml) of 1,3,5-tri-
aza-7-phosphaadamantane (PTA, 0.314 g, 2.0 mmol) was
added at room temperature and the solution was stirred
for 5 h. A methanol solution (10 ml) of Li[LCS2] (0.314 g,
1.0 mmol) was added and the reaction mixture was stirred
for 3 h. The solvent was removed under vacuum, the result-
ing solid was treated with methanol/diethyl ether (50 ml) and
salt removed by filtration. The solution was concentrated
under vacuum and an orange solid was filtered off and re-
crystallized from methanol to give complex 4 in 78% yield.
Crystal and experimental data are summarized in Table 1.
Crystallization of compound [LCS2]Cu[P(C6H5)3], 1, from
chloroform/n-hexane solution, yields crystals suitable for
the X-ray crystallography analysis performed on a XCS-
Huber four-circle diffractometer (Department of Chemistry,
University of Rome ‘‘La Sapienza’’) using zirconium-mono-
˚
chromatized Mo Ka radiation (0.71073 A). The cell param-
eters were refined by least square from the angular positions
of 48 reflections in the range 11.76ꢁ < 2h < 27.13ꢁ. The data
were measured at room temperature for 4.42ꢁ < 2h < 59.94ꢁ
using a h/2h scan technique, and showed no decay. The data
were processed to yield values of I and r(I) corrected for
Lorentz, polarization, and shape anisotropy effects. A total
of 4133 independent reflections having Fo > 3r(Fo) were
processed by the direct methods, which provided the com-
plete structure. All non-hydrogen atoms were refined by a
full-matrix least squares method with anisotropic thermal
parameters. The hydrogen atoms were idealized (C–
1
M.p. 237 ꢁC dec. H NMR (CDCl3, 293 K): d 2.23 (s, 6H,
3-CH3), 2.46 (s, 6H, 5-CH3), 4.26 (d, 6H, CH2), 4.62 (s,
1
6H, CH2), 5.92 (s, 2H, 4-CH), 7.47 (s, 1H, CHCS2). H
NMR (DMSO, 293 K): d 2.18 (s, 6H, 3-CH3), 2.40 (s, 6H,
5-CH3), 4.19 (d, 6H, CH2), 4.50 (m, 6H, CH2), 6.10 (s, 2H,
4-CH), 7.28 (s, 1H, CHCS2). 31P{1H} NMR (CDCl3,
293 K): d ꢀ90.19 (sbr). 31P{1H} NMR (CDCl3, 223 K): d
ꢀ90.78 (sbr). IR (nujol, cmꢀ1): 3126w, 3096w (CH); 1555s
(C@N, C@C); 1095s, 1066s, 1040s ðmasymCS2ꢀÞ; 880m,
851s, 812s ðmsymCS2ꢀÞ; 581s, 573s (R3P); 480m, 467m,
451m, 430m, 396m, 340w; 295mbr (Cu–N). ESIMS (major
positive-ions, CH3OH), m/z (%): 501 (100) [{(LCS2)-
Cu[PTA] + H}]+, 523 (80) [{(LCS2)Cu[PTA] + Na}]+, 687
(70) [{(LCS2)2Cu2 + H}]+. ESIMS (major negative-ions,
CH3OH), m/z (%): 279 (100) [LCS2]ꢀ. Anal. Calc. for
C18H27CuN7PS2: C, 43.23; H, 5.44; N, 19.61; S, 12.82.
Found: C, 43.09; H, 5.41; N, 19.48; S, 12.66%.
˚
H) = 0.96 A; each of them was assigned 1.3 equiv. isotro-
*
pic temperature factor of the parent atom and allowed to
ride on it. The final difference Fourier map, with a root-
ꢀ3
˚
mean-square deviation of electron density of 0.06 e A
showed minimum and maximum values of ꢀ0.42 and 0.44,
respectively. Calculations were performed using: XCS data
collection program [38]; DARX2002 data reduction program
[39]; ‘‘Il milione’’ structure determination and refinement
package [40]; PLATON to prepare supplementary material
[41]. The crystal structure is shown in Fig. 2 along with the
atom-numbering scheme. The most interesting bond lengths
and angles are presented in Table 2.
