Di- and tri-nuclear molybdenum-palladium complexes bearing strong π-acceptor P-N-P ligands, MeN{P(OR)2}2 (R = CH2CF3 or Ph)

Article abstract of DOI:10.1016/j.jorganchem.2004.10.053

The dipalladium complexes, [PdCl(μ-MeN{P(OR)₂} ₂)]₂ (R = CH₂CF₃, 1a; Ph, 1b) react with [Mo₂(η⁵-C₅H₅) ₂(CO)₆] in boiling benzene to afford the molybdenum-palladium heterometallic complexes, [(η⁵-C ₅H₅)(CO)Mo(μ-MeN{P(OR)₂}₂) ₂PdCl] (R = CH₂CF₃, 3a; Ph, 3b), [(η⁵-C₅H₅)Mo(μ₃-CO) ₂(μ-MeN{P(OR)₂}₂)₂Pd ₂Cl], (R = CH₂CF₃, 5a; Ph, 5b), [(η⁵-C₅H₅)(Cl)Mo(μ₂-CO) (μ₂-Cl)(μ-MeN{P(OR)₂}₂)PdCl], (R = CH₂CF₃, 6a; Ph, 6b) and also the mononuclear complex [Mo(CO)Cl(η⁵-C₅H₅)(κ²- MeN{P(OR)₂}₂)], (R = Ph, 4b). These complexes have been separated by column chromatography and are characterised by elemental analysis, IR, ¹H, ³¹P{¹H} NMR data. The structures of 1a, 3a, 4b, 5b and 6a have been confirmed by single crystal X-ray diffraction. The CO ligands in 5b and 6a adopt a semi-bridging mode of bonding; the Mo-CO distances (1.95-1.97 A?) are shorter than the Pd-CO distances (2.40-2.48 A?). The Pd-Mo distances fall in the range, 2.63-2.86 A?. The reaction of [Mo₂(η⁵-C₅H₅) ₂(CO)₆] with MeN{P(OPh)₂}₂ in toluene gives [Mo₂(CO)₄(η⁵-C ₅H₅)₂(κ¹-MeN{P(OPh) ₂}₂)₂] (2) in which the diphosphazane acts as a monodentate ligand.

Full text of DOI:10.1016/j.jorganchem.2004.10.053

Journal of Organometallic Chemistry 690 (2005) 1080–1091
www.elsevier.com/locate/jorganchem
Di- and tri-nuclear molybdenum–palladium complexes bearing strong
p-acceptor ‘‘P–N–P’’ ligands, MeN{P(OR)2}2 (R = CH2CF3 or Ph) q
*
Mani Ganesan, Setharampattu S. Krishnamurthy , Munirathinam Nethaji
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
Received 10 July 2004; accepted 4 October 2004
Abstract
The dipalladium complexes, [PdCl(l-MeN{P(OR)2}2)]2 (R = CH2CF3, 1a; Ph, 1b) react with [Mo2(g5-C5H5)2(CO)6] in boiling
benzene to afford the molybdenum–palladium heterometallic complexes, [(g5-C5H5)(CO)Mo(l-MeN{P(OR)2}2)2PdCl]
(R = CH2CF3, 3a; Ph, 3b), [(g5-C5H5)Mo(l3-CO)2(l-MeN{P(OR)2}2)2Pd2Cl], (R = CH2CF3, 5a; Ph, 5b), [(g5-C5H5)(Cl)Mo(l2-
CO)(l2-Cl)(l-MeN{P(OR)2}2)PdCl], (R = CH2CF3, 6a; Ph, 6b) and also the mononuclear complex [Mo(CO)Cl(g5-C5H5)(j2-
MeN{P(OR)2}2)], (R = Ph, 4b). These complexes have been separated by column chromatography and are characterised by
1
elemental analysis, IR, H, 31P{1H} NMR data. The structures of 1a, 3a, 4b, 5b and 6a have been confirmed by single crystal
˚
X-ray diffraction. The CO ligands in 5b and 6a adopt a semi-bridging mode of bonding; the Mo–CO distances (1.95–1.97 A) are
5
˚
˚
shorter than the Pd–CO distances (2.40–2.48 A). The Pd–Mo distances fall in the range, 2.63–2.86 A. The reaction of [Mo2(g -
C5H5)2(CO)6] with MeN{P(OPh)2}2 in toluene gives [Mo2(CO)4(g5-C5H5)2(j1-MeN{P(OPh)2}2)2] (2) in which the diphosphazane
acts as a monodentate ligand.
ꢀ 2004 Elsevier B.V. All rights reserved.
1. Introduction
erometallic complexes (Fe–Co, Fe–Rh, Fe–Ir, Mo–Ni,
Mo–Pt, Mo–Rh and Mo–Ir) of the diphosphazane li-
gand MeN(PF2)2 have been reported by Mague and
coworker [5]. Braunstein and coworkers [6] have synthe-
sized palladium–cobalt, palladium–molybdenum and
platinum–cobalt trinuclear clusters of diphosphazane li-
gands, RN(PPh2)2 [R = H, Me or (CH2)3Si(OEt)3].
Heterometallic complexes containing carbon monox-
ide and phosphane ligands have attracted considerable
attention in recent years owing to their propensity to
promote cooperative activation of substrates and exhibit
site-specific reactivities as catalysts [1,2]. As a part of our
research program on the organometallic chemistry of
diphosphazane ligands based on the ‘‘P–N–P’’ frame-
work [3], we report in this paper the synthesis and struc-
tural characterization of dipalladium, dimolybdenum
and heterometallic palladium–molybdenum complexes
bearing strong p-acceptor diphosphazane ligands
MeN{P(OR)2}2 (R = CH2CF3 or Ph) [4]. Several het-
2. Experimental
2.1. Materials and physical measurements
All reactions and manipulations were carried out un-
der a nitrogen atmosphere using standard Schlenk-line
1
techniques. The H and 31P{1H} NMR spectra were re-
corded using a Bruker ACF – 200 or a Bruker AMX-400
q
Part 22 of the series, ‘‘Organometallic Chemistry of Diphospha-
zanes’’; for Part 21, see [3h].
1
spectrometer with Me4Si as an internal standard for H
*
Corresponding author. Tel.: +91 80 2293 2401; fax: +91 80 2360
NMR measurements and 85% H3PO4 as an external
standard for 31P NMR measurements. Chemical shifts
0683.
