Copper(I) complexes of a thioether-functionalized short-bite aminobis(phosphonite), [PhN{P(-OC10H6(μ-S)C10H6O-)}2]

Article abstract of DOI:10.1016/j.poly.2008.10.014

Copper(I) complexes of short-bite aminobis(phosphonite), PhN{P(-OC₁₀H₆(μ-S)C₁₀H₆O-)}₂ (1) have been synthesized. Reactions of 1 with an excess of CuX (X = Cl, Br, and I) afforded the ligand-bridged bi

Full text of DOI:10.1016/j.poly.2008.10.014

Polyhedron 28 (2009) 101–106
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Polyhedron
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Copper(I) complexes of a thioether-functionalized short-bite
aminobis(phosphonite), [PhN{P(–OC10H6(l-S)C10H6O–)}2]
Benudhar Punji a, Joel T. Mague b, Shaikh M. Mobin c, Maravanji S. Balakrishna a,
*
a Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
b Department of Chemistry, Tulane University, New Orleans, LA 70118, USA
c National Single Crystal X-ray Facility Center, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 5 June 2008
Accepted 14 October 2008
Available online 20 November 2008
Copper(I) complexes of short-bite aminobis(phosphonite), PhN{P(–OC10H6(
synthesized. Reactions of 1 with an excess of CuX (X = Cl, Br, and I) afforded the ligand-bridged binuclear
complexes, [PhN(PR- P)2{Cu( -X)(MeCN)}2] (2, X = Cl; 3, X = Br; 4, X = I; R = –OC10H6( -S)C10H6O–),
whereas treatment with 0.5 equiv. of [Cu(MeCN)4]PF6 produces the mononuclear bischelated cationic
complex, [{PhN(PR- P)2}2Cu](PF6) (5). Single crystal X-ray structures of complexes 3 and 4 are reported.
Complex 3 shows strong stacking interactions between the naphthyl moieties, whereas complex 4
shows ligand-supported CuÁ Á ÁCu metallophilic interactions.
l-S)C10H6O–)}2 (1) have been
j
l
l
j
Keywords:
Aminobis(phosphonite)
p–p stacking interactions
Metallophilic interactions
p–p
Ó 2008 Elsevier Ltd. All rights reserved.
Copper complexes
Short-bite ligands
1. Introduction
mylation of styrene [5]. However, diphosphazanes with donor
atoms such as O, N or S incorporated into the ligand framework
are less well known [6]. The development of such hybrid ligands
is of particular significance because they can generate interesting
coordination chemistry mainly for the synthesis of heterobimetallic
and high-nuclearity complexes. In this context, we have recently
Short-bite ligands have drawn considerable attention over the
last three decades owing to their novelty in organometallic chem-
istry and catalytic applications [1]. In such bidentate ligands, the
donor atoms are generally separated by a single atom fragment
such as CR2, NR, O or S and can coordinate to metal centers in
monodentate, chelating or bridging modes. In mononuclear chelate
complexes, the ligand forms a highly strained four-membered ring
with conformational rigidity whereas the bridging coordination
mode brings the two metal centers into close proximity to facili-
tate a cooperative metallophilic interaction between two or more
metal centers [2f]. Both of these factors, either conformational
rigidity or metallophilic interaction, can activate the substrate
molecules during catalysis [2]. Among the short-bite ligands, the
P–C–P framework i.e. bis(diphenylphosphino)methane (dppm)
and similar diphosphines has been widely investigated and
achieved considerable success [1c,3]. In contrast, although the
coordination chemistry of P–N–P framework ligands i.e. diphosp-
hazane (or diphosphinoamine) has been well documented [1d,4],
their catalytic applications have been much less explored.
Recently, Faraone and co-workers have prepared diphosphazane li-
gands containing a dinaphthyl backbone between the phosphorus
centers and used them in the enantioselective palladium-catalyzed
allylic substitution reactions and the rhodium catalyzed hydrofor-
synthesized
PhN{P(–OC10H6(
a
thioether-functionalized aminobis(phosphonite),
-S)C10H6O–)}2 (1) and reported its reactivity with
l
platinum metals where it exhibits interesting coordination behav-
iors producing neutral, cationic and anionic complexes (Chart 1)
which show excellent catalytic activities [7].
