Reactions of Cu3(dppm)33(μ3-OH) (ClO4)2(dppm=bis-(diphenylphosphino) methane) with Soft Heterocumulenes

Article abstract of DOI:10.1016/j.jorganchem.2004.05.026

The reaction of [Cu₃(dppm)₃(μ₃-OH)] (ClO₄)₂(1) with heterocumulenes (X C S; X = NPh, NMe and S) has been studied. The μ₃-OH ligand inserts into PhNCS and MeNCS only in the presence of metha

Full text of DOI:10.1016/j.jorganchem.2004.05.026

Journal of Organometallic Chemistry 689 (2004) 2726–2732
www.elsevier.com/locate/jorganchem
Note
Reactions of Cu3(dppm)3(l3-OH)(ClO4)2
(dppm=bis-(diphenylphosphino) methane) with
Soft Heterocumulenes
*
C. Sivasankar, J.K. Bera, M. Nethaji, A.G. Samuelson
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Malleswaram, Bangalore 560012, India
Received 6 October 2003; accepted 21 May 2004
Available online 3 July 2004
Abstract
The reaction of [Cu3(dppm)3(l3-OH)](ClO4)2 (1) with heterocumulenes (X‚C‚S; X=NPh, NMe and S) has been studied. The
l3-OH ligand inserts into PhNCS and MeNCS only in the presence of methanol. Insertion products are formed in accord with ear-
lier observations made with copper(I)–aryloxides. On heating, the insertion products convert to a S bridged cluster [Cu4(dppm)4(l4-
S)](ClO4)2 (8), having a tetrameric core. However, in the reaction with CS2, 1 is converted to 8 even at room temperature in the
presence of methanol. On the other hand, the dimeric complex [Cu2(dppm)2(CH3CN)4](ClO4)2, reacts with CS2 to give (diph-
enylphosphinomethyl)-diphenylphosphine sulfide, Ph2P–CH2–P(‚S)Ph2 (dppmS), which forms the complex [Cu(dppmS)2]ClO4
(9). A single crystal X-ray crystallographic study of 9, the first copper(I) complex of dppmS has been taken up to confirm the
mono-oxidation of the dppm ligand and the nuclearity of the complex. Reactions of complex 1 with heterocumulenes and with
elemental sulfur, are compared.
ꢀ 2004 Elsevier B.V. All rights reserved.
Keywords: Heterocumulenes reactions; Cu(I)-dppm; Ligand oxidation; dppmS; Copper(I); Insertion reaction
1. Introduction
aryloxides, especially in their reactions with electro-
philes such as SO2, CO2, and COS [5]. In contrast with
the number of studies on metal alkoxides and arylox-
ides, the chemistry of metal hydroxides is less explored
[6]. In part this is due to the lack of well characterized
hydroxy metal complexes. Recent efforts, primarily by
Bergman and others, have uncovered routes to several
late transition metal hydroxides [7]. Unusual insertion
reactions patterns have been observed. For example,
with the Ir(I) hydroxo complex studied by Werner, a
facile methanol dehydrogenation has been observed in-
stead of simple substitution [8]. In the case of Pt hy-
droxo complexes, both Wacker type insertion
reactions and acid base reactions take place [9] while
Pd hydroxo complexes undergo exchange/insertion
reactions [10]. A dinuclear tungsten complex has been
found to undergo several unusual rearrangements
Late transition metal alkoxides and aryloxides have
been the subject of numerous studies in the last two
decades [1]. Extensive studies done with heterocumu-
lenes indicate the major reaction pathway to be an in-
sertion of the OR group of M–OR fragment into the
more polar double bond of Y‚C‚X [2]. This is fol-
lowed by a rearrangement if necessary to form a M–
X or M–Y bond or even a chelated complex with both
X and Y bonded to M [3,4]. In the recent past, it has
come to light that there could be significant differences
in the reactivity of late transition metal alkoxides and
*
Corresponding author. Tel.: +(080)-293-2663/+91-803-942-663;
fax: +(080)-360-1552/+91-803-601-552.
