Synthesis and characterization of derivatives of copper(I) with N- and S-donor ligands: V. Imidazole and imidazoline-2(3H)-thione derivatives

Article abstract of DOI:10.1016/S0277-5387(99)00089-3

New copper(I) complexes of the type [(PBz₃)L₃Cu]X, (PBz₃)L₂CuX, [(PBz₃)₂L₂Cu]X, [(PBz₃)₃LCu]X (L=monodentate N-donor imidazole- or pyrazole-type ligand, Bz=benzyl, X=NO₃ or ClO₄), (PBz₃)_y(N-N)_xCuNO₃ (N-N=bis(pyrazol-1-yl)methane, x=y=1; N-N=bis(1,2,4-triazol-1-yl)methane, x=y=2), (PPh₃)L₂′CuX, (PPh₃)₂L′CuX, [(PPh₃)L₃′Cu]X and (PPh₃)L′CuX, (L′=monodentate S-donor 1-methyl-imidazoline-2(3H)-thione or imidazoline-2(1,3H)-thione) were obtained from the reaction of (PR₃)_nCuX with the appropriate N- or S-donor ligand. Reaction between [(PPh₃)_nCu(L)_m]X with PBz₃ often resulted in the formation of new [(PBz₃)_zL_m-1Cu]X (z=n or n+1) complexes upon displacement of one molecule of L and two or three molecules of PPh₃, whereas reaction of [(N-N)₂Cu]ClO₄ with PBz₃ and 1,10-phenanthroline (Phen) yielded [(PBz₃)₂CuClO₄] and [(Phen)₂Cu]ClO₄, respectively, upon displacement of both molecules of bidentate chelating ligands. No reaction occurred between (PPh₃)L₂′CuX, (PPh₃)₂L′CuX or [(PPh₃)L′₃Cu]X and PBz₃. All the derivatives obtained were characterized by IR spectroscopy, ¹H NMR, and conductance studies, and in some cases also by molecular weight measurements. Elsevier Science Ltd.

Full text of DOI:10.1016/S0277-5387(99)00089-3

Polyhedron 18 (1999) 1941–1951
Synthesis and characterization of derivatives of copper(I) with N- and
S-donor ligands
V. Imidazole and imidazoline-2(3H)-thione derivatives
*
Claudio Pettinari , Riccardo Pettinari, Maura Pellei, Giancarlo Gioia Lobbia
`
Dipartimento di Scienze Chimiche, Universita degli Studi di Camerino, via S. Agostino 1, I-62032 Camerino, MC, Italy
Received 5 February 1999; accepted 15 March 1999
Abstract
New copper(I) complexes of the type [(PBz3)L3Cu]X, (PBz3)L2CuX, [(PBz3)2L2Cu]X, [(PBz3)3LCu]X (L5monodentate N-donor
imidazole- or pyrazole-type ligand, Bz5benzyl, X5NO3 or ClO4), (PBz3)y(N-N)xCuNO3 (N-N5bis(pyrazol-1-yl)methane, x5y51;
9
9
N-N5bis(1,2,4-triazol-1-yl)methane, x5y52), (PPh3)L2CuX, (PPh3)2L9CuX, [(PPh3)L3Cu]X and (PPh3)L9CuX, (L95monodentate
S-donor 1-methyl-imidazoline-2(3H)-thione or imidazoline-2(1,3H)-thione) were obtained from the reaction of (PR3)nCuX with the
appropriate N- or S-donor ligand. Reaction between [(PPh3)nCu(L)m]X with PBz3 often resulted in the formation of new
[(PBz3)zLm21Cu]X (z5n or n11) complexes upon displacement of one molecule of L and two or three molecules of PPh3, whereas
reaction of [(N-N)2Cu]ClO4 with PBz3 and 1,10-phenanthroline (Phen) yielded [(PBz3)2CuClO4] and [(Phen)2Cu]ClO4, respectively,
9
upon displacement of both molecules of bidentate chelating ligands. No reaction occurred between (PPh3)L2CuX, (PPh3)2L9CuX or
1
9
[(PPh3)L3Cu]X and PBz3. All the derivatives obtained were characterized by IR spectroscopy, H NMR, and conductance studies, and in
some cases also by molecular weight measurements. 1999 Elsevier Science Ltd. All rights reserved.
Keywords: Copper(I); N-donor ligand; S-donor ligand; IR spectroscopy
1. Introduction
found
that
compounds
of
empirical
formula
PR3(imidazole)CuX are often dinuclear when X is halide,
whereas all the perchlorato derivatives are in general ionic,
the ClO4 group often being strongly hydrogen bonded to
the azole ligand [26].
Coordination compounds of copper(I) containing mono-
or bi-dentate N-donor ligands have been extensively
investigated in recent years [1–7]. This class of derivatives
is often very interesting due to their relevant structural
features [8–13] and their potential application in catalysis,
[14–16] CVD techniques, [17–19] and also in the study of
redox-active copper containing proteins [20–23].
In a series of studies [24–26] involving the reactivity of
the triorganophosphinocopper(I)-nitrato, -halide and
-perchlorato complexes of N-donor ligands, we found that
from the interaction of (PR3)nCuX (R5phenyl or cyclo-
hexyl, n51–4, X5Cl, Br, I, NO3 or ClO4) with azole
ligands L, complexes with different nuclearity, stoichiome-
try and geometry could be obtained depending on the steric
hindrance and pKa of phosphorus donor PR3, basicity and
steric requirements of the azole type N-donor ligand L, and
finally on the nature of the counter-ion. For example, we
Along this line of research, many dimeric, tetrameric
and polymeric adducts with heterocyclic thione as ligands
have been synthesized and structurally characterized [27–
33]. In fact heterocyclic thiones represent more accurately
the thioamido moieties present in the proximity of copper
within biological media, but no systematic studies on
mononuclear [34] copper(I) complexes of heterocyclic
thiones has been reported. The present study marks the
completion of our research on the vast series of the
above-mentioned azole-phosphino copper(I) compounds,
we report on the synthesis and characterization of new
triphenylphosphino copper(I) complexes of imidazoline-
2(3H)-thiones.
In addition, until now the data reported in the literature
has been limited to triphenyl- (PPh3) and tricyclohexyl-
phosphine (PCy3) derivatives, no study has been reported
on the interaction of azole with tribenzylphosphinecop-
*Corresponding author. Tel.: 139-0737-402217; fax: 139-0737-
637345.
0277-5387/99/$ – see front matter
PII: S0277-5387(99)00089-3
1999 Elsevier Science Ltd. All rights reserved.

1942
C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
per(I) acceptors. The tribenzylphosphine ligand (PBz3) is
more basic and more hindered than PPh3, and less basic
and less hindered than PCy3, therefore we decided to
extend our study to the interaction of PBz3 with Cu(I) and
different classes of azoles, with the aim to obtain complex-
es with new stoichiometries, nuclearity, and spectroscopic
and structural properties.
177–1808C dec. Found: C, 68.3; H, 6.1; N, 2.1. Calc. for
C42H42CuNO3P2, C, 68.7; H, 5.8; N, 1.9. IR (nujol,
cm21): 1956w, 1882w, 1816w, 1756w, 1694w, 1417s,
1317s, 849s, 717s, 699s n(NO ), 481m (Ph), 360m, 352vw,
308m, 280w. H NMR (CDCl3): d, 3.0 (d, 12H, PCH2),
7.0–7.4 (m br, 30H, C6H5).
