Probing stepwise reaction of NNP-ligand copper(I) complex with elemental sulfur by using N-heterocyclic carbene as a trapper

Article abstract of DOI:10.1021/ic200008z

The dinuclear NNP-ligand copper(I) complex [o-N=CH(C₄H ₃N)-PPh₂C₆H₄]₂Cu ₂ (1) has been synthesized by the reaction of (CuMes)₄ (Mes = 2,4,6-Me₃C₆

Full text of DOI:10.1021/ic200008z

ARTICLE
pubs.acs.org/IC
Probing Stepwise Reaction of NNPꢀLigand Copper(I) Complex with
Elemental Sulfur by Using N-Heterocyclic Carbene as a Trapper
Gengwen Tan and Hongping Zhu*
State Key Laboratory of Physical Chemistry of Solid Surfaces, National Engineering Laboratory for Green Chemical Productions of
Alcohols, Ethers and Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian, 361005, China
S Supporting Information
b
ABSTRACT: The dinuclear NNPꢀligand copper(I) complex
[o-NdCH(C4H3N)ꢀPPh2C6H4]2Cu2 (1) has been synthe-
sized by the reaction of (CuMes)4 (Mes = 2,4,6-Me3C6H2) with
N-((1H-pyrrol-2-yl)-methylene)-2-(diphenylphosphino)benzen-
amine under an elimination of MesH. Further reaction
of 1 with an excess of S8 produced a mononuclear Cu(II)
complex [o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]2Cu (5) and CuS.
CuS was identified by Raman spectroscopy and 1 and 5 were
clearly confirmed by X-ray crystallography. The N-heterocyclic
carbene was employed to react with 1 to give a mononuclear
[o-NdCH(C4H3N)ꢀPPh2C6H4]Cu{C[N(iPr)CMe]2} (2). The
1
2
5
reactions of 2 were carried out with /8, /8, and /8 equiv of
S8, leading to compounds [o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]-
Cu{C[N(iPr)CMe]2} (3), [o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]-
Cu (4), and 5 respectively, in which CuS was generated in the
third reaction and SdC[N(iPr)CMe]2 in the latter two reac-
tions. The clean confirmation of 2ꢀ4 demonstrates a stepwise reaction process of 1 with S8 to 5 and CuS and the N-heterocyclic
carbene acts well as a trapping agent.
’ INTRODUCTION
2R-diaminocyclohexane).9 The N-ligands subtly tunable whether
in steric hindrance, charge state, or in chelate mode have a great
influence on the formation of the different copper sulfides
although some of these compounds are produced depending
on the reaction conditions.8b
Reactions of copper(I) complexes with elemental sulfur have
been intensively investigated in recent years.1 This is mainly in
focus on synthetic and structural modeling studies of the active
sites of the naturally existed copper thiolate- or sulfide-containing
biological enzyme systems.2 Moreover, these reactions exhibit an
extensive chemistry with respect to the rich copperꢀsulfur
interactions and result in a number of novel copper sulfide
complexes.1,3 It has been shown that the naked Cu(I) ion, which
is paired by weakly coordinating anions (WCAs), reacts with S8,
giving complexes Cu(η2-S8)2(AsF6), [Cu(1,5,9-η3-S12)(η1-S8)]-
[Al(ORF)4], and [Cu(1,5,9-η3-S12)(CH2Cl2)][Al(ORF)4] (RF =
C(CH3)(CF3)2) in which the metal is still in the oxidation state
of +1.4 On the basis of the stabilization by organic N-chelate
ligands, the Cu(I) complexes react with S8, generating Cu(II) com-
plexes [(TMPA)2Cu2(μ-1,2-S2)](AN)2 (TMPA = tris[(2-pyridyl)-
methyl]amine, AN = ClO4, or PF6),5 [(TMEDA)2Cu2(μ-1,
2-S2)2](OTF)2 (TMEDA = N,N,N0,N0-tetramethylethylenedia-
mine, OTF = O3SCF3),6 [(Me2NPY2)2Cu2(μ-η2:η2-S2)]-
It has also been demonstrated by Karlin,7 Tolman,8b and co-
workers that the Cu2(μ-η2:η2-S2) core complexes can occur
further by a sulfur atom-transfer reaction from the copper sulfur
moiety either to the external substrates or to the intramolecular
ligand and the metal is reduced back to the original oxidation
state of +1. In the case of PPh3 as the substrate, SdPPh3 was
formed and detected dissociating from the Cu(I) center. When
excessively used, PPh3 can further coordinatively stabilize the
Cu(I) species produced during the reaction.7,8b Probably the
PPh3-stabilized Cu(I) compound could react again with S8 and
recover the Cu2(μ-η2:η2-S2) core complexes. All of these actually
show an interesting copperꢀsulfurꢀphosphine interaction
chemistry, which, however, is studied in a less extent.3b,7,8b,11
Moreover, because of the formation of the discrete Cu(I) species
and SdPPh3, it seems not facile to draw a picture of such
interaction. We now report on the preparation of an NNP-type
ligand Cu(I) complex and the further investigation of its reaction
[B(C6F5)4]2 2CH2Cl2 (Me2NPY2 = N,N-bis-{2-[2-(N0,
3
N0-4-dimethylamino)pyridyl]ethyl}methylamine),7 (HL0Me2)2-
Cu2(μ-η2:η2-S2) (HL0
= N-[2-(2,6-dimethylphenylamino)-
Me2
benzylidene]-2,6-dimethylaniline),8 and Cu(II)Cu(III) complexes
[L3Cu3(μ3-S)2]X3 (L = TMEDA, X = SbF6; L = TMCHD,
X = PF6, TMCHD = N,N,N0,N0-tetramethyl-trans-1R,
Received: January 31, 2011
Published: June 23, 2011
r
2011 American Chemical Society
6979
dx.doi.org/10.1021/ic200008z Inorg. Chem. 2011, 50, 6979–6986
|

Inorganic Chemistry
ARTICLE
with S8. With respect to the NNP ligand character that has an
intramolecular phosphine group linkage at the N,N-chelate, we
reason that this reaction could hintthe interesting copper ꢀsulfurꢀ
phosphine reaction. The NNP ligand, N-((1H-pyrrol-2-yl)-
methylene)-2-(diphenylphosphino)benzenamine has recently been
employed for synthesizing the Ni, Pd,12 Y,13 Cr, and Bi14 com-
pounds, and, however, it has not been utilized so far for the
copper complexes. By this ligand, we prepared a dinuclear
copper(I) complex [o-NdCH(C4H3N)ꢀPPh2C6H4]2Cu2 (1).