E-mail address: ashoka@ipc.iisc.ernet.in (A.G. Samuelson).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.05.026

C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
2727
[11]. These studies warrant further investigations of
metal hydroxo complexes.
slower flipping and so the three methylene signals are
differentiated. The phenyl protons resonate from
d 6.98–7.34 ppm. A signal at 9.9 ppm for a single proton
exchanges with D2O and has been assigned to the NH
proton with a sulfur cap (Scheme 1). An alternative ni-
trogen-capped species is not likely as it would have a
much lower d value for the –SH group.
We choose to study copper(I) hydroxo complexes, for
interesting reactivity patterns have emerged from the
mismatch of a hard donor and the soft metal center
Cu(I). Reactions of Cu(I)–aryloxide which has a hard do-
nor coordinated to it reacts with heterocumulenes to give
insertion products [3]. These are followed by rearrange-
ments driven by the tendency of Cu(I) to have soft ligands
around it [3,4]. Similar reactions or increased reactivity is
expected for Cu(I) hydroxides, due to the increased hard-
ness of the ligand. In the light of what has been said of late
transition metal hydroxo complexes and as part of our
continuing study of the reactivity of the Cu(I)–O bond,
we have studied the well-characterized complex
[Cu3(dppm)3(l3-OH)](ClO4)2 [16a] with three heterocu-
mulenes PhNCS, MeNCS, CS2 and for comparison, ele-
mental sulfur. The reactivity of a triply bridging
hydroxide ligand is also interesting for another reason.
It serves as a model for the reactivity of a hydroxide lig-
and coordinated to the surface of metal or metal oxide.
Likewise in a mixture of CH2Cl2 and CH3OH, reaction
of MeNCS gives a pale yellow colored solution. The
NMR and analyses data show the formation of a complex
where MeNCS has inserted into the OH group to give
[Cu3(dppm)3(l3-SC(O)NHCH3)] (7), analogous to 6. At-
tempts to recrystallise 7 from acetonitrile solution led to
the formation of crystalline [Cu2(dppm)2(CH3CN)4]-
(ClO4)2 [4] as the major product. The reversible insertion
of MeNCS has been documented recently in the case of
Cu(I)–aryloxy complexes [3]. Such a ready extrusion of
PhNCS was not observed in the case of complex 6.
In the reaction of [Cu3(dppm)3(l3-OH)](ClO4)2 with
CS2, the insertion product analogous to 6 and 7 is not
isolated and the product isolated has a sulfide capped
cluster. This is surprising since similar adducts have
been isolated in the case of CS2, PhNCS and MeNCS,
in the absence of methanol. This result is also completely
different from the reactivity patterns exhibited by aryl-
oxide ligands [3] and hence unique to the hydroxide lig-
and and CS2. The isolated S-capped tetrameric cluster 8
is known in the literature from the reaction of
[Cu2(dppm)2(NO3)2] with Na2S [13]. This illustrates yet
another unique reaction pathway available to Cu(I)-
dppm complexes and a heterocumulene.
2. Results and discussion
2.1. Reactions of the hydroxo complex
The reaction of a soft heterocumulene (HC) with
[Cu3(dppm)3(l3-OH)](ClO4)2 (1) leads to complexes of
the type [1 HC] in pure dichloromethane. The presence
of one equivalent of PhNCS, MeNCS or CS2 in the
products 3, 4 and 5, respectively, was inferred from an-
alytical data, NMR and IR spectroscopy. Repeated
washing of this product with the solvent did not remove
the heterocumulene from the complex. Since no signifi-
cant changes are observed in the IR stretching frequency
of the heterocumulene in the complex, it is assumed that
the HC is encapsulated in the complex rather than in-
serted into the hydroxide ligand.