E-mail address: sskrish@ipc.iisc.ernet.in (S.S. Krishnamurthy).
0022-328X/$ - see front matter ꢀ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.10.053

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1081
downfield from the standard were assigned positive val-
ues. Infrared spectra were recorded using a BIO-RAD
FTIR Model FTS-7 or a Perkin–Elmer Model 457 spec-
trometer. The ligands, MeN{P(OR)2}2 (R = CH2CF3 or
Ph) [7] and the metal precursors, [PdCl(MeN-
{P(OR)2}2)]2 (R = Ph) [8], [Mo2(g5-C5H5)2(CO)6] [9]
and [PdCl2(COD)] [10] were prepared as reported
previously.
petrol–dichloromethane (1:1), dichloromethane and
dichloromethane–ethyl acetate (2:1) gave red, green and
orange coloured fractions, respectively. The solvent was
removed from each fraction in vacuum to obtain the
complexes 3a, 5a and 6a, respectively. Single crystals of
3a suitable for X-ray diffraction studies were obtained
from diethylether at ꢀ15 ꢁC; single crystals of 6a were ob-
tained by fractional crystallization of the reaction mix-
ture from CH2Cl2–petrol (1:2 v/v) at ꢀ15 ꢁC. When the
reaction was carried out with a 1:2 stoichiometric ratio
of the starting dipalladium and dimolybdenum com-
plexes and the reaction mixture subjected to column
chromatography, initial elution with petrol–dichlorome-
thane (3:1) gave an orange coloured fraction from which
solvent was removed to obtain a solid residue. The 31P
NMR spectrum of this product showed two singlets at
d 168.0 and 181.8. The nature of the product could not
be ascertained. Complexes 3a, 5a and 6a were also iso-
lated from this reaction as described above.
2.2. The reactions of [Pd(COD)Cl2] with
MeN{P(OCH2CF3)2}2
2.2.1. Synthesis of [Pd2Cl2(l-MeN{P(OCH2CF3)2}2)2]
(1a)
A solution of [Pd(COD)Cl2] (0.143 g, 0.50 mmol) and
MeN{P(OCH2CF3)2}2 (0.488 g, 1.00 mmol) in 25 ml of
CH2Cl2 was stirred for 3 h. The solution was filtered and
the filtrate concentrated to 8 ml. Addition of 8 ml of pet-
rol followed by cooling at ꢀ15 ꢁC gave orange crystals
of 1a. Yield: 275 mg (86.0%). Anal. Calc. for
C18Cl2F24H22N2O8P4Pd2: C, 17.2; H, 1.8; N, 2.2.
2.2.4. Synthesis of [(g5-C5H5)(CO)Mo(l-MeN-
1
Found: C, 17.1; H, 1.9; N, 2.2%. H NMR (200 MHz,
{P(OPh)2}2)2] (3b), [Mo(CO)Cl(g5-C5H5)(j2-MeN-
{P(OPh)2}2)] (4b), [(g5-C5H5)Mo(l3sb-CO)2(l-MeN-
{P(OPh)2}2)2Pd2Cl]-(5b) and [(g5-C5H5)ClMo-
(lsb-CO)(l-Cl)(l-MeN{P(OPh)2}2)PdCl] (6b)
A solution of [Pd2Cl2(MeN{P(OPh)2}2)2] (0.100 g,
0.083 mmol) and [Mo2Cp2(CO)6] (0.045 g, 0.092
mmol) in 40 ml benzene was heated under reflux for
3 days using an oil bath maintained at 90 ꢁC. The
reaction mixture was cooled to 25 ꢁC and the solvent
removed in vacuum. The residue was dissolved in 6ml
of dichloromethane and loaded on top of a silica gel
column. Successive elutions with petrol–diethyl ether,
4:1, 2:1 and 1:1 v/v mixtures gave pink, orange and
green fractions, respectively. The solvent was removed
from each fraction under reduced pressure to obtain
the complexes 3b, 4b and 5b, respectively. Further elu-
tion with diethylether–dichloromethane (4:1) gave an
orange fraction from which the solvent was removed
in vacuum to isolate 6b; this was recrystallized from
CH2Cl2/petrol (1:2) at ꢀ15 ꢁC. Single crystals of 4b
and 5b suitable for X-ray diffraction studies were ob-
tained from CH2Cl2/petrol (1:3 v/v) and CH2Cl2/pet-
rol/diethylether (1:1:2 v/v) at ꢀ15 ꢁC, respectively.
The yields (based on Mo), analytical and spectro-
scopic data for the complexes are given below.
CDCl3, 25 ꢁC): d 2.82 (m, 6H, NMe), 4.54–4.73 (m,
16H, CH2 of OCH2CF3). 31P{1H} NMR (161.9 MHz,
CDCl3, 25 ꢁC): d 120.0 (s).
2.2.2. Synthesis of [Mo2(g5-C5H5)2(CO)4
(j1-MeN{P-(OPh)2}2)2] (2)
A solution of [Mo2(g5-C5H5)2(CO)6] (0.095 g, 0.19
mmol) and MeN{P(OPh)2}2 (0.090 g, 0.19 mmol) in tol-
uene (25 ml) was heated under reflux for 8 h. The solvent
was evaporated and the residue extracted with diethyl
ether. The extract was filtered to give a red solution,
which was allowed to stand for 12 h to give dark green
micro crystals of 2. Yield: 66 mg (25.0%) Anal. Calc. for
C64H56Mo2N2O12P4: C, 56.5; H, 4.1; N, 2.1. Found: C,
55.0; H, 4.4; N, 2.2%. IR (Neat, cmꢀ1): m(CO) 1898 (s),
3
1978 (s). 1H NMR: d 2.70 (dd, JHP = 5.6 Hz, 6H,
NMe), 4.90 (s, 10H, C5H5), 7.0–7.4 (m, 20H, Ph).
2
31P{1H} NMR: d 179.6 (d, JPP = 32.7 Hz, P–Mo),
112.1 (d, JPP = 32.7 Hz, P (dangling)).
