Cyclodiphosphazanes with hemilabile ponytails: Synthesis, transition metal chemistry (Ru(II), Rh(I), Pd(II), Pt(II)), and crystal and molecular structures of mononuclear (Pd(II), Rh(I)) and bi- and tetranuclear rhodium(I) complexes

Article abstract of DOI:10.1021/ic0509478

Cyclodiphosphazanes having hemilabile ponytails such as cis-[ ^tBuNP(OC₆H₄OMe-o)]₂ (2), cis-[ ^tBuNP(OCH₂CH₂OMe)]₂ (3), cis-[ ^tBuNP(OCH₂CH₂SMe)]₂ (4), and cis-[^tBuNP(OCH₂CH₂NMe₂)] ₂ (5) were synthesized by reacting cis-[tBuNPCl]₂ (1) with corresponding nucleophiles. The reaction of 2 with [M(COD)Cl₂] afforded cis-[MCl₂(2)₂] derivatives (M = Pd (6), Pt (7)), whereas, with [Pd(NCPh)₂Cl₂], trans-[MCl ₂(2)₂] (8) was obtained. The reaction of 2 with [Pd(PEt₃)Cl₂]₂, [{Ru(η⁶-p- cymene)Cl₂]₂, and [M(COD)Cl]₂ (M = Rh, Ir) afforded mononuclear complexes of Pd(II) (9), Ru(II) (11), Rh(I) (12), and Ir(I) (13) irrespective of the stoichiometry of the reactants and the reaction condition. In the above complexes the cyclodiphosphazane acts as a monodentate ligand. The reaction of 2 with [PdCl(η³-C₃H ₅)]₂ afforded binuclear complex [(PdCl(η³- C₃H₅))₂{(^tBuNP(OC₆H ₄OMe-o))₂-κP}] (10). The reaction of ligand 3 with [Rh(CO)₂Cl]₂ in 1:1 ratio in CH₃CN under reflux condition afforded tetranuclear rhodium(I) metallamacrocycle (14), whereas the ligands 4 and 5 afforded bischelated binuclear complexes 15 and 16, respectively. The crystal structures of 8, 9, 12, 14, and 16 are reported.

Full text of DOI:10.1021/ic0509478

Inorg. Chem. 2005, 44, 7925−7932
Cyclodiphosphazanes with Hemilabile Ponytails: Synthesis, Transition
Metal Chemistry (Ru(II), Rh(I), Pd(II), Pt(II)), and Crystal and Molecular
Structures of Mononuclear (Pd(II), Rh(I)) and Bi- and Tetranuclear
Rhodium(I) Complexes
P. Chandrasekaran,† Joel T. Mague,‡ and Maravanji S. Balakrishna*,†
Departments of Chemistry, Indian Institute of Technology Bombay, Powai,
Mumbai 400 076, India, and Tulane UniVersity, New Orleans, Louisiana 70118
Received June 11, 2005
Cyclodiphosphazanes having hemilabile ponytails such as cis-[tBuNP(OC6H4OMe-o)]2 (2), cis-[tBuNP(OCH2CH2-
OMe)]2 (3), cis-[tBuNP(OCH2CH2SMe)]2 (4), and cis-[tBuNP(OCH2CH2NMe2)]2 (5) were synthesized by reacting
cis-[tBuNPCl]2 (1) with corresponding nucleophiles. The reaction of 2 with [M(COD)Cl2] afforded cis-[MCl2(2)2]
derivatives (M
2 with [Pd(PEt3)Cl2]2, [
)
Pd (6), Pt (7)), whereas, with [Pd(NCPh)2Cl2], trans-[MCl2(2)2] (8) was obtained. The reaction of
Ru( Rh, Ir) afforded mononuclear complexes of
6-p-cymene)Cl2]2, and [M(COD)Cl]2 (M
{
η
)
Pd(II) (9), Ru(II) (11), Rh(I) (12), and Ir(I) (13) irrespective of the stoichiometry of the reactants and the reaction
condition. In the above complexes the cyclodiphosphazane acts as a monodentate ligand. The reaction of 2 with
3-C3H5)]2 afforded binuclear complex [(PdCl( 3-C3H5))2 (tBuNP(OC6H4OMe-o))2-κ
[PdCl(η η { P}] (10). The reaction of
ligand 3 with [Rh(CO)2Cl]2 in 1:1 ratio in CH3CN under reflux condition afforded tetranuclear rhodium(I)
metallamacrocycle (14), whereas the ligands 4 and 5 afforded bischelated binuclear complexes 15 and 16,
respectively. The crystal structures of 8, 9, 12, 14, and 16 are reported.
Chart 1. Possible Coordination Modes of Cyclodiphosphazanes
Introduction
The main group and transition metal chemistry of dianionic
bis(amido)cyclodiphosphazanes, cis-[tBuNP(tBuN-)]2, and
their chalcogenide derivatives, cis-[tBuNP(E)(tBuN-)]2 (E )
O, S, Se), has been studied extensively by Chivers,1 Stahl,2
and others.3 In contrast, the coordination chemistry of neutral
cyclodiphosphazanes is less extensive4 despite their ability
to show monodentate (I; Chart 1) and bridged bidentate (II)
modes of coordination. Krishnamurthy et al. have reported
some homo- and heterobinuclear complexes of group 6 and
8 metals with cyclodiphosphazanes showing both mono- and
bridged bidentate modes of coordination.5 A nickel complex
* To whom correspondence should be addressed. E-mail: krishna@
iitb.ac.in.
(3) (a) Axenov, K. V.; Kotov, V. V.; Klinga, M.; Leskela¨, M.; Repo, T.
Eur. J. Inorg. Chem. 2004, 695. (b) Bashall, A.; Bond, A. D.; Doyle,
E. L.; Garcia, F.; Kidd, S.; Lawson, G. T.; Parry, M. C.; McPartlin,
M.; Woods, A. D.; Wright, D. S. Chem.sEur. J. 2002, 3377. (c)
Beswick, M. A.; Elvidge, B. R.; Feeder, N.; Kidd, S. J.; Wright, D.
S. Chem. Commun. 2001, 379. (d) Kommana, P.; Kumara Swamy,
K. C. Inorg. Chem. 2000, 39, 4384.
(4) (a) Balakrishna, M. S.; Sreenivasa Reddy, V.; Krishnamurthy, S. S.;
Nixon, J. F.; St. Laurent, J. C. T. R. B. Coord. Chem. ReV. 1994,
129, l. (b) Balakrishna, M. S.; Krishnamurthy, S. S. J. Organomet.
Chem. 1992, 424, 243. (c) Sreenivasa Reddy, V.; Krishnamurthy, S.
S.; Nethaji, M. J. Organomet. Chem. 1992, 438, 99. (d) Prakasha, T.
K.; Krishnamurthy, S. S.; Davies, S. E.; Meidine, M. F.; Nixon, J. F.
J. Organomet. Chem. 1992, 438, 241. (e) Hawker, P. N.; Jenkins, L.
S.; Willey, G. R. J. Organomet. Chem. 1976, 118, C44.
† Indian Institute of Technology Bombay.
‡ Tulane University.
(1) (a) Briand, G. G.; Chivers, T.; Krahn, M. Coord. Chem. ReV. 2002,
233-234, 237. (b) Chivers, T.; Krahn, M.; Parvez, M. Chem. Commun.