One possibility for the reactivity difference is that the
intermediate complex analogous to 6 and 7 transforms
to 8. Complex 7 can indeed be converted to 8 on reflux-
ing in a solution of CH2Cl2 and MeOH. On standing at
room temperature for several days, 3 or 4 also slowly
convert to 8, whereas 5 which contains a volatile hetero-
cumulene does not and reverts to 1 rather than 8.
On the other hand, in a mixture of CH2Cl2/CH3OH,
addition of PhNCS to a solution of [Cu3(dppm)3(l3-
OH)](ClO4)2 immediately results in a color change and
a yellow colored solution is formed. The structure of
the isolated insertion product 6 has been assigned on
the basis of analysis data and the NMR spectra in chlo-
roform. The 31P{1H} NMR value at d ꢀ15.4 ppm is a
good indication that the trimeric moiety, Cu3(dppm)3,
is intact. The 1H NMR spectrum of the isolated product
shows methylene signals at d 3.25 and 4.13 ppm in a 2:1
ratio. This is caused by the methylene groups oriented in
a 2-up and 1-down fashion with respect to the Cu3P6
plane. In the presence of a symmetrical cap like a halo-
gen or acetylide, Cu3(dppm)3 complexes exhibit a single
methylene resonance due to rapid flipping of the methyl-
ene flap of the Cu–P–CH2–P–Cu unit [12]. The very
bulky nature of the cap in complex 1 leads to much
2.2. Reactions of the dimer 2
The dimeric complex 2 is converted to 1 in the presence
of methanol. In the case of PhNCS and MeNCS, the re-
action with 2 is slow and so the conversion of 2–1 takes
place at a comparable rate leading to products 6 and 7.
However the reaction of 2 with CS2 is faster than its con-
version to 1. Addition of CS2 to a CH2Cl2/CH3OH solu-
tion of [Cu2(dppm)2(CH3CN)4(ClO4)2] (2) immediately
results in a red color. After work-up, the major product
was found to be [Cu(dppmS)2]ClO4 (9) which could be
isolated and has been characterized by elemental analy-
sis, IR and NMR spectroscopy (Scheme 2).
1H NMR spectra of 9 in CDCl3 has a single reso-
nance at d 3.73 ppm due to the methylene protons.
The phenyl protons exhibit peaks ranging from d
7.17 to 7.44 ppm along with multiplets at d 7.70–

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C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
[Cu (dppm) OH]
(ClO4)2
3
3
1
CH3OH
CH2Cl2
(1:1)
x=c=y
CH2Cl2
R
[Cu3(dppm)3OH](ClO4)2 X=C=Y
NH
O
X=PhN, Y=S
3
Ph
Ph
X=MeN, Y=S
4
S
P
Ph
CH3OH
CH2Cl2
X=S, Y=S
5
P
[ClO4]2
Ph
Ph
Ph
Ph
Cu
Cu
CS2
P
P
y
Cu
P
Ph
crystalization(7 da s)
CH2Cl2
Ph
P
Ph
Ph
Ph
n-Hexane
(except 5)
6
7
R=Ph
R=Me
=
=
[Cu4(dppm)4S](ClO4)2
8
reflux
24h
CH2Cl2
Scheme 1.
2+
2+
H
Ph
Ph
O
Ph
P
PPh2
Ph2P
P
Ph
Ph
Ph
Cu
P
Cu
MeOH/CH2Cl2 or H2O
MeCN
MeCN
NCMe
NCMe
Ph
P
P
Cu
Ph
Cu
Cu
Ph
P
Ph
Ph
Ph
Ph2P
PPh2
[Cu3(dppm)3(OH)]2+
[Cu2(dppm)2(MeCN)4]2+
1
2
MeOH/CH2Cl2
S8
MeOH/CH2Cl2
CS2
+
Ph
Ph
Ph
P
Ph
S
P
Cu
Ph
MeOH/CH2Cl2
S8
Ph
Ph
P
Ph
P
S
P
P
S
Ph
Ph
Ph
Ph
[Cu(dppms)2]+
S
10
9
+
CuS
Scheme 2.