2.1.5. [LCS2]Cu[P(CH2OH)3]2 (5)
To a methanol/acetonitrile (1:2) solution (50 ml) of
[Cu(CH3CN)4][PF6] (0.373 g, 1.0 mmol) and P(CH2OH)3

M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
1459
Table 1
Crystal data and structure refinement parameters for [LCS2]Cu[P(C6H5)3],
1
Molecular formula
M
C30H30CuN4PS2
605.24
Crystal size/mm
Temperature (K)
Wavelength (A)
(0.45 · 0.25 · 0.25)
293
0.71073
˚
Crystal system
Space group
a (A)
monoclinic
ꢀ
P21
˚
13.067 (2)
˚
b (A)
14.262 (2)
17.121 (3)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
112.21(2)
90
2954.0(9)
3
˚
Volume (A )
Z
4
Dc (Mg mꢀ3
)
1.361
0.961
1256
l (mmꢀ1
F(000)
)
Data collection range
Index ranges
2.2ꢁ < h < 30.0ꢁ
0 6 h 6 17; 0 6 k 6 19;
ꢀ22 6 l 6 21
9229
4499 [0.0091]
4133 [F > 3r(F)]
343
Reflections collected
Independent reflections [Rint
Observed reflections
Parameters refined
]
a,b,c in the weighting scheme
w ¼ 1:0=ða þ bF o þ cF 2oÞ
Final Ra indices
0.5483, 0.0452, 0.0004
Fig. 2. The molecular structure of complex 1. Ellipsoids are at the 30%
probability level, and hydrogen atoms have been omitted for clarity.
R = 0.029; wR = 0.040
Goodness-of-fit, Sb
(D/r)max
0.95
0.06
0.44
ꢀ3
Table 2
˚
Dqmax (e Aꢀ3
)
Selected geometries, [LCS2]Cu[P(C6H5)3], 1
˚
Dqmin (e A
)
ꢀ0.43
P
P
P
P
2
2 1=2
a
Atoms
Parameter
Atoms
Parameter
R ¼ jjFoj ꢀ jF cjj= Fo; wR ¼ f wðjF oj ꢀ jF cjÞ = wjF oj g
.
P
2
1=2
b
˚
S ¼ f wðjFoj ꢀ jFcjÞ =ðNrefl ꢀ NparamÞg
.
Distances (A)
Cu1–S1
Cu1–P1
Cu1–N1
Cu1–N3
S1–C12
2.332(1)
2.1851(8)
2.089(2)
2.080(2)
1.687(3)
1.658(3)
1.832(3)
1.828(3)
1.830(3)
N1–N2
N1–C1
N2–C3
N2–C11
N3–N4
N3–C6
N4–C8
N4–C11
C11–C12
1.362(4)
1.336(3)
1.372(4)
1.450(4)
1.356(4)
1.336(3)
1.359(4)
1.456(4)
1.539(4)
3. Results and discussion
3.1. Synthesis, properties and spectroscopic characterization
S2–C12
P1–C13
P1–C19
P1–C25
According to Eq. (1), 1:1:1 N-donor:copper:triorgano-
phosphine Cu(I) complexes 1–4 have been obtained in high
yields from the interaction of 1 equiv. of the lithium salt
Li[LCS2] with equimolar quantities of CuCl and tertiary
monophosphines PR3, in a methanol/acetonitrile (1:2)
solution at room temperature. The use of an excess of the
phosphine did not change the stoichiometry of the resulting
complexes.
Angles (ꢁ)
Cu1–S1–C12
N1–Cu1–N3
N1–Cu1–P1
N3–Cu1–P1
S1–Cu1–N1
100.6(1)
88.23(7)
121.80(8)
120.77(7)
92.25(7)
S1–Cu1–N3
S1–Cu1–P1
S1–C12–C11
S2–C12–S1
S2–C12–C11
94.60(7)
128.90(4)
119.1(2)
126.1(2)
114.7(2)
Li½LCS2ꢁ þ CuCl þ PR3 ! ½LCS2ꢁCu½PR3ꢁ þ LiCl
ð1Þ
plex 5 (Eq. (2)), likely due to the small sterical hindrance of
the P(CH2OH)3 phosphine.