The reaction of 1 with an excess of the S8, however, afforded
a mononuclear copper(II) compound [o-NdCH(C4H3N)ꢀ
P(S)Ph2C6H4]2Cu (5), in which an insoluble CuS was con-
comitantly produced. This result compares significantly different
from those generated by the reactions of the N-chelate copper(I)
complexes with S8.5ꢀ8 Herein, we present this result and further
report on the use of the N-heterocyclic carbene as a trapping
agent for detecting the reaction process.
toluene (10 mL) was added to a solution of 1 (0.83 g, 1.0 mmol) in
toluene (15 mL). The mixture was stirred for 2 h. After workup, toluene
was removed under vacuum and an orange-yellow crystalline solid of
2 was obtained (1.15 g, 96%). Mp: 176 °C. 1H NMR (400 MHz, C6D6,
298 K, ppm): δ = 1.29 (d, 12 H, 3JHH = 6.8 Hz, CHMe2), 1.55 (s, 6 H,
CMe), 4.64 (sept, 2 H, 3JHH = 6.8 Hz, CHMe2), 6.83ꢀ6.88 (m, 2 H),
6.94ꢀ6.98 (m, 1 H) (NC4H3), 6.99ꢀ7.04 (m, 8 H), 7.17ꢀ7.23 (m, 1
H), 7.36ꢀ7.42 (m, 4 H), 7.74 (s, br, 1 H) (C6H4, C6H5), 7.93 (s, 1 H,
NdCH); 13C NMR (100 MHz, C6D6, 298 K, ppm): δ = 9.09 (CHMe2),
22.90 (CMe), 51.56 (CHMe2), 111.89, 117.62, 119.08, 122.79, 123.05,
128.22, 128.26, 128.29, 130.12, 132.68, 133.02, 133.06, 133.92, 134.11,
136.76, 137.74, 137.68, 141.07, 154.50, 154.52, 156.70, 156.90 (C6H4,
C6H5, NC4H3, CMe), 179.88 (NdC), 180.18 (CuꢀCcarbene); 31P NMR
(160 MHz, C6D6, 298 K, ppm): δ = ꢀ20.75. ESI-MS: m/z (%) 598.2
(6, [M + H]+), 355.2 (16, [L + H]+), 181.1 (100, [C[N(iPr)CMe]2 +
H]+) (L = o-NdCH(C4H3NH)ꢀPPh2C6H4). Anal. Calcd for C34H38-
CuN4P (Mr = 597.19): C, 68.38; H, 6.41; N, 9.38. Found: C, 68.52;
H, 6.56; N, 9.28. X-ray quality single crystals of 2 were obtained by
recrystallization in toluene at ꢀ30 °C.
’ EXPERIMENTAL SECTION
[o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]Cu{C[N(iPr)CMe]2} (3). At
ꢀ20 °C, a solution of S8 (2.5 mL, 0.0625 mmol, 0.025 M THF solution)
was added to a solution of 2 (0.30 g, 0.50 mmol) in toluene (40 mL).
The mixture was warmed to room temperature and stirred for 12 h.
An orange-red solution was formed. All solvents were removed under
vacuum and the residue was washed with cold n-hexane (5 mL) to
give an orange-yellow solid of 3 (0.27 g, 90%). Mp: 159 °C. 1H NMR
Materials and Methods. All syntheses and manipulations were
carried out on a dual-manifold Schlenk line or in an argon-filled MBraun
glovebox (typically oxygen and moisture were controlled at less than
1.2 ppm). The organic solvents including toluene, n-hexane, tetrahy-
drofuran, and diethyl ether were predried over fine sodium wires
for more than one week and then subjected to reflux with sodium/
potassium benzophenone under nitrogen atmosphere prior to use.
CH2Cl2 and CHCl3 were refluxed with CaH2 at least for 3 d before
use. Benzene-d6, toluene-d8, and THF-d8 were degassed and dried
over sodium/potassium alloy, and CDCl3 and CD2Cl2 were similarly
3
(400 MHz, C6D6, 298 K, ppm): δ = 1.32 (d, 12 H, JHH = 6.8 Hz,
CHMe2), 1.56 (s, 6 H, CMe), 4.62 (sept, 2 H, 3JHH = 6.8 Hz, CHMe2),
6.72ꢀ6.83 (m, 3 H, NC4H3), 6.91ꢀ7.00 (m, 7 H), 7.11ꢀ7.19 (m, 1 H),
7.45ꢀ7.65 (br, 3 H), 7.80ꢀ7.94 (m, 4 H) (C6H4, C6H5, NdCH);13C
NMR (100 MHz, C6D6, 298 K, ppm): δ = 9.17 (CHMe2), 23.16 (CMe),
51.52 (CHMe2), 111.37, 118.00, 121.49, 121.68, 122.28, 123.04, 130.58,
130.59, 132.49, 132.60, 132.88, 133.26, 133.55, 133.61, 134.02, 134.09,
136.55, 139.80, 154.53, 158.12 (C6H4, C6H5, NC4H3, CMe), 176.93
(NdC), 178.66 (CuꢀCcarbene); 31P NMR (160 MHz, C6D6, 298 K,
ppm): δ = 38.19. ESI-MS: m/z (%) 630.4 (2, [M + H]+), 387.2 (100,
[L(S) + H]+) (L(S) = o-NdCH(C4H3NH)ꢀP(S)Ph2C6H4). Anal.
Calcd for C34H38CuN4PS (Mr = 629.25): C, 64.89; H, 6.09; N, 8.90.
Found: C, 64.84; H, 6.22; N, 8.75. X-ray quality single crystals of
3 were obtained by recrystallization in toluene at room temperature.
treated and dried over CaH2. 1H (400 MHz), 13C (100 MHz), and 31
P
NMR (160 MHz) NMR spectra were recorded on a Bruker Avance II
400 MHz spectrometer. Melting points were measured in sealed glass
tubes using B€uchi-540 instrument. EI mass spectra were measured on
Esquire HCT spectrometer. Fluorescence data were obtained on a
Hitachi F-7000 spectrometer. Magnetic measurements were carried out
with the Quantum Design SQUID MPMS-XL instrument, and EPR
ones on the Bruker ER200D-SRC spectrometer. Elemental analysis was
performed on a Thermo Quest Italia SPA EA 1110 instrument.
Commercially available reagents were purchased from Aldrich, Acros,
Alfa-Assar, or Lvyin Chemical Co. and used as received. o-NdCH-
(C4H3NH)ꢀPPh2C6H4,12 (CuMes)4 (Mes = 2,4,6-Me3C6H2),15 and
C[N(iPr)CMe]216 were prepared according to published procedures.
[o-NdCH(C4H3N)ꢀPPh2C6H4]2Cu2 (1). At room temperature a
solution of (CuMes)4 (0.65 g, 0.75 mmol) in THF (10 mL) was added
to a solution of o-NdCH(C4H3NH)ꢀPPh2C6H4 (1.06 g, 3.0 mmol) in
THF (40 mL). The mixture was stirred for 4 h, and a red solution was
formed. All volatiles were removed under vacuum followed by washing
with n-hexane (2 mL) to give a red crystalline solid of 1 (1.18 g, 95%).