2000, 463. (c) Chivers, T.; Fedorchuk, C.; Krahn, M.; Parvez, M.;
Schatte, G. Inorg. Chem. 2001, 40, 1936. (d) Chivers, T.; Krahn, M.;
Parvez, M.; Schatte, G. Inorg. Chem. 2001, 40, 2547. (e) Briand, G.
G.; Chivers, T.; Parvez, M.; Schatte, G. Inorg. Chem. 2003, 42, 525.
(2) (a) Stahl, L. Coord. Chem. ReV. 2000, 210, 203. (b) Lief, G. R.; Moser,
D. F.; Stahl, L.; Staples, R. J. J. Organomet. Chem. 2004, 689, 1110.
(c) Moser, D. F.; Grocholl, L.; Stahl, L.; Staples, R. J. J. Chem. Soc.,
Dalton Trans. 2003, 1402. (d) Haagenson, D. C.; Moser, D. F.; Stahl,
L.; Staples, R. J. Inorg. Chem. 2002, 41, 1245. (e) Lief, G. R.; Carrow,
C. J.; Stahl, L.; Staples, R. J. Organometallics 2001, 20, 1629.
10.1021/ic0509478 CCC: $30.25
Published on Web 09/21/2005
© 2005 American Chemical Society
Inorganic Chemistry, Vol. 44, No. 22, 2005 7925

Chandrasekaran et al.
Scheme 1
Scheme 2
containing chelating cyclodiphosphazanes was reported
without appropriate phosphorus-31 NMR data or structural
support.5c In an effort to utilize the rigid cyclodiphosphazanes
as heterodifunctional and bi- or tetradentate ligands, we
incorporated pendant hemilabile functionalities on phospho-
rus centers so that they can show a variety of coordinating
modes. As a part of our interest6 and the interest of others7
in transition metal chemistry of cyclic and acyclic phosphorus
based ligands, we describe here the preparation and transition
metal chemistry of cyclodiphosphazanes containing pendant
hemilabile ponytails. The crystal and molecular structures
of mononuclear (palladium(II), rhodium(I)) and bi- and
tetranuclear rhodium(I) complexes are also reported.
phorus-31 chemical shifts.9 Further, the structure and com-
positions of compounds 2-5 were confirmed by analytical
1
data and H NMR spectroscopy and mass spectrometry.
Results and Discussion
Palladium and Platinum Derivatives. The reactions of
cis-[tBuNP(OC6H4OMe-o)]2 (2) with [M(COD)Cl2] (M ) Pd
or Pt) are independent of stoichiometry and the reaction
conditions and afford exclusively cis complexes, 6 and 7,
with the ligand exhibiting monodentate coordination. In
contrast, the reaction of 2 equiv of 2 with [Pd(NCPh)2Cl2]
in dichloromethane affords a mononuclear trans-palladium-
(II) derivative 8 as shown in Scheme 2. The 31P NMR
spectrum of complex 6 exhibits two doublets centered at 67.9
and 121.2 ppm, respectively, for coordinated and free
phosphorus centers with a 2JPP coupling of 53 Hz. Similarly,
the phosphorus-31 chemical shift due to the coordinated
phosphorus of 7 appears at 40.4 ppm whereas the uncoor-
dinated phosphorus resonates at 126.1 ppm. The 2JPP coupling
is 7.3 Hz. The platinum-bound phosphorus center exhibits
Ligand Synthesis. The reactions of cis-[tBuNPCl]2 (1)
with 2 equiv of 2-(methoxy)phenol or 2-substituted ethanols,
ECH2CH2OH (E ) OMe, SMe), in the presence of trieth-
ylamine afford the corresponding hemilabile cyclodiphos-
phazane derivatives cis-[tBuNP(OC6H4OMe-o)]2 (2)8 and cis-
[tBuNP(OCH2CH2EMe)]2 (3; E ) OMe, 4; SMe) in
quantitative yield. The corresponding amine-functionalized
derivative, cis-[tBuNP(OCH2CH2NMe2)]2 (5), was prepared
by reacting cis-[tBuNPCl]2 (1) with the sodium salt of
2-(dimethylamino)ethanol in THF (Scheme 1). Compound
2 is a white crystalline solid whereas 3-5 are oily liquids
which were purified by vacuum distillation. The 31P NMR
spectra of 2-5 exhibit single resonances at 145.6, 133.8,
134.1, and 133.7 ppm, respectively. Interestingly, all these
compounds exist in cis-conformation as indicated by phos-
1
platinum-195 satellites with a large JPtP coupling of 4861
Hz, which is consistent with the proposed cis geometry10
for 7. The trans-palladium(II) complex 8 exhibits two single
resonances at 128.3 and 84.6 ppm, respectively, for unco-
(5) (a) Reddy, V. S.; Krishnamurthy, S. S.; Nethaji, M, J. Chem. Soc.,
Dalton Trans. 1994, 2661. (b) Reddy, V. S.; Krishnamurthy, S. S.;
Nethaji, M. J. Chem. Soc., Dalton Trans. 1995, 1933. (c) Kuhn, N.;
Winter, M. J. Organomet. Chem. 1983, 243, C47.
(6) (a) Balakrishna, M. S.; Panda, R.; Mague, J. T. Inorg. Chem. 2001,
40, 5620. (b) Balakrishna, M. S.; Panda, R. Phosphorus, Sulfur, Silicon
Relat. Elem. 2003, 178, 1391. (c) Balakrishna, M. S.; Panda, R.;
Mague, J. T. J. Chem. Soc., Dalton Trans. 2002, 4617. (d) Balakrishna,
M. S.; Chandrasekaran, P.; George, P. P. Coord. Chem. ReV. 2003,
241, 87. (e) Priya, S.; Balakrishna, M. S.; Mobin, S. M.; McDonald,
R. J. Organomet. Chem. 2003, 688, 227. (f) Balakrishna, M. S.;
Abhyankar, R. M.; Mague, J. T. J. Chem. Soc., Dalton Trans. 1999,
1407.
2
ordinated and coordinated phosphorus centers, and no JPP
coupling was observed. Treatment of cis-[tBuNP(OC6H4-
OMe-o)]2 (2) with palladium(II) dimer [Pd(PEt3)Cl2]2 in an
equimolar ratio also affords a mononuclear complex 9
containing monodentate cyclodiphosphazane and PEt3 ligands
in mutually cis dispositions. The 31P NMR spectrum of
complex 9 consists of three resonances; uncoordinated
phosphorus of cyclodiphosphazane and PEt3 appear as
(7) (a) Mahalakshmi, L.; Krishnamurthy, S. S.; Nethaji, M. Curr. Sci.
2002, 83, 870. (b) Schuman, M.; Trevitt, M.; Redd, A.; Gouverneur,
V. Angew. Chem., Int. Ed. 2000, 39, 2491. (c) Berenguer, J. R.;
Bernechea, M.; Fornies, J.; Garcia, A.; Lalinde, E.; Teresa Moreno,
M. Inorg. Chem. 2004, 43, 8185.
doublets at 127.2 (2JPP ) 3.9 Hz) and 35. 8 ppm (2JPP
)
(9) Keat, R.; Rycroft, D. S.; Thompson, D. G. J. Chem. Soc., Dalton Trans.
1980, 321.
(8) Chandrasekaran, P.; Mague, J. T.; Balakrishna, M. S. Organometallics
2005, 24, 3780.
(10) Balakrishna, M. S.; Santarsiero, B. D.; Cavell, R. G. Inorg. Chem.
1994, 33, 3079.