2
2.2.3. Synthesis of [(g5-C5H5)(CO)Mo(l-MeN{P-
(OCH2CF3)2}2)2PdCl] (3a), [(g5-C5H5)Mo(l3sb-CO)2-
(l-MeN-{P(OCH2CF3)2}2)2Pd2Cl] (5a), and [(g5-C5H5)-
ClMo(lsb-CO)(l-Cl)(l-MeN{P(OCH2CF3)2}2)PdCl]
(6a)
A solution of [Pd2Cl2(MeN{P(OCH2CF3)2}2)2] (0.100
g, 0.080 mmol) and [Mo2(g5-C5H5)2(CO)6] (0.038 g,
0.077 mmol) in 40 ml of C6H6 was heated under reflux
for 4 days using an oil bath maintained at 90 ꢁC. The
reaction mixture was cooled to 25 ꢁC and the solvent re-
moved in vacuum. The residue was dissolved in CH2Cl2
(6 ml) and subjected to chromatography using a column
of dimensions 50 cm length and 1.5 cm inner diameter
packed with 50 g of silica gel. Successive elutions with
2.2.5. [(g5-C5H5)(CO)Mo(l-
MeN{P(OCH2CF3)2}2)2PdCl] (3a)
Yield: 57 mg, 28.4%. Anal. Calc. for
C24ClF24H27MoN2O9P4Pd: C, 22.1; H, 2.1; N, 2.2.
Found: C, 22.2; H, 2.1; N, 2.2%. IR (Nujol, cmꢀ1):
1
m(CO) 1863 (s). H NMR: d 2.83 (m, 6H, NMe), 4.04–
4.90 (m, 16H, CH2 of OCH2CF3), 5.28 (d, JHP = 3.8
Hz, 5H, C5H5).
3

Table 1
Details of the X-ray data collection, structure solution and refinement for compounds 1a, 3a, 4b, 5b and 6a
1a
3a
4b Æ CH2Cl2
5b Æ 0.5CH2Cl2
6a
Empirical formula
C
18Cl2F24H22,
C24ClF24H27MoN2O9P4Pd C31ClH28MoNO5P2 Æ CH2Cl2 C57ClH51MoN2O10P4Pd2 Æ 0.5CH2Cl2 C15Cl3F12H16MoNO5P2Pd
N2O8P4Pd2
1257.9
293(2)
Triclinic
Formula weight
Temperature (K)
Crystal system
Space group
1305.15
293(2)
772.80
293(2)
Triclinic
1435.54
293(2)
Triclinic
888.92
293(2)
Monoclinic
P21/n
Monoclinic
P21/c
ꢀ
ꢀ
ꢀ
P1
P1
P1
11.946(8)
21.09(2)
˚
a (A)
9.067(1)
9.759(1)
11.882(1)
82.79(1)
80.57(1)
82.65(1)
1022.8(2)
1
12.058(1)
18.203(4)
21.481(1)
90.00
10.262(6)
12.554(2)
14.864(2)
106.45(2)
104.24(2)
103.29(3)
1685.2(1)
2
14.537(7)
19.163(2)
21.363(4)
90.00
˚
b (A)
˚
c (A)
23.757(7)
96.62(4)
99.19(4)
a (ꢁ)
b (ꢁ)
c (ꢁ)
106.158(9)
90.00
108.18(3)
90.00
89.84(6)
3
˚
Volume (A )
4528.9(1)
4
1.914
5867.9(6)
4
1.625
5654.1(3)
8
2.089
Z
DC (mg mꢀ3
)
2.042
1.317
610
1.523
0.762
784
l (Mo Ka) (mmꢀ1
F(0 0 0)
)
1.019
2552
1.075
2876
1.584
3440
Crystal size (mm)
h Ranges (ꢁ)
h,k,l Ranges
0.8 · 0.5 · 0.15
1.75–30.44
0 6 h 6 10,
ꢀ11 6 k 6 11,
ꢀ14 6 l 6 14
3833
0.8 · 0.6 · 0.13
1.49–24.97
0 6 h 6 14,
0 6 k 6 21,
ꢀ25 6 l 6 24
8980
0.19 · 0.14 · 0.140
1.52–24.96
0 6 h 6 12,
ꢀ14 6 k 6 14,
ꢀ17 6 l 6 17
6313
0.8 · 0.8 · 0.12
1.23–24.98
0 6 h 6 14,
ꢀ25 6 k 6 25,
ꢀ28 6 l 6 27
24,194
0.7 · 0.4 · 0.11
1.46–24.98
0 6 h 6 17,
0 6 k 6 22,
ꢀ25 6 l 6 24
10,450
Reflections collected
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit on F2
)
3585 (0.0093)
3584/90/267
0.982
7956 (0.0345)
7944/225/583
1.076
5908 (0.0199)
5907/0/397
0.862
20,580 (0.0208)
20,544/0/1413
1.067
9939 (0.0499)
9915/180/711
1.059
Final R indices [I < 2r(I)]
R1 = 0.0500,
wR2 = 0.1469
R1 = 0.0552,
wR2 = 0.1551
R1 = 0.0700,
wR2 = 0.1775
R1 = 0.1213,
wR2 = 0.2248
R1 = 0.0440,
wR2 = 0.1190
R1 = 0.0497,
wR2 = 0.1283
1.131 and ꢀ1.314
R1 = 0.0937,
wR2 = 0.2213
R1 = 0.1549,
wR2 = 0.2855
1.869 and ꢀ2.342
R1 = 0.0676,
wR2 = 0.1411
R1 = 0.1433,
wR2 = 0.1932
0.890 and ꢀ0.716
R indicesa,b (all data)
Largest difference peak and hole (e Aꢀ3
)
0.946 and ꢀ0.918 0.791 and ꢀ0.649
P
P
a
R1 ¼ kF oj ꢀ jF ck= jF cj.
P
P
2
2 0:5
b
wR2 ¼ ½ ½wðF 2o ꢀ F c2Þ ꢁ= ½wðF 2oÞ ꢁꢁ
.
2
w ¼ 1=½r2ðF 2oÞ þ ð0:1001 ꢂ pÞ þ 3:3972 ꢂ pꢁ where p ¼ ðMaxðF 2o; 0Þ þ 2 ꢂ F 2oÞ=3 for complex 1a.
2
w ¼ 1=½r2ðF 2oÞ þ ð0:1084 ꢂ pÞ þ 15:8530 ꢂ pꢁ where p ¼ ðMaxðF 2o; 0Þ þ 2 ꢂ F 2oÞ=3 for complex 3a.
2
w ¼ 1=½r2ðF 2oÞ þ ð0:1065 ꢂ pÞ þ 2:6045 ꢂ pꢁ where p ¼ ðMaxðF 2o; 0Þ þ 2 ꢂ F 2oÞ=3 for complex 4b.