Mp: 258 °C. 1H NMR (400 MHz, C6D6, 298 K, ppm): δ = 6.51ꢀ6.54
(m, 2 H), 6.69ꢀ6.77 (m, 4 H) (NC4H3), 6.82ꢀ6.89 (m, 8 H),
6.92ꢀ6.97 (m, 8 H), 7.00ꢀ7.10 (m, 10 H), 7.15 (m, 2 H) (C6H4,
C6H5), 7.96 (s, 2 H, NdCH). 13C NMR (100 MHz, C6D6, 298 K, ppm):
δ = 113.39, 120.36, 122.94, 123.81, 125.44, 128.40, 128.45, 128.49,
129.10, 131.45, 133.15, 133.30, 133.42, 133.50, 133.59, 139.13, 140.39,
155.58, 156.87, 156.96, 157.05. 31P NMR (160 MHz, C6D6, 298 K,
ppm): δ = ꢀ16.87. ESI-MS: m/z (%) 835.5 (5, [M + H]+), 355.2 (100,
[L + H]+) (L = o-NdCH(C4H3NH)ꢀPPh2C6H4). Anal. Calcd for
C46H38Cu2N4P2 (Mr = 834.12): C, 66.10; H, 4.58; N, 6.70. Found: C,
[o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]Cu (4). At ꢀ20 °C, a solution
of S8 (5 mL, 0.125 mmol, 0.025 M of THF solution) was added to a
solution of 2 (0.30 g, 0.50 mmol) in toluene (40 mL). The mixture was
warmed to room temperature and stirred for 12 h. A deep-red solution
was formed. All solvents were removed under vacuum and the residue
was extracted with toluene (20 mL). The extract was concentrated
(ca. 10 mL) and to it n-hexane (10 mL) was layered on the top. After
keeping at ꢀ20 °C for 3 d, red-black crystals of 4 were yielded (0.15 g,
64%). The mother lique was concentrated (ca. 3 mL) and kept at
ꢀ20 °C for one week, colorless crystals were produced and identified as
SdC[N(iPr)CMe]2. All the analytic data is for 4. Mp: 223 °C. 1H NMR
(400 MHz, C6D6, 298 K, ppm): δ = 6.64ꢀ6.69 (m, 2 H), 6.82ꢀ6.90
(m, 1 H) (NC4H3), 6.91ꢀ6.99 (m, 7 H), 7.04 (dd, 1 H), 7.06ꢀ7.14
q(m, 1 H), 7.48 (s, br, 1 H), 7.59 (q, br, 4 H) (C6H4, C6H5,), 8.01 (s, br,
1 H, NdCH); 13C NMR (100 MHz, C6D6, 298 K, ppm): δ = 114.59,
117.78, 117.84, 118.34, 119.26, 121.74, 121.77, 121.91, 128.49, 128.62,
130.66, 131.53, 131.85, 131.87, 132.26, 132.36, 134.07, 134.18, 134.23,
141.08, 141.58, 150.12, 151.79 (C6H4, C6H5, NC4H3), 182.6 (NdC);
31P NMR (160 MHz, C6D6, 298 K, ppm): δ = 30.22. ESI-MS: m/z (%)
449.3 (10, [M + H]+), 387.2 (100, [L(S) + H]+) (L(S) = o-NdCH-
(C4H3NH)ꢀP(S)Ph2C6H4). Anal. Calcd for C23H18CuN2PS (Mr =
448.99): C, 61.53; H, 4.04; N, 6.24. Found: C, 61.91; H, 4.30; N, 6.23.
Note: When this reaction was carried out under similar conditions but
65.92; H, 4.46; N, 6.78. X-ray quality single crystals of 1 THF were
3
obtained by recrystallization in THF/n-hexane (1:1) solvent mixture
at ꢀ30 °C.
[o-NdCH(C4H3N)ꢀPPh2C6H4]Cu{C[N(iPr)CMe]2} (2). At room
temperature, a solution of C[N(iPr)CMe]2 (0.36 g, 2.0 mmol) in
6980
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
Table 1. Crystal Data and Structure Refinement for 1ꢀ5a
1 THF
2
3
4 5
5 n-hexane
3
3
3
formula
fw
C
50H44Cu2N4OP2
C34H38CuN4P
597.19
C34H38CuN4PS
629.25
C69H54Cu2N6P3S3
1283.35
C52H50CuN4P2S2
920.56
905.91
cryst syst
space group
a/Å
monoclinic
P2(1)/c
orthorhombic
Pbca
monoclinic
P2(1)
monoclinic
P2(1)/c
orthorhombic
Pbca
12.2441(3)
13.6298(4)
13.6298(4)
15.9968(7)
17.4056(7)
22.3356(10)
11.1838(8)
8.8057(8)
16.4636
13.0045(10)
21.9160(14)
21.3005(18)
14.2716(6)
17.6685(9)
35.8182(16)
b/Å
c/Å
R/deg
β/deg
γ/deg
V/Å3
Z
96.909(2)
97.681(7)
98.395(7)
4640.2(2)
4
6219.0(5)
8
1606.8(2)
2
6005.7(8)
9031.8(7)
8
4
F
calcd/g cmꢀ3
μ/mmꢀ1
1.297
1.276
1.301
1.419
1.354
3
1.025
0.783
0.823
0.941
0.688
F(000)
1872
2512
660
2644
3848
cryst size/mm3
θ range/deg
index ranges
0.40 ꢁ 0.40 ꢁ 0.10
2.30ꢀ26.00
ꢀ15 e h e 15
ꢀ16 e k e 16
ꢀ34 e l e 34
47 999
0.25 ꢁ 0.20 ꢁ 0.18
2.34ꢀ26.00
ꢀ19 e h e 19
ꢀ19 e k e 21
ꢀ23 e l e 27
47 761
0.10 ꢁ 0.06 ꢁ 0.04
2.90ꢀ26.00
ꢀ10 e h e 13
ꢀ10 e k e 10
ꢀ20 e l e 20
14 042
0.20 ꢁ 0.15 ꢁ 0.08
2.71ꢀ26.00
ꢀ16 e h e 15
ꢀ24 e k e 27
ꢀ23 e l e 26
54 732
0.40 ꢁ 0.40 ꢁ 0.20
2.16ꢀ26.00
ꢀ17 e h e 17
ꢀ21 e k e 21
ꢀ44 e l e 43
91 351
collected data
unique data
9088 (Rint = 0.0373)
99.7%
6101 (Rint = 0.1325)
100.0%
5908 (Rint = 0.0753)
99.8%
11780 (Rint = 0.1453)
99.9%
8866 (Rint = 0.1094)
99.9%
completeness to θ
data/restraints/params
GOF on F2
9088/20/567
0.968
6101/0/367
0.802
5908/5/376
0.687
15 358/0/748
0.788
8866/10/545
1.177
final R indices [I > 2σ(I)]
R1 = 0.0418
wR2 = 0.1187
R1 = 0.0604
wR2 = 0.1242
0.735/ꢀ0.309
R1 = 0.0472
wR2 = 0.0612
R1 = 0.1234
wR2 = 0.0714
0.764/ꢀ0.466
R1 = 0.0451
wR2 = 0.0389
R1 = 0.1029
wR2 = 0.0453
0.720/ꢀ0.406
R1= 0.0568
wR2 = 0.0821
R1= 0 0.1643
wR2 = 0 0.0975
R1 = 0.0933
wR2 = 0.2131
R1 = 0.1181
wR2 = 0.2262
R indices (all data)
largest diff peak/hole (e Åꢀ3
)
0.998/ꢀ0.624
1.109/ꢀ0.712
3
aAll data were collected at 173(2) K using Mo KR (λ = 0.71073 Å) radiation. R1 = ∑( Fo| ꢀ|Fc )/∑|Fo|, wR2 = {∑[w(Fo ꢀ Fc2)2/∑[w(Fo ) ]}2}1/2
,
2
2 2
GOF = {∑[w(Fo ꢀ Fc2)2]/(No ꢀ Np)}1/2
.
2
using ca. 2.2/8 equiv of S8, cocrystals of 4 and 5 was produced during
crystallization under similar conditions.
The mother liquor was concentrated again (ca. 4 mL) and to it n-hexane
(5 mL) was layered on the top. After keeping at ꢀ20 °C for one week, a
second crop of 5 together with colorless crystals of SdC[N(iPr)CMe]2
were obtained. Total yield of 5, 0.32 g, 76% (based on 2).
[o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]2Cu (5). Method A. At room
temperature, an excess of S8 (16 mg, 0.0625 mmol) was added to a
solution of 1 (0.083 g, 0.10 mmol) in toluene (40 mL). The mixture was
stirred for 12 h, and a dark-brown solution was formed together with
insoluble black solids. The black solids were collected by filtration and
washed with THF (20 mL) to remove unreacted S8. The filtrate was
concentrated (ca. 15 mL) and kept at ꢀ20 °C. Three days later, dark-
brown crystals of 5 were yielded (0.043 g, 50%). Mp: 238 °C. 1H NMR
(400 MHz, C6D6, 298 K, ppm): δ = 7.70 (br), 8.30 (br); 31P NMR (160
MHz, C6D6, 298 K, ppm): no resonances were observed. ESI-MS: m/z
(%) 835.3 (66, [M + H]+), 387.2 (100, [L(S) + H]+) (L(S) = o-
NdCH(C4H3NH)ꢀP(S)Ph2C6H4). Anal. Calcd for C46H36CuN4P2S2
(Mr = 834.43): C, 66.21; H, 4.35; N, 6.71. Found: C, 66.88; H, 4.41; N, 6.94.