7926 Inorganic Chemistry, Vol. 44, No. 22, 2005

Cyclodiphosphazanes with Hemilabile Ponytails
Scheme 3
Figure 1. Molecular structure of 8. For clarity, solvent and all hydrogen
atoms have been omitted. Thermal ellipsoids are drawn at 50% probability.
Selected bond distances (Å): P(1)-Pd, 2.299(1); Pd-Cl(1), 2.293(1); P(1)-
N(1), 1.671(2); P(1)-N(2), 1.664(2); P(2)-N(1), 1.733(2); P(2)-N(2),
1.719(2). Selected bond angles (deg): Cl(1)-Pd-P(1), 94.20(2); Cl(1)-
Pd-P(1_a), 85.80(2); Cl(1_a)-Pd-P(1), 85.80(2); Cl(1_a)-Pd-P(1_a),
94.20(2); Cl(1)-Pd-Cl(1_a), 180.00; P(1)-Pd-P(1_a), 180.00; P(1)-N(1)-
P(2), 95.83(9); P(1)-N(2)-P(2), 96.64(10).
16.8 Hz), respectively, and are coupled to the coordinated
phosphorus, which appears as a doublet of doublets centered
at 85.7 ppm. Further structural evidences come from H
1
NMR and mass spectral data, elemental analysis, and single-
crystal X-ray diffraction studies in the case of complexes 8
and 9. The 1:1 reaction between 2 and [PdCl(η3-C3H5)]2 in
dichloromethane affords a dinuclear palladium(II) complex,
[(PdCl(η3-C3H5))2{(tBuNP(OC6H4OMe-o))2-κP}] (10), with
cyclodiphosphazane acting as a bridging ligand. The 31P
NMR spectrum of 10 shows a sharp singlet at 121.1 ppm
indicating the symmetrical coordination of cyclodiphospha-
zane.
couplings are in the range 42-47 Hz.11 In 1H NMR spectra
of bischelated Rh(I) complexes 15 and 16, the chemical shifts
due to SMe and NMe2 are downfield shifted considerably
as compared to the same in the free ligands, which confirms
the coordination of SMe and NMe2 to the metal centers. In
contrast, in the 1H NMR spectrum of 14, the chemical shift
due to OMe appeared almost at same position as in the free
ligand 3 which indicates the absence of OMe coordination
to Rh(I) center.12 The IR spectra of complexes 14-16 show
two absorptions in the range 1993-2034 cm-1, which is
clearly consistent with the cis-related CO/phosphine struc-
tures proposed for these complexes.10 The structures of
compounds 14 and 16 were further confirmed by low-
temperature single-crystal X-ray diffraction studies.
The mononuclear Ru(II) complex 11 was prepared by
reacting 2 equiv of cis-[tBuNP(OC6H4OMe-o)]2 (2) with [Ru-
(η6-p-cymene)Cl2]2 in dichloromethane. Even with an excess
of metal reagent, only the mononuclear product was obtained.
In the 31P NMR spectrum of 11, the uncoordinated phos-
phorus appears as a doublet centered at 133.5 ppm whereas
the chemical shift due to the coordinated phosphorus appears
2
at 109.6 ppm. The JPP coupling is 8.7 Hz.
Crystal and Molecular Structures of Complexes 8, 9,
12, 14, and 16. Perspective views of the molecular structures
of compounds 8, 9, 12, 14, and 16 with atom numbering
schemes are shown in Figures 1-5, respectively. The
crystallographic data and the details of the structure deter-
mination are given in Table 1, while selected bond length
and bond angles appear below the corresponding figures.
Single crystals of trans-[PdCl2{(tBuNP(OC6H4OMe-o))2-
κP}2] (8) were grown from the 1:1 mixture of dichlo-
romethane and diethyl ether solution at -30 °C. The
asymmetric unit contains half a molecule of the metal
complex and one molecule of dichloromethane. The pal-
ladium occupies the center of the square planar geometry,
and the corners are occupied by two chlorines and two
phosphorus centers from cyclodiphosphazane. The P(1)-
Pd-P(1_a) and Cl(1)-Pd-Cl(1_a) bond angles are perfectly
linear. The Cl(1)-Pd-P(1) bond angle is 94.20(2)°. The Pd-
P(1) bond length (2.299(1) Å) in trans-Pd(II) derivative 8 is
longer as compared to the Pd-P(1) bond length (2.232(1)
Å) in complex 9; this is due to the greater trans influence of
phosphine ligands in the latter as compared with chloride.
Rhodium Derivatives. The reactions of cis-[tBuNP-
(OC6H4OMe-o)]2 (2) with [M(COD)Cl]2 (M ) Rh, Ir) in
1:1 molar ratio affords neutral mononuclear complexes 12
and 13 with cyclodiphosphazane showing monodentate
coordination as indicated by 31P NMR data. The 31P NMR
spectrum of 12 shows a doublet at 102.8 ppm for the
coordinated phosphorus center (1JRhP ) 229 Hz), whereas
the resonance due to the uncoordinated phosphorus appears
as a singlet at 131.7 ppm. Similarly, the iridium complex
13 also shows singlets for coordinated and uncoordinated
phosphorus centers at 133.0 and 88.5 ppm, respectively.
The reactions of cyclodiphosphazane derivatives with [Rh-
(CO)2Cl]2 afford a variety of products, depending upon the
stoichiometry of the reactants, reaction conditions, and also
the nature of the donor functionalities present in the pendant
groups. The tetranuclear complex 14 containing two [Rh-
(µ-Cl)]2 units and two bridging cyclodiphosphazanes was
obtained when the [Rh(CO)2Cl]2 and the ligand 3 were taken
in 1:1 molar ratios. Interestingly, the reaction of 4 and 5
with 1 equiv of [Rh(CO)2Cl]2 in acetonitrile under reflux
conditions afforded the dinuclear bischelated Rh(I) com-
plexes 15 and 16, respectively, as shown in Scheme 3. The
31P NMR spectra of complexes 14-16 show multiplets with
(11) The 31P NMR spectra of 14-16 are best interpreted as “A” part of an
XAA“X” nuclear spin system with JXX′ ) 0.
(12) Priya, S.; Balakrishna, M. S.; Mague, J. T. J. Organomet. Chem. 2004,
689, 3335.
2
chemical shifts in the range of 115-124 ppm. The JPP
Inorganic Chemistry, Vol. 44, No. 22, 2005 7927

Chandrasekaran et al.
Table 1. Crystallographic Information for Compounds 8, 9, 12, 14, and 16
param 8‚2CH2Cl2
formula C44H64Cl2N4O8P4Pd·2CH2Cl2 C28H47Cl2N2O4P3Pd C30H44ClN2O4P2Rh
9
12
14
16‚CH3CN
C32H64Cl4N4O12P4Rh4 C18H38Cl2N4O4P2Rh2‚CH3CN
fw
1248.04
monoclinic
P21/n (14)
10.1978(9)
19.0612(2)
15.4490(10)
90
107.1080(10)
90
2870.1(3)
2
745.89
orthorhombic
Pca21 (29)
22.008(3)
9.4530(10)
16.257(2)
90
90
90
3382.1(7)
4
1.465
696.97
monoclinic
P21/c
10.7960(10)
28.138(2)
11.649(5)
90
115.860(10)
90
3184.4(14)
4
1374.19
monoclinic
P21/n (14)
9.3390(9)
18.286(2)
14.9160(10)
90
754.24
cryst system
space group (No.)