3
1
2.2.2. Perchloratobis(tribenzylphosphine)copper(I)
(PBz3)2CuClO4 was prepared by the same procedure as
(PBz3)2CuNO3 by using 5.0 g of PBz3 and 2.07 g of
Cu(ClO4)2?6H2O; and re-crystallized from methanol (23
10 ml) (80% yield). M.p. 244–2488C dec. Found: C, 65.6;
H, 6.0. Calc. for C42H42CuClO4P2, C, 65.4; H, 5.5. IR
(nujol, cm21): 3110w, 3060w n(CH), 1599w, 1581w
2. Experimental section
All solvents were dried by standard techniques. All
operations were carried out under an atmosphere of
dinitrogen. The samples were dried in vacuo to constant
weight (208C, |0.1 Torr). Elemental analyses were carried
out in-house with a Fisons Instruments 1108 CHNSO-
elemental analyser. IR spectra from 4000 to 150 cm21
were recorded with a Perkin-Elmer System 2000 FT-IR
n(C C), 1089s br, 622s (ClO4), 484s (Ph) 382w, 346w,
. . .
1
309w, 284w. H NMR (CDCl3): d, 2.9 (br, 12H, PCH2),
7.0–7.3 (m br, 30H, C6H5).
1
instrument. H and 31P NMR spectra were recorded on a
2.2.3. Tetrafluoroboratetetrakis(triphenylphosphine)copp-
er(I)
VXR-300 Varian Spectrometer operating at room tempera-
ture (300 for 1H and 121.4 MHz for 31P, respectively).
Melting points were taken on an IA 8100 Electrothermal
instrument. The electrical resistance of solutions were
measured with a Crison CDTM conductimeter at room
temperature. Molecular weight determinations were per-
formed with a Knauer membrane osmometer. (Caution.
The perchlorato derivatives reported in this paper may
explode by shock or heating when dry. Small quantities
(#0.5 g) of the dry products should be handled with all
possible precaution).
(PPh3)4CuBF4 was prepared by the same procedure as
(PBz3)2CuNO3 by using 21.0 g of PPh3 and 2.9 g of
Cu(BF4)2?xH2O; and re-crystallized from ethanol (2310
ml) (90% yield). M.p. 143–1448C dec. Found: C, 71.9; H,
4.8. Calc. for C72H60CuBF4P4, C, 72.1; H, 5.0. IR (nujol,
cm21): 3054w n(CH), 1964w, 1888w, 1812w, 1759w n(BF
,
)
4
1583w n(C C), 1052s n(BF ), 523m, 499m (Ph), 429w,
. . .
398w. 1H NMR (CDCl3): d,4 7.0–7.4 (m br, 60H, C6H5).
2.2.4. Thiocyanatebis(triphenylphosphine)copper(I),
nitratebis(triphenylphosphine)copper(I),
nitratebis(tricyclohexylphosphine)copper(I),
2.1. Synthesis of the ligands
perchloratetetrakis(triphenylphosphine)copper(I),
bromotris-(triphenyl-phosphine)copper(I)
The above compounds were prepared according to
previously published studies [37–42].
[(PBz3 )(ImH)3Cu]NO3?Et2O, 1. Imidazole (ImH) (0.27
g, 4.0 mmol) was added to a diethyl ether suspension (30
ml) of [(PBz3)2CuNO3] (0.734 g, 1.0 mmol). After 3 h
stirring, the solid was filtered and washed with diethyl
ether, affording compound 1 (0.616 g, 0.87 mmol) (87%
yield). M.p. 165–1688C dec. Found: C, 57.7; H, 5.8; N,
13.4. Calc. for C34H43CuN7PO4, C, 57.7; H, 6.1; N, 13.8.
IR (nujol, cm21): 3250–2800 br n(NH), 1950w, 1881w,
The donors bis(pyrazol-1-yl)methane, bis(1,2,4-triazol-
1-yl)methane and bis(3,5-dimethylpyrazol-1-yl)methane
were prepared according to previously published methods
[35,36]. Imidazole (ImH), 1-methylimidazole (1-Meim),
2-methylimidazole (2-MeimH), 1-benzylimidazole (1-
Bzim), 4-phenylimidazole (4-PhimH), benzoimidazole
(BzimH), pyrazole (pzH), 1-methyl-imidazoline-2(3H)-
thione (Hmimt) or imidazoline-2(1,3H)-thione) (Himt),
triphenylphosphine
(PPh3),
tricyclohexylphosphine
(PCy3), tribenzylphosphine (PBz3), 1,10-phenanthroline
(Phen) were purchased from Aldrich.
1759w, 1694w, 1350s (br), 835m, 703s n(NO ), 480m (Ph),
2.2. Synthesis of the copper(I) complexes
3
385vw, 352vw, 305vw, 292w. 1H NMR (CD3CN): d, 2.99
(d, 6H, PCH2), 5.2 (br, 3H, NHImH), 6.9 (br, 3H, CHImH),
7.0–7.3 (m, 15H, C6H5), 7.6 (br, 6H, CHImH). Lm
2.2.1. Nitratobis(tribenzylphosphine)copper(I)
PBz3 (5.0 g, 16.6 mmol) in warm methanol (30 ml) was
treated with Cu(NO3)2?2.5H2O (1.0 g, 4.3 mmol) in
methanol. The copper salt dissolved immediately and the
blue color of the solution was discharged within 5 min.
The solution was heated at reflux for 24 h and then stirred
at room temperature for 3 h. A colorless precipitate was
formed which was filtered off and washed with methanol
(235 ml) and diethyl ether (235 ml) (95% yield). M.p.
(CH3CN, c50.9431023 M): 129.4 V21cm2 mol21
.
[(PBz3 )2(2-MeimH)2Cu]NO3 , 2. Complex 2 was pre-
pared by the same procedure as 1 by using 2.0 mmol of
2-methylimidazole (2-MeimH) and 1.0 mmol of
[(PBz3)2CuNO3] (82% yield). M.p. 1378C dec. Found: C,
66.3; H, 6.0; N, 7.6. Calc. for C50H54CuN5O3P2, C, 66.8;
H, 6.1; N, 7.8. IR (nujol, cm21): 3200br n(NH) 1957w,

C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
1943
1886w, 1815w, 1716w, 1690w, 1350s (br), 850s, 841s,
H, 5.7; N, 9.2. IR (nujol, cm21): 3400br n(O–H), 3137w
n(NH), 1944w, 1890w, 1810w, 1750w, 1684w, 1417m,
699s n(NO ), 482m (Ph), 386vw, 351vw, 305vw, 309w. 1H
3
1350br, 840m, 823m, 705sh, 696s n(NO ), 1599m, 1581m,
NMR (CD3CN): d, 2.1 (s, 6H, CH3), 3.0 (d, 12H, PCH2),
7.0–7.2 (m br 12H, C6H5), 7.4 (m, 22H, C6H5 1
CH2-MeimH). 1H NMR (CDCl3): d, 2.0 (br, 6H, CH3), 2.9 (s
br, 12H, PCH2) 6.6 (br, 2H, CH2-MeimH), 6.9–7.4 (m, 34H,
C6H51CH2-MeimH). Lm (CH3CN, c50.9831023 M):
161.7 V21cm2 mol21. M.W. (CHCl3, c50.531023 M):
341.
3
1559w n(C
and n(C N), 478s (Ph), 386w, 359w,
. . .
. . .
C)
319w, 305w. 1H NMR (CD3CN): d, 2.3 (br, 2H, OH), 3.0
(d, 6H, PCH2), 5.18 (s, 4H, N–CH2), 7.11 (m, 6H,
CH1-Bzim 1C6H5), 7.2 (m, 12H, C6H5), 7.3 (m, 8H,
CH1-Bzim 1C6H5). Lm (CH3CN, c51.0331023 M): 115.6
V
21cm2 mol21
.