Here we sought to examine the reactivity of this thioether-func-
tionalized aminobis(phosphonite) with copper(I) derivatives as
their complexes can be ideal candidates for luminescence studies.
The dinaphthyl moiety was chosen as it is well known for exhibit-
ing aromatic–aromatic
p-stacking interactions which in turn can
contribute to self assembly or molecular recognition processes [8].
As a part of our research in organometallic chemistry [9] and
catalytic investigation [10] of phosphorus-based ligands, we report
in this paper the copper(I) complexes of thioether-functionalized
aminobis(phosphonite) (1).
2. Results and discussion
2.1. Copper derivatives
In our recent investigation on the coordination behavior of thi-
oether-aminobis(phosphonite) 1 with platinum metal precursors,
interesting anionic complexes with phosphorus and sulfur coordi-
* Corresponding author. Tel.: +91 22 2576 7181; fax: +91 22 2576 7152/2572/
3480.
E-mail addresses: krishna@chem.iitb.ac.in, msb_iitb@yahoo.com (M.S. Balakrishna).
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.10.014

102
B. Punji et al. / Polyhedron 28 (2009) 101–106
Ph
N
O
O
+
OTf
-
O
N
+
O
O
O
O
Et3 NH
O
P
P
Cl
Cl
Pd
Pd
P
P
S
P
P
O
O
O
O
O
O
-
S
S
Cl
O
O
Pd
Pd
S
Cl
II
III
I
O
O
O
=
S
O
Chart 1.
nation as well as neutral platinum complexes with highly strained
four-membered chelate rings were produced and their catalytic
applications were explored [7]. However, the reactivity of
aminobis(phosphonite) with group 11 metal precursors is consid-
erably different. Thus the reaction of 1 with an excess of CuX
(X = Cl, Br, and I) in dichloromethane and acetonitrile afforded
structure determinations are given in Table 1 while selected bond
lengths and bond angles appear in Table 2.
In the molecular structures of 3 and 4, the molecules consist of
two copper atoms linked by one bridging aminophosphonite ligand
and two bridging halides (bromide or iodide) with one acetonitrile
coordinated to each copper center. Complex 3 has crystallograph-
ically-imposed mirror symmetry with all Cu, P, S and N atoms lying
on the mirror. In both the complexes, the copper centers display
distorted tetrahedral geometry with internal angles in the range
99.04(2)–115.13(2)° for complex 3 and 97.17(1)–127.82(1)° for
complex 4. The Cu–P distances (Cu1–P1 = 2.185(1), Cu2–
P2 = 2.194(1) Å for 3 and Cu1–P1 = 2.214(1), Cu2–P2 = 2.220(1) Å
for 4) are shorter than those shown by other polynuclear copper
(I) complexes containing dppm (Cu–P ꢀ 2.277(6) Å) and dppf
the corresponding binuclear complexes, [PhN(PR-
jP)2{Cu(l-X)
(MeCN)}2], (2, X = Cl; 3, X = Br; 4, X = I; R = ÀOC10H6(
l-S)C10H6O–)
(Scheme 1). The bromo and iodo derivatives are highly soluble in
dichloromethane whereas the chloro derivative is only partially solu-
ble in dichloromethane. The 31P NMR spectra of complexes 2–4 show
single resonances at 102.9, 94.9 and 91.8 ppm, respectively. In the 1H
NMR spectra of all these complexes, a singlet is observed in the region
2.01–2.16 ppm which is assigned to the protons of the coordinated
acetonitrile groups. Treatment of CuX with 1 equiv. of 1 did not give
the four-membered chelate complexes; instead the same binuclear
complexes 2–4 are obtained in excellent yield. The reaction of 1 with
0.5 equiv. of [Cu(MeCN)4]PF6 produces the mononuclear bischelated
(Cu–P ꢀ 2.306(7) Å) ligands [11]. The CuÁ Á ÁCu distance in
3
(2.800(1) Å) is significantly longer than that in 4 (2.638(7) Å) with
the latter somewhat shorter than the value of 2.695(1) Å found in
[(PhN(PR2)2Cu2(
However, the span of CuÁ Á ÁCu separations in {Cu(
moieties containing P–N–P type ligands is rather large and
includes values of 2.742(2) Å in [(MeCN)2(Cu( -Br)2Cu)((R2P)2
NC6H4N(PR2)2) (Cu( -Br)2Cu) (MeCN)2] and 2.920(3) and
2.941(3) Å in [(L)2(Cu( -I)2Cu)((R2P)2NC6H4N(PR2)2)(Cu( -I)2Cu)
l
-Br)2(L)]n (R = o-MeOC6H4O; L = 4,4’-bipy) [12a].