1: PR3 = P(C6H5)3
2: PR3 = P(C6H5)2(4-C6H4COOH)
3: PR3 = P(C6H5)2(2-C6H4COOH)
4: PR3 = PTA
Li½LCS2ꢁ þ CuCl þ PðCH2OHÞ3
! ½LCS2ꢁCu½PðCH2OHÞ3ꢁ2 þ LiCl
ð2Þ
The stoichiometry of this compound was not affected by
decreasing (1 equiv.) or increasing (>2 equiv.) the amount
of P(CH2OH)3.
Compounds 1–4 are reasonably stable in air and show a
good solubility in methanol, acetone, and chlorinated sol-
The reaction between Li[LCS2] and CuCl, carried in the
presence of 2 equiv. of tris(hydroxymethyl)phosphine,
under the conditions detailed above, yielded the mononu-
clear 1:1:2 N-donor:copper:triorganophosphine Cu(I) com-

1460
M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
vents; derivative 5 is only soluble in DMSO. Derivatives 1–
5 have been characterized by analytical and spectral data.
The infrared spectra carried out on the solid samples (nujol
mull) showed all the bands required by the presence of the
organic nitrogen and the phosphine ligands: weak absorp-
tions in the range 3048–3126 cmꢀ1 are due to the azolyl
ring C–H stretchings, and medium to strong absorptions
near 1555 cmꢀ1 are related to ring ‘‘breathing’’ vibrations.
The presence of the CS2 moiety is detected by intense
absorptions in the range 1019–1099 cmꢀ1 andꢀ791–880
cmꢀ1, due to the asymmetric and symmetric CS2 stretch-
ing modes, the shift with respect to free neutral ligand [35]
being observed upon complex formation. These values fit
those reported for analogous Ti(IV) [26,35], Zr(IV) [33],
Hf(IV) [33], Y(III) and Sc(III) [21] complexes. In the far-
IR spectra of derivatives 1–5, we have assigned the broad
absorptions from 400 to 550 cmꢀ1 to the phenyl quadrant
in and out of plane bending vibrations, on the basis of
previous reports on free phosphines [42], and cop-
per(I)phosphine complexes [43]. In all the complexes weak
to medium bands at ca. 300 cmꢀ1 are observed; they are
similar to those described for copper– and silver–azolato
complexes [7,44], which have been tentatively assigned to
m(M–N) stretching vibrations.
tion of an excess of free phosphines, shifts upfield without
observing a distinct resonance of the free phosphines; this
is consistent with a fast exchange of coordinated and free
phosphine ligands [46–48] and the 31P–63/65Cu spin cou-
plings (63Cu and 65Cu, I = 3/2) are not observed.
Electrospray ionization mass spectroscopy was used to
probe the existence of aggregates of the scorpionate ligand
with Cu(I) and phosphine co-ligands in solution. Both
positive-ion and negative-ion spectra of complexes 1–5, dis-
solved in methanol, were recorded at low voltage (3.5–
4.0 kV); under these experimental conditions the dissocia-
tion is minimal and most of the analyte is transported to
the mass spectrometer as the intact molecular species.