Method B. At ꢀ20 °C, an excess of S8 (0.16 g, 0.625 mmol) was added
to a solution of 2 (0.60 g, 1.0 mmol) in toluene (30 mL). The mixture
was warmed to room temperature and stirred for 12 h. A brown solution
was formed together with insoluble black solids. The black solids were
collected and washed with large amount of THF to remove unreacted S8.
Raman spectral measurement indicates the black solids of CuS. The
filtrate was concentrated (ca. 10 mL) and to it n-hexane (5 mL) was
layered on the top again. The solution was kept at ꢀ20 °C. One week
later, dark-brown crystals of 5 were grown and collected by filtration.
X-ray Crystallographic Analyses of 1ꢀ5. The crystallographic
data of 1ꢀ5 were collected on an Oxford Gemini S Ultra system. In all
cases, graphite-monochromated MoꢀKR radiation (λ = 0.71073 Å) was
used. Absorption corrections were applied using the spherical harmonics
program (multiscan type). The structures were solved by direct methods
(SHELXS-96)17 and refined against F2 using SHELXL-97.18 In general,
the non-hydrogen atoms were located by difference Fourier synthesis
and refined anisotropically, and hydrogen atoms were included using the
riding model with Uiso tied to the Uiso of the parent atoms unless
otherwise specified. In 1 THF and 5 n-hexane, the THF and n-hexane
3
3
solvent molecules were both disclosed in disorder and refined in split
positions with non-hydrogen atoms in isotropic model. In 3, one of the
iPr groups from the N-heterocyclic carbene was similarly found and
treated in the same way. A summary of cell parameters, data collection,
and structure solution and refinement is given in Table 1.
’ RESULTS AND DISCUSSION
Synthesis and Characterization of a Dinuclear NNP
Copper(I) Complex and Its Reaction with Elemental Sulfur.
6981
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
Scheme 1. Synthesis of 1
Scheme 2. Reaction of 1 with S8 to 5 and CuS
and two neutral imido groups. 1 can be actually ascribed as an
ion pair with the Cu(1) as the anionic center, whereas the Cu(2)
the cationic center. Compound [(phen)2Cu]+[Cu(NPh2)2]ꢀ
(phen = 1,10-phenanthroline) has recently been reported as a
common separated ion pair and thought to be predominantly
double salt in both polar and less polar solvents.19 Compound 1,
in comparison, represents one of the examples with the two ionic
parts in one molecule20 and shows little difference in solubility
either in polar or in nonpolar organic solvents. The Cu(1)ꢀN(1)
and Cu(1)ꢀN(3) bond lengths (1.856(3) Å) are similar to those
in the anionic [Cu(NPh2)2]ꢀ (1.860(2)ꢀ1.879(2) Å),19 whereas
the Cu(2)ꢀN(2) (2.112(2) Å) and Cu(2)ꢀN(4) (2.187(2) Å)
as well as the Cu(2)ꢀP(1) (2.2506(8) Å) and Cu(2)ꢀP(2)
(2.2559(8) Å) bond distances appear close to those in a cationic
[Cu(1,10-pp-N2P2)]+ (CuꢀN, 2.173(7) and 2.185(7) Å; CuꢀP,
2.251(2) and 2.255(2) Å; 1,10-pp-N2P2 = 1,10-bis(diphenyl-
phosphino)-4,7-dimethyl-4,7-diazadecane).21 It is interesting to find
Figure 1. X-ray crystal structure of 1 with thermal ellipsoids drawn at
the 50% probability. Selected bond lengths [Å] and angles [°]: Cu(1)ꢀ
N(1) 1.856(3), Cu(1)ꢀN(3) 1.856(3), Cu(2)ꢀN(2) 2.112(2), Cu(2)ꢀ
N(4) 2.187(2), Cu(2)ꢀP(1) 2.2506(8), Cu(2)ꢀP(2) 2.2559(8), Cu-
that the Cu(1) Cu(2) separation is 2.6399(5) Å. This distance
(1) Cu(2) 2.6399(5); N(1)ꢀCu(1)ꢀN(3) 173.95(11), N(2)ꢀ
3 3 3
3 3 3
Cu(2)ꢀN(4) 151.82(9), P(1)ꢀCu(2)ꢀP(2) 117.58(3).
can be comparable to those in a cluster compound Cu24O24Si8R8
(R = (2,6-iPr2C6H3)N(SiMe3), 2.6296(8)ꢀ2.7204(8) Å),22
suggesting a weak Cu(I) Cu(I) d10 d10 attractive interac-
3 3 3
3 3 3
tion.23 Further emission spectra measurement of 1 in the solid state
The reaction of (CuMes)4 (Mes = 2,4,6-Me3C6H2) with
o-NdH(C4H3NH)ꢀPPh2C6H4 in a molar ratio of 0.25:1 pro-
ceeded smoothly in THF at room temperature, and afforded
under an elimination of MesH a dinuclear compound [o-Nd
CH(C4H3N)ꢀPPh2C6H4]2Cu2 (1, Scheme 1). 1 was isolated as
a red crystalline solid in an almost quantitative yield (95%) by
removal of all volatiles and washing with n-hexane (2 mL). It is
air-sensitive and changes the color to brown when exposed to air
whether in the solid state or in solution. However, it is stable in an
inert gas atmosphere and also thermally stable as indicated by a
clear melting temperature at 258 °C. 1 has a good solubility in
chlorohydrocarbons, such as CH2Cl3 and CHCl3, and aromatic
hydrocarbons such as toluene and benzene as well as in donor
solvents like THF and Et2O. The 31P NMR spectrum of 1
recorded in C6D6 shows one resonance at δ ꢀ16.87 ppm and this
resonance compares a little upfielded from that of the free NNP
at room temperature shows a peak at 683 nm band, indicating a
tentative Cu(I) Cu(I) interaction (Figure 2s of the Support-
3 3 3
ing Information). This has been commonly discussed in M
M
3 3 3
interaction-containing group 9 metal complexes.24
The reaction of 1 with an excess of S8 was conducted in
toluene at room temperature (Scheme 2). After workup, a black
insoluble solid was formed, which was collected and washed with
a large amount of THF to remove unreacted S8. This solid was
analyzed by Resonance Raman spectroscopy (Figure 1s of the
Supporting Information) and identified as CuS with the char-
acteristic band at 474 nm similar to those reported in references25
and literature databases.26 The concentration of the filtrate
followed by keeping at ꢀ20 °C for three days afforded brown
crystals of [o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]2Cu (5) in mod-
erate yield (50%). The 1H NMR spectrum showed broad
resonances centered at δ 7.70 and 8.30 ppm respectively,
whereas no resonances were able to be observed in the 31P
NMR spectrum. This implies a paramagnetic ground state of 5
having the Cu(II) center. Further SQUID and EPR measure-
ments prove this property of 5 (Figures 4s and 6s of the
Supporting Information). The exact composition and structure
of 5 were determined by X-ray single crystal diffraction.
1
ligand (δ ꢀ12.8 ppm).12 The H NMR spectrum exhibits one
resonance at δ 7.96 ppm as a singlet corresponding to the imine
NdCH proton, and the resonances at δ 6.51ꢀ6.54 and
6.69ꢀ6.77 ppm respectively as multiplets assignable to the pyrrol
ring protons, whereas the ones at a separated wide range of
δ 6.82ꢀ7.15 ppm to the phenyl protons due to the combination
of the two different types of the aryl groups (C6H5 and C6H4).
The exact structure of 1 was disclosed based on the X-ray single
crystal diffraction study.