7.78 ppm. The presence of peaks beyond d 7.6 ppm
suggested the oxidation of P(III) of the dppm ligand
to P(V). The 31P{1H} NMR spectrum of complex 9
in CDCl3 exhibits two well-separated signals at d
ꢀ9.98 and d 50.9 ppm. The signal in the high field re-
gion is characteristic of P(V) and in particular the
(R)Ph2P‚S group [14] coordinated to a metal center.
The other signal is typical of a tertiary phosphorus
center coordinated to Cu(I) [10,14]. The spectroscopic
evidence is clearly indicative of the oxidation of dppm
ligand during the course of reaction, although, not suf-
ficient to distinguish between an unsymmetrically oxi-
The molecular structure of the complex was confirmed
by a single-crystal X-ray structure determination of 9. A
perspective drawing of the cationic part of 9 with selected
atomic numbering scheme is shown in Fig. 1 and the sum-
mary of crystallographic information is given in Table 1.
The molecular structure consists of the cationic [Cu(dpp-
mS)2]+ unit and an isolated ClO4ꢀ. Oxidation of one of
the phosphorus atoms of the dppm ligand to P‚S makes
it a good chelating ligand compared to dppm which can
only function as a bridging ligand with small metal ions.
A mononuclear complex is formed as a result of this
transformation. The coordinating environment around
the copper is distorted tetrahedral with two sulfur and
two phosphorus atoms of two dppmS ligands. The
dised ligand and a mixture of unoxidised and
oxidised ligands coordinated to copper.

C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
2729
sets collected from three different crystals. In spite of these
limitations, the structural study provides better under-
standing of the chemistry of heterocumulenes and their
reaction with the [Cu3(dppm)3OH]2+ cluster (Scheme 2).
Another interesting fact to note is that the addition of
excess CS2 or prolonged reaction times does not lead to
oxidation of the second phosphorus center. Although
the doubly oxidised ligand is known and has been struc-
turally characterized in the complexed form, only the
mono-oxidised product is isolated in this reaction. Such
a preference for mono-oxidation on treatment with ele-
mental sulfur, has been reported for other metals [14].
The formation of a stable five-membered chelate ring
probably hinders further oxidation. The fate of the sec-
ond copper(I) ion is not clear in this reaction.
Fig. 1. ORTEP view of the complex cation of 9 with selected atomic
numbering scheme. Phenyl rings of the dppe and hydrogen atoms are
omitted for clarity. Thermal ellipsoids are shown at the 40%
˚
probability level. Selected bond lengths (A) and angles (ꢁ) for 9:
Cu(1)–P(1) 2.273(2), Cu(1)–P(3) 2.274(2), Cu(1)–S(2) 2.392(3), Cu(1)–
S(1) 2.398(3), S(1)–P(2) 1.975(3), S(2)–P(4) 1.981(3), P(1)–Cu(1)–P(3)
126.88(9), P(1)–Cu(1)–S(2) 112.55(9), P(3)–Cu(1)–S(2) 97.21(8), P(1)–
Cu(1)–S(1) 96.43(8), P(3)–Cu(1)–S(1) 115.90(10), S(2)–Cu(1)–S(1)
107.37(11).
2.3. Reactions of 2 and 1 with elemental S
The transfer of a sulfur atom to the ligand from the
heterocumulene suggested the possibility of adding a sul-
fur atom to the ligand by reaction with elemental sulfur.
Reactions with elemental sulfur were carried out under
similar reaction conditions but with different results. With
the dimeric complex 2, CuS and dppmS2 were isolated. In
this case, the formation of the dppmS complex of copper 9
could not be detected. A similar observation was made
when the trimeric complex was treated with sulfur. A
plausible explanation for this behavior was obtained by
the treatment of [Cu(dppmS)2]ClO4 with sulfur. Under
the reaction conditions, only the free ligand dppmS2
and a brown solid were formed. The brown solid was
shown to be a mixture of sulfides of copper from EDAX
analysis. The dppmS complex is apparently unstable in
the presence of sulfur and converts to CuS.