a, Å
b, Å
monoclinic
P21/c (14)
14.0780(10)
12.7090(10)
18.035(2)
90
109.8820(10)
90
3034.4(5)
4
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
99.7530(10)
90
2510.4(4)
4
1.818
1.688
1376
F
calcd, g cm-3
1.444
0.765
1288
1.454
0.757
1448
1.651
1.403
1528
µ(Mo KR), cm-1
F(000)
0.883
1544
cryst size (mm3)
T (K)
0.13 × 0.14 × 0.15
0.11 × 0.22 × 0.28 0.13 × 0.16 × 0.18
0.08 × 0.08 × 0.21
0.14 × 0.20 × 0.21
100
293
100
100
100
2θ range, deg
tot. no. reflcns
1.7-28.3
25 110
1.9-28.3
28 984
1.5-28.3
47 078
1.8-27.7
21 656
1.5-27.8
26 237
no. of indepdt reflcns 6845 (Rint ) 0.021)
8108 (Rint ) 0.028) 47 176 (Rint ) 0.000) 5749 (Rint ) 0.026)
7018 (Rint ) 0.028)
a
R1
0.0371
0.0979
1.05
0.0228
0.0523
1.03
0.0484
0.1068
0.90
0.0320
0.0839
1.10
0.0273
b
wR2
0.0650
1.05
GOF (F2)
2
2
2
2
2
2
a R ) Σ||Fo| - |Fc||/Σ|Fo|. b Rw ) {[Σw(Fo - Fc )/Σw(Fo )2]}1/2; w ) 1/[σ2(Fo ) + (xP)2], where P ) (Fo + 2Fc )/3.
Figure 2. Molecular structure of 9. For clarity, all hydrogen atoms have
been omitted. Thermal ellipsoids are drawn at 50% probability. Selected
bond distances (Å): P(1)-Pd, 2.232(1); P(3)-Pd, 2.289(1); Pd-Cl(1),
2.359(1); Pd-Cl(2), 2.345(1); P(1)-O(1), 1.606(1); P(2)-O(2), 1.657(1);
P(1)-N(1), 1.667(2); P(1)-N(2), 1.664(2); P(2)-N(1), 1.729(2); P(2)-
N(2), 1.718(2). Selected bond angles (deg): P(1)-Pd-P(3), 95.71(2);
Cl(1)-Pd-Cl(2), 89.55(2); Cl(1)-Pd-P(1), 85.53(2); Cl(2)-Pd-P(3),
89.52(2); P(1)-N(1)-P(2), 96.22(8); P(1)-N(2)-P(2), 96.78(9).
Figure 3. Molecular structure of 12. For clarity, all hydrogen atoms have
been omitted. Thermal ellipsoids are drawn at 50% probability. Selected
bond distances (Å): Rh-P(1), 2.244(1); Rh-Cl, 2.361(1); Rh-C(23),
2.109(2); Rh-C(26), 2.235(2); Rh-C(27), 2.213(2); Rh-C(30), 2.133(2);
P(1)-N(1), 1.693(2); P(1)-N(2), 1.673(2); P(2)-N(1), 1.719(2); P(2)-
N(2), 1.708(2). Selected bond angles (deg): P(1)-Rh-Cl, 87.82(2); P(1)-
Rh-C(23), 93.00(5); Cl-Rh-C(26), 91.62(6); C(23)-Rh-C(26), 81.32(7);
P(1)-N(1)-P(2), 96.30(6); P(1)-N(2)-P(2), 97.46(8).
The two (P2N2) rings are arranged in opposite orientations,
whereas, in a similar structurally characterized Rh(I) com-
plex, trans-[RhCl(CO){(tBuNP(OC6H4OMe-o))2-κP}2], they
are arranged in a parallel manner.8
The molecular structure of 12 is shown in Figure 3. The
rhodim(I) center in 12 occupies the center of distorted square
planar geometry. The square planar corners were occupied
by phosphorus, chloride, and 1,5-cyclooctadiene. The Rh-
P(1) and Rh-Cl bond distance are 2.2438(11) and 2.3608-
(11) Å, respectively, and are in good agreement with the
literature values for similar rhodium(I) complexes.13 The
P(1)-Rh-Cl bond angle is 87.82(2)°.
Single crystals of 14 were grown from the slow diffusion
of hexane into a dichloromethane solution at room temper-
ature. The molecular structure of tetranuclear Rh(I) complex
14 consists of two [Rh(µ-Cl)(CO)]2 units bridged by two
cyclodiphosphazanes via P(III) centers to give a tetranuclear
In the molecular structure of 9, palladium center is
coordinated through two different phosphorus centers and
two chlorine atoms in a square planar fashion with cis angles
varying from 95.71(2)° (P(1)-Pd-P(3)) to 85.53(2)° (Cl-
(1)-Pd-P(1)). The two phosphorus centers are arranged in
cis conformation. The P(1)-Pd (2.2325(6) Å) bond is slightly
shorter than Pd-P(3) (2.2892(6) Å) bond, which is due to
the stronger π-acceptor nature of the cyclodiphosphazane
ligand 2 as compared to PEt3. The P(1)-O(1)-C(1) (129.78-
(12)°) bond angle is shorter than P(2)-O(2)-C(8) (117.79-
(12)°), which indicates that the two exo cyclic phenyl
substitutions are in different orientations. The (P2N2) ring is
in a slightly puckered conformation with angles around
nitrogen is ∼355°.
(13) St. Laurent, J. C. T. R. B.; Hitchcock, P. B.; Nixon, J. F. J. Organomet.
Chem. 1983, 249, 243.
7928 Inorganic Chemistry, Vol. 44, No. 22, 2005

Cyclodiphosphazanes with Hemilabile Ponytails
Chart 2
the phosphorus ligand as compared to the carbonyl ligand.
The Rh(1)-Cl(1)-Rh(2) and Rh(1)-Cl(2)-Rh(2) bond
angles are 94.0 and 90.7°, respectively. These differences
arise due to the presence of shorter and longer Rh-Cl bonds
in complex 14. The Rh(1)-Rh(2) distance of 3.365 Å
indicates the absence of metal-metal-bonding interaction.
Previously, Nixon and co-workers15 have reported an
insoluble complex of the type [RhCl(CO){µ-(tBuNPF)2}]n
(IV; Chart 2), whereas Stahl and co-workers16 have reported
a 16-electron anionic dinickel(II) cyclodiphosphazane com-
plex, V, containing two three-membered metallacycles. In
both the complexes, the cyclodiphosphazanes act as four-
electron donor bridging ligands. Krishnamurthy and co-
workers have reported the crystal structures of dimolybdenum
and mixed molybdenum-tungsten complexes with cyclo-
diphosphazane [{PhNP(OC6H4Me-p)}2] exhibiting a bridged
bidentate mode of coordination.5a,b Interestingly, the ligand
[{PhNP(OC6H4Me-p)}2] exists in a trans form in the solid
state but undergoes isomerization during complexation and
exhibits both cis and trans conformations in the complexes
probably governed by the steric attributes at the metal centers.
Surprisingly, the ligands in the present investigation exist
in cis form and no isomerization was observed during
complexation. Complex 16 is the first example of a cyclo-
diphosphazane performing as an eight-electron donor tet-
radentate ligand to form two chelate rings with rhodium(I)
centers in slightly distorted square planar environments. The
CO and the phosphorus center of cyclodiphosphazane are
arranged cis to each other with P(1)-Rh(1)-C(1) and P(2)-
Rh(2)-C(6) bond angles of 88.90(8) and 90.54(9)°, respec-
tively. The P2N2 ring is orthogonal to two chelate rings. The
Rh(1)-P(1) bond distance of 2.178(1) Å is slightly shorter
than Rh(2)-P(2) of 2.194(1) Å. Surprisingly, there are not
much differences in other bond distances such as Rh-N,
Rh-CO, and Rh-Cl. The P(1)-Rh(1)-N(3) and P(2)-Rh-
(2)-N(4) bond angles are 95.75(12) and 96.21(6)°, respec-
tively. In both the complexes 14 and 16 the P2N2 rings are
planar with bond angles around nitrogen summing to ∼360°.