The crystal structure of 5 shown in Figure 2 unambiguously
confirmed a formation of a mononuclear Cu(II) compound incor-
porating two phosphine sulfide NNP(S) ligands. The copper
center is four-coordinated by two pyrrolide and two imido
groups with the CuꢀNpyrrolide bond lengths (Cu(1)ꢀN(1),
1.953(4) and Cu(1)ꢀN(3), 1.965(5) Å) relatively shorter than
The crystal structural analysis clearly proves 1 a dinuclear
compound (Figure 1), and the two copper centers, however, are
located into different coordination environments. The Cu(1) is
linearly ligated by the two anionic pyrrolide groups, whereas the
Cu(2) tetrahedrally coordinated by the two neutral phosphido
6982
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
Scheme 3. N-Heterocyclic Carbene Degradation of 1 to 2
Figure 2. X-ray crystal structure of 5 with thermal ellipsoids drawn at
the 50% probability. Selected bond lengths [Å] and angles [°]: Cu-
(1)ꢀN(1) 1.953(4), Cu(1)ꢀN(2) 2.077(4), Cu(1)ꢀN(3) 1.965(5),
Cu(1)ꢀN(4) 2.039(4), P(1)ꢀS(1) 1.9557(18), P(2)ꢀS(2)
1.9642(18), Cu(1) S(1) 3.310, Cu(1) S(2) 2.836; N(1)ꢀCu-
3 3 3
3 3 3
(1)ꢀN(2) 81.55(18), N(1)ꢀCu(1)ꢀN(3) 98.6(2), N(2)ꢀCu(1)ꢀN-
(4) 100.60(16), N(3)ꢀCu(1)ꢀN(4) 81.89(18).
those of the CuꢀNimido bond (Cu(1)ꢀN(2), 2.077(4) and
Cu(1)ꢀN(4), 2.039(4) Å). The Cu(1)(N(1)N(2)N(3)N(4)
least-squares plane is calculated by Δ = 0.2475 Å, and is a little
deviated from the ideal plane. This indicates a distortedly square-
planar geometry around the Cu(II) center fitting to an orbital
Figure 3. X-ray crystal structure of 2 with thermal ellipsoids drawn at
the 50% probability. Selected bond lengths [Å] and angles [°]: Cu-
(1)ꢀN(1) 1.940(2), Cu(1)ꢀN(2) 2.211(2), Cu(1)ꢀC(31) 1.882(3),
hybridization of the dsp2-type. The different Cu S separations are
Cu(1) P(1) 3.500; N(1)ꢀCu(1)ꢀN(2) 80.96(10), C(31)ꢀCu-
3 3 3
3 3 3
observed by 3.310 (S(1) Cu(1)) and 2.836 Å (S(2) Cu(1)),
(1)ꢀN(1) 151.09(12), C(31)ꢀCu(1)ꢀN(2) 127.62(11).
3 3 3
3 3 3
respectively, so it is with the different PꢀS bond lengths ((P(1)ꢀ
S(1), 1.9557(18) and (P(2)ꢀS(2), 1.9642(18) Å), which are of
double bond character, however, are a little longer than those
found in free SdPPh3 (1.950(3) Å)27 and o-NH(Ph)NHꢀ
P(S)Ph2C6H4 (1.9477(7) Å).28 This suggests the two unba-
(L = 2,6-(RNdCH)2-4-tBuC6H2, R = 2,6-iPr2C6H3), which
can be used as a good precursor for an interesting conjugated
addition to the organic azide molecule.29 Following this similar
way, we successfully prepared a mononuclear NNP N-hetero-
cyclic carbene Cu(I) compound [o-NdCH(C4H3N)ꢀPPh2-
C6H4]Cu{C[N(iPr)CMe]2} (2, Scheme 3).
The reaction of 1 with two equiv of C[N(iPr)CMe]2 was
accomplished in toluene at room temperature, affording 2 in almost
quantitative yield (96%). 2 has been characterized by multinuclear
NMR (1H, 13C, and 31P) spectroscopy, X-ray crystallography,
and elemental analysis. As shown in Figure 3, the Cu center is
three-coordinated by the NNP ligand and C[N(iPr)CMe]2 in
lanced weak Cu S interactions, which may give rise to a little
3 3 3
elongation of the PꢀS bond lengths and the further deviated
square planar geometry over the Cu(II) center.
Obviously, the conversion of 1 with S8 to 5 and CuS may imply
a multiple reaction process including the degradation of 1 by a
dinuclear to a mononuclear form, sulfur abstraction by the
phosphine, and the oxidation state change of the copper center
accompanying with the NNP(S) ligand redistribution. This
result appears different when compared to those by the reactions
of the N-chelate Cu(I) complexes with S8 especially in the
formation of the Cu(II) or Cu(II)Cu(III) sulfide complexes
with the Sn2ꢀ (n = 1 or 2) linkage as well as of the sulfur-to-ligand
transfer compounds CuI4(SR)4 (SR = SCH[(CMe)(NAr)]2,
Ar = 2,6-R’2C6H3, R0 = Me or Et),5ꢀ9 and also different from
that by a disproportionation partially occurred during the reaction of
[(tmeda)CuI(CH3CN)](O3SCF3) (tmeda=Me2NCH2CH2NMe2)
an ideal trigonal-planar geometry (ΔCu(1)C(31)N(1)N(2)
=
0.0207 Å). The Cu(1)ꢀN(1) bond length (1.940(2) Å) is
shorter than that of the Cu(1)ꢀN(2) (2.211(2) Å). This differ-
ence has also been observed in 5 mostly on account of a bonding
of the metal to the anionic N-pyrrolide donor for the former
while to the neutral N-imido one for the latter. The Cu(1)ꢀ
C(31) bond distance (1.882(3) Å) locates in those for Cu(I) N-
heterocyclic carbene compounds (1.862(10)ꢀ1.911(4) Å).11d,29
and S8 to [(tmeda)2CuII (μ-1,2-S2)2](O3SCF3)2 and metallic
The separation of the Cu(1) P(1) is 3.500 Å within van der
2
3 3 3
copper,6 although the sulfur abstraction by phosphine compounds
is well-known.3b,27,28 This prompts us a further investigation
on this reaction detail.
Waals distance and is much longer than those in 1, indicating of a
very weak donorꢀacceptor interaction. In the 31P NMR spec-
trum the phosphorus resonance is observed at δ ꢀ20.75 ppm.
The reaction of 2 was first carried out with 1/8 equiv of S8 in
toluene from ꢀ20 °C to room temperature, producing a phosphine
sulfide compound [o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]Cu{C-
[N(iPr)CMe]2} (3) in high yield (90%). Under similar reac-
Synthesis and Characterization of a Mononuclear NNP
N-Heterocyclic Carbene Copper(I) Complex and Its Stepwise
Reactions with Elemental Sulfur. More recently, we have
shown a reaction of N-heterocyclic carbene, 1,3-diisopropyl-4,
5-dimethylimidazol-2-ylidene with a L2Cu8Br6 cluster com-
pound, smoothly giving a mononuclear LCu{C[N(iPr)CMe]2}
2
tion conditions but using /8 equiv of S8 instead compound
[o-NdCH(C4H3N)ꢀP(S)Ph2C6H4]Cu{C[N(iPr)CMe]2} (4)
6983
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
Scheme 4. Stepwise Reaction of 2 with S8 to 3ꢀ5
30
was afforded (70%) and in the meantime SdC[N(iPr)CMe]2
was isolated too. And then we tried the reaction of 2 with a little
excess (5/8 equiv) of S8 and 5 (76%), CuS, and SdC[N-
(iPr)CMe]2 were all able to be isolated. This result seems almost
the same as that from the reaction of 1 and an excess of S8 except
for the formation of SdC[N(iPr)CMe]2. Obviously, under the
control of the S8 amount, the generation of 5 from 2 indicates a
stepwise reaction process (Scheme 4).