[(PBz3 )2(1-Meim)2Cu]NO3 , 3. Complex 3 was prepared
by the same procedure as 1 by using 4.0 mmol of 1-
[(PBz3 )hbis(pyrazol-1-yl)methanejCu]NO3 , 7. Complex
7 was prepared by the same procedure as 1 by using 5.0
mmol of bis(pyrazol-1-yl)methane and 1.0 mmol of
[(PBz3)2CuNO3] (58% yield). M.p. 172–177.8C dec.
Found: C, 58.7; H, 5.3; N, 11.8. Calc. for
C28H29CuN5O3P, C, 58.2; H, 5.1; N, 12.1. IR (nujol,
methylimidazole
(1-Meim)
and
1.0
mmol
of
[(PBz3)2CuNO3] (82% yield). M.p. 170–1758C. Found: C,
66.5; H, 6.1; N, 7.4. Calc. for C50H54CuN5O3P2, C, 66.8;
H, 6.1; N, 7.8. IR (nujol, cm21): 3114w n(CH), 1950w,
cm21): 3126w n(NH), 1948w, 1887w, 1815w, 1760w,
1890w, 1820w, 1738w, 1682w, 1330br, 850sh, 844br,
701s n(NO ), 1598, 1532 (C . . . C, C . . . N), 482m (Ph),
1317br, 868m, 823m, 702s n(NO ), 1599m, 1581w, 1557w,
3
3
392w, 351w, 308w. 1H NMR (CD3CN): d, 2.9 (s br, 12H,
PCH2), 3.6 (br, 6H, N-CH3), 6.6 (br, 2H, CH1-Meim) 6.8
(br, 2H, CH1-Meim), 6.8 (m, 12H, C6H5), 7.3 (m, 18H,
C6H5), 7.6 (br, 2H, CH1-Meim). Lm (CH3CN, c51.093
1514w n(C
and n(C N), 483s (Ph), 414w, 386m,
. . .
. . .
C)
1
361w, 305w, 288w. H NMR (CD3CN): d, 2.99 (br, 6H,
PCH2), 6.60 (br, 2H, CH2 ), 6.80 (br, 2H, CHN-N), 7.00
N-N
(m, 6H, C6H5), 7.3 (m, 11H, C6H5 1CHN-N), 7.6 (br, 2H,
CHN-N). Lm (CH3CN, c50.9831023 M): 182.6
1023 M): 175.2 V21cm2 mol21. M.W. (CHCl3, c50.93
1023 M): 448.
V
21cm2 mol21
.
(PBz3 )(4-PhimH)2CuNO3 , 4. Complex 4 was obtained
by the same procedure as 1 by using 2.0 mmol of 4-
phenylimidazole (4-PhimH) and 1.0 mmol of
[(PBz3)2CuNO3] (56% yield). M.p. 117–1198C. Found: C,
64.7; H, 5.4; N, 9.4. Calc. for C39H37CuN5O3P, C, 65.2;
H, 5.2; N, 9.7. IR (nujol, cm21): 3120 br n(NH), 1946w,
1883w, 1812w, 1750w, 1409s, 1377s, 1317s, 860m, 834d
[(PBz3 )2 hbis(1,2,4-triazol-1-yl)methanej2Cu]NO3 ,
8.
Complex 8 was prepared by the same procedure as 1 by
using 3.0 mmol of bis(1,2,4-triazol-1-yl)methane and 1.0
mmol of [(PBz3)2CuNO3] (34% yield). M.p. 1708C dec.
Found: C, 60.5; H, 5.4; N, 17.8. Calc. for
C52H54CuN13O3P2, C, 60.4; H, 5.3; N, 17.6. IR (nujol,
cm21): 3111w n(CH), 1950w, 1883w, 1812w, 1748w,
1345m, 1320m, 850m, 700m n(NO ), 1597m, 1580w,
br, 701s, 690sh n(NO ), 1599m, 1587m n(C C), 482m (Ph),
. . .
3
1557w, 1506w n(C
and n(C N),3 483m (Ph), 392w,
439m (Ph4-PhimH), 352w, 309w. 1H NMR (CD3CN): d, 3.0
. . .
. . .
C)
385w, 351w, 309m. 1H NMR (CD3CN): d, 2.9 (br, 12H,
(d, 6H, PCH2), 7.0 (m, 6H, C6H5), 7.2 (m, 6H, C6H5), 7.4
(br, 9H, CH4-PhimH1C6H5
), 7.7 (br, 8H, CH4-PhimH 1
4-PhimH
PCH2), 6.5 (s, 4H, CH2 ), 7.0 (m, 12H, C6H5), 7.2–7.3
). Lm (CH3CN, c50.9131023 M): 136.3
N-N
C6H5
(m, 18H, C6H5), 7.8 (s, 4H, CHN-N), 8.49 (s, 4H, CHN-N).
4-PhimH
21cm2 mol21
(PBz3 )(BzimH)2CuNO3 , 5. Complex 5 was prepared by
.
Lm (CH3CN, c51.9631023 M): 109 V21cm2 mol21
.
V
[(PBz3 )2(pzH)Cu]NO3?H2O, 9. Complex 9 was prepared
by the same procedure as 1 by using 4.0 mmol of pyrazole
(pzH) and 1.0 mmol of [(PBz3)2CuNO3] (98% yield).
M.p. 180–1848C. Found: C, 65.8; H, 5.8; N, 4.7. Calc. for
C45H48CuN3O4P2, C, 65.9; H, 5.4; N, 5.1. IR (nujol,
cm21): 3200–2800br n(NH), 3053w n(C–H), 1955w, 1890w,
the same procedure as 1 by using 2.0 mmol of benz-
imidazole (BzimH) and 1.0 mmol of [(PBz3)2CuNO3]
(99% yield). M.p. 1608C dec. Found: C, 63.6; H, 5.4; N,
10.6. Calc. for C35H33CuN5O3P, C, 63.1; H, 5.0; N, 10.5.
IR (nujol, cm21): 3184br n(NH), 1940w br, 1890w br,
1779w, 1734w, 1418m, 1374br, 1350br, 839m, 826w,
1807w, 1738w, 1308br, 850m, 701m n(NO ), 1633 (O–H),
3
705s, 698s n(NO 1622m, 1597m n(C C), 477m (Ph),
. . .
1598m, 1580w, 1577w n(C
and n(C N), 483s, 351w,
. . .
. . .
)
C)
3
389w, 358w, 311w, 279w. 1H NMR (CD3CN): d, 3.0 (d,
6H, PCH2), 4.7 (br, 2H, NHBzimH), 7.0–7.1 (m, 8H, C6H5),
308m. 1H NMR (CD3CN): d, 2.9 (br, 12H, PCH2), 3.2 (br,
2H, H2O), 6.6 (br, 1H, CHpzH), 7.0 (m, 12H, C6H5), 7.2
(m, 18H, C6H5), 7.7 (br, 2H, CHpzH). 1H NMR (CDCl3): d,
3.0 (d, 12H, PCH2), 6.0–7.0 (br, 1H, CHpzH), 7.0–7.4 (br,
32H, C6H5 1CHpzH). Lm (CH3CN, c50.9931023 M):
7.2–7.4m (m, 12H, C6H5 1C6H5
), 7.6 (br, 3H,
BzimH
CHBzimH), 8.0 (br, 2H, CHBzimH). Lm (CH3CN, c50.863
1023 M): 112.6 V21cm2 mol21
.