2
w ¼ 1=½r2ðF 2oÞ þ ð0:1449 ꢂ pÞ þ 53:3663 ꢂ pꢁ where p ¼ ðMaxðF 2o; 0Þ þ 2 ꢂ F 2oÞ=3 for complex 5b.
2
w ¼ 1=½r2ðF 2oÞ þ ð0:0718 ꢂ pÞ þ 38:6963 ꢂ pꢁ where p ¼ ðMaxðF 2o; 0Þ þ 2 ꢂ F 2oÞ=3 for complex 6a.

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1083
2.2.6. [(g5-C5H5)(CO)Mo(l-MeN{P(OPh)2}2)2PdCl]
(3b)
Yield: 5 mg, 2.2%. This compound was formed in low
yield (<5%) and could not be obtained in a pure state. It
was only identified from 31P NMR data (Table 3).
refinements are given in Table 1. The structures were
solved by conventional Patterson method using
SHELXS-86 and refined by full-matrix least squares with
SHELXL-93 [11]. All hydrogen atoms were included in
˚
the calculated positions [C–H = 0.96–0.97 A] with a
fixed isotropic displacement parameters except the dis-
ordered atoms. All non-hydrogen atoms were refined
anisotropically except the disordered ones. In the struc-
ture of 1a, disorder of fluorine atoms attached to C6
and C9 was observed. In the structure of 3a, disorder
of C16, C18, C24 and fluorines attached to C18, C19,
C22, C23, and C24 was observed. In the structure of
6a, disorder of C12 and C27 and the fluorine atoms at-
tached to C12, C13, C27 and C29 was observed. In the
structure of 5b, disorder of the phenyl group and sol-
vent (CH2Cl2) carbon atoms was observed. The refine-
ments of these atoms were carried out using SADI
option available in SHELXL-93 and stopped near
convergence. The site occupancy factors are given in
Section 5.
2.2.7. [Mo(CO)Cl(g5-C5H5)(j2-MeN{P(OPh)2}2)]
(4b) Æ CH2Cl2
Yield: 36 mg, 26.2%. Anal. Calc. for C32Cl3H30Mo-
NO5P2: C, 49.7; H, 3.9; N, 1.8. Found: C, 49.1; H,
3.7; N, 1.7%. IR (Nujol, cmꢀ1): m(CO) 1880 (s). 1H
3
NMR: d 2.61 (dd, JHP = 12, 10 Hz, 3H, NMe), 4.83
(d, JHP = 2.6 Hz, 5H, C5H5), 5.3 (s, 2H, solvated
CH2Cl2), 6.6–7.5 (m, 20H, Ph).
3
2.2.8. [(g5-C5H5)Mo(l3sb-CO)2-
(l-MeN{P(OCH2CF3)2}2)2Pd2Cl] (5a)
Yield: 58 mg, 26.1%. Anal. Calc. for
C25ClF24H27MoN2O10P4Pd2: C, 20.8; H, 1.9; N, 1.9.
Found: C, 20.4; H, 1.6; N, 1.8%. IR (Nujol, cmꢀ1):
1
3
m(CO) 1815. H NMR: d 2.72 (t, JHP = 6.5 Hz, 3H,
NMe), 2.86 (t, JHP = 6.7 Hz, 3H, NMe), 3.87–5.01
(m, 16H, CH2 of OCH2CF3), 5.33 (s, 5H, C5H5).
3
3. Results and discussion
2.2.9. [(g5-C5H5)Mo(l3sb-CO)2-
3.1. Dinuclear palladium complex, [Pd2Cl2(l-
MeN{P(OCH2CF3)2}2)2] (1a)
(l-MeN{P(OPh)2}2)2Pd2Cl] (5b) Æ 0.5CH2Cl2
Yield: 65 mg, 24.6%. Anal. Calc. for C57.5Cl2H52Mo-
N2O10P4Pd2: C, 48.1; H, 3.7; N, 1.9. Found: C, 48.5; H,
3.4; N, 1.9%. IR (Nujol, cmꢀ1): m(CO) 1795 (s). 1H
3.1.1. Synthesis, spectroscopic data and structure
The dipalladium complex 1a can be isolated as the
major product (86%) from the reaction of [PdCl2(COD)]
and MeN{P(OCH2CF3)2}2 in CH2Cl2 by using 1:2 stoi-
chiometry of the reactants and by crystallization of the
reaction mixture from CH2Cl2/petrol (1:1 v/v) [12]. An
analogous reaction of [PdCl2(COD)] with MeN-
{P(OPh)2}2 produces the dipalladium complex,
[PdCl(l-MeN{P(OPh)2}2)]2 (1b) and the chelate com-
plex, [PdCl2(j2-MeN{P(OPh)2}2)] as shown by the 31P
NMR spectrum of the reaction mixture. Dipalladium
complexes of type 1a and 1b containing two bridging
diphosphorus ligands are usually prepared by a dispro-
portionation reaction between Pd(II) and Pd(0)
complexes [13]. Several studies have shown that Pd(0)–
phosphine complexes are formed by the reduction of
divalent palladium in the presence of a monophosphine
ligand [14–17] and adventitious water. In addition to
water, a fluorinating agent such as NaBF4 or AgF facil-
itates the reduction of Pd(II) when a diphosphine [18,19]
{e.g., Ph2PCH2PPh2 (dppm)} is used. The reduction of
Pd2+ to Pd1+ to form the dinuclear complex 1a occurs
(evidently in the presence of adventitious water) without
the need to use a reducing agent to bring about the
reduction because of the strong p-acceptor ability of
the diphosphazane ligands, MeN{P(OR)2}2 (R =
CH2CF3 or Ph) [7].
3
NMR: d 2.53 (t, JHP = 6.7 Hz, 3H, NMe), 2.81 (t,
3JHP = 6.4 Hz, 3H, NMe), 4.50 (s, 5H, C5H5), 5.3 (s,
2H, solvated CH2Cl2), 6.8–7.6 (m, 40H, Ph).
2.2.10. [(g5-C5H5)ClMo(lsb-CO)(l-Cl)-
(l-MeN{P(OCH2CF3)2}2)PdCl] (6a)
Yield: 30 mg, 21.9%. Anal. Calc. for
C15Cl3F12H16MoNO5P2Pd: C, 20.3; H, 1.8; N, 1.6.