Table 1
Summary of crystallographic information for complex 9
Crystal data
Complex 9
Empirical formula
Formula weight
C50H44ClCuO4P4S2
995.84
ꢀ
Crystal system, space group
˚
Triclinic, P1
11.473(2)
a (A)
˚
b (A)
˚
c (A)
14.048(2)
15.762(3)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90.60(2)
98.35(2)
107.57(2)
2392.1(7)
1.383
3
˚
V (A)
qcalc (mg/m3)
Z
2
0.777
1028
Absolute coefficient (mmꢀ1
F(000)
)
Crystal size
Range
0.3·0.3·0.2 mm
1.31–24.97ꢁ
8868/8408 (Rint =0.0246)
8408/0/559
1.084
Reflections collected/unique
Data/restraints/parameters
Goodness-of-fit on F2
3. Summary
The reactions carried out here with the hydroxo com-
plex reveals the unique reaction pathways accessible to
copper in the presence of the OH group rather than
the aryloxy group. The importance of a protic solvent
in the reaction of heterocumulenes is also noteworthy.
Since alcohols and phenols have been shown to be in-
volved in hydrogen bonding, the presence of these sol-
vents invoke different reactivity pathways. Lastly, the
heterocumulenes, especially CS2, transfer S in a mild
and effective manner.
Final R1a, wR2b, [I>2r(I)]
R1 =0.0967, wR2 =0.2774
R1 =0.1595, wR2 =0.3027
Final R1a, wR2 (all data)
b
a
R1 ¼ ðRjjF 0j ꢀ jF cjjÞ=ðRjF 0jÞ.
2
2
2
2
2 1=2
b
wR2 ¼ ½RwðjF 0j ꢀ jF cj Þ ꢁ=R½wjF 0j Þ ꢁ
.
P1–Cu1–P3 angle is 126.88(9)ꢁ, higher than the ideal tet-
rahedral value of 109ꢁ. The P1–Cu1–S1 and P3–Cu1–S2
angles (96.43(8)ꢁ and 97.21(8)ꢁ, respectively) are much
less than the ideal tetrahedral values but larger than what
is observed for the same ligand in Rh, and Hg complexes
[14,15]. The copper–phosphorus distances are similar to
that found in other Cu(I)-dppm complexes [12]. The
˚
Cu1–S2 distance is 2.392(3) A while Cu1–S1 is 2.398(3)
4. Experimental
˚
A. There are no inter or intra molecular S–S interactions
in the complex. Carbon atoms of one phenyl ring are con-
siderably disordered and is reflected in the larger R factor.
There was no improvement even after attempts were
made to solve the structure from three independent data
4.1. Materials
Dichloromethane, methanol, petroleum ether and n-
hexane were purified and dried by conventional methods

2730
C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
and distilled under nitrogen. [Cu(CH3CN)4]ClO4 was
freshly prepared before use. (Caution! Perchlorate salts
of metal complexes with organic ligands are potentially ex-
plosive.) Bis(diphenylphosphino)methane, PhNCS and
MeNCS were purchased from Aldrich. Carbondisulfide
was bought from Spectrochem (India).
pressure resulting in a red solid. It was redissolved in
minimum amount of CH2Cl2 and addition of petroleum
ether resulted in the precipitation of the product. The
precipitate was washed with n-hexane to give analytical-
1
ly pure compound 5: Yield 71%; H NMR (200 MHz,
CDCl3, 297 K): d 3.30–3.45 (m, 6H, CH2,), 6.94–7.21
(m, 60H, Ph), 5.31 (2H, CH2Cl2). IR (KBr, cmꢀ1):
1097 (s, br), 623 (m) [ClO4]; 1125 (C‚S): Anal. Calc.
for C77H69Cu3O9P6S2Cl4: C, 53.85; H, 4.05. Found: C,
53.35; H, 4.73%.