(PBz3 )(1-Bzim)2CuNO3?H2O, 6. Complex 6 was pre-
pared by the same procedure as 1 by using 4.0 mmol of
1-benzylimidazole (1-Bzim) and 1.0 mmol of
[(PBz3)2CuNO3] (94% yield). M.p. 149–1528C. Found: C,
63.8; H, 5.7; N, 9.5. Calc. for C41H43CuN5O4P, C, 64.4;
130.4 V21cm2 mol21
.
[(PBz3 )2(ImH)2Cu]ClO4 , 10. Complex 10 was prepared
by the same procedure as 1 by using 4.0 mmol of ImH and
1.0 mmol of (PBz3)2CuClO4 (40% yield). M.p. 160–
1658C. Found: C, 62.3; H, 5.6; N, 6.1. Calc. for

1944
C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
C48H50ClCuN4O5P2, C, 62.3; H, 5.7; N, 6.1. IR (nujol,
prepared by the same procedure as 13 by using 2 mmol of
tribenzylphosphine and 1 mmol of [(PPh3)Cu(1-Bzim)3]-
ClO4 as previously prepared according to the literature
[26] (90% yield). M.p. 169–1708C dec. Found: C, 66.6; H,
5.9; N, 4.8. Calc. for C62H66ClCuN4O5P2, C, 66.2; H, 5.9;
cm21): 3258 n(NH), 3128w, 3098w, 3028w n(CH), 1955mbr,
1884w, 1812w, 1762w, 1160–1050br, 623s n(ClO ), 1600m,
4
1584w, 1538w n(C
and n(C N), 482s (Ph), 389m,
. . .
. . .
C)
1
352w, 337w, 305m, 297sh, 256w. H NMR (CD3CN):
compound 10 is completely dissociated in CD3CN solution
and for this reason we observed in this solvent only the
signal of Bz3P=O and PBz3. 1H NMR (CDCl3): d, 3.1 (d,
12H, PCH2), 6.9 (s, 2H, CHImH), 7.0 (br, 4H, CHImH),
7.1–7.3 (br, 30H, C6H5). Lm (CH3CN, c50.8831023
N, 5.0. IR (nujol, cm21): 3500br n(O–H), 3040w n(C–H)
,
,
1952w, 1888w, 1819w, 1772w, 1130–1050br, 621s n(ClO
)
4
1598m, 1580w, 1558w, 1517m, 1512m n(C
and
. . .
C)
n(C N), 479m, 392w, 316w, 301w. 1H NMR (CDCl3): d,
. . .
1.9 (br, 4H, OH), 2.9 (s (br) 12H, PCH2), 5.2 (br, 4H,
NCH2), 6.9 (m, 12H, CH1-Bzim 1C6H5), 7.2 (m, 22H,
CH1-Bzim 1C6H5), 7.3 (m, 12H, CH1-Bzim 1C6H5). Lm
M): 172.7 V21cm2 mol21
.
[(PBz3 )2(2-MeimH)2Cu]ClO4?2H2O, 11. Complex 11
was prepared by the same procedure as 1 by using 2.0
mmol of 2-MeimH and 1.0 mmol of (PBz3)2CuClO4 (90%
yield). M.p. 1808C dec. Found: C, 61.6; H, 6.0; N, 5.4.
Calc. for C50H58ClCuN4O6P2, C, 61.8; H, 6.0; N, 5.8. IR
(nujol, cm21): 3500–3000br (N–H), 1958m (br), 1887m,
1810m, 1776m, 1150–1050br, 621s (ClO4), 1626br OH,
(CH3CN, c51.0331023 M): 139.4 V21cm2 mol21
.
[(PBz3 )2(BzimH)Cu]ClO4?Et2O, 15 Complex 15 was
prepared by the same procedure as 13 by using 2 mmol
of tribenzylphosphine and
1
mmol of [(PPh3)2-
Cu(BzimH)2]ClO4 as previously prepared according to the
literature [26] (88% yield). M.p. 240–2508C dec. Found:
C, 65.8; H, 5.8; N, 2.4. Calc. for C53H58ClCuN2O5P2, C,
66.0; H, 6.0; N, 2.9. IR (nujol, cm21): 3200–2800br
1599m, 1581w, 1567m n(C
and n(C N), 482s (Ph),
. . .
. . .
C)
387m, 348w, 304m, 282w, 272w. 1H and 31P NMR
(CD3CN): compound 11 is completely dissociated in
CD3CN solution and it is possible only to observe the
signal of Bz3P=O (d 31P541.3) and PBz3 (d 31P52
11.8). Lm (CH3CN, c50.8731023 M): 196.5
n(N–H), 3050w n(C–H), 1960w, 1888w, 1817w, 1765w,
1621w, 1599m, 1581w, 1557w n(C
and n(C
,
. . .
. . .
C)
N)
1140–1050br n(ClO ), 621s n(ClO ), 484m, 431w, 427w,
4
4
395w, 384w, 346w, 309w, 280w. 1H NMR (CDCl3): d, 3.0
(d, 12H, PCH2), 7.0 (m, 2H, CHBzimH), 7.2–7.3 (m, 30H,
C6H5), 7.4–7.7 (m, 4H, CHBzimH). Lm (CH3CN, c51.063
V
21cm2 mol21. M.W. (CHCl3, c50.831023 M): 658.
[(PBz3 )(1-Meim)3Cu]ClO4?Et2O, 12. Complex 12 was
1023 M): 106.7 V21cm2 mol21
.
prepared by the same procedure as 1 by using 6.0 mmol of
1-Meim and 1.0 mmol of (PBz3)2CuClO4 (81% yield).
M.p. 1858C dec. Found: C, 56.0; H, 5.7; N, 10.3. Calc. for
C37H49ClCuN6O5P, C, 56.4; H, 6.3; N, 10.7. IR (nujol,
cm21): 3120w (N–H), 1950w, 1890w, 1815w, 1774w,
[(PPh3 )(Himt)2Cu]ClO4 , 16. Complex 16 was prepared
the same procedure as 1 by using 2 mmol of Himt and 1
mmol of [(PPh3)4Cu]ClO4 (48% yield). M.p. 216–2188C.
Found: C, 45.7; H, 3.8; N, 8.8; S, 9.8. Calc. for
C24H23ClCuN4O4PS2, C, 46.1; H, 3.7; N, 9.0; S, 10.2. IR
1150–1050br, 618s n(ClO ), 1599m, 1581w, 1534m, 1518m
4
(nujol, cm21): 3400br n(NH), 1582m n(C
and n(C
,
n(C
and n(C N), 482s (Ph), 385m, 352w, 304w, 268w,
. . .
. . .
. . .
. . .
C)
C)
N)
230w. 1H NMR (CD3CN): d, 3.0 (br, 6H, PCH2), 3.6 (br,
9H, N–CH3), 7.0 (m, 6H, C6H5), 7.2 (m, 9H, C6H5). Lm
(CH3CN, c50.9831023 M): 168.9 V21cm2 mol21. M.W.
(CHCl3, c50.631023 M): 388.
1094s, 623m n(ClO ), 521m, 498m (Ph), 434w, 314w,
4
1
280w. H NMR (CDCl3): d, 6.8 (s, 4H, 4-CHHimt and
5-CHHimt), 7.4–7.7 (m, 15H, C6H5). 31P NMR (CDCl3): d,
21.7 br. Lm (acetone, c51.0331023 M): 73.4
V
21cm2 mol21
.