Found: C, 19.9; H, 1.9; N, 1.55%. IR (Nujol, cmꢀ1):
1
3
m(CO) 1935. H NMR: d 2.96 (t, JHP = 7.5 Hz, 3H,
NMe), 4.3–5.2 (m, 8H, CH2 of OCH2CF3), 5.70 (d,
3JHP = 2.8 Hz, 5H, C5H5).
2.2.11. [(g5-C5H5)ClMo(lsb-CO)(l-Cl)-
(l-MeN{P(OPh)2}2)PdCl] (6b)
Yield: 8 mg, 5.0%. Anal. Calc. for C31Cl3H28Mo-
NO5P2Pd: C, 43.0; H, 3.2; N, 1.6. Found; C, 42.6; H,
3.0; N, 1.5%. IR (Nujol, cmꢀ1): m(CO) 1910, 1H
3
NMR: d 3.15 (t, JHP = 7.6 Hz, 3H, NMe), 5.26 (d,
3JHP = 2.6 Hz, 5H, C5H5), 7.2–7.8 (m, 20H, Ph).
2.3. X-ray crystallography
The diffraction data for complexes 1a, 3a, 4b, 5b and
6a were collected using a Enraf-Nonius CAD-4 diffrac-
tometer with graphite monochromated Mo Ka radia-
The 1H NMR spectrum of 1a shows a quintet pattern
for the N-methyl protons which is a characteristic signal
˚
tion (k = 0.7107 A). Details of the data collection and

1084
M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
for the presence of two diphosphazane ligands. The
31P{1H} NMR spectrum shows a sharp singlet at d
120.0 which lies upfield to the chemical shift for the li-
gand (dcomplex ꢀ dligand = ꢀ29.9 ppm). The structure of
1a is confirmed by single crystal X-ray diffraction. A
perspective view of the molecule is shown in Fig. 1. Se-
lected bond distances and angles are listed in Table 2.
The molecule is centrosymmetric unlike the analogous
phenyl derivative [Pd2Cl2{PhN(P(OPh)2)2}2] [8]. The
coordination geometry around palladium is distorted
3.2. Reaction of [Mo2(g5-C5H5)2(CO)6] with
MeN{P(OPh)2}2
The reaction between [Mo2(g5-C5H5)2(CO)6] and
MeN{P(OPh)2}2 in boiling toluene affords the complex,
[Mo2(CO)4(g5-C5H5)2(j1-MeN{P(OPh)2}2)2] 2 as dark
green micro crystals. The compound is isolated by crystal-
lization of the reaction mixture from diethyl ether
(Scheme 1). Although the elemental analysis results give
a slightly lower carbon percentage than the value expected
for the above formula, the relative integrated intensities of
˚
square planar. The Pd–Pd separation [2.629(1) A] and
1
˚
the mean Pd–P distance [2.259(2) A] lie in between those
the methyl, C5H5 and aryl proton resonances in the H
observed for the closely related dipalladium(I) com-
plexes, [Pd2Cl2{PhN(P(OPh)2)2}2] [8] and [Pd2Cl2{HN-
(PPh2)2}2] [20].
NMR spectrum support the above formula. A doublet
of doublets is observed for the N-methyl protons at d
2.70 indicating that the phosphorus nuclei are nonequiv-
alent. The 31P NMR spectrum shows two doublets cen-
tered at d 179.6 and 112.1 (2JPP = 32.7 Hz) which can be
assigned to the coordinated and uncoordinated phospho-
rus nuclei, respectively. Such a considerable deshielding
of the coordinated phosphorus has also been noted for
many molybdenum complexes containing j1-coordinated
MeN(PF2)2 ligand [21] and molybdenum carbonyl com-
plexes of j1-cooridnated cyclodiphosphazanes [3a]. The
IR spectrum of 2 shows strong peaks at 1898 and 1978
cmꢀ1 which signify the presence of terminal carbonyl
groups. A cis or trans orientation of the Cp (or diphosp-
hazane) ligands is possible for compound 2 and a trans-
structure is tentatively assigned to it.
The reaction of [(g5-C5H5)2Mo2(CO)6] with the
diphosphazane, PriN(PPh2)2 gives both
a
salt-
like complex, [(g5-C5H5){PriN(PPh2)2}(CO)2Mo]+[(g5-
C5H5)-(CO)3Mo]ꢀ and diphosphazane bridged complex
[Mo2-(CO)4(g5-C5H5)2{l-PriN(PPh2)2}] [22]. The reac-
tion of MeN(PF2)2 with [(g5-C5H5)2Mo2(CO)4] gives the
diphosphazane bridged complex [Mo2(CO)4(g5-C5H5)2-
(l-MeN(PF2)2)] [5b]. In the present study, it is observed
CH3
N
CO
Mo
CO
CO
Fig. 1. The molecular structure of [Pd2Cl2(l-MeN{P(OCH2CF3)2}2)2]
(1a).
Mo
CO
(RO)
2 P
+
(OR)
P
2
R = Ph
CO
CO
Toluene/106 0C/24h
Table 2
˚
Selected bond distances (A) and bond angles (ꢁ) in 1a
(RO)
2 P
Pd(1)–Pd(1A)
Pd(1)–P(1)
Pd(1)–P(2A)
Pd(1)–Cl(1)
P(1)–N(1)
2.629(1)
2.257(2)
2.261(2)
2.395(2)
1.658(5)
1.656(5)
N
CH3
(RO)2
P
OC
OC
CO
CO
Mo
Mo
P(2)–N(1)
P
(RO)2
P(1)–Pd(1)–Cl(1)
P(2A)–Pd(1)–Cl(1)
P(1)–Pd(1)–Pd(1A)
P(2A)–Pd(1)–Pd(1A)
Cl(1)–Pd(1)–Pd(1A)
P(1)–Pd(1)–P(2A)
P(1)–N(1)–P(2)
87.7(1)
87.8(1)
92.0(1)
92.6(1)
176.9(1)
174.6(1)
116.2(3)
N
CH3
P
(OR)2
2, R = Ph
Scheme 1.