cationic complex, [{PhN(PR-
NMR spectrum of complex
j
P)2}2Cu](PF6) (5) in good yield. The 31P
shows single resonance at
l-X)2Cu}
5
a
100.7 ppm for the phosphorus of the aminobis(phosphonite) and a
l
1
À
septet at À145.9 ppm for the PF6 group with a JPF coupling of
713 Hz. The structures of 3 and 4 are confirmed by single crystal
X-ray diffraction studies.
l
l
l
(L)2] (R = o-MeOC6H4O; L = HNC5H9C3H3N2 [12b]. These last com-
pare favorably with those found in trinuclear complexes of the
2.2. Crystal structures of complexes 3 and 4
type [Cu3(l3
-
g
1-C@CR)(
l
-dppm)n] (CuÁ Á ÁCu = 2.997(3) Å) [11a].
In the case of complex 3, the eight-membered ring containing
phosphorus and sulfur atoms is in the anti chair-like conformation
and the sulfur atom lies far away from the copper center thus pre-
venting any SÁ Á ÁCu interaction. In contrast, the phosphorus- and
Perspective views of the molecular structures of complexes 3
and 4 with the atom numbering schemes are shown in Figs. 1
and 2, respectively. The crystallographic data and details of the
-
PF6
O
O
O
O
Ph
N
Ph
N
P
P
O
O
P
P
O
O
+
Cu
O
O
O
O
CuX
[Cu(MeCN)4]PF6
P
S
Ph
P
Ph
N
N
P
P
X
X
1
Cu
Cu
O
O
O
O
O
O
O
O
NCMe
MeCN
=
2 X= Cl
3 X= Br
4 X= I
5
Scheme 1.

B. Punji et al. / Polyhedron 28 (2009) 101–106
103
Fig. 1. (a) Molecular structure of 3. For clarity, solvent and all hydrogen atoms have been omitted. (b) Molecular structure of 3 showing p–p stacking interactions.
Fig. 2. Molecular structure of 4. For clarity, solvent and all hydrogen atoms have been omitted.

104
B. Punji et al. / Polyhedron 28 (2009) 101–106
Table 1
H26cÁ Á ÁCg(ring) = 2.71 Å; 151° (intramolecular) and C26–
Crystallographic data for complexes 3 and 4.
H26aÁ Á ÁCg (ring at x, ½ À y, z) = 2.67 Å; 158°) as well as weak
C–HÁ Á ÁBr interactions (C6–H6Á Á ÁBr (at 1 À x, Ày, Àz) = 2.90 Å;
177° and C16–H16Á Á ÁBr (at Àx, Ày, 1 À z) = 2.91 Å; 157°). Complex
4 shows a weak C37–H37Á Á ÁO1 (at 1 À x, 1 À y, Àz) interaction
(2.67 Å; 162°) as well as intermolecular C–HÁ Á ÁI interactions with
the acetonitrile ligands in two adjacent molecules (I1Á Á ÁH48c–
C48 (at 1 À x, 1 À y, 1 À z) = 3.05 Å; 176° and I1Á Á ÁH50b–C50b (at
2 À x, 1 À y, 1 À z) = 3.14 Å; 157°.