[(PBz3 )3(4-PhimH)Cu]ClO4?Et2O, 13. Tribenzylphos-
phine (0.6 g, 2.0 mmol) in diethyl ether was added to a
diethyl ether suspension of [(PPh3)2Cu(4-PhimH)2]ClO4
(0.90 g, |1.0 mmol) as previously prepared according to
the literature [26]. The suspension was stirred for 2 days,
and then filtered off, washed with diethyl ether, affording
compound 13 (90% yield). M.p. 158–1608C dec. Found:
C, 70.9; H, 6.1; N, 2.1. Calc. for C76H81ClCuN2O4P3, C,
[(PPh3 )(Himt)2Cu]NO3 , 17. Complex 17 was prepared
by the same procedure as 1 by using 2 mmol of Himt and
1 mmol of [(PPh3)2CuNO3] (68% yield). Compound 17 is
insoluble in acetone and CH2Cl2. M.p. 182–1858C. Found
C, 49.0; H, 3.7; N, 11.8; S, 10.6. Calc. for
C24H23CuN5O3PS2, C, 49.0; H, 3.9; N, 11.9; S, 10.9. IR
(nujol, cm21): 3100–2800br n(NH), 1581m n(C
and
. . .
C)
71.4; H, 6.4; N, 2.2. IR (nujol, cm21): 3277br n(N–H)
,
n(C N), 1330 br, 693m n(NO ). 1H NMR (CDCl3): d, 6.6
. . .
3
3040w n(C–H), 1966w, 1888w, 1823w, 1772w, 1121br,
(s, 4H, 4-CHHimt and 5-CHHimt), 7.2–7.6 (m, 15H, C6H5).
1091br, 1065br, 623s n(ClO ), 1611w, 1601m, 1584w,
4
[(PPh3 )(Himt)2Cu]BF4 , 18. Complex 18 was prepared
by the same procedure as 1 by using 4 mmol of Himt and
1 mmol of [(PPh3)4Cu]BF4 (55% yield). M.p. 151–1568C.
Found C, 46.7; H, 3.5; N, 9.1; S, 10.3. Calc. for
C24H23BCuF4N4PS2, C, 47.0; H, 3.8; N, 9.1; S, 10.5. IR
1558w, 1540w n(C
and n(C N), 485s, 438w, 414w,
. . .
. . .
C)
1
386m, 348w, 310w. H NMR (CDCl3): d, 3.1 (d, 18H,
PCH2), 7.1 (s, 2H, CH4-PhimH), 7.2–7.5 (m, 45H, C6H5),
7.5–8.0 (m, 4H, CH4-PhimH), 8.3 (br, 4H, CH4-PhimH). Lm
(CH3CN, c50.9631023 M): 64.7 V21cm2 mol21
.
(nujol, cm21): 3300br n(NH), 3100w n(CH), 1583s n(C
. . .
C)
[(PBz3 )2(1-Bzim)2Cu]ClO4?2H2O, 14. Complex 14 was
and n(C N), 1132s br, 1094s br, 1037s br n(BF ), 521m,
. . .
4

C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
1945
1
499m (Ph), 436w, 397w, 353w, 327w, 314w, 280w. H
NMR (acetone): d, 6.9 (s, 4H, 4-CHHimt and 5-CHHimt),
7.3–7.5 (m, 15H, C6H5), 11.1 (br, 2H, NH). Lm (acetone,
n(C N), 1051s br n(BF ), 518m, 497m (Ph), 437w, 414w.
. . .
4
1H NMR (CDCl3): d, 3.6 (br, 9H, NCH3), 6.7 (br, 3H,
4-CHHmimt or 5-CHHmimt), 6.8 (br, 3H, 4-CHHmimt or 5-
CHHmimt), 7.2–7.8 (m, 15H, C6H5), 11.4 (br, 3H, NH). Lm
c50.9931023 M): 75.1 V21cm2 mol21
.
(acetone, c50.6031023 M): 124.3 V21cm2 mol21
.
[(PPh3 )(Himt)2(SCN)Cu], 19. Complex 19 was prepared
by the same procedure as 1 by using 2 mmol of Himt and
1 mmol of [(PPh3)2CuSCN] (74% yield). M.p.178–1828C.
Found: C, 51.8; H, 3.7; N, 12.3; S, 16.9. Calc. for
C25H23CuN5PS3, C, 51.4; H, 4.0; N, 12.0; S, 16.5. IR
[(PPh3 )(Hmimt)2(SCN)Cu], 24. Complex 24 was pre-
pared by the same procedure as 1 by using 6 mmol of
Hmimt and 1 mmol of [(PPh3)2CuSCN] (60% yield). M.p.
178–1828C. Found: C, 53.4; H, 4.3; N, 11.6; S, 15.9. Calc.
for C27H27CuN5PS3, C, 53.0; H, 4.4; N, 11.4; S, 15.7. IR
(nujol, cm21): 3250br n(NH), 2094m n(CN) 1584s n(C
. . .
C)
(nujol, cm21): 3200–2700br n(NH), 2095m n(CN), 1570m
and n(C N), 519s, 503s (Ph), 440w, 425w, 420w, 415w,
. . .
1
380w, 348m, 340m. 1H NMR (DMSO-d6): d, 6.8 (s, 4H,
4-CHHimt and 5-CHHimt), 7.2–7.5 (m, 15H, C6H5), 12.0
n(C
and n(C N), 505s (Ph), 429w, 417w, 348w. H
. . .
. . .
C)
NMR (CDCl3): d, 3.6 (br, 6H, NCH3), 6.7 (br, 2H,
4-CHHmimt or 5-CHHmimt), 6.8 (br, 2H, 4-CHHmimt or 5-
CHHmimt), 7.3–7.8 (m, 15H, C6H5). Lm (acetone, c51.03
(br, 2H, NH). Lm (acetone, c51.0231023 M): 7.0
V
21cm2 mol21
.
1023 M): 6.2 V21cm2 mol21
.
[(PPh3 )2(Himt)BrCu], 20. Complex 20 was prepared by
(PPh3 )(Hmimt)BrCu, 25. Complex 25 was prepared by
the same procedure as 1 by using 2 mmol of Hmimt and 1
mmol of [(PPh3)3CuBr] (38% yield). M.p. 215–2168C.
Found: C, 51.1; H, 3.9; N, 5.4; S, 6.0. Calc. for
C22H21BrCuN2PS, C, 50.8; H, 4.1; N, 5.4; S, 6.2. IR
the same procedure as 1 by using 2 mmol of Himt and 1
mmol of [(PPh3)3CuBr] (71% yield). M.p. 170–1728C.
Found: C, 60.5; H, 4.6; N, 4.0; S, 4.3. Calc. for
C39H34BrCuN2P2S, C, 61.0; H, 4.5; N, 3.6; S, 4.2. IR
(nujol, cm21): 3200br n(NH), 1581s n(C
and n(C
,
. . .
. . .
C)
N)
(nujol, cm21): 3200–2800br n(NH), 1572w n(C
and
. . .
C)
524s, 516s, 503s, 491s (Ph), 442w, 426w, 419w, 334w,
n(C N), 523m, 508m, 494m (Ph), 440w, 428w, 412w. 1H
. . .
1
340m. H NMR (CDCl3): d, 6.6 (s, 2H, 4-CHHimt and
NMR (CDCl3): d, 3.6 (br, 3H, NCH3), 6.8 (br, 1H,
4-CHHmimt or 5-CHHmimt), 6.9 (br, 1H, 4-CHHmimt or 5-
CHHmimt), 7.1–7.8 (m br, 15H, C6H5), 12.6 (br, 1H, NH).
5-CHHimt), 7.2–7.5 (m, 15H, C6H5), 11.0 (br, 2H, NH).
Lm (acetone, c51.0831023 M): 0.3 V21cm2 mol21
.
[(PPh3 )(Hmimt)3Cu]ClO4 , 21. Complex 21 was pre-
pared by the same procedure as 1 by using 2 mmol of
Hmimt and 1 mmol of [(PPh3)4Cu]ClO4 (40% yield).