Figure 4. X-ray crystal structure of 3 with thermal ellipsoids drawn at
the 50% probability. Selected bond lengths [Å] and angles [°]: Cu(1)ꢀ
C(31) 1.913(4), Cu(1)ꢀN(1) 1.968(3), Cu(1)ꢀN(2) 2.326(3),
P(1)ꢀS(1) 1.9517(15), Cu(1) S(1) 2.6420(12); C(31)ꢀCu(1)ꢀ
3 3 3
N(1) 142.86(15), C(31)ꢀCu(1)ꢀN(2) 124.11(15), N(1)ꢀCu(1)ꢀ
3 and 4 both have been definitely confirmed by multinuclear
NMR (1H, 13C, and 31P) spectroscopy as well as by X-ray
crystallography. The 31P NMR spectra show the resonance at
δ 38.19 ppm for 3 and at δ 30.22 ppm for 4 and these chemical
shifts are significantly downfielded when compared to those for
compounds 1 and 2, indicating a formation of the phosphine
sulfide moiety. Similar example is observed in o-NH(Ph)NHꢀ
N(2) 77.25(15).
1
P(S)Ph2C6H4 (δ 42.6 ppm).28 The H NMR spectrum of 3
shows the presence of the carbene ligand proton resonances at a
range of δ 1.30ꢀ4.70 (δ 1.32, doublet, CHMe2; 1.56, singlet,
CMe; 4.62, septet, CHMe2); however, these resonances are not
observed in that of 4.
When compared to the structure of 2, in 3 (Figure 4) the S
atom is bonded to the P with the PꢀS bond length of 1.9517(15)
Å a little longer than that in the similar free ligand o-NH-
(Ph)NHꢀP(S)Ph2C6H4 (1.9477(7) Å).28 The Cu(1) S(1)
3 3 3
distance is 2.6420(12) Å, suggesting a weak Cu S inter-
3 3 3
action like those found in 5. The Cu(1) center keeps three-
coordinated. However, it is worthy to note that the Cu(1)C-
(31)N(1)N(2) least-squares plane is calculated by 0.1521 Å and
thus the Cu(1) center is away from the C(31)N(1)N(2) plane by
0.4187 Å. Moreover, the peripheral angle around the Cu(1)
(344.22°) significantly deviates from ideal 360°. These data
indicate a distorted trigonal-planar geometry over the Cu(1)
center in 3 markedly different from the one featured in 2,
Figure 5. X-ray crystal structure of 4 with thermal ellipsoids drawn at
the 50% probability. Selected bond lengths [Å] and angles [°]: Cu-
(2)ꢀN(1) 1.913(4), Cu(2)ꢀN(2) 2.170(4), Cu(2)ꢀS(1) 2.1705(15),
P(1)ꢀS(1) 2.0089(17); N(1)ꢀCu(2)ꢀN(2) 82.55(17), N(1)ꢀ
Cu(2)ꢀS(1) 172.36(14), N(2)ꢀCu(2)ꢀS(1) 104.37(12), P(1)ꢀ
S(1)ꢀCu(2) 91.57(7).
suggesting a relatively strong Cu S interaction although the
3 3 3
This may indicate a paramagnetic ground state of 4 and a probable
temperature-dependent antiferromagnetic interaction occurred.
However, the EPR of 4 is silent (Figure 3s of the Supporting
Information). These data suggest that an electron charge is in
great what transferred from the P to the Cu center via the S
bridge, giving rise to the significant bond parameter changes of
the PꢀS and CuꢀS when compared to those in 2, 3, and 5. The
copper center in 4 is three-coordinate with a closely linear N(1)ꢀ
Cu(2)ꢀS(1) bond angle (172.36(14)°) and a perfectly planar
Cu(2)N(1)N(2)S(1) plane (Δ = 0.0187 Å), revealing a
T-shaped geometry over the copper center.
PꢀS bond length is not seriously changed. In 4 (Figure 5), the
P(1)ꢀS(1) distance (2.0089(17) Å) becomes longer and locates
between the PꢀS double and single bonds,31 whereas the
corresponding Cu(2)ꢀS(1) distance (2.1705(15) Å) much shorter
when compared to those in 3 and 5, indicative of a covalent bond
character. Similar cases are observed in compounds (Ph3P)2-
Cu[(SPPh2)(O2SMe)N] and (Ph3P)2Cu[(SPPh2)(O2SC6H4-
Me-4)N] 0.5toluene (PꢀS and CuꢀS bond lengths, 1.9886(14)
3
and 2.3912(11) Å for the former; 1.995(2) and (2.3761(18) Å
for the latter).32 Thus, 4 is better described as a zwitterionic
compound with positive charge at the P while negative charge at
the Cu center. Temperature-dependent molar magnetic suscept-
On the basis of the disclosure of the structures of 2ꢀ4, it is
ibility (χm T) versus temperature (T) measurement for 4 from
pictured to us that the bonding of the carbene to the Cu(I) center
3
2 to 300 K at a magnetic field of 1000 Oe showed that at room
in 2 weakens the CuꢀP bond and then a weak Cu
P
3 3 3
temperature the χm T value was 0.44 cm3 K molꢀ1, and
interaction is shown. This significantly changes the structural
modes of the original two coppers in 1 despite that the metal is
located either in the cationic or in the anionic center. The initial
3
3 3
with the decrease of the T, this value gradually decreased to
0.03 cm3 K molꢀ1 (Figure 5s of the Supporting Information).
3
3
6984
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
Scheme 5. Plausible Reaction of 4 with S8 to 5 and CuS
corresponding copper compounds. This may reflect a complexity
of this stepwise reaction process. The current endeavor is to
isolate the transient Cu2(μ-S) core compound, and this work is
underway.
’ ASSOCIATED CONTENT
S
Supporting Information. Resonance Raman spectrum
b
of CuS, emission spectra of the NNP ligand and 1, X-band
EPR spectra of 4 and 5, temperature-dependent molar suscepti-
bility versus temperature plot of 4 and 5, proton NMR spectra
of 4 detected at varied temperatures, structure of 5 in cocrystal of
reaction of 2 with S8 could be considered as an insertion of the
sulfur atom into the Cu P weak bond and the further reaction
3 3 3
with S8 might be believed to occur by an insertion of the sulfur
into the CuꢀCcarbene bond. SdC[N(iPr)CMe]2 was formed and
dissociated from the copper center. This makes the copper center
more Lewis acidic33 and then the S atom of the PdS bond
triggers the Cu(I) by the strong donorꢀacceptor interaction
resulting in the formation of the covalent CuꢀS bond.
4 5, and CIF data for 1ꢀ5. This material is available free of
3
charge via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION
Corresponding Author
*E-mail: hpzhu@xmu.edu.cn.
Now, we can find that it is 4 that directly undergoes the
reaction of the Cu(I) to Cu(II) species with S8 to form 5 and
CuS. We treated a C6D6 solution of 4 at varied temperatures
(room temperature to 80 °C) without an addition of S8, the 1H
NMR spectra detected showed almost no changes of the proton
resonances (Figures 7sꢀ10s of the Supporting Information).
Moreover, 4 was measured to exhibit a good thermal stability in
the solid state in an inert atmosphere (mp, 223 °C). This implies
no disproportionation reaction occurred for 4 in the absence of
S8, even upon heat treatment. We further performed a reaction
using 2 and 2.2/8 equiv of S8 to see if the presence of the excess
of S8 as an initiator would lead to the disproportionation of 4. As
a result, CuS was still produced rather than the copper metal and
in the meantime cocrystals of 4 and 5 were isolated, which are
structurally confirmed (Figure 11s of the Supporting Information).