The supramolecular structures of all the complexes are
dominated by intra- and intermolecular C-H‚‚‚Cl, C-H‚‚‚
π, and C-H‚‚‚O interactions.
Figure 4. Molecular structure of 14. For clarity, all hydrogen atoms have
been omitted. Thermal ellipsoids are drawn at 50% probability. Selected
bond distances (Å): Rh(1)-P(1), 2.191(1); Rh(2)-P(2), 2.198(1); Rh(1)-
Cl(1), 2.368(1); Rh(1)-Cl(2), 2.423(1); Rh(2)-Cl(1), 2.354(1); Rh(2)-
Cl(2), 2.429(1); Rh(1)-C(1), 1.823(3); Rh(2)-C(9), 1.805(4); P(1)-N(1),
1.689(3); P(2)-N(2), 1.692(3); Rh(1)···Rh(2), 3.454. Selected bond angles
(deg): P(1)-Rh(1)-Cl(1), 94.44(3); P(1)-Rh(1)-C(1), 88.63(11); Cl(1)-
Rh(1)-Cl(2), 84.16(3); Cl(1)-Rh(2)-P(2), 94.98(3); P(2)-Rh(2)-C(9),
90.42(10); Rh(1)-Cl(1)-Rh(2), 94.00(4); Rh(1)-Cl(2)-Rh(2), 90.77(3);
P(1)-N(1)-P(2_a), 96.77(14); P(1_a)-N(2)-P(2), 96.58(14).
Figure 5. Molecular structure of 16. For clarity, solvent and all hydrogen
atoms have been omitted. Thermal ellipsoids are drawn at 50% probability.
Selected bond distances (Å): P(1)-Rh(1), 2.178(1); P(2)-Rh(2), 2.194-
(1); Rh(1)-N(3), 2.181(2); Rh(2)-N(4), 2.193(4); Rh(1)-Cl(1), 2.409(1);
Rh(2)-Cl(2), 2.403(1); Rh(1)-C(1), 1.816(3); Rh(2)-C(6), 1.809(3); P(1)-
N(1), 1.690(2); P(1)-N(2), 1.695(2); P(2)-N(1), 1.691(2); P(2)-N(2),
1.693(2). Selected bond angles (deg): P(1)-Rh(1)-N(3), 96.21(6); P(2)-
Rh(2)-N(4), 95.75(12); P(1)-Rh(1)-C(1), 88.90(8); P(2)-Rh(2)-C(6),
90.54(9); Cl(1)-Rh(1)-N(3), 89.72(6); Cl(2)-Rh(2)-N(4), 89.40(12);
P(1)-N(1)-P(2), 97.14(10); P(1)-N(2)-P(2), 96.85(11); Cl(1)-Rh(1)-
P(1), 171.56(2); Cl(2)-Rh(2)-P(2), 173.66(2).
macrocycle. This is a rare example of cyclodiphosphazanes
stabilizing [Rh2(µ-Cl)2] units to form a centrosymmetric
tetranuclear rhodium(I) macrocycle. The Rh-P distances are
(Rh(1)-P(1), 2.191(1) Å; Rh(2)-P(2), 2.198 (1) Å) shorter
than that found in the structure of [Rh(µ-Cl)(PPh3)2]2 (2.213
(2) Å).14 Two planar P2N2 rings are almost orthogonal to
the slightly inward-puckered two [Rh2(µ-Cl)2] rings. The
structural features are similar to those of dimolybdenum
complex [Mo(CO)4{PhNP(OC6H4Me-o)}2]2.5a In both the
complexes, the ligands adopt cis-orientation with no signifi-
cant differences in the P-N bond distances and the P-N-P
bond angles. The distances Rh(1)-Cl(1) (2.368(1) Å) and
Rh(1)-Cl(2) (2.423(1) Å) differ significantly. This difference
can most likely be attributed to a greater trans-influence of
Conclusion
The cyclodiphosphazanes containing hemilabile ponytails
exhibit versatile coordination properties. The exclusive
formation of either cis or trans Pd(II) complexes was
achieved by using appropriate metal reagents. The reactions
(15) St. Laurent, J. C. T. R. B.; Sinclair, J.; Nixon, J. F. J. Organomet.
Chem. 1984, 262, 379.
(16) Lief, G. R.; Carrow, C. J.; Stahl, L.; Staples, R. J. Chem. Commun.
2001, 1562.
(14) Curtis, M. D.; Butler, W. M.; Greene, J. Inorg. Chem. 1978, 17, 2928.
Inorganic Chemistry, Vol. 44, No. 22, 2005 7929

Chandrasekaran et al.
δ 133.8 (s). Anal. Calcd for C14H32N2P2O4: C, 47.45; H, 9.10;
N, 7.90. Found: C, 46.97; H, 9.42; N, 7.52. MS (EI): 355.10
(m/z + 1).
with Rh(I), Ir(I), Pd(II), and Ru(II) metal dimers selectively
afforded the corresponding mononuclear complexes, in which
cyclodiphosphazane acts as a monodentate ligand. On the
other hand, the treatment with [PdCl(η3-C3H5)]2 resulted in
the formation of a dinuclear complex. The cyclodiphospha-
zane having ether functionality was found to preferably form
the tetranuclear rhodium(I) metallacycle, whereas cyclo-
diphosphazanes containing thioether and amine functionality
gives the bichelated dinuclear rhodium(I) complexes. The
latter complexes are the first examples of cyclodiphospha-
zanes performing as eight-electron donor tetradentate ligands.
Further research in the utilization of these novel ligands to
build polymetallic complexes and clusters of high nuclearity
is in progress.
Synthesis of cis-[tBuNP(OCH2CH2SMe)]2 (4). A mixture of
2-(methylthio)ethanol (2.32 g, 2.2 mL, 24.12 mmol) and Et3N (2.4
g 3.4 mL, 12.06 mmol) in 20 mL of diethyl ether was added
dropwise over 30 min to a well-stirred diethyl ether solution (80
mL) of cis-[tBuNPCl]2 (1) (3.3 g, 12.06 mmol) at 0 °C. The reaction
mixture was stirred for 24 h at room temperature. The amine
hydrochloride was filtered off, and the solvent was removed at
reduced pressure to get a colorless liquid of 4, which was purified
by vacuum distillation at 220 °C (0.4 Torr). Yield: 79% (3.6 g,
9.31 mmol). 1H NMR (400 MHz, CDCl3): 4.04 (m, CH2OP, 4H),
2.69 (t, SCH2, 1JHH ) 7.3 Hz, 4H), 2.16 (s, SMe, 6H), 1.30 (s, tBu,
18H). 31P{1H} NMR (121 MHz, CDCl3): δ 134.1 (s). Anal. Calcd
for C14H32N2P2O2S2: C, 43.50; H, 8.34; N, 7.24; S, 16.59. Found:
C, 43.38; H, 8.57; N, 7.52; S, 17.01. MS (EI): 387.05 (m/z + 1).