4.2. Synthesis
All reactions were carried out in an atmosphere of
dried nitrogen using standard Schlenk and vacuum
line techniques. [Cu3(dppm)3OH](ClO4)2 [16a] and
[Cu2(dppm)2(CH3CN)4](ClO4)2 [16b] were prepared us-
ing the procedure reported in the literature.
4.6. Preparation of [Cu3(dppm)3(SC(O)NHPh)]-
(ClO4)2 (6)
Following procedure used for preparing 3, a solution
of [Cu3(dppm)3OH] (ClO4)2 (0.3 g, 0.023 mmol) in 20 ml
of CH2Cl2 and CH3OH (1:1), PhNCS 0.084 ml (0.07
mmol) were reacted at room temperature. The yellow
4.3. Preparation of [Cu3(dppm)3OH] (ClO4)2 ÆPhNC-
SÆ2CH2Cl2 (3)
1
To a solution of [Cu3(dppm)3OH] (ClO4)2 0.3 g
(0.023 mmol) in 20 ml of CH2Cl2, PhNCS 0.084 ml
(0.07 mmol) was added at room temperature. The mix-
ture immediately turned yellow and was stirred for 8 h
at room temperature. The solvent was removed under
reduced pressure resulting in an oily residue. Trituration
with n-hexane resulted in the precipitation of an yellow
product identified as 3: Yield 79%; 1H NMR (200 MHz,
CDCl3, 297 K): d 3.25–3.49 (m, 6H, CH2), 6.94–7.35 (m,
65H, Ph), 5.31 (4H, CH2Cl2). 31P{1H} NMR (400 MHz,
CDCl3, 297 K): d ꢀ14.6 ppm. IR (KBr, cmꢀ1): 1098 (s,
br), 620 (m) [ClO4]; 2065 (br, N‚C‚S): Anal. Calc. for
C84H76Cu3N1O9P6S1Cl6: C, 54.22; H, 4.12; N, 0.75.
Found: C, 54.43; H, 4.81; N, 1.08%.
product was identified as 6: Yield 75%; H NMR (200
MHz, CDCl3, 297 K): d 4.32 (s, 2H, CH2), 3.1–3.2 (m,
4H, CH2), 6.94–7.34 (m, 65H, Ph), 10.4 (br, 1H, NH).
31P{1H} NMR (400 MHz, CDCl3, 297 K): d ꢀ14.2
ppm. IR (KBr, cmꢀ1): 1092 (s, br), 624 (m) [ClO4]; 510
(C–S); 1450 (C–N); 1550 (C‚O); 3325 (b, N–H): Anal.
Calc. for C82H72Cu3N1O9P6S1Cl2: C, 58.19; H, 4.29; N,
0.83. Found: C, 57.78; H, 4.72; N, 0.69%.
4.7. Preparation of [Cu3(dppm)3(SC(O)NHMe)]-
(ClO4)2 ÆCH2Cl2 ÆCH3OH (7)
To a solution of [Cu3(dppm)3OH] (ClO4)2 0.3 g
(0.023 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
MeNCS 0.048 ml (0.07 mmol) was added at room tem-
perature. Following the procedure reported for 3, gave a
yellow product 7: Yield 73%; 1H NMR (200 MHz,
CDCl3, 297 K): d 3.26–3.50 (m, 6H, CH2), 6.95–7.31
(m, 60H, Ph), 7.81 (br, 1H, NH). 5.30 (2H, CH2Cl2),
3.49 (3H, CH3OH). 31P{1H} NMR (400 MHz, CDCl3,
297 K): d ꢀ13.9 ppm. IR (KBr, cmꢀ1): 1092 (s, br),
623 (m) [ClO4]; 507 (C–S); 1450 (C–N); 1625 (C‚O);
3250 (b, N–H): Anal. Calc. for C79H76Cu3-
N1O10P6S1Cl4: C, 53.91; H, 4.18; N, 0.79. Found: C,
53.71; H, 4.59; N, 1.71%.