3
4
Formula
C50H35Br2Cu2N3O4P2S2
.CH3CN
1195.9
C50H35I2N3O4P2S2Cu2
Mol. wt.
Crystal system
Crystal size (mm)
Space group
a (Å)
1248.8
monoclinic
0.06 Â 0.07 Â 0.12
P21/m (no. 11)
12.482(1)
14.214(1)
13.847(1)
98.965(1)
2426.7(3)
2
1.662
2.754
1215
100
monoclinic
0.35 Â 0.28 Â 0.21
P21/n
13.722(1)
29.801(5)
14.010(2)
114.947(8)
5194.3(2)
4
1.643
2.199
2536
293(2)
b (Å)
c (Å)
3. Conclusion
b (°)
V (Å3)
Copper(I) complexes of
obis(phosphonite) ligand have been synthesized. The amin-
obis(phosphonite) 1, which contains hemilabile thioether
a thioether-functionalized amin-
Z
qcalc. (g cmÀ3
)
l
(Mo K
a
), (mmÀ1
)
a
F(000)
Temperature (K)
functionality, shows versatile coordination properties. By choosing
appropriate metal reagents and reaction conditions both mononu-
clear and bridged binuclear complexes are obtained. In the solid
hmin–max (°)
1.5, 28.3
0.72
0.0467
3.00, 25.00
0.993
0.0492
Goodness-of-fit (F2)
a
R1
state complex 3 shows strong
p–p stacking interactions while in
b
wR2
0.1274
0.0921
complex 4 there is a significant ligand-supported metallophilic
interactions.
P
P
a
R1
=
|Fo| À |Fc|/ |Fo|.
P
P
b
wR2 = { w[(F2o À F2c)2]/ [w(F2o)2]}1/2
.
4. Experimental
Table 2
Selected bond distances (Å) and bond angles (°) for complexes 3 and 4.
All experimental manipulations were carried out under an
atmosphere of dry nitrogen or argon using Schlenk techniques. Sol-
vents were dried and distilled prior to use by conventional meth-
ods. Aminobis(phosphonite) (1) [7a], CuX (X = Cl, Br) [14] and
[Cu(MeCN)4PF6] [15] were prepared according to the published
procedures. Other reagents were obtained from commercial
sources and used after purification. The 1H and 31P{1H} NMR (d in
ppm) spectra were obtained on a Varian VRX 400 spectrometer
operating at frequencies of 400 and 162 MHz, respectively. The
spectra were recorded in CDCl3 (or DMSO-d6) solutions with CDCl3
(or DMSO-d6) as an internal lock; TMS and 85% H3PO4 were used as
internal and external standards for 1H and 31P{1H} NMR, respec-
tively. Positive shifts lie downfield of the standard in all of the cases.
Microanalyses were carried out on a Carlo Erba (Model 1106) ele-
mental analyzer. Melting points of all compounds were determined
on Veego melting point apparatus and were uncorrected.