Experimental Section
Synthesis of cis-[tBuNP(OCH2CH2NMe2)]2 (5). A mixture of
2-(dimethylamino)ethanol (1.6 g, 1.9 mL, 18.87 mmol) and sodium
(0.43 g, 18.87 mmol) was taken in 30 mL of THF in a two-necked
flask attached with reflux condenser and a dropping funnel. The
reaction mixture was refluxed for 6 h and then allowed to cool to
room temperature. The THF (60 mL) solution of cis-[tBuNPCl]2
(2.59 g, 9.4 mmol) was transferred to the dropping funnel through
a cannula, and this was added dropwise to the reaction mixture at
0 °C. The reaction mixture was further stirred for 12 h at room
temperature and then filtered through a frit. The solvent was
removed under reduced pressure to get an oily liquid, which was
distilled at 154 °C (0.3 Torr) to get 5 as a colorless liquid. Yield:
All manipulations were performed under rigorously anaerobic
conditions using Schlenk techniques. All the solvents were purified
by conventional procedure and distilled prior to use.17 The
compounds cis-[tBuNPCl]2 (1),18 cis-[tBuNP(OC6H4OMe-o)]2 (2),8
[M(COD)Cl2] (M ) Pd, Pt),19 [Pd(NCPh)2Cl2],20 [Pd(PEt3)Cl2]2,21
[PdCl(η3-C3H5)]2,22 [Ru(η6-p-cymene)Cl2]2,23 [Rh(COD)Cl]2,24
[Ir(COD)Cl]2,25 and [Rh(CO)2Cl]226 were prepared according to the
published preocedures. 2-(Methoxy)ethanol (SD Fine chemicals)
and 2-(dimethylamino)ethanol (Lancaster) were purified prior to
use by conventional methods. 2-(Methylthio)ethanol was purchased
1
from Lancaster and used as received. The H and 31P{1H} NMR
(δ in ppm) spectra were recorded using a Varian spectrometer
operating at the appropriate frequencies using TMS and 85% H3-
PO4 as internal and external references, respectively. Positive shifts
lie downfield in all the cases. IR spectra were recorded on a Nicolet
Impact 400 FT-IR instrument in KBr disks. Microanalyses were
performed on a Carlo Erba model 1112 elemental analyzer. Mass
spectrometry experiments were carried out using a Waters Q-
Tofmicro-YA-105. Melting points were recorded in capillary tubes
and are uncorrected.
1
82% (2.93 g, 7.70 mmol). H NMR (400 MHz, CDCl3): δ 3.96
(m, CH2OP, 4H), 2.51 (t, NCH2, 1JHH ) 3.6 Hz, 4H), 2.27 (s, NMe2,
t
12H), 1.29 (s, Bu, 18H). 31P{1H} NMR (121 MHz, CDCl3): δ
133.7 (s). Anal. Calcd for C16H38N4P2O2: C, 50.51; H, 10.06; N,
14.72. Found: C, 50.86; H, 10.43; N, 15.14. MS (EI): 380.31
(m/z + 1).
Synthesis of cis-[PdCl2{(tBuNP(OC6H4OMe-o))2-κP}2] (6). A
solution of [Pd(COD)Cl2] (21 mg, 0.076 mmol) in 10 mL of CH2-
Cl2 was added dropwise to a solution of cis-[tBuNP(OC6H4OMe-
o)]2 (69 mg, 0.153 mmol) in CH2Cl2 (7 mL) at room temperature.
The reaction mixture was stirred for 5 h to give a clear yellow
solution, which was concentrated to 5 mL, diluted with 3 mL of
Et2O, and then cooled to -30 °C for 1 day to get an analytically
pure yellow crystalline product (6). Yield: 80% (65 mg, 0.06
mmol). Mp: 203-205 °C. 1H NMR (300 MHz, CDCl3): δ 7.03-
6.85 (m, Ph, 16H), 3.88 (s, OMe, 6H), 3.82 (s, OMe, 6H), 1.54 (s,
tBu, 36H). 31P{1H} NMR (121 MHz, CDCl3): δ 121.2 (d), 67.9
(d, 2JPP ) 53 Hz). Anal. Calcd for C44H64N4P4O8PdCl2: C, 49.01;
H, 5.98; N, 5.19. Found: C, 48.75; H, 6.02; N, 5.28. MS (EI):
1043.38 (m/z - Cl).
Synthesis of cis-[tBuNP(OCH2CH2OMe)]2 (3). A mixture of
2-(methoxy)ethanol (1.7 g, 1.8 mL, 22.86 mmol) and triethylamine
(2.2 g, 3.1 mL, 22.86 mmol) in 30 mL of diethyl ether was added
dropwise over 30 min to a well-stirred diethyl ether (120 mL)
solution of cis-[tBuNPCl]2 (1) (3.14 g, 11.43 mmol) at 0 °C. The
reaction mixture was then stirred at room temperature for 24 h.
Et3NHCl was filtered off, and the solvent was removed at reduced
pressure to get a colorless liquid, which was further purified by
vacuum distillation at 190 °C (0.4 Torr) to give the product 3.
1
Yield: 84% (3.4 g, 9.59 mmol). H NMR (400 MHz, CDCl3): δ
1
4.01 (m, CH2OP, 4H), 3.53 (t, OCH2, JHH ) 5 Hz, 4H), 3.37 (s,
OMe, 6H), 1.29 (s, tBu, 18H). 31P{1H} NMR (121 MHz, CDCl3,):
Synthesis of cis-[PtCl2{(tBuNP(OC6H4OMe-o))2-κP}2] (7). A
dichloromethane solution (10 mL) of [Pt(COD)Cl2] (30 mg, 0.088
mmol) was added to cis-[tBuNP(OC6H4OMe-o)]2 (79 mg, 0.176
mmol) in 10 mL of CH2Cl2 at 25 °C. The resultant clear solution
was stirred for 6 h. Then the solution was concentrated to 5 mL,
diluted with 5 mL of Et2O, and stored at -30 °C for 1 day to afford
an analytically pure white crystalline product (7). Yield: 77% (79
mg, 0.067 mmol). Mp: 182-184 °C. 1H NMR (400 MHz,
CDCl3): δ 7.14-6.86 (m, Ph, 16H), 3.84 (s, OMe, 6H), 3.85 (s,
(17) Armarego, W. L. F.; Perrin, D. D. Purification of Laboratory
Chemicals, 4th ed.; Butterworth-Heinemann: Linacre House, Jordan
Hill, Oxford, U.K., 1996.
(18) Bashall, A.; Doyle, E. L.; Tubb, C.; Kidd, S. J.; McPartlin, M.; Woods,
A. D.; Wright, D. S. Chem. Commun. 2001, 2542.
(19) Drew, D.; Doyle, J. R. Inorg. Synth. 1990, 28, 346.
(20) Braunstein, P.; Bender, R.; Jeanmarc, J. Inorg. Synth. 1989, 26, 341.
(21) Dey, S.; Jain, V. K.; Varghese, B. J. J. Organomet. Chem. 2001, 623,
48.
(22) Tatsuno, Y.; Yoshida, T.; Seiotsuka. Inorg. Synth. 1990, 28, 342.
(23) Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K. Inorg.
Synth. 1982, 21, 74.
t
OMe, 6H), 1.49 (s, Bu, 36H). 31P{1H} NMR (121 MHz, CDCl3):
δ 126.1 (d), 40.3 (d, 2JPP ) 7.3 Hz, 1JPtP ) 4861 Hz). Anal. Calcd
for C44H64N4P4O8PtCl2: C, 45.28; H, 5.52; N, 4.80. Found: C,
45.17; H, 5.76; N, 4.57.