An attempt to isolate the copper sulfide compounds by a direct
reaction of 4 with S8 under varied conditions was yet not
successful, and 5 and CuS were always generated.34 Accordingly,
we assume that the formation of 5 and CuS from the reaction of
4 with S8 or even 1 and 2 respectively, with an excess of S8 might
proceed through a transient state A followed by the ligand
redistribution (Scheme 5).
’ ACKNOWLEDGMENT
This work was supported by the National Nature Science
Foundation of China (20972129 and 91027014) and the Scientific
Research Foundation for ROCS, SEM (2009060011500466), and
for PCOSS (20923004). We thank the reviewers for the helpful
suggestions in this manuscript and also thank Prof. Jun Tao and
associated Prof. Chengbing Ma for helpful discussions on the
magnetic properties of 4 and 5.
’ REFERENCES
(1) (a) Miyoshi, K.; Sugiura, Y.; Ishizu, K.; Iitaka, Y.; Nakamura, H.
J. Am. Chem. Soc. 1980, 102, 6130–6136. (b) Ramli, E.; Rauchfuss, T. B.;
Stern, C. L. J. Am. Chem. Soc. 1990, 112, 4043–4044. (c) Dance, L.;
Fisher, K. In Prog. Inorg. Chem.; Karlin, K. D., Ed.; John Wiley & Sons:
New York, 1994; Vol. 41, pp 637ꢀ803. (d) Holm, R. H.; Kennepohl, P.;
Solomon, E. L. Chem. Rev. 1996, 96, 2239–2314. (e) Messerschmidt, A.
Struct. Bonding (Berlin) 1998, 90, 37–68. (f) Fox, S.; Stibrany, R. T.;
Potenza, J. A.; Knapp, S.; Schugar, H. J. Inorg. Chem. 2000, 39,
4950–4961. (g) Ohta, T.; Tachiyama, T.; Yoshizawa, K.; Yamabe, T.;
Uchida, T.; Kitagawa, T. Inorg. Chem. 2000, 39, 4358–4369. (h) Dehnen,
S.; Eichh€ofer, A.; Fenske, D. Eur. J. Inorg. Chem. 2002, 270–317. (i) York,
J. T.; Bar-Nahum, I.; Tolman, W. B. Inorg. Chem. 2007, 46, 8105–8107.
(2) (a) Tolman, W. B.; Spencer, D. J. E. Curr. Opin. Chem. Biol. 2001,
5, 188–195. (b) Dobbek, H.; Gremer, L.; Kiefersauer, R.; Huber, R.;
Meyer, O. Proc. Natl. Acad. Sci. U.S.A. 2002, 99, 15971–15976.
(c) Haltia, T.; Brown, K.; Tegoni, M.; Cambillau, C.; Saraste, M.;
Mattila, K.; Djinovic-Carugo, K. Biochem. J. 2003, 369, 77–88. (d) Chen.,
P.; Gorelsky, S. I.; Ghosh, S.; Solomon, E. I. Angew. Chem., Int. Ed. 2004,
43, 4132–4140. (e) Henkel, G.; Krebs, B. Chem. Rev. 2004,
104, 801–824. (f) Rorabacher, D. B. Chem. Rev. 2004, 104, 651–697.
(g) Tolman, W. B. J. Biol. Inorg. Chem. 2006, 11, 261–271.
(3) (a) Groysman, S.; Holm, R. H. Inorg. Chem. 2009, 48, 621–627.
(b) Sivasankar, C.; Bera, J. K.; Nethaji, M.; Samuelson, A. G.
J. Organomet. Chem. 2004, 698, 2726–2732.
(4) Santiso-Qui~nones, G.; Br€uckner, R.; Knapp, C.; Dionne, I.;
Passmore, J.; Krossing, I. Angew. Chem., Int. Ed. 2009, 48, 1133–1137.
(5) Helton, M. E.; Chen, P.; Paul, P. P.; Tyeklꢀar, Z.; Sommer, R. D.;
Zakharov, L. N.; Rheingold, A. L.; Solomon, E. I.; Karlin, K. D. J. Am.
Chem. Soc. 2003, 125, 1160–1161.
(6) York, J. T.; Brown, E. C.; Tolman, W. B. Angew. Chem., Int. Ed.
2005, 44, 7745–7748.
(7) Helton, M. E.; Maiti, D.; Zakharov, L. N.; Rheingold, A. L.;
Porco, J. A., Jr.; Karlin, K. D. Angew. Chem., Int. Ed. 2006, 45, 1138–1141.
’ CONCLUSIONS AND REMARKS
In summary, we have reported on the synthesis of the
NNPꢀligand copper(I) complex 1 and its further reaction with
S8. The formation of the copper(II) compound 5 and CuS shows
a stepwise reaction process including the degradation of 1, sulfur
abstraction by the phosphine, and the oxidation state change of
the copper center accompanying with the NNP(S) ligand
redistribution. This result appears different from those reported
by the reactions of the N-chelate ligand-stabilized copper(I)
species with S8.5ꢀ9 This reaction process has been further
detected by the introduction of the N-heterocyclic carbene as a
trapping agent through the formation of the mononuclear
carbene-coordinated 2 and 3 and SdC[N(iPr)CMe]2-disso-
ciated 4 and 5, respectively, based on the strong Lewis donor
character of the carbene in the former two compounds and the
noted sulfur abstraction ability in the latter two ones.3a,11d,16,29
Moreover, the presence of the intramolecular phosphine group
linkage at the N,N-chelate in the NNP ligand allows to reveal such
varied interactions as P Cu, PdSCu, and P+ꢀSꢀCuꢀ, and
3 3 3
these interactions bring the significant structural changes of the
6985
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986

Inorganic Chemistry
ARTICLE
(8) There are a number of the Cu2(μ-η2:η2-S2) core complexes
incorporating various β-diketiminate or anilido-imine ligands, see:
(a) Brown, E. C.; Aboelella, N. W.; Reynolds, A. M.; Aullꢀon, G.; Alvarez,
S.; Tolman, W. B. Inorg. Chem. 2004, 43, 3335–3337. (b) Brown, E. C.;
Bar-Nahum, I.; York, J. T.; Aboelella, N. W.; Tolman, W. B. Inorg. Chem.
2007, 46, 486–496. (c) Bar-Nahum, I.; York, J. T.; Young, V. G., Jr.;
Tolman, W. B. Angew. Chem., Int. Ed. 2008, 47, 533–536. Such a type of
(27) Codding, P. W.; Kerr, K. A. Acta Crystallogr. 1978, B34,
3785–3787.
(28) Yamamura, M.; Kano, N.; Kawashima, T. Inorg. Chem. 2006,
45, 6497–6507.
(29) An, D.; Wang, J.; Dong, T.; Yang, Y.; Wen, T.; Zhu, H.; Lu, X.;
Wang, Y. Eur. J. Inorg. Chem. 2010, 4506–4512.
(30) SdC[N(iPr)CMe]2 has been characterized by mp measure-
ment and 1H NMR spectroscopic analysis and showed the same data as
reported in ref 16.
core compound has also been prepared with the TpiPr2 ligand (TpiPr2
=
hydrotris(3,5-diisopropyl-1-pyrazolyl)borate) by thermal decomposi-
tion of a thiolate complex, see: (d) Fujisawa, K.; Moro-oka, Y.; Kitajima,
N. J. Chem. Soc., Chem. Commun. 1994, 623–624.
(31) (a) MacLennan, M. J.; Darvesh, K. V. Can. J. Chem. 1995,
73, 544–549. (b) Burford, N.; Royan, B. N.; White, P. S. Acta Crystallogr.