4.4. Preparation of [Cu3(dppm)3OH] (ClO4)2 ÆMeNC-
SÆ2CH2Cl2 (4)
Following the procedure adopted for obtaining 3, the
reaction of [Cu3(dppm)3OH] (ClO4)2 0.3 g (0.023 mmol)
in 20 ml of CH2Cl2 with MeNCS 0.048 ml (0.07 mmol)
gave compound 4: Yield 76%; 1H NMR (200 MHz,
CDCl3, 297 K): d 3.2–3.51 (m, 6H, CH2, 3H, CH3),
6.94–7.26 (m, 60H, Ph), 5.31 (4H, CH2Cl2). 31P{H}
NMR (400 MHz, CDCl3, 297 K): d ꢀ14.2 ppm. IR
(KBr, cmꢀ1): 1092 (s, br), 623 (m) [ClO4]: 2055 (br,
N‚C‚S): Anal. Calc. for C79H74Cu3N1O9P6S1Cl6: C,
52.63; H, 4.08; N, 0.78. Found: C, 51.48; H, 4.75; N,
1.53%.
4.8. Reaction of [Cu3(dppm)3OH] (ClO4)2 with CS2
(8)
To a solution of [Cu3(dppm)3OH] (ClO4)2 0.3 g
(0.023 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
CS2 0.042 ml (0.07 mmol) was added at room tempera-
ture and the yellow mixture stirred for 8 h at room tem-
perature. The solvent was removed under reduced
pressure to give a yellow solid. The solid was redissolved
in a minimum amount of CH2Cl2 and addition of petro-
leum ether resulted in the precipitation of the product.
which was washed with n-hexane to give pure 8
4.5. Preparation of [Cu3(dppm)3OH] (ClO4)2 ÆC-
S2 ÆCH2Cl2 (5)
To a solution of [Cu3(dppm)3OH] (ClO4)2 0.3 g
(0.023 mmol) in 20 ml of CH2Cl2, CS2 0.042 ml (0.07
mmol) was added at room temperature the mixture
turned red immediately and was stirred for 8 h at room
temperature. The solvent was removed under reduced

C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
2731
[Cu4(dppm)4S] (ClO4)2: Yield 85%; 1H NMR (200 MHz,
CDCl3, 297 K): d 3.21 (s, 4H, CH2), 3.36 (s, 4H, CH2),
6.91–7.19 (m, 80H, Ph). Anal. Calc. for C100H88Cu4
O8P8S1Cl2: C, 59.38; H, 4.38. Found: C, 59.28; H,
4.43%.
removed by filtration, this contains 50.13% of copper,
39.38% of sulfur and 10.47% of chloride by EDAX anal-
ysis, the solvent from the filtrate removed under reduced
pressure resulting in a white solid 7(C25H22P2S2); yield
92%: H NMR (200 MHz, CDCl3, 297 K): d 4.23 (2H,
CH2), 7.26–7.39 (m, 16H, Ph), 7.62–7.69 (4H, Ph): IR
(KBr, cmꢀ1): 610 (s, P‚S).
1
4.9. Reaction of [Cu2(dppm)2(CH3CN)4] (ClO4)2 with
PhNCS
4.13. Reaction of [Cu2(dppm)2(CH3CN)4] (ClO4)2
with S8
To a solution of [Cu2(dppm)2(CH3CN)4] (ClO4)2 0.15
g (0.117 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
PhNCS 0.042 ml (0.351 mmol) was added at room tem-
perature. The mixture immediately turned yellow and
was stirred for 8 h at room temperature. The solvent
was removed under reduced pressure resulting in an oily
residue identified as 6 from spectroscopic data. Tritura-
tion with n-hexane resulted in the precipitation of 6 in
78% yield.
To a solution of [Cu2(dppm)2(CH3CN)4] (ClO4)2 0.15
g (0.117 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1), S8
0.120 g (0.468 mmol) was added at room temperature.
After stirring for a period of 8 h at room temperature,
a brown solid precipitated out leaving behind a colorless
solution. The brown solid was removed by filtration, the
filtrate was concentrated and dried under reduced pres-
sure to give compound 10; (73% yield).