The positive-ion spectra of compounds 1 and 2 were dom-
inated by the fragments [{(LCS2)Cu[P(C6H5)3]2 + Cu]}]+
at m/z 931 (100%) and [{(LCS2)Cu[P(C6H5)2-
(4-C6H4COOH)]2 + Cu}]+ at m/z 1019 (100%), respectively;
in the spectrum of derivative 2 we also observed a minor
peak due to the protonated species [{(LCS2)Cu[P(C6H5)2-
(4-C6H4COOH)] + H}]+. Instead, in the positive-ion spec-
trum of compound 3 we observed the peak attributable to
the fragment ion [{Cu[P(C6H5)2(2-C6H4COOH)]2}]+,
generated by the loss of the scorpionate ligand. The
negative-ion spectra of compounds 1, 2 and 3 were domi-
nated by the fragments due to the free scorpionate ligand
[LCS2]ꢀ, or the related copper(I) aggregate [{(LCS2)Cu +
Cl}]ꢀ. Only in the negative-ion spectrum of compound 3
we observed peaks attributable to the species
1
The room-temperature H NMR spectra of derivatives
1–5 in CDCl3 or DMSO solution (see Section 2), exhibit
only one set of signals for the protons of the pyrazolyl rings
of the [LCS2]ꢀ ligand, lightly shifted with respect to the
same signals in the free ligand. This effect is particularly
[P(C6H5)2(2-C6H4COOH)-H]ꢀ
and
[{Cu[P(C6H5)2(2-
significant for the aliphatic CH signal of the CHCS2 moi-
C6H4COOH)]2-2H}]ꢀ, generated by the loss of one or
two protons of the phosphane ligand. In the positive-ion
spectrum of compound 4 we observed the peaks due to
the fragments [{(LCS2)Cu[PTA] + H}]+ at m/z 501
(100%) and [{(LCS2)Cu[PTA] + Na}]+ at m/z 523
(100%). The positive- and negative-ion spectrum of com-
pound [LCS2]Cu[P(CH2OH)3]2, 5 were dominated by the
fragments {Cu[P(CH2OH)3]2}+ at m/z 312 (100%) and
[LCS2]ꢀ at m/z 279 (100%), respectively.
ꢀ
1
ety in the H NMR spectra of complexes 1–5 recorded in
DMSO. The signals in the range 7.28–7.41 ppm were
attributable to the CH aliphatic groups bound to the coor-
dinated CS2ꢀ, strongly deshieldꢀed with respect to the signal
at d = 6.76 ppm in the CHCS2 moiety of the free ligand:
this is in accordance with a j3-N,N,S coordination of the
ligand in all the Cu(I) complexes. The tridentate coordina-
tion of the [LCS2]ꢀ ligand is confirmed by the 13C{1H}
NMR data. In particular for compounds 1 and 5 the sig-
nals at d = 79.36 and 78.59 ppm, respectively, were
3.2. X-ray crystallography
ꢀ
assigned to the CHCS2 moiety, whileꢀthe signal at
d = 87.19 ppm corresponds to the CHCS2 group in the
free ligand. In the 31P{1H} NMR spectra of complexes
1–3 only one broad peak is observed at 293 K and no sig-
nificant variations are detected in the 31P{1H} NMR pro-
files on lowering the temperature; at 223 K, the signals
fall at 6.91, 7.16 and 0.91 ppm, in agreement with a CuP
coordination core. The room temperature 31P{1H} NMR
spectrum of complex 4, in chloroform solution, exhibits a
broadened signal centred at ꢀ90.19 ppm (at ꢀ90.78 in
the spectrum recorded at 223 K). The room temperature
31P{1H} NMR spectrum of complex 5, in DMSO solution,
exhibits a broadened signal centred at ꢀ8.20 ppm, typical
of a CuP2 coordination core [45], significantly downfield
shifted if compared to the signal at d ꢀ24.7 ppm exhibited
by uncoordinated P(CH2OH)3. The 31P{1H} NMR spectra
of derivatives 1–5 exhibit a broad singlet which, on addi-
The monomeric complex 1 contains the tridentate het-
eroscorpionate ligand bonded to metal through the two
nitrogen atoms from the pyrazolyl rings and the sulfur
atom from the thioacetate group of the [LCS2]ꢀ ligand.
The copper centre is in a tetrahedral environment with
the P1 phosphorus atom from the triphenylphosphine co-
ligand and the S1, N1, N3 atoms occupying the vertices.
The Cu distances from the base planes of the tetrahedron
˚
are 0.659(2)A (plane P1–N1–N3), 0.516(3) (plane S1–P1–
˚
N1), 0.497(2) (plane S1–P1–N3) and 1.210(2) A (plane
S1–N1–N3) showing a deviation from the ideal tetrahedral
coordination. Furthermore, the angle between the plane
(P1–N1–N3) and the Cu–S1 axis, 68.6(2)ꢁ, the plane (S1–
P1–N1) and the Cu–N3 axis, 71.5(3)ꢁ, the plane (S1–P1–
N3) and the Cu–N1 axis, 70.5(3)ꢁ, the plane (S1–N1–N3)
and the Cu–P1 axis, 82.3(2)ꢁ, and the values of the angles

M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
1461
[2] M.C. Linder, M. Hazegh-Azam, Am. J. Clin. Nutr. 63 (1996) 797S.