M.p. 125–1288C. Found: C, 46.9; H, 4.0; N, 10.9; S, 12.4.
Calc. for C30H33ClCuN6O4PS3, C, 46.9; H, 4.3; N, 10.9;
Lm (acetone, c50.7331023 M): 1.03 V21cm2 mol21
.
[(PPh3 )2(Himt)Cu]BF4 , 26. Complex 26 was obtained
when a diethyl ether solution of compound 18 reacted with
an excess of PBz3; and re-crystallized from methanol
(45% yield). M.p. 165–1688C. Found: C, 60.0; H, 4.5; N,
3.6; S, 3.9. Calc. for C39H34BCuF4N2P2S, C, 60.4; H, 4.4;
S, 12.5. IR (nujol, cm21): 3400br n(NH), 3133w n(CH)
1569w, 1559w, 1503w n(C and n(C N), 1090sh,
,
N, 3.6; S, 4.1. IR (nujol, cm21): 3200–2800br n(NH)
,
. . .
. . .
C)
1
1076s, 622m n(ClO ), 518m, 493m (Ph), 437w. H NMR
1577w n(C
and n(C N), 516s, 502s, 486s (Ph), 441m,
. . .
. . .
4
C)
418m, 333w. 1H NMR (CDCl3): d, 6.6 (br, 2H, 4-CHHimt
and 5-CHHimt), 7.2–7.5 (m br, 30H, C6H5), 11.0 (br, 2H,
(CDCl3): d, 3.5 (s, 9H, NCH3), 6.6 (d br, 3H, 4-CHHmimt or
5-CHHmimt), 6.8 (d br, 3H, 4-CHHmimt or 5-CHHmimt),
7.3–7.7 (m, 15H, C6H5), 11.0 (br, 3H, NH). Lm (acetone,
NH). Lm (acetone, c50.331023 M): 31.0 V21cm2 mol21
.
c50.893 1023 M): 121.3 V21cm2 mol21
.
[(PPh3 )(Hmimt)2NO3Cu], 22. Complex 22 was prepared
by the same procedure as 1 by using 2 mmol of Hmimt
and 1 mmol of [(PPh3)2CuNO3] (73% yield). M.p. 100–
1108C dec. Found: C, 51.0; H, 4.3; N, 11.6; S, 10.6. Calc.
for C26H27CuN5O3PS2, C, 50.7; H, 4.4; N, 11.4; S, 10.4.
2.3.1. Reaction between [(PPh3 )2bis(pyrazol-1-
yl)methaneCu]ClO4 and PBz3
The
reaction
between
[(PPh3)2bis(pyrazol-1-
yl)methaneCu]ClO4 and PBz3 was carried out following
the procedure indicated above for compound 13. A color-
IR (nujol, cm21): 3100–2800br n(NH), 1575w n(C
and
. . .
C)
less precipitate was obtained and identified as a compound
of empirical formula (PBz3)4(L1)(CuClO4)2. The H, 31
P
1
n(C N), 1320s, 696m n(NO ), 518m, 506m, 489m (Ph),
. . .
3
418w. 1H NMR (CDCl3): d, 3.8 (br, 6H, NCH3), 6.6–6.7
(d br, 2H, 4-CHHmimt or 5-CHHmimt), 7.1 (s, 2H, 4-CHHmimt
or 5-CHHmimt), 7.5–8.0 (m, 15H, C6H5), 12.4 (br, 2H,
NMR and IR spectra are in accordance with a mixture of
two different compounds [(PBz3)2CuClO4] and
[(PBz3)2bis(pyrazol-1-yl)methaneCu]ClO4 that is impos-
sible to separate due to the very fast oxidation of CuI to
CuII.
NH). Lm (acetone, c51.031023 M): 19.3 V21cm2 mol21
.
[(PPh3 )(Hmimt)3Cu]BF4 , 23. Complex 23 was prepared
by the same procedure as 1 by using 4 mmol of Hmimt
and 1 mmol of [(PPh3)4Cu]BF4 (37% yield). M.p. 130–
1318C. Found: C, 47.2; H, 4.0; N, 10.8; S, 12.4. Calc. for
C30H33BCuF4N6PS3, C, 47.7; H, 4.4; N, 11.1; S, 12.7. IR
2.3.2. Reaction between [(PPh3 )2bis(3,5-dimethylpyrazol-
1-yl)methaneCu]ClO4 and PBz3
This reaction was carried out following the procedure
indicated above for compound 13 by using 1 mmol of
(nujol, cm21): 3100–2700br n(NH), 1571m n(C
and
. . .
C)

1946
C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
[(PPh3)2bis(3, 5 - dimethylpyrazol - 1 - yl)methaneCu]ClO4
and 2 mmol of PBz3. A colorless precipitate was obtained
and identified as [(PBz3)2CuClO4] by analysis, IR and H
[(PPh3)yCuX] 1 xL9 → (PPh3)y2n(L9)xCuX 1 nPPh3 (2)
1
16–25
NMR spectra.
16: L95Himt, X5ClO4,
y54, x52, n53
21: L95Hmimt, X5ClO4,
y54, x53, n53
17: L95Himt, X5NO3,
y5x52, n50
18: L95Himt, X5BF4,
y54, x52, n51
19: L95Himt, X5SCN,
y5x52, n51
20: L95Himt, X5Br, y5
3, x5n51
22: L95Hmimt, X5NO3,
y5x52, n51
23: L95Hmimt, X5BF4,
y54, x5n53
24: L95Hmimt, X5SCN,
y5x52, n51
25: L95Hmimt, X5Br,
y53, x51, n52
2.3.3. Reaction between [bishbis(3,5-dimethylpyrazol-1-
yl)methanejCu]ClO4 and PBz3
This reaction was carried out following the procedure
indicated above for compound 13 by using 1 mmol of
[bishbis(3,5-dimethylpyrazol-1-yl)methanejCu]ClO4 and 5
mmol of PBz3. A colorless precipitate was obtained and
identified as [(PBz3)2CuClO4] by analysis, IR and 1H
NMR spectra.
When less than two equivalents of the azole were used,
unreacted starting material was recovered from the re-
action. No reaction took place from the reaction of
[(PBz3)2CuClO4] with 4-PhimH, BzimH and 1-Bzim,
even when the reaction was carried out under forcing
conditions, i.e. strong excess of ligand and refluxing
solvent. However, it is possible to obtain tribenzylphos-
phinecopper(I)perchlorate derivatives containing the ligand
indicated above (4-PhimH, BzimH and 1-Bzim) by re-
action of their triphenylphosphinecopper(I)perchlorato de-
rivatives with tribenzylphosphine in accordance with Eq. 3,
or also by reduction of the 4:1 copper(I) complexes
[(L)4Cu(II)](ClO4)2 (L54-PhimH, BzimH or 1-Bzim)
with PBz3, which again yielded compounds 13–15
2.3.4. Reaction between [(PBz3 )2CuClO4 ] and 1,10-
phenanthroline (Phen)
This reaction was carried out following the procedure
indicated above for compound 13 by using 1 mmol of
[(PBz3)2CuClO4] and 2 mmol of Phen. The colorless
precipitate obtained was identified as [(Phen)2Cu]ClO4 by
1
analysis, IR and H NMR spectra.
2.3.5. Reaction between [bishbis(3,5-dimethylpyrazol-1-
yl)methanejCu]ClO4 and Phen
This reaction was carried out following the procedure
indicated above for compound 13 by using 1 mmol of
[bishbis(3,5-dimethylpyrazol-1-yl)methanejCu]ClO4 and 2
mmol of Phen. A colorless precipitate was obtained and
identified as [(Phen)2Cu]ClO4 by analysis, IR and 1H
NMR spectra.