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1085
CH3
N
CO
(RO)
Cl
2 P
P
CO
(OR)2
Cl
CO
Mo
CO
C6H6/760C/3-4 days
Mo
+
Pd
Pd
CO
CO
(RO)2 P
P
(OR)2
N
CH3
1a R = CH2CF3
1b R = Ph
CH3
N
(RO)2
P
P(OR)2
(RO)2
P
Mo
Mo
Pd
Cl
CO
C
O
P
(OR)2
Cl
N
P
P
(OR)2
(RO)2
H3C
N
CH3
3a R = CH2CF3
3b R = Ph
4b R =Ph
(OR)2
P
O
H3C
Cl
C
N
P
Mo
Mo
Cl
Pd
Cl
CO
(RO)2
CO
(RO)2 P
P
(OR)2
Pd
Pd
P
Cl
N
CH3
(OR)
(RO)2 P
2
N
CH3
6a R = CH2CF3
6b R = Ph
5a R = CH2CF3
5b R = Ph
Scheme 2.
that the reaction of [(g5-C5H5)2Mo2(CO)6] with MeN-
{P(OPh)2}2 gives the dimolybdenum complex 2 bearing
two j1-coordinated diphosphazane ligands as a result of
pairwise substitution of the CO ligands by the strong p-
acceptor diphosphazane ligand MeN{P(OPh)2}2. This
behavior is also observed in the reactions of [(g5-
C5H5)2Mo2(CO)6] with phosphites such as P(OBun)3 or
P(OPh)3 [23].
several products (Scheme 2). Three complexes, 3a, 5a
and 6a can be isolated in a pure form from the reaction
mixture by column chromatography over silica gel. No
definitive evidence could be obtained for the formation
of the chelate complex [Mo(CO)Cl(g5-C5H5)(j2-MeN-
{P(OCH2CF3)2}2)] analogous to 4b. Treatment of an
equimolar quantity of the phenoxy substituted diphosp-
hazane complex [Pd2Cl2(l-MeN{P(OR)2}2)2] (R = Ph)
1b with [Mo2(g5-C5H5)2(CO)6] yields the complexes
3b, 4b, 5b and 6b which are separated by column chro-
matography over silica gel (Scheme 2). The relative
yields of the different complexes in the trifluoroethoxy
(3a, 5a and 6a) and the phenoxy series (3b–6b) vary
(see Section 2). The trifluoroethoxy substituted ligand
prefers to form a bridging type of complex rather than
3.3. Molybdenum–palladium heterometallic complexes
3.3.1. Synthesis and spectroscopic data
Treatment
(R = CH2CF3) 1a with an equimolar quantity of [Mo2-
of
[Pd2Cl2(l-MeN{P(OR)2}2)2]
(g5-C5H5)2(CO)6] in boiling benzene for 4 days gives

1086
M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
a chelate type of complex. There is no reaction between
the dipalladium complex (1a or 1b) and [Mo2(g5-
C5H5)2(CO)6] in toluene at 25 ꢁC for 24 h; the dipalla-
dium complex is recovered unchanged.
The structures of 3a, 5a and 6a and 3b–6b are de-
duced from their IR and NMR spectroscopic data and
confirmed by single crystal X-ray diffraction studies
for 3a, 4b, 5b and 6a. The 31P NMR data are given in
Table 3.
Both 3a and 3b represent examples of a 32-valence
electron Mo–Pd heterometallic complex. Their 31P
NMR spectra are of the AA0XX0 type. The low field res-
onances (XX0 region) are assigned to the phosphorus
nuclei attached to molybdenum and the high field reso-
nances (AA0 region) are assigned to the phosphorus nu-
clei attached to palladium. The analysis of the XX0
region of the spectrum of 3a yields the parameters
sis could not be carried out for 3b as the outer lines in
the AA0XX0 spectrum were not observed. The 1H
NMR spectrum of 3a shows a quintet pattern for the
methyl group attached to nitrogen consistent with pres-
ence of two diphosphazane ligands attached to the metal
centers. The 31P NMR spectrum of 4b shows the ex-
2
pected AX spin pattern. The magnitude of JPP (43.7
Hz) is larger than that observed for the analogous
Ph2P(CH2)2PPh2 (dppe) complex, [CpMo(Cl)CO(dppe)]
[2JPP = 38.0 Hz] [25].
The complexes 5a and 5b represent examples of a
44-valence electron Mo–Pd trinuclear cluster and are
similar to the dppm complex, [Pd2Mo(g5-C5H5)(Cl)-
(l3-CO)2(l-dppm)2], which was prepared and structur-
ally characterized by Braunstein et al. [26]. The IR
spectra of 5a and 5b show a strong peak at 1815 and
1795 cmꢀ1, respectively, which can be ascribed to
semi-bridging CO groups. The 31P NMR spectra of 5a
and 5b provide interesting examples of a four spin sys-
tem in which all four phosphorus nuclei are magnetically
0
shown in Table 3. The JAA value (839.7 Hz) is much
higher than that reported for the complex, [Pd(l-
CO)(l-dppm)2Mo(g5-C5H5)(CO)]+ [24]. Such an analy-
Table 3
The 31P NMR data for heterometallic molybdenum–palladium complexes 3–6a
Complex
d, 31P-{1H}
3a
134.8 (m, PA–Pd), 185.8 (m, PX–Mo)b
JAA = 839.7, JAX = JA0X0 = 174.2
0
0
0
0
JAX = JA X = 38.1, JXX = 31.1
3b
4b
130.4 (m, P–Pd), 176.7 (m, P–Mo)c
2
143.2 (d, P–Mo), 153.7 (d, P–Mo) JPP 43.7
5ad,e
109.124 (ddd, P1–Pd), 125.409 (ddd, P3–Pd), 126.607 (ddd, P2–Pd), 190.636 (ddd, P4–Mo), J1,2 70.4, J1,3 = 142.5,
J1,4 201.6, J2,3 = 121.7, J2,4 = 49.0, J3,4 = 23.9
5be
88.2 (ddd, P1–Pd), 110.5 (ddd, P3–Pd), 112.8 (ddd, P2–Pd), 178.2 (ddd, P4–Mo), J1,2 = 88.1, J1,3 = 157.3,
J1,4 = 190.3, J2,3 118.9, J2,4 = 55.7, J3,4 = 38.7
2
123.9 (d, P–Pd), 154.0 (d, P–Mo) JPP = 117.5
2
108.3 (d, P–Pd), 151.0 (d, P–Mo) JPP = 114.7
6a
6b
a
Recorded in CDCl3 at 161.9 MHz, 25 ꢁC, d in ppm, J in Hz.
b
c
AA0XX0 spectrum.
AA0XX0 spectrum; outer lines could not be observed.
Recorded at 243 MHz.