[3] M.C. Linder, Mutat. Res. 475 (2001) 141.
[4] C. Santini, M. Pellei, G. Gioia Lobbia, D. Fedeli, G. Falcioni, J.
Inorg. Biochem. 94 (2003) 348.
[5] C. Santini, M. Pellei, G. Gioia Lobbia, S. Alidori, M. Berrettini, D.
Fedeli, Inorg. Chim. Acta 357 (2004) 3549.
S–Cu–P, 128.90(4)ꢁ, and S–Cu–N, 92.25(7)ꢁ and 94.60(7)ꢁ,
show the extent of distortion around the copper atom, due
to the constraints imposed by the chelating ligand. The
metal atom is displaced from the plane defined by the
˚
N1–N2–N3–N4 atoms by 0.978(2) A. In addition the Cu
[6] M. Pellei, G. Gioia Lobbia, C. Santini, R. Spagna, M. Camalli, D.
Fedeli, G. Falcioni, Dalton Trans. (2004) 2822.
atom is out of the pyrazolyl planes, defined by N1–N2–
C1–C2–C3 and N3–N4–C6–C7–C8, at distances of
[7] C. Marzano, M. Pellei, S. Alidori, A. Brossa, G. Gioia Lobbia, F.
Tisato, C. Santini, J. Inorg. Biochem. 100 (2006) 299.
[8] C. Marzano, M. Pellei, D. Colavito, S. Alidori, G. Gioia Lobbia, V.
Gandin, F. Tisato, C. Santini, J. Med. Chem. 49 (2006) 7317.
[9] S. Trofimenko, J. Am. Chem. Soc. 88 (1966) 1842.
[10] C. Pettinari, C. Santini, Compr. Coordin. Chem. II 1 (2004) 159.
[11] S. Trofimenko, Scorpionates: The Coordination Chemistry of
Poly(pyrazolyl)borate Ligands, Imperial College Press, London,
1999.
[12] S. Trofimenko, J. Am. Chem. Soc. 92 (1970) 5118.
[13] E.E. Pullen, D. Rabinovich, C.D. Incarvito, T.E. Concolino, A.L.
Rheingold, Inorg. Chem. 39 (2000) 1561.
[14] E. Psillakis, J.C. Jeffery, J.A. McCleverty, M.D. Ward, J. Chem. Soc.,
Dalton Trans. (1997) 1645.
[15] T.N. Sorrell, W.E. Allen, P.S. White, Inorg. Chem. 34 (1995) 952.
[16] M. Porchia, G. Papini, C. Santini, G. Gioia Lobbia, M. Pellei, F.
Tisato, G. Bandoli, A. Dolmella, Inorg. Chim. Acta 359 (2006) 2501.
[17] H. Kopf, C. Pietraszuk, E. Huebner, N. Burzlaff, Organometallics 25
(2006) 2533.
[18] V. Chandrasekhar, P. Thilagar, P. Sasikumar, J. Organomet. Chem.
691 (2006) 1681.
[19] N. Kitanovski, A. Golobic, B. Ceh, Inorg. Chem. Commun. 9 (2006)
296.
[20] Z.-K. Wen, H.-B. Song, M. Du, Y.-P. Zhai, L.-F. Tang, Appl.
Organometal. Chem. 19 (2005) 1055.
[21] A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
Sanchez, L. Sanchez-Barba, E. Martinez-Caballero, A.M. Rodriguez,
I. Lopez-Solera, Inorg. Chem. 44 (2005) 5336.
[22] M. Porchia, G. Papini, C. Santini, G. Gioia Lobbia, M. Pellei, F.
Tisato, G. Bandoli, A. Dolmella, Inorg. Chem. 44 (2005) 4045.