Complex 3
Complex 4
Cu1–Br
Cu2–Br
Cu1–P1
Cu2–P2
Cu1–N2
Cu2–N3
P1–N1
2.513(6)
2.502(5)
2.185(1)
2.194(1)
1.996(4)
1.995(5)
1.679(4)
1.681(4)
2.801
Cu1–I1
Cu1–I2
Cu2–I2
Cu2–I1
Cu1–P1
Cu2–P2
Cu2–N3
Cu1–N2
P1–N1
2.641(6)
2.750(7)
2.660(6)
2.700(7)
2.214(1)
2.220(1)
1.997(4)
1.995(3)
1.698(3)
1.695(3)
2.638(7)
P2–N1
Cu1Á Á ÁCu2
P2–N1
Cu1Á Á ÁCu2
Cu1–Br–Cu2
Br–Cu1–P1
Br–Cu1–N2
Br–Cu1–Bri
P1–Cu1–N2
Br–Cu2–P2
Br–Cu2–N3
Br–Cu2–Bri
P2–Cu2–N3
P1–N1–P2
67.89(2)
110.43(3)
110.33(8)
99.04(2)
115.13(2)
108.67(3)
112.76(7)
99.62(2)
113.42(1)
116.5(2)
122.7(3)
120.7(3)
Cu1–I1–Cu2
Cu2–I2–Cu1
I1–Cu1–I2
P1–Cu1–I1
P1–Cu1–I2
N2–Cu1–P1
N2–Cu1–I2
I1–Cu2–I2
P2–Cu2–I1
P2–Cu2–I2
N3–Cu2–P2
N3–Cu2–I1
P1–N1–P2
P1–N1–C41
P2–N1–C41
59.171(2)
58.330(2)
114.01(2)
109.62(3)
101.22(3)
127.73(1)
97.17(1)
115.04(2)
103.71(3)
105.77(3)
127.82(1)
102.19(1)
120.02(2)
120.1(2)
4.1. Synthesis of [PhN(PR-jP)2{Cu(l-Cl)(MeCN)}2]
(2, R = –OC10H6(-S)C10H6O–)
A solution of CuCl (0.030 g, 0.303 mmol) in acetonitrile (4 ml)
was added dropwise to a solution of 1 (0.059 g, 0.076 mmol) in
dichloromethane (10 ml) and the reaction mixture was stirred for
1 h. The suspension was filtered to remove unreacted CuCl and
the mother liquor was concentrated under vacuum, to give a crys-
talline product 2 at À25 °C. Yield: 85% (0.069 g), m.p.: 194–196 °C
P1–N1–C21
P2–N1–C21
119.8(2)
3
(dec.). 1H NMR (400 MHz, DMSO-d6): d 8.70 (d, 4H, JHH = 9.2 Hz,
sulfur-containing eight-membered rings in complex 4 are in a syn
boat-like conformation which places the sulfur atoms syn to the
four-membered Cu2I2 ring. As the Cu1Á Á ÁS1 (3.459(8) Å) and
Cu2Á Á ÁS2 (3.438(8) Å) separations are noticeably less than the
sum of the corresponding van der Waals radii (4.12 Å), attractive
CuÁ Á ÁS interactions are likely present. In the solid state 3 shows a
Ar), 7.51–7.95 (m, 20H, Ar, 5H, Ph), 2.10 (s, 6H, CH3CN). 31P{1H}
NMR (121.4 MHz, DMSO-d6):
d 102.9 (s). Anal. Calc. for
C50H35Cl2N3O4P2S2Cu2: C, 56.34; H, 3.31; N, 3.94; S, 6.02. Found:
C, 56.31; H, 3.29; N, 3.92; S, 5.99%.
4.2. Synthesis of [PhN(PR-jP)2{Cu(l-Br)(MeCN)}2] (3)
strong
p-p stacking interaction-ring involving the C1–C3;C8–C10
portion of one naphthyl group and the C11–C13;C18–C20 portion
of the one in the molecule at 1 À x, Ày, 1 À z. There is a 9.91° dihe-
dral angle between the mean planes of these two rings and the
distance between their centroids (Cg) is 3.489(2) Å while the per-
pendicular distance from the Cg of the latter ring to the mean plane
of the former is 3.299(3) Å [13]. In addition, there are C–HÁ Á ÁCg
This was synthesized by a procedure similar to that for 2 using
CuBr (0.050 g, 0.348 mmol) and 1 (0.068 g, 0.087 mmol). Yield: 87%
(0.087 g), m.p.: 210 °C (dec.). 1H NMR (400 MHz, CDCl3): d 8.51 (d,
3
4H, JHH = 8.8 Hz, Ar), 7.11–7.56 (m, 16H, Ar, 5H, Ph), 7.01 (d, 4H,
3JHH = 8.8 Hz, Ar), 2.16 (s, 6H, CH3CN). 31P{1H} NMR (162 MHz,
CDCl3): d 94.9 (s). Anal. Calc. for C50H35Br2N3O4P2S2Cu2: C, 52.00;
H, 3.05; N, 3.64; S, 5.55. Found: C, 51.97; H, 2.99; N, 3.62; S, 5.51%.