For labeling of the P nuclei, see Fig. 2.
d
e
Fig. 2. The 31P{1H} NMR spectrum (243 MHz) of [(g5-C5H5)Mo(l3-CO)2(l-MeN{P(OCH2CF3)2}2)2Pd2Cl] (5a): (a) experimental; (b) simulated.

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1087
nonequivalent and coupled to each other. The spectra
have been analyzed by iterative computer simulation
and the parameters are listed in Table 3. The experimen-
tal and the computer simulated spectra for 5a are illus-
trated in Fig. 2. The assignment of the chemical shifts
and consequently the coupling constants are tentative
except the highly deshielded one which is assigned to
the phosphorus attached to molybdenum. An AX type
pattern is observed in the 31P NMR spectra of the hete-
rodinuclear complexes 6a and 6b. The IR spectra show
strong peaks at 1935 and 1910 cmꢀ1 for the semi-bridg-
ing CO groups. These values are considerably higher
than those reported for [PdMo(l-Ph2PPy)2(l-CO)-
(CO)2Cl2] [27] and [(Cp)Co{l,g2-P,O–P(O)(OMe)2}3-
Mo(CO)(l,g2-C,N–C(C6H4Me–P)(C6H4CH2NMe2)-
(l-CO)PdI] [28]. containing semi-bridging CO groups.
This is probably due to the formal higher oxidation state
(+2.5) of molybdenum in 6a and 6b.
Fig. 4. The molecular structure of [(g5-C5H5)Mo(CO)Cl(j2-MeN-
{P(OPh)2}2)] (4b).
3.4. Crystal and molecular structures of 3a, 4b, 5b and 6a
The molecular structures of 3a, 4b, 5b and 6a as
determined by single crystal X-ray diffraction studies
are depicted in Figs. 3–6, respectively. Selected bond dis-
tances and bond angles are summarized in Tables 4–7.
The molecule of 3a may be regarded as one derived
from the Pd(I) dimer by the replacement of a ꢀPd–Clꢁ
unit by a ꢀCpMo(CO)ꢁ unit. Molybdenum and palla-
dium are linked by two bridging diphosphazane ligands
which are disposed nearly trans to each other. The coor-
dination geometry around the Mo atom is that of a four
legged piano stool (including M–M bond). The geome-
Fig. 5. The molecular structure of [(g5-C5H5)Mo(l3-CO)2(l-MeN-
{P(OPh)2}2)2Pd2Cl] (5b). For clarity only the ipso carbons of the
phenyl rings are shown.
try around the Pd atom is distorted square planar. The
molecule adopts a partially staggered configuration;
the torsion angles of P(2)–Pd(1)–Mo(1)–P(1) and P(3)–
Pd(1)–Mo(1)–P(4) are 28.1(1)ꢁ and ꢀ31.1(1)ꢁ, respec-
tively. The P(1)–Mo(1)–P(4) angle [118.7(1)ꢁ] deviates
from collinearity compared to P(2)–Pd(1)–P(3) angle
[179.3(1)ꢁ] owing to the presence of the cyclopentadienyl
ligand at molybdenum. The Mo–Pd distance [2.860(1)
Fig. 3. The molecular structure of [(g5-C5H5)(CO)Mo(l-MeN-
{P(OCH2CF3)2}2)2PdCl] (3a). The CF3 groups have been omitted for
clarity.

1088
M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
Table 6
Selected bond distances (A) and bond angles (ꢁ) in 5b (molecule 1)
˚
Pd(1)–P(1)
Pd(1)–Cl(1)
Pd(1)–C(1)
Pd(1)–Pd(2)
Pd(1)–C(2)
Pd(1)–Mo(1)
Pd(2)–P(3)
Pd(2)–P(2)
Pd(2)–C(1)
Pd(2)–C(2)
Pd(2)–Mo(1)
Mo(1)–P(4)
Mo(1)–C(2)
Mo(1)–C(1)
P(4)–N(2)
2.211(5)
2.402(4)
2.54(2)
2.537(2)
2.58(1)
2.774(3)
2.245(3)
2.250(4)
2.46(2)
2.48(1)
2.758(2)
2.401(4)
1.98(2)
2.00(2)
1.68(1)
1.66(1)
1.67(1)
1.67(1)
P(1)–Pd(1)–Cl(1)
P(1)–Pd(1)–Pd(2)
Cl(1)–Pd(1)–Pd(2)
P(1)–Pd(1)–Mo(1)
Cl(1)–Pd(1)–Mo(1)
Pd(2)–Pd(1)–Mo(1)
P(3)–Pd(2)–P(2)
94.4(2)
97.4(1)
168.2(1)
159.6(1)
105.9(1)
62.4(1)
105.8(1)
164.1(1)
90.1(1)
P(3)–Pd(2)–Pd(1)
P(2)–Pd(2)–Pd(1)
P(3)–Pd(2)–Mo(1)
P(2)–Pd(2)–Mo(1)
Pd(1)–Pd(2)–Mo(1)
P(4)–Mo(1)–Pd(2)
P(4)–Mo(1)–Pd(1)
Pd(2)–Mo(1)–Pd(1)
P(3)–N(2)–P(4)
101.1(1)
152.7(1)
63.0(1)
81.2(1)
135.8(1)
54.6(1)
P(2)–N(1)
P(3)–N(2)
P(1)–N(1)
115.1(6)
117.0(8)
P(2)–N(1)–P(1)
Fig. 6. The molecular structure of [(g5-C5H5)ClMo(l2-CO)(l2-Cl)(l-
MeN{P(OCH2CF3)2}2)PdCl] (6a).