[23] M. Pellei, C. Santini, G. Gioia Lobbia, F. Cantalamessa, C. Nasuti,
M. Di Prinzio, R. Gabbianelli, G. Falcioni, Appl. Organometal.
Chem. 19 (2005) 583.
[24] F. Marchetti, M. Pellei, C. Pettinari, R. Pettinari, E. Rivarola, C.
Santini, B.W. Skelton, A.H. White, J. Organomet. Chem. 690 (2005)
1878.
˚
˚
0.102(1) A and 0.283(1) A, respectively. The two pyrazolyl
planes are planar within the limits of experimental values
˚
˚
(max deviations are 0.002(3) A and 0.009(2) A, respec-
tively) and the angle between them is 50.3(2)ꢁ.
˚
The two Cu–N bond distances, 2.089(2) A and
˚
2.080(2) A, are comparable with the values found in the
complex of copper(I), HB-(l-pz)3-Cu[P(C6H5)3], 2.081(5)
˚
˚
A and 2.065(5) A [49] and HB(3,5-Me2pz)3-Cu[P(C6H5)3],
˚
˚
2.10(1) A and 2.09(1) A [50]. The Cu–P bond distance
2.1851(8) A lies at the lower limit of the range 2.15–
2.30 A reported for phosphine copper(I) complexes [50],
but is significantly longer than the values 2.153(2) A [49]
˚
˚
˚
˚
and 2.166(6) A [50]. The Cu–S1 bond distance,
˚
2.332(1) A, is significantly shorter than the values observed
in complexes containing CuI–S–C(@S)R moieties such as
˚
˚
2.395(1), 2.429(1) A [51] and 2.431(1), 2.456(1) A [52]. Even
if the C12–S1, 1.687(3) A, is slightly longer than C12–S2,
1.658(3) A, they fall in the lower end of the normal range
observed in similar compounds, 1.64–1.79 A [53]. This
˚
˚
˚
seems to indicate the existence of a delocalized S–C–S bond
in the complex.
The intraligand N3–Cu–N1, N3–Cu–S1, N1–Cu–S1
angles are restrained by the chelate rings to 88.23(7),
94.60(7) and 92.25(7)ꢁ. The values of distances and angles
around the copper atom are comparable to those previously
reported in analogous phosphine copper(I) derivatives of
tris(pyrazolyl)methanesulfonate ligand (Tpms) coordinated
to copper(I) in the j3-N,N0,O fashion [54], and in (uniden-
tate phosphine)(bidentate pyrazolate)metal(I) arrays of
the type [Tp]MI(R3P)n (MI = CuI or AgI; n = 1 or 2;
Tp = bis- or tetrakis-(pyrazolyl)borate) [55].
[25] J.N. Smith, J.T. Hoffman, Z. Shirin, C.J. Carrano, Inorg. Chem. 44
(2005) 2012.
[26] A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
Sanchez, L. Sanchez-Barba, A.M. Rodriguez, Dalton Trans. (2004)
3963.
Acknowledgment
[27] B.S. Hammes, B.S. Chohan, J.T. Hoffman, S. Einwaechter, C.J.
Carrano, Inorg. Chem. 43 (2004) 7800.
[28] M. Ortiz, A. Diaz, R. Cao, R. Suardiaz, A. Otero, A. Antinolo, J.
Fernandez-Baeza, Eur. J. Inorg. Chem. (2004) 3353.
[29] R. Mueller, E. Huebner, N. Burzlaff, Eur. J. Inorg. Chem. (2004)
2151.
This work was supported by University of Camerino
(FAR-2006), Italy.
Appendix A. Supplementary material
[30] A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
Sanchez, L. Sanchez-Barba, A.M. Rodriguez, Eur. J. Inorg. Chem.
(2004) 260.
[31] L. Peters, N. Burzlaff, Polyhedron 23 (2004) 245.
[32] M. Ortiz, A. Diaz, R. Cao, A. Otero, J. Fernandez-Baeza, Inorg.
Chim. Acta 357 (2004) 19.
[33] A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
Sanchez, L. Sanchez-Barba, M. Fernandez-Lopez, I. Lopez-Solera,
Inorg. Chem. 43 (2004) 1350.