(p
-ring) interactions involving the acetonitrile attached to Cu1
and the C3–C8 portion of one naphthyl group (C26–

B. Punji et al. / Polyhedron 28 (2009) 101–106
105
4.3. Synthesis of [PhN(PR-jP)2{Cu(l-I)(MeCN)}2] (4)
Appendix A. Supplementary data
This was synthesized by a procedure similar to that for 2 using
CuI (0.050 g, 0.315 mmol) and 1 (0.062 g, 0.079 mmol). Yield: 91%
(0.09 g), m.p.: 174 °C (dec.). 1H NMR (400 MHz, CDCl3): d 8.87 (d,
CCDC 673994 and 673995 contain the supplementary crystallo-
graphic data for 3 and 4. These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail: de-
posit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/j.poly.
2008.10.014.
3
4H, JHH = 9.2 Hz, Ar), 6.67–7.86 (m, 20H, Ar, 5H, Ph), 2.01 (s, 6H,
CH3CN). 31P{1H} NMR (162 MHz, CDCl3): d 91.8 (s). Anal. Calc. for
C50H35I2N3O4P2S2Cu2: C, 48.09; H, 2.82; N, 3.36; S, 5.14. Found: C,
48.02; H, 2.79; N, 3.34; S, 5.11%.
4.4. Synthesis of [{PhN(PR-jP)2}2Cu](PF6) (5)
References
To a solution of 1 (0.084 g, 0.107 mmol) in dichloromethane
(12 ml) Cu(MeCN)4PF6 (0.020 g, 0.054 mmol) was added and the
reaction mixture was stirred for 2 h. The colorless solution ob-
tained was concentrated and diethyl ether (8 ml) was added to
precipitate out the white product. This was then filtered off and
dried under vacuum. Yield: 89% (0.085 g), m.p.: 180 °C (dec.). 1H
[1] (a) G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.), Comprehensive
Organometallic Chemistry, Pergamon Press, Oxford, 1982;
(b) L.H. Pignolet (Ed.), Homogeneous Catalysis with Metal Phosphine
Complexes, Plenum, New York, 1983, p. 167;
(c) B. Chaudret, B. Delavaux, R. Poilblanc, Coord. Chem. Rev. 86 (1988) 191;
(d) M.S. Balakrishna, V.S. Reddy, S.S. Krishnamurthy, J.F. Nixon, J.C.T.R.B. St.
Laurent, Coord. Chem. Rev. 129 (1994) 1;
3
NMR (400 MHz, CDCl3): d 8.49 (d, 8H, JHH = 7.6 Hz, Ar), 7.14–
8.23 (m, 40H, Ar, 10H, Ph). 31P{1H} NMR (162 MHz, CDCl3): d
(e) M. Witt, H.W. Roesky, Chem. Rev. 94 (1994) 1163.
[2] (a) D.J. Anderson, K.W. Kramarz, R. Eisenberg, Inorg. Chem. 35 (1996) 2688;
(b) G. Francio, R. Scopelliti, C.G. Arena, G. Bruno, D. Drommi, F. Faraone,
Organometallics 17 (1998) 338;
1
100.7 (s, 4 P), À145.9 (septet, 1P, PF6, JPF = 713 Hz). Anal. Calc.
for C92H58F6N2O8P5S4Cu: C, 62.07; H, 3.28; N, 1.57; S, 7.21. Found:
C, 62.01; H, 3.25; N, 1.53; S, 7.18%.
(c) A. Scrivanti, V. Beghetto, E. Campagna, M. Zanato, U. Matteoli,
Organometallics 17 (1998) 630;
(d) J.R. Torkelson, F.H. Antwi-Nsiah, R. Mc Donald, M. Cowie, J.G. Pruis, K.J.
Jalkanen, R.L. DeKock, J. Am. Chem. Soc. 121 (1999) 3666;
(e) Y. Gao, J.K. Kuncheria, H.A. Jenkins, R.J. Puddephatt, G.P.A. Yap, J. Chem.