[(PPh3)x(L)yCu]ClO4 1 nPBz3
→ (PBz3)n(L)y21CuClO4 1 xPPh3 1 L (3)
13: L54-PhimH, x5y52, n53
14: L51-Bzim, x51, y53, n52
15: L5BzimH, x5y5n52
3. Results and discussion
The copper complexes 1–12 and 16–25 (see Section 2)
were prepared by reacting an excess of the corresponding
heterocyclic N-, N2-, or S-donor ligand as in Fig. 1 with a
diethyl ether suspension of [(PR3)nCuX] previously syn-
thesized.
No reaction took place between the copper(I) derivatives
of 1-methyl-imidazoline-2(3H)-thione or imidazoline-
2(1,3H)-thione 16–25 and PBz3. In this case no displace-
ment of the PPh3 by PBz3 was observed. However, in
some cases when compounds 16–25 were stored for a long
time in diethyl ether suspension, a dissociation occurred
which yielded a derivative different from the starting
reagent: for example, compound [(PPh3)2(Himt)Cu]BF426
[(PBz3)2CuX] 1 xL → (PBz3)22n(L)xCuX 1 nPBz3
(1)
1–12
1: L5ImH, X5NO3, x5
3, n51
2: L52-MeimH, X5NO3,
x52, n50
3: L51-Meim, X5NO3,
x52, n50
4: L54-PhimH, X5NO3,
x52, n51
5: L5BzimH, X5NO3,
x52, n51
6: L51-Bzim, X5NO3,
x52, n51
7: L5bis(pyrazol-1-yl)
was obtained when [(PPh3)(Himt) Cu]BF418 reacted for
2 days with PBz3 in diethyl ether.
2
methane, X5NO3, x5n51
8: L5bis(triazol-1-yl)me-
thane, X5NO3, x52, n50
9: L5pzH, X5NO3, x5
1, n50
10: L5ImH, X5ClO4,
x52, n50
11: L52-MeimH, X5
ClO4, x52, n50
From the reaction of [bishbis(3,5-dimethylpyrazol-1-
yl)methanejCu]ClO4 or [(PPh3)2bis(3,5-dimethylpyrazol-
1-yl)methaneCu]ClO4 with PBz3, [(PBz3)2CuClO4] was
always obtained, suggesting that the bond between Cu and
the chelating N2-donor hbis(3,5-dimethylpyrazol-1-
yl)methane is weaker than that between Cu and imida-
zoles. We also observed that the bond between Cu(I) and
1,10-phenanthroline is stronger than that between Cu and
triorganophosphines and that between Cu and bis(3,5-
dimethylpyrazol-1-yl)methane; in fact, from the reaction of
12: L51-Meim, X5ClO4,
x53, n51

C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
1947
Fig. 1. Structures of the ligands employed.
[(PBz3)2CuClO4]
yl)methanejCu]ClO4
[(Phen)2Cu]ClO4 was always obtained.
or
[bishbis(3,5-dimethylpyrazol-1-
with Phen the derivative
basic with respect to ImH, yielded only the 2:1:1 adduct
(PBz3)2(pzH)CuNO3?H2O 9. No adduct can be prepared
from the reaction of pzH with (PBz3)2CuClO4, and the
reaction of 9 with excess PBz3 also yielded untractable
material. If the reaction was carried out in the presence of
a strong excess, no displacement of PBz3 occurred, in
accordance with the behavior previously observed with
other triorganophosphinecopper(I) acceptors [24–26].
Instead the stoichiometry of the imidazoline-2(3H)-
thione derivatives 16–26 is strongly dependent on the
nature of the counter ion: the ligands Himt and Hmimt are
able to displace not only the PPh3 ligand but also the NO3,
BF4 and ClO4 groups from the coordinations sphere of
Cu(I) yielding 1:2:1 or 1:3:1 adducts, but are generally
It was found that the steric effects and the basicity of the
heterocyclic donor determine, to a great extent, the coordi-
nation environment on the copper center and also the
stoichiometry of the complexes obtained. Adducts 1:3:1 of
[PBz3(L)3Cu]X can be obtained only when the azole donor
is ImH or 1-Meim, which are less sterically hindered and
also more basic than the other imidazole-type ligands
employed here, whereas 1:2:1 [PBz3(L)2Cu]X and 2:1:1
[(PBz3)2(L)Cu]X adducts are generally afforded when L is
BzimH, 4-PhimH or 1-Bzim.
As previously observed, the ligand pzH which is less

1948
C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
unable to displace strongly coordinating groups such as
SCN or Br.
ly reported for triphenylphosphine derivatives, our tri-
benzylphosphine complexes 1–15 presumably dissociate
partly in these solvents, in accordance with their ionic
nature or partial ligand loss in solution (Eqs. 4 and 5).
We also found that in the same conditions it is more
easy to displace the PBz3 ligand (pKa 56.0) from Cu(I),
not only than PCy3 (pKa 59.70) but also than the less
basic PPh3 (pKa 52.73) [43,44]. This is due to the greater
Tolman cone angle of PBz3 (1658) with respect to PPh3
(1458) [45].
[(PBz3)yLxCu]X↔[(PBz3)y2nLxCuX] 1 nPBz3
(5)
The dissociation is strongly dependent on the concentration
of the solutions and also on the Tolman cone angle: [45] r
generally decreases with decreasing concentration, and
decreases with increasing cone angle value.
All the compounds are generally insoluble in diethyl
ether and ethanol, and soluble in acetone, DMSO, chlori-
nated solvents, and acetonitrile. They may be crystallized
by slow diffusion of diethyl ether into an acetonitrile
solution in which they are stable; however it was im-
possible to obtain crystals suitable for X-ray analysis.
Instead, they are generally unstable in CHCl3 and in
acetone solution where they are readily oxidized by air,
rapidly giving a blue solution. However, none of the
tribenzylphosphine complexes synthesized are very stable
in solution. We observed that the substitution of tri-
phenylphosphine with tribenzylphosphine increases the
dissociation of the copper(I) complexes, and then also of
the oxidation of Cu(I) to Cu(II). The oxidation is strongly
dependent on the number of PBz3 groups coordinated to
Cu: the [(PBz3)3LCu]X complexes are stable in chloro-
form solution also for several hours, the [(PBz3)2L2Cu]X
derivatives for a time which can vary from 15 min to 2 h,
and finally the [(PBz3)L3Cu]X ones are completely oxi-
dized within 20 min.
On the other hand, all the imidazoline-2(3H)-thione
derivatives 16–26 are stable in solution for a very long
time, suggesting that the formation of the Cu–S bond can
allow Cu(I) derivatives to be obtained, which are suffi-
ciently stable to be spectroscopically characterized.
The conductivity measurements carried out only on the
sufficiently stable compounds in dichloromethane or in
acetonitrile (the choice is determined only by the solubility
of compounds) show that the nitrato, perchlorato and
tetrafluoroborato derivatives (1–3, 10–16, 18, 21, 23 and
26) are electrolytes also in non-ionizing solvents such as
dichloromethane, which is in reasonable agreement with
their ionic structure proposed in Fig. 2. In a few cases
(compounds 19, 22, 24 and 25) the conductivity values are
considerably lower than those expected for a 1:1 elec-
trolyte: this is likely due to the little amount of non-ionic
dissociation such as 4, which likely yields non-ionic
compounds.