Table 7
˚
Table 4
Selected bond distances (A) and bond angles (ꢁ) in 6a (molecule 1)
˚
Selected bond distances (A) and bond angles (ꢁ) in 3a
Mo(1)–C(1)
Mo(1)–P(2)
Mo(1)–Cl(2)
Mo(1)–Cl(1)
Mo(1)–Pd(1)
Pd(1)–P(1)
Pd(1)–Cl(3)
Pd(1)–Cl(2)
Pd(1)–C(1)
P(2)–N(1)
1.99(1)
2.437(3)
2.479(3)
2.494(3)
2.629(2)
2.150(3)
2.352(4)
2.395(3)
2.45(1)
1.66(1)
1.67(1)
1.14(1)
Cl(3)–Pd(1)–Cl(2)
P(1)–Pd(1)–Cl(3)
P(1)–Pd(1)–Cl(2)
P(1)–Pd(1)–Mo(1)
Cl(3)–Pd(1)–Mo(1)
Cl(2)–Pd(1)–Mo(1)
C(1)–Mo(1)–P(2)
C(1)–Mo(1)–Cl(2)
P(2)–Mo(1)–Cl(2)
C(1)–Mo(1)–Cl(1)
P(2)–Mo(1)–Cl(1)
Cl(2)–Mo(1)–Cl(1)
C(1)–Mo(1)–Pd(1)
P(2)–Mo(1)–Pd(1)
Cl(2)–Mo(1)–Pd(1)
Cl(1)–Mo(1)–Pd(1)
Pd(1)–Cl(2)–Mo(1)
P(2)–N(1)–P(1)
104.1(2)
97.1(1)
156.4(1)
99.3(1)
162.9(1)
58.9(1)
85.1(4)
85.1(4)
141.9(1)
140.1(4)
82.6(1)
81.7(1)
62.1(4)
87.2(1)
55.8(1)
79.5(1)
65.2(1)
119.1(6)
Pd(1)–P(3)
Pd(1)–P(2)
Pd(1)–Cl(1)
Pd(1)–Mo(1)
Mo(1)–C(1)
Mo(1)–P(4)
Mo(1)–P(1)
P(1)–N(1)
P(2)–N(1)
P(3)–N(2)
P(4)–N(2)
O(1)–C(1)
2.246(3)
2.248(3)
2.440(3)
2.860(1)
1.95(1)
2.350(3)
2.354(3)
1.70(1)
1.65(1)
1.65(1)
1.67(1)
1.16(1)
P(3)–Pd(1)–P(2)
P(3)–Pd(1)–Cl(1)
P(2)–Pd(1)–Cl(1)
P(3)–Pd(1)–Mo(1)
P(2)–Pd(1)–Mo(1)
Cl(1)–Pd(1)–Mo(1)
C(1)–Mo(1)–P(4)
C(1)–Mo(1)–P(1)
P(4)–Mo(1)–P(1)
C(1)–Mo(1)–Pd(1)
P(4)–Mo(1)–Pd(1)
P(1)–Mo(1)–Pd(1)
P(3)–N(2)–P(4)
179.3(1)
90.7(1)
89.9(1)
89.5(1)
90.0(1)
163.6(1)
75.9(3)
76.3(3)
118.7(1)
136.6(3)
81.82(7)
82.8(1)
P(1)–N(1)
O(1)–C(1)
114.4(5)
113.1(5)
178.4(10)
P(2)–N(1)–P(1)
O(1)–C(1)–Mo(1)
Table 5
˚
Selected bond distances (A) and bond angles (ꢁ) in 4b
the strong p-acceptor nature of the diphosphazane li-
gand. The mean Pd–P distance and the P–N–P angles are
comparable to those in [Pd2Cl2(l-PhN{P(OPh)2}2)2] [8].
The geometry around molybdenum in the monome-
tallic chelate complex 4b is that of a four-legged piano
stool with cisoidal orientation of Cl and CO as reflected
in the angles Cl–Mo–C(1) [83.5(1)ꢁ] and P(1)–Mo–P(2)
[63.4(3)ꢁ]. The two phosphorus atoms are coordinated
Mo(1)–P(1)
Mo(1)–P(2)
Mo(1)–C(1)
Mo(1)–Cl(1)
P(1)–N(1)
2.388(1)
2.420(1)
1.955(4)
2.518(1)
1.682(3)
1.679(3)
C(1)–Mo(1)–P(1)
C(1)–Mo(1)–P(2)
P(1)–Mo(1)–P(2)
C(1)–Mo(1)–Cl(1)
P(1)–Mo(1)–Cl(1)
P(2)–Mo(1)–Cl(1)
Mo(1)–P(2)–P(1)
P(2)–N(1)–P(1)
81.7(1)
103.2(1)
63.4(3)
83.5(1)
135.7(1)
80.0(1)
57.7(1)
97.5(1)
175.2(3)
P(2)–N(1)
O(1)–C(1)–Mo(1)
˚
at different distances; the longer Mo–P(2) [2.420(1) A]
bond pertains to the phosphorus atom situated closer
to the chloride ligand while the shorter [Mo–
˚
P(1) = 2.388(1) A] distance corresponds to the phospho-
˚
˚
A] falls within the range [2.93–2.69 A] observed for other
dinuclear molybdenum–palladium complexes (Table 8).
rus further from the chloride ligand. Both the distances
are considerably shorter than those in the analogous
dppe complex, [(g5-C5H5)Mo(CO)(dppe)Cl] [Mo–
˚
The mean Mo–P [2.352 A] and Pd–P distances [2.245
˚
A] are shorter than those for the corresponding
Ph2PCH2PPh2 complexes. This trend is in accord with
˚
˚
P = 2.496(4) A, 2.439(5) A] [36]. This trend again reflects

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1089
Table 8
The Mo–Pd bond distances in dinuclear Mo–Pd and trinuclear Mo–Pd2 complexes
˚
Mo–Pd (A)
Complex
Reference
0
[(t-BuNC)(CO)3Mo(l-dppm)2PdI]PF6
2.870(2)
2.826(2)
2.926(2)
2.799(1)
2.817(1)
2.916(2)
2.760(1)
2.748(1)
2.692(2)
[29]
[29]
[29]
[24]
[27]
[30]
[31]
[32]
[33]
[(t-BuNC)(CO)ClMo(l-CO)(l-dppm)2PdCl]
[(CN)(CO)3Mo(l-dppm)2PdCN]
[PdMo(l-CO)(CO)(g5-C5H5)(dppm)2][PF6]
[PdMo(l-Ph2Ppy)2(l-CO)(CO)2Cl2]
[PdMo(l-PCy2)2{PH(Cy)2}2(g5-C5H5)(CO)2]
[PdMo(l-PCy2)2(PPh3)(CO)4]
[PdMo(l-PPh2)2(CO)4PPh3]
[PdI{l-C(p-tolyl)-dmba}{l-CO}Mo(Cp)(t-BuNC)2]
[C-(p-tolyl)-dmba = Me2NCH2C6H4–C–C6H4–Me-p]
[(g5-C5H5)(CO)Mo(l-MeN{P(OCH2CF3)2}2)2PdCl], 3a
[(g5-C5H5)ClMo(l2-CO)(l2-Cl)(l-MeN{P(OCH2CF3)2}2)PdCl], 6a
[Pd2Mo(g5-C