Sect. C: Cryst. Struct. Commun. 1990, C46, 274–275.
(9) Brown, E. C.; York, J. T.; Antholine, W. E.; Ruiz, Eliseo; Alvarez,
S.; Tolman, W. B. J. Am. Chem. Soc. 2005, 127, 13752–13753.
(10) Jancik, V.; Peng, Y.; Roesky, H. W.; Li, J.; Neculai, D.; Neculai,
A. M.; Herbst-Irmer, R. J. Am. Chem. Soc. 2003, 125, 1452–1453.
(11) There are reported a lot of phosphine or N,P-chelate copper(I)
complexes, however, their reactions with the elemental sulfur are less
investigated, see: (a) Dempsey, D. F.; Girolami, G. S. Organometallics
1988, 7, 1208–1213. (b) Cheng, Y.; Schiffrin, D. J. Inorg. Chem. 1994,
33, 765–769. (c) Song, H.-B.; Wang, Q.-M.; Zhang, Z.-Z.; Mak, T. C. W.
Chem. Commun. 2001, 1658–1659. (d) Niemeyer, M. Z. Anorg. Allg.
Chem. 2003, 629, 1535–1540. (e) Hughes, G.; Kimura, M.; Buchwald,
S. L. J. Am. Chem. Soc. 2003, 125, 11253–11258. (f) Lipshutz, B. H.;
Shimizu, H. Angew. Chem., Int. Ed. 2004, 43, 2228–2230. (g) Medina, I.;
Jacobsen, H.; Mague, J. T.; Fink, M. J. Inorg. Chem. 2006, 45, 8844–8846.
(h) Goj, L. A.; Blue, E. D.; Delp, S. A.; Gunnoe, T. B.; Cundari, T. R.;
Petersen, J. L. Organometallics 2006, 25, 4097–4104. (i) Mankad, N. P.;
Peters, J. C. Chem. Commun. 2008, 1062–1063. (j) Daly, S.; Haddow,
M. F.; Orpen, A. G.; Rolls, G. T. A.; Wass, D. F.; Wingad, R. L.
Organometallics 2008, 27, 3196–3202. (k) Over, D.; de la Lande, A.;
Zeng, X.; Parisel, O.; Reinaud, O. Inorg. Chem. 2009, 48, 4317–4330.
(l) van Der Vlugt, J. I.; Pidko, E. A.; Vogt, D.; Lutz, M.; Spek, A. L. Inorg.
Chem. 2009, 48, 7513–7515.
(32) Pop, A.; Rotar, A.; Rat, C.; Silvestru, A. Inorg. Chim. Acta 2008,
361, 255–261.
(33) There are a number of the N-chelate Cu(I) complexes which
are stabilized by the donor molecules, indicative of a strong Lewis acidic
metal center, see: (a) Dai, X.; Warren, T. H. Chem. Commun. 2001,
1998–1999. (b) Spencer, D. J. E.; Reynolds, A. M.; Holland, P. L.;
Jazdzewski, B. A.; Duboc-Toia, C.; Rape, L. L.; Yokota, S.; Tachi, Y.;
Itoh, S.; Tolman, W. B. Inorg. Chem. 2002, 41, 6307–6321. (c) Spencer,
D. J. E.; Aboelella, N. W.; Reynolds, A. M.; Holland, P. L.; Tolman, W. B.
J. Am. Chem. Soc. 2002, 124, 2108–2109. (d) Laitar, D. S.; Mathison,
C. J. N.; Davis, W. M.; Sadighi, J. P. Inorg. Chem. 2003, 42, 7354–7356.
(e) Amisial, L. D.; Dai, X.; Kinney, R. A.; Krishnaswamy, A.; Warren,
T. H. Inorg. Chem. 2004, 43, 6537–6539. (f) Badiei, Y. M.; Warren, T. H.
J. Organomet. Chem. 2005, 690, 5989–6000. (g) Aboelella, N. W.;
Gherman, B. F.; Hill, L. M. R.; York, J. T.; Holm, N.; Young, V. G.,
Jr.; Cramer, C. J.; Tolman, W. B. J. Am. Chem. Soc. 2006, 128,
3445–3458.
(34) This reaction was first carried out at room temperature and the
solution color change from deep red to dark brown was immediately
observed. Finally, 5 and CuS were isolated. And then we performed the
reaction by adding a precooled (ꢀ20 °C) toluene solution of 4 to the
similarly treated solution of S8 at ꢀ20 °C without stirring during which
no color change was found. The solution was kept at this temperature for
one week, still affording 5 and CuS.
(12) Han, F.-B.; Zhang, Y.-L.; Li, B.-G.; Guo, Y.-H.; Tang, Y.
Organometallics 2008, 27, 1924–1928.
(13) Yang, Y.; Li, S.; Cui, D.; Chen., X.; Jing, X. Organometallics
2007, 26, 671–678.
(14) (a) He, L.-P.; Liu, J.-Y.; Pan, L.; Wu, J.-Q.; Xu, B.-C.; Li, Y.-S.
J. Polym. Sci., Part A: Polym. Chem. 2009, 47, 713–721. (b) We have
recently prepared the NNP Cr(III) and Bi(III) complexes, unpublished
work.
ꢂ
(15) Eriksson, H.; Hakansson, M. Organometallics 1997, 16, 4243–
4244.
(16) Kuhn, N.; Kratz, T. Synthesis 1992, 561–562.
(17) Sheldrick, G. M. SHELXS-90, Program for Structure Solution;
Acta Crystallogr., Sect. A 1990, 46, 467ꢀ473.
(18) Sheldrick, G. M. SHELXL-97, Program for Crystal Structure
Refinement; University of G€ottingen: G€ottingen, Germany, 1997.
(19) Giri, R.; Hartwig, J. F. J. Am. Chem. Soc. 2010, 132, 15860–15863.
(20) He, X.; Olmstead, M. M.; Power, P. P. J. Am. Chem. Soc. 1992,
114, 9668–9670.
(21) Mohr, B.; Schmidt, J.; Brooks, E. E.; Heeg, M. J.; Ho, D. M.;
Deutsch, E. Inorg. Chem. 1993, 32, 3236–3240.
(22) Tan, G.; Yang, Y.; Chu, C.; Zhu, H.; Roesky, H. W. J. Am. Chem.
Soc. 2010, 132, 12231–12233.
(23) (a) Mehrotra, P. K.; Hoffmann, R. Inorg. Chem. 1978,
17, 2187–2189. (b) Merz, K. M., Jr.; Hoffmann, R. Inorg. Chem. 1988,
27, 2120–2127.
(24) (a) Samantaray, M. K.; Pang, K.; Shaikh, M. M.; Ghosh, P.
Inorg. Chem. 2008, 47, 4153–4165. (b) Strasser, C. E.; Catalano, V. J.
J. Am. Chem. Soc. 2010, 132, 10009–10011.
(25) (a) Minceva-Sukarova, B.; Najdoski, M.; Grozdanov, I.; Chunnilall,
C. J. J. Mol. Struct. 1997, 410ꢀ411, 267–270. (b) Wang, S.-Y.; Wang, W.; Lu,
Z.-H. Mater. Sci. Eng. 2003, 103, 184–188. (c) Xu, K.; Ding, W. Mater. Lett.
2008, 62, 4437–4439. (d) Jin, P.-J.; Yao, Z.-Q.; Zhang, M.-L.; Li, Y.-H.; Xing,
H.-P. J. Raman Spectrosc. 2010, 41, 222–225.
(26) Bouchard, M.; Smith, D. C. Spectrochim. Acta, Part A 2003,
59, 2247–2266.
6986
dx.doi.org/10.1021/ic200008z |Inorg. Chem. 2011, 50, 6979–6986