4.10. Reaction of [Cu2(dppm)2(CH3CN)4] (ClO4)2
with MeNCS
4.14. Reaction of [Cu(dppmS)2] ClO4 with S8
To a solution of [Cu2(dppm)2(CH3CN)4] (ClO4)2 0.15
g (0.117 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
MeNCS 0.024 ml (0.07 mmol) was added at room tem-
perature. On stirring for 10 min, the reaction mixture
turned light yellow and was further stirred for 8h at
room temperature. The solvent was removed under re-
duced pressure resulting in an oily residue. Trituration
with n-hexane resulted in the precipitation of 7 as an yel-
low solid (Yield 72%).
To a solution of [Cu(dppmS)2] ClO4: 0.1 g (0.1 mmol)
in 20 ml of CH2Cl2 and CH3OH (1:1), S8 0.102 g (0.4
mmol) was added and after a period of stirring for 8 h
at room temperature, a brown solid was precipitated leav-
ing a colorless solution. The brown solid was removed by
filtration, the solvent was removed from the filtrate under
reduced pressure to give compound 10; (94% yield).
4.15. X-ray structure determination
4.11. Reaction of [Cu2(dppm)2(CH3CN)4] (ClO4)2
with CS2 to give [Cu4(dppm)4S](ClO4)2 (8)
Crystals of complex 9 suitable for diffraction studies
were glued to the tip of glass fibers and transferred to a
computer controlled Enraf-Nonius CAD4 diffractometer
equipped with graphite-monochromatized Mo Ka radia-
tion. The intensity data were collected and corrected for
Lorentz, polarization and absorption effects using DI-
FABS. The positions of the heavy atoms were determined
by Patterson methods using SHELXS-86 [17]. The remain-
ing atoms were located from difference Fourier analysis
using SHELXTL-97 [18]. Carbon atoms C2, C3, C11 and
C12 on the phenyl ring attached to P1 showed positional
disorder and so they were assigned sharing occupancy
and refined isotropically using constraints. H atoms at-
tached to these carbons could neither be located nor
fixed. Hydrogen atoms were included in the final stage
of the refinement on calculated positions bonded to their
carrier atoms. All crystallographic computations were
performed using the WINGX package [19].
To a solution of [Cu2(dppm)2(CH3CN)4] (ClO4)2 0.15
g (0.117 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
CS2 0.021 ml (0.07 mmol) was added at room tempera-
ture. On stirring for 10 min, the reaction mixture turned
light yellow and was further stirred for 8 h at room tem-
perature. The solvent was removed under reduced pres-
sure to give compound 9 [Cu(dppmS)2] ClO4: Yield
43.5% with respect to copper; 1H NMR (200 MHz,
CDCl3, 297 K): d 3.73 (m, 4H, CH2), 7.15–7.47 (m,
32H, Ph), 7.67–7.76 (8H, Ph); Anal. Calc. for
C50H54CuO4P4S2Cl: C, 60.30; H, 4.45. Found: C,
60.39; H, 4.57%. CCDC 217020.
4.12. Reaction of [Cu3(dppm)3OH] (ClO4)2 with S8
To a solution of [Cu3(dppm)3OH] (ClO4)2 0.3 g
(0.023 mmol) in 20 ml of CH2Cl2 and CH3OH (1:1),
S8 0.024 mg (0.092 mmol) was added at room tempera-
ture and the mixture turned yellow. After stirring for 8 h
at room temperature, a brown solid precipitated out and
a colorless solution remained. The brown solid was
Acknowledgement
This work was supported by a grant from CSIR (New
Delhi).

2732
C. Sivasankar et al. / Journal of Organometallic Chemistry 689 (2004) 2726–2732
Appendix A. Supplementary material
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Crystallographic data (excluding structural factors)
for the structural analysis of 9, has been deposited with
the Cambridge Crystallographic Data Centre, CCDC
No. 217020. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-
336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk). Supplementary data asso-
ciated with this article can be found, in the online ver-
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