Soc., Dalton Trans. (2000) 3212;
5. X-ray crystallography
A crystal of 3 which proved to be twinned was mounted in a
(f) G.A. Bowmaker, J.V. Hanna, R.D. Hart, P.C. Healy, A.H. White, J. Chem. Soc.,
Dalton Trans. (1994) 2621 and references cited therein.
[3] R.J. Puddephatt, Chem. Soc. Rev. 12 (1983) 99.
CryoloopTM with a drop of Paratone oil and placed in the cold nitro-
TM
gen stream of the Kryoflex attachment of the Bruker APEX CCD
diffractometer. A full sphere of data was collected using 606 scans
[4] (a) R.B. King, Acc. Chem. Res. 13 (1980) 243;
(b) T. Appleby, J.D. Woollins, Coord. Chem. Rev. 235 (2002) 121.
[5] (a) G. Calabrò, D. Drommi, G. Bruno, F. Faraone, Dalton Trans. (2004) 81;
(b) G. Calabrò, D. Drommi, C. Graiff, F. Faraone, A. Tiripicchio, Eur. J. Inorg.
Chem. (2004) 1447.
[6] (a) R.P. Kamalesh Babu, S.S. Krishnamurthy, M. Nethaji, J. Organomet. Chem.
454 (1993) 157;
in
x (0.3° per scan) at U = 0°, 120° and 240° using the SMART soft-
ware package [16]. The raw data were reduced to F2 values using
the SAINT+ software [17] and a global refinement of unit cell param-
eters using 9500 reflections chosen from the full data set was per-
formed. Multiple measurements of equivalent reflections provided
the basis for an empirical absorption correction as well as a correc-
tion for any crystal deterioration during the data collection
(b) R.P. Kamalesh Babu, S.S. Krishnamurthy, M. Nethaji, Tetrahedron:
Asymmetry 6 (1995) 427;
(c) R.P. Kamalesh Babu, K. Aprna, S.S. Krishnamurthy, M. Nethaji, Phosphorus,
Sulfur Silicon Relat. Elem. 103 (1995) 39.
[7] (a) B. Punji, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 46 (2007) 11316;
(b) B. Punji, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 46 (2007) 10268;
(c) B. Punji, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 45 (2006) 9454.
[8] (a) For example see: P.J. Stang, B. Olenyuk, Acc. Chem. Res. 30 (1997) 502;
(b) D. Ranganathan, V. Haridas, R. Gilardi, I.L. Karle, J. Am. Chem. Soc. 120
(1998) 10793;
(
TWINABS [18]). The structure was solved by direct methods and
refined by full-matrix least-squares procedure using the SHELXTL
program package [19]. Hydrogen atoms were placed in calculated
positions and included as riding contributions with isotropic dis-
placement parameters tied to those of the attached non-hydrogen
atoms.
(c) M. Mazik, D. Blaser, R. Boese, Tetrahedron 55 (1999) 7835;
(d) I.S. Lee, D.M. Shin, Y.K. Chung, Cryst. Growth Des. 3 (2003) 521;
(e) T.Q. Nguyen, R. Martel, P. Avouris, M.L. Bushey, L. Brus, C. Nuckolls, J. Am.
Chem. Soc. 126 (2004) 5234;
(f) D.S. Li, Y.Y. Wang, X.J. Luan, P. Liu, C.H. Zhou, H. Ma, Q.H. Shi, Eur. J. Inorg.
Chem. (2005) 2678.
A crystal of 4 was mounted on a OXFORD DIFFRACTION XCALI-
BUR-S CCD system equipped with graphite monochromated Mo K
radiation (0.71073 Å). The data were collected in the –2h scan
a
x
[9] (a) P. Chandrasekaran, J.T. Mague, M.S. Balakrishna, Organometallics 24 (2005)
3780;
mode and an absorption correction was applied by using multi-
scan techniques. The structure was solved by direct methods
(b) P. Chandrasekaran, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 44 (2005)
7925;
(
SHELXS 97) and refined by full-matrix least-squares against F2 using
the SHELXL 97 software [19b]. Non-hydrogen atoms were refined
with anisotropic thermal parameters. All hydrogen atoms were
geometrically fixed and allowed to refine using a riding model.