(24) Giordano, G.; Crabtree, R. H. Inorg. Synth. 1990, 28, 88.
(25) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1990, 28, 90.
(26) McCleverty, J. A.; Wilkinson, G. Inorg. Synth. 1990, 28, 84.
7930 Inorganic Chemistry, Vol. 44, No. 22, 2005

Cyclodiphosphazanes with Hemilabile Ponytails
Synthesis of trans-[PdCl2{(tBuNP(OC6H4OMe-o))2-κP}2] (8).
A dichloromethane solution (7 mL) of [Pd(NCPh)2Cl2] (26 mg,
0.07 mmol) was added dropwise to a 5 mL of a dichloromethane
solution of cis-[tBuNP(OC6H4OMe-o)]2 (63 mg, 0.14 mmol) at room
temperature. The reaction mixture was stirred for 4 h and then
concentrated to 7 mL, diluted with 2 mL of Et2O, and placed at
-30 °C for 2 days to afford yellow crystals. Yield: 82% (68 mg,
0.057 mmol). Mp: 210-212 °C. 1H NMR (400 MHz, CDCl3): δ
8.02-6.83 (m, Ph, 16H), 3.88 (s, OMe, 6H,), 3.82 (s, OMe, 6H),
1.54 (s, tBu, 36H). 31P{1H} NMR (161 MHz, CDCl3): δ 128.3 (s),
84.6 (br s). Anal. Calcd for C44H64O8P4N4PdCl2: C, 49.01; H, 5.98;
N, 5.19. Found: C, 49.03; H, 5.97; N, 5.22.
226 °C (dec). 1H NMR (400 MHz, CDCl3): δ 8.06-6.81 (m, Ph,
8H), 4.28 (d, CH, 4H), 3.81 (s, OMe, 3H), 3.81 (s, OMe 3H), 2.49
and 1.75 (d, CH2, 8H), 1.52 (s, tBu, 18H). 31P{1H} NMR (161 MHz,
CDCl3): δ 131.7 (s), 102.8 (d, JRhP ) 229 Hz). Anal. Calcd for
C30H44P2N2O4RhCl: C, 51.69; H, 6.36; N, 4.01. Found: C, 51.29;
1
H, 6.38; N, 4.00. MS (EI): 661.32 (m/z - Cl).
Synthesis of [IrCl(COD){(tBuNP(OC6H4OMe-o))-κP}2] (13).
This was synthesized by a procedure similar to that for 12 using
[Ir(COD)Cl]2 (13 mg, 0.019 mmol) and cis-[tBuNP(OC6H4OMe-
o)]2 (17 mg, 0.038 mmol). Yield: 72% (0.021 g, 0.026 mmol).
1
Mp: 208-210 °C (dec). H NMR (400 MHz, CDCl3): δ 8.07-
6.60 (m, Ph, 8H), 4.43 (d, CH, 4H), 3.89 (s, OMe, 3H), 3.81 (s,
OMe 3H), 2.37 and 1.83 (d, CH2, 8H), 1.45 (s, tBu, 18H). 31P{1H}
NMR (161 MHz, CDCl3): δ 133.0 (s), 88.5 (s). Anal. Calcd for
C30H44P2N2O4IrCl: C, 45.82; H, 5.64; N, 3.56. Found: C, 46.03;
H, 5.42; N, 3.65.
Synthesis of cis-[PdCl2(PEt3){(tBuNP(OC6H4OMe-o))2-κP}]
(9). A red colored solution of [Pd(PEt3)Cl2]2 (31 mg, 0.052 mmol)
in 5 mL of CH2Cl2 was added dropwise to a CH2Cl2 solution (7
mL) of cis-[tBuNP(OC6H4OMe-o)]2 (49 mg, 0.11 mmol) at room
temperature. The reaction mixture was stirred for 6 h. The clear
pale yellow solution obtained was concentrated to 3 mL, diluted
with 3 mL of Et2O, and placed at -30 °C for 1 day to get
analytically pure product (9) as pale yellow crystals. Yield: 74%
Synthesis of [Rh2(CO)2Cl2{(tBuNP(OCH2CH2OMe))2}-κP]2
(14). A mixture of [Rh(CO)2Cl]2 (30 mg, 0.077 mmol) and cis-
[tBuNP(OCH2CH2OMe)]2 (27 mg, 0.077 mmol) in CH3CN (10 mL)
was stirred under reflux condition for 4 h. The solvent was removed
under reduced pressure, redissolved in 3 mL of CH2Cl2, and diluted
with 3 mL of petroleum ether. Keeping this solution at room
temperature for 1 day afforded orange color microcrystals. Yield:
76% (40 mg, 0.058 mmol). Mp: 128-220 °C (dec). 1H NMR (300
MHz, CDCl3): δ 4.12 (m, CH2OP, 4H), 3.50 (t, OCH2, 4H,
1
(58 mg, 0.077 mmol). Mp: 204-206 °C. H NMR (400 MHz,
CDCl3): δ 7.03-6.85 (m, Ph, 8H), 3.85 (s, OMe, 3H), 3.81 (s,
t
OMe, 3H), 2.25 (m, CH2, 2H), 1.51 (s, Bu, 18H), 1.25 (m, CH3,
3H). 31P{1H} NMR (161 MHz, CDCl3): δ 127.2 (s), 85.7 (dd,
2JPP ) 3.9 Hz, 2Jpp ) 16.8 Hz), 35.8 (d, 2JPP ) 17 Hz). Anal. Calcd
for C28H47N2P3O4PdCl2: C, 45.08; H, 6.35; N, 3.75. Found: C,
45.35; H, 6.74; N, 3.34. MS (EI): 711.29 (m/z - Cl).
t
1JHH ) 4.64 Hz), 3.32 (s, OMe, 6H,), 1.73 (s, Bu, 18H). 31P{1H}
1
3
NMR (121 MHz, CDCl3): δ 116.6 (m, | JRhP + JRhP| ) 267,
Synthesis of [(PdCl(η3-C3H5))2{(tBuNP(OC6H4OMe-o))2-κP}]
(10). A solution of [PdCl(η3-C3H5)]2 (27 mg, 0.075 mmol) in 7
mL of dichloromethane was added dropwise over a dichloromethane
(5 mL) solution of cis-[tBuNP(OC6H4OMe-o)]2 (33 mg, 0.075
mmol) at room temperature. The reaction mixture was stirred for
4 h and then concentrated to 3 mL, diluted with 3 mL of Et2O, and
kept at -30 °C for 1 day to get pure crystalline product. Yield:
77% (47 mg, 0.057 mmol). Mp: 162-164 °C (dec). 1H NMR (400
MHz, CDCl3): δ 7.58-6.88 (m, Ph, 8H), 5.64 (br, CH, 2H), 4.66
(d, syn CH2, JHH ) 7.5 Hz, 4H), 3.65 (d, anti CH2, JHH ) 14.7 Hz,
2JPP ) 42 Hz). FT-IR (KBr disk): νCO 2013 (s), 1998 (s) cm-1
.
Anal. Calcd for C32H64N4P4O12Rh4Cl4: C, 27.96; H, 4.69; N, 4.07.
Found: C, 27.68; H, 4.54; N, 4.11.
Synthesis of [Rh(CO)Cl{tBuNP(OCH2CH2SMe)-κP,κS}]2 (15).