CCDC 644148 contains the supplementary crystallo-
graphic data for 1. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre
via http://www.ccdc.cam.ac.uk/data_request/cif. Supple-
mentary data associated with this article can be found, in
the online version, at doi:10.1016/j.ica.2007.09.017.
References
[34] A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
Sanchez, Dalton Trans. (2004) 1499.
[35] A. Otero, J. Fernandez-Baeza, A. Antinolo, F. Carrillo-Hermo-
silla, J. Tejeda, A. Lara-Sanchez, L. Sanchez-Barba, M. Fernan-
[1] M.C. Linder, Biochemistry of Copper, Plenum Press, New York,
1991.

1462
M. Pellei et al. / Inorganica Chimica Acta 361 (2008) 1456–1462
dez-Lopez, A.M. Rodriguez, I. Lopez-Solera, Inorg. Chem. 41
(2002) 5193.
[36] M. Ortiz, A. Penabad, A. Diaz, R. Cao, A. Otero, A. Antinolo, A.
Lara, Eur. J. Inorg. Chem. (2005) 3135.
[37] M. Pellei, G. Gioia Lobbia, M. Ricciutelli, C. Santini, J. Coord.
Chem. 58 (2005) 409.
[45] E.L. Muetterties, C.W. Alegranti, J. Am. Chem. Soc. 94 (1972) 6386.
[46] B. Mohr, E.E. Brooks, N. Rath, E. Deutsch, Inorg. Chem. 30 (1991)
4541.
[47] P.A. Grutsch, C. Kutal, J. Am. Chem. Soc. 101 (1979) 4228.
[48] D. Saravana Bharathi, M.A. Sridhar, J. Shashidhara Prasad, A.G.
Samuelson, Inorg. Chem. Commun. 4 (2001) 490.
[38] M. Colapietro, G. Cappuccio, C. Marciante, A. Pifferi, R. Spagna,
J.R. Helliwell, J. Appl. Crystallogr. 25 (1992) 192.
[49] G. Gioia Lobbia, C. Pettinari, F. Marchetti, B. Bovio, P. Cecchi,
Polyhedron 15 (1996) 881.
[39] A. Pifferi, Personal communication.
[50] N. Kitajima, T. Koda, S. Hashimoto, T. Kitagawa, Y. Morooka, J.
Am. Chem. Soc. 113 (1991) 5664.
[51] F. Jian, F. Bei, L. Lu, X. Yang, X. Wang, I.A. Razak, S.S.S. Raj, H.-
K. Fun, Acta Crystallogr. C56 (2000) e288.
[40] M.C. Burla, R. Caliandro, M. Camalli, B. Carrozzini, G.L. Cascar-
ano, L. De Caro, C. Giacovazzo, G. Polidori, D. Siliqi, R. Spagna, J.
Appl. Crystallogr. 40 (2007) 609.
[41] A.L. Spek, J. Appl. Crystallogr. 36 (2003) 7.
[52] T.C. Deivaraj, J.J. Vittal, Acta Crystallogr. E57 (2001) m566.
[53] F.H. Allen, J.E. Davies, J.J. Galloy, O. Johnson, O. Kennard, C.F.
Macrae, E.M. Mitchell, G.F. Mitchell, J.M. Smith, D.G. Watson, J.
Chem. Inf. Comput. Sci. 31 (1991) 187.
[54] C. Santini, M. Pellei, G. Gioia Lobbia, A. Cingolani, R. Spagna, M.
Camalli, Inorg. Chem. Commun. 5 (2002) 430.
[42] D. Bormann, S. Tilloy, E. Monflier, Vib. Spectrosc. 20 (1999) 165.
[43] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds; Part B: Applications in Coordination,
Organometallic, and Bioinorganic Chemistry, fifth ed., John Wiley &
Sons, New York, 1997.
[44] G. Gioia Lobbia, M. Pellei, C. Pettinari, C. Santini, B.W. Skelton,
A.H. White, Inorg. Chim. Acta 358 (2005) 3633.
[55] M. Pellei, C. Pettinari, C. Santini, B.W. Skelton, N. Somers, A.H.
White, J. Chem. Soc., Dalton Trans. (2000) 3416.