(c) B. Punji, M.S. Balakrishna, Indian J. Chem. A 45 (2006) 1390;
(d) B. Punji, J.T. Mague, M.S. Balakrishna, Eur. J. Inorg. Chem. (2007) 720;
(e) P. Chandrasekaran, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 45 (2006)
5893;
(f) P. Chandrasekaran, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 44 (2006)
6678;
(g) D. Suresh, M.S. Balakrishna, K. Rathinasamy, D. Panda, J.T. Mague, Dalton
Trans. (2008) 2285;
Acknowledgments
(h) S. Priya, M.S. Balakrishna, J.T. Mague, Inorg. Chem. Commun. 4 (2001) 437.
[10] (a) B. Punji, M.S. Balakrishna, J. Organomet. Chem. 692 (2007) 1683;
(b) R. Venkateswaran, J.T. Mague, M.S. Balakrishna, Inorg. Chem. 46 (2007)
809;
We are grateful to the Department of Science and Technology
(DST), New Delhi for funding through Grant SR/S1/IC-02/2007.
B.P. thanks CSIR for Research Fellowship (JRF and SRF). We also
thank Department of Chemistry Instrumentation Facilities,
Bombay, for spectral and analytical data and the Louisiana Board
of Regents through Grant LEQSF (2002-03)-ENH-TR-67 for pur-
chase of the CCD diffractometer and the Chemistry Department
of Tulane University for support of the X-ray laboratory. National
Single Crystal X-ray Facility Center, IIT Bombay is acknowledged
for solving one of the structures.
(c) B. Punji, J.T. Mague, M.S. Balakrishna, J. Organomet. Chem. 691 (2006)
4265;
(d) B. Punji, J.T. Mague, M.S. Balakrishna, Dalton Trans. (2006) 1322;
(e) B. Punji, C. Ganesamoorthy, M.S. Balakrishna, J. Mol. Catal. A: Chem. 259
(2006) 78;
(f) B. Kaboudin, M.S. Balakrishna, Synth. Commun. 31 (2001) 2773.
[11] (a) J. Diez, M.P. Gamasa, J. Gimeno, E. Lastra, A. Aguirre, S. Garcfa-Granda,
Organometallics 12 (1993) 2213;
(b) I.D. Salter, S.A. Williams, T. Adatia, Polyhedron 14 (1995) 2803;

106
B. Punji et al. / Polyhedron 28 (2009) 101–106
(c) J. Diez, M.P. Gamasa, J. Gimeno, A. Aguirre, S. Garcia-Granda, J. Holubova,
L.R. Falvello, Organometallics 18 (1999) 662.
[12] (a) C. Ganesamoorthy, M.S. Balakrishna, P.P. George, J.T. Mague, Inorg. Chem.
46 (2007) 848;
[14] B.S. Furniss, A.J. Hannaford, P.W.G. Smith, A.R. Tatchell, Vogel’s Textbook of
Practical Organic Chemistry, 5th ed., ELBS, England, 1989, p. 428.
[15] G.J. Kubas, Inorg. Synth. 28 (1990) 68.
[16] Bruker-AXS, SMART, Version 5.625, Madison, WI, 2000.
[17] Bruker-AXS, SAINT+, Version 6.35A, Madison, WI, 2002.
[18] G.M. Sheldrick, TWINABS, Version 1.02, University of Göttingen, Germany, 2005.
[19] (a) Bruker-AXS, SHELXTL, Version 6.10, Madison, WI, 2000;
(b) G.M. Sheldrick, SHELXS97 and SHELXL97, University of Göttingen, Germany,
1997.
(b) C. Ganesamoorthy, M.S. Balakrishna, J.T. Mague, H.M. Tuononen, Inorg.
Chem. 47 (2008) 2764;
(c) C. Ganesamoorthy, M.S. Balakrishna, J.T. Mague, H.M. Tuononen, Inorg.
Chem. 47 (2008) 7035.
[13] C. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885.