A mixture of [Rh(CO)2Cl]2 (36 mg, 0.094 mmol) and cis-[tBuNP-
(OCH2CH2SMe)]2 (34 mg, 0.094 mmol) in CH3CN (10 mL) was
stirred under reflux condition for 4 h. The solution was concentrated
to 3 mL, added to 3 mL of Et2O, and stored at -30 °C for 1 day
to get yellow crystalline product (15). Yield: 79% (53 mg, 0.073
1
mmol). Mp: 214-216 °C (dec). H NMR (300 MHz, CDCl3): δ
t
4H), 3.85 (s, OMe, 6H), 1.55 (s, Bu, 18H). 31P{1H} NMR (161
4.36 (m, CH2OP, 4H), 2.92 (s, SMe, 6H), 2.67 (t, SCH2, 1JHH ) 4
MHz, CDCl3): δ 121.1 (s). Anal. Calcd for C28H42O4P2N2Pd2Cl2:
C, 41.19; H, 5.18; N, 3.43. Found: C, 41.30; H, 5.03; N, 3.41.
Synthesis of [RuCl2(η6-cymene){(tBuNP(OC6H4OMe-o))2-κP}]
(11). A dichloromethane solution (10 mL) of [Ru(η6-cymene)Cl2]2
(53 mg, 0.087 mmol) was added dropwise to a 7 mL of a
dichloromethane solution of cis-[tBuNP(OC6H4OMe-o)]2 (78 mg,
0.17 mmol) at room temperature. The reaction mixture was stirred
for 6 h and then concentrated to 10 mL, diluted with 5 mL of Et2O,
and placed at -30 °C for 1 day to get analytically pure crystalline
product. Yield: 84% (110 mg, 0.14 mmol). Mp: 168-170 °C. 1H
NMR (400 MHz, CDCl3): δ 8.53-6.85 (m, Ph, 8H), 5.98 (d,
cymene Ph, JHH ) 6.4 Hz, 2H), 5.75 (d, cymene Ph, 2H), 3.95 (s,
OMe, 3H), 3.81 (s, OMe, 3H), 3.07 (septet, CH, 1H), 2.23 (s, CH3,
3H), 1.40 (s, tBu, 18H), 1.30 (d, C(CH3)2, JHH ) 6.7 Hz, 6H). 31P-
{1H} NMR (121 MHz, CDCl3): δ 133.5 (d, 2JPP ) 8.7 Hz), 109.6
(d). Anal. Calcd for C32H46P2N2O4RuCl2: C, 50.79; H, 6.12; N,
3.70. Found: C, 50.33; H, 6.08; N, 3.72. MS (EI): 685.28 (m/z -
2Cl).
Synthesis of [RhCl(COD){(tBuNP(OC6H4OMe-o))2-κP}] (12).
A dichloromethane (5 mL) solution of [Rh(COD)Cl]2 (19 mg, 0.039
mmol) was added dropwise to cis-[tBuNP(OC6H4OMe-o)]2 (35 mg,
0.079 mmol) in 7 mL of CH2Cl2. The reaction mixture was stirred
for 4 h and then concentrated to 5 mL, diluted with 2 mL of Et2O,
and placed at -30 °C for 1 day to get analytically pure product as
yellow crystals. Yield: 87% (0.047 g, 0.068 mmol). Mp: 224-
Hz, 4H), 1.66 (s, tBu, 18H). 31P{1H} NMR (121 MHz, CDCl3): δ
1
3
2
121.9 (m, | JRhP + JRhP| ) 235 Hz, JPP ) 45 Hz). FT-IR (KBr
disk): νCO 2028 (s), 2013 (s) cm-1. Anal. Calcd for C16H32N2P2O4S2-
Rh2Cl2: C, 26.71; H, 4.48; N, 3.89; S, 8.91. Found: C, 27.14; H,
4.64; N, 3.67, S; 8.53. MS (EI): 683.42 (m/z - Cl).
Synthesis of [Rh(CO)Cl{tBuNP(OCH2CH2NMe2)-κP,κN}]2
(16). A mixture of [Rh(CO)2Cl]2 (32 mg, 0.084 mmol) and cis-
[tBuNP(OCH2CH2NMe2)]2 (32 mg, 0.084 mmol) in CH3CN (10
mL) was stirred under reflux condition for 4 h. The solution was
allowed to cool to room temperature, concentrated to 5 mL, and
stored at -30 °C for 1 day to get yellow crystals of 16. Yield:
76% (43 mg, 0.062 mmol). Mp: 218-220 °C (dec). 1H NMR (300
MHz, CDCl3): δ 4.19 (m, CH2OP, 4H), 2.72 (s, NMe2, 12H), 2.68
1
t
(t, NCH2, JHH ) 6 Hz), 2.01 (s, CH3CN, 3H), 1.72 (s, Bu, 18H).
31P{1H} NMR (121 MHz, CDCl3): δ 124.5 (m, | JRhP + JRhP| )
259 Hz, 2JPP ) 44 Hz). FT-IR (KBr disk): νCO 2018 (s), 1998 (s)
cm-1. Anal. Calcd for C18H38N4P2O4Rh2Cl2CH3CN: C, 31.84; H,
5.47; N, 9.28. Found: C, 31.98; H, 5.68; N, 9.59. MS (EI): 677.05
(m/z - Cl).
1
3
X-ray Crystallography. Crystals of 8, 9, 12, 14, and 16 were
mounted in a Cryoloop with a drop of Paratone oil and placed in
the cold nitrogen stream of the Kryoflex attachment of the Bruker
APEX CCD diffractometer. A full sphere of data was collected
using 606 scans in ω (0.3°/scan) at æ ) 0, 120, and 240° using the
Inorganic Chemistry, Vol. 44, No. 22, 2005 7931

Chandrasekaran et al.
SMART software package.27 The raw data were reduced to F2
values using the SAINT+ software,28 and a global refinement of
unit cell parameters employing 5880-8410 reflections chosen from
the full data set was performed. Multiple measurements of
equivalent reflections provided the basis for an empirical absorption
correction as well as a correction for any crystal deterioration during
the data collection (SADABS29). The structures were solved by
direct method and refined by full-matrix least-squares procedures
using the SHELXTL program package.30 Hydrogen atoms were
placed in calculated positions and included as riding contributions
with isotropic displacement parameters tied to those of the attached
non-hydrogen atoms.
Acknowledgment. We are grateful to the Department of
Science and Technology (DST), New Delhi, for funding
through grant SR/S1/IC-05/2003. P.C. thanks the CSIR for
a Research Fellowship. We also thank the RSIC, Mumbai,
and Department of Chemistry Instrumentation Facilities,
Bombay, for spectral and analytical data, The Louisiana
Board of Regents through Grant LEQSF(2002-03)-ENH-TR-
67 for the purchase of the CCD diffractometer, and the
Chemistry Department of Tulane University for support of
the X-ray laboratory.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of 8, 9, 12, 14, and
16. This material is available free of charge via the Internet at
http://pbs.acs.org.
(27) SMART, version 5.625; Bruker-AXS: Madison, WI, 2000.
(28) SAINT+, version 6.35A; Bruker-AXS: Madison, WI, 2002.
(29) Sheldrick, G. M. SADABS, version 2.05; University of Go¨ttingen:
Go¨ttingen, Germany, 2002.
(30) (a) SHELXTL, version 6.10; Bruker-AXS: Madison, WI, 2000. (b)
Sheldrick, G. M. SHELXS97 and SHELXL97; University of Go¨ttin-
gen: Go¨ttingen, Germany, 1997.
IC0509478
7932 Inorganic Chemistry, Vol. 44, No. 22, 2005