3.1. Spectroscopy
3.1.1. IR spectra
The main vibrational bands of the starting copper(I)
phosphino and their azole adducts are given Section 2. The
n(NH) bands of the imidazoles, pyrazole and imidazoline-2-
thiones are observed as medium to strong broad bands in
the 3300–2600 cm21 region. The slight shift and the
broadening and also the appearance of new medium
absorptions in the 3300–3000 cm21 region, suggest the
participation of the NH groups in hydrogen bonding.
The copper(I) nitrato derivatives 1–9, 17 and 22 show
spectra in the regions 2000–1600, 1400–1100 and 1000–
700 cm21; these are considerably different from the
spectra of their starting [(PBz3)2CuNO3] and
[(PPh3)2CuNO3] which contain bidentate nitrato groups.
Compounds 1–3 show four absorptions at approximately
1350, 1040, 830 and 700 cm21 characteristic of an ionic
nitrato group [46]. In the spectra of compounds 4–6, 9, 17
and 22, the n1 and n4 differ in frequency by approximately
60–90 cm21. This suggests for these compounds, in the
solid state, the presence of a monodentate nitrato group
[47,48]. This hypothesis is also confirmed by the splitting
of the combination band (n1 1n4) which appears in the
1800–1700 cm21 region, and also by the splitting of the n4
(near 700 cm21) in two bands, as expected for unidentate
nitrato groups [49]. In the other nitrato complexes, the
bands are often hidden under some ligand absorption, so
that it is not possible to distinguish between unidentate or
ionic nitrato groups.
The IR spectra of the perchlorato and tetrafluoroborato
derivatives 10–16, 18, 21, 23 and 26 all show two
absorptions characteristic of ClO4 and BF4 groups: a
strong absorption between 1100 and 1000 cm21 and a
strong sharp band at approximates 625 cm21: these
absorptions, similar to those found in the ionic compounds
[(PPh3)4Cu]XY4 (XY4 5ClO4 or BF4), are indicative of
the presence of ionic uncomplexed XY4 group [50], in
accordance with the structures proposed in Fig. 2. The
absorptions are very similar to those observed in tri-
cyclohexylphosphinecopper(I)perchlorato derivatives of
imidazoles in which the perchlorato group is strongly
hydrogen bonded [26].
[(PBz3)yLxCu]X ↔[(PBz3)yCuX] 1 xL
(4)
The compounds 4–9, which are not ionic in the solid state,
are 1:1 electrolytes in dichloromethane, in accordance with
an ionic dissociation in this solvent. Molecular weight
measurements were also performed in chloroform on
selected sufficiently stable derivatives. The ratio r between
the vaporimetric molecular weight and the formula weight
lies in the range 0.38–0.75 and indicates that, as previous-
The NCS group may be bonded to a metal through the N

C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
1949
Fig. 2. Selected structures of the complexes obtained.

1950
C. Pettinari et al. / Polyhedron 18 (1999) 1941–1951
or S atom or may form a bridge between the two metals by
using both atoms. In our complexes 19 and 24, we found
n(CN) near 2100 cm21, several bands of low intensity near
420 cm21 due to d(NCS), and finally a medium absorption
near 700 cm21 due to n(CS), all typical of S-bonded
complexes [51–54]. A neutral structure as in that in Fig. 2
is likely. In derivatives 16–26, the n(C=S) vibrations, found
ance with the relative strength of the Cu–N and Cu–S
bonds.
The presence of a broad resonance at approximately 7.4
ppm in the 1H NMR spectrum of compound 1 and at
approximately 6.6 ppm in the 1H NMR spectrum of
derivatives 16–20, instead of the two expected signals for
the two H4 and H5 hydrogens, may be due to a rapid
interchange of the azole in a dissociative process, a
‘shuttling’ of the H and the copper(I) atom between the
pair of N atoms [56,57].
in the free ligands at approximately 770 and 740 cm21
respectively, exhibit a slight shift by 615 cm21. Slight
changes (610 cm21) also occur in the d(CS) (670 cm21
,
)
1
and p(CS) (530 cm21) bands, and finally some absorp-
tions having n(CS) character appear at approximately 700
cm21, which suggests coordination of the imidazoline-
thiones to the copper(I) atom throughout the thiocarbonyl
sulfur as previously observed [55]. This observation is
supported by the presence of weak absorptions at approxi-
mately 300 cm21, absent in the spectrum of the free
S-donors and of the starting copper(I) derivative, due to
n(Cu–S) stretching vibration [28].
In the H NMR spectra in CDCl3 of tribenzylphosphino
compounds 1–15, a broad signal at approximately 3.0 ppm
and a complex multiplet between 7.0 and 7.30 ppm often
appear, which are due to the formation of Bz3P=O in
accordance with the previously described fast oxidation of
free PBz3 in CHCl3.
4. Conclusions
The two bromide complexes 20 and 25 exhibit a very
different far IR spectrum, as expected on the basis of their
stoichiometry: compound 20 exhibits a band at ca. 200
cm21, characteristic of a terminal Cu–Br bond and in
accordance with a tetrahedral structure, whereas the spec-
trum of 25 is very similar to those reported for dinuclear
complexes synthesized by Raper and Clegg [31] The
thioamide IV bands in the free ligand at 770 and 740 cm21
are replaced with a sharp but split band in the complex.
Slight shift and band splitting have also been found for
d(CS) at 670 cm21 and p(CS) at 525 cm21. On the basis
of these similarities, the dinuclear structure in Fig. 2 is
likely.
The conclusions of our study on the interaction between
monodentate N- or S-donor, or bidentate N2-donor ligands
and triorganophosphinecopper(I)X acceptors showed that
different compounds can be obtained depending on:
1. steric hindrance, basicity, and atom donor of the azole-
type ligand;
2. steric hindrance (Tolman cone angle) and basicity (pKa)
of the phosphorus donor;
3. reaction conditions (solvent, temperature, ligand to
metal ratio employed . . . .);
4. nature of the counter-ion.
While it is generally very simple to obtain triphenylphos-
phino derivatives by direct interaction of the starting
[(PR3)nCuX] with the azole ligand, the tribenzyl- and
tricyclohexyl-phosphino derivatives can be more efficiently
prepared by substitution reaction of the phosphorus donor
ligand.
The complexes containing S-donor ligands are generally
more stable than complexes containing N-donor ligands;
complexes containing three triorganophosphines are more
stable than those containing two triorganophosphines,
which, however, are more stable than those containing
only one triorganophosphine ligand. Stability generally
decreases with increasing Tolman cone angle and with
decreasing pKa of the triorganophosphine, so that it is not
possible to indicate which triorganophosphine is the better
ligand.
3.1.2. 1H NMR spectra
The 1H NMR spectra recorded in chloroform or in
acetonitrile only when the compounds were sufficiently
soluble and the solution sufficiently stable, support the
formulae proposed and show that our N- and S-donors
have not undergone any structural changes upon coordina-
tion.
As previously observed for the tricyclohexylphosphine
and the triphenylphosphino derivatives [24–26], a small
coordination shift is generally found which is due to a
partial dissociation of complexes in solution. The observed
resonances are averaged between those of the complex and
free ligand owing to a rapid exchange reaction between
both (Eq. 4). The dissociation is often larger in the
complexes containing sterically hindered imidazoles, i.e
compounds 2, 4–6, 11, and 13–15. The small coordination
shifts are therefore assignable to the small fraction of the
complex present in solution and are caused by a change in
the electron density of the donor owing to the formation of
the Cu–N or Cu–S bond. The coordination chemical shifts
are generally greater in complexes containing imidazoline-
thiones than in those containing N-donor azoles, in accord-
Acknowledgements
We would like to thank the Italian Ministry of the
University (MURST) and the University of Camerino for
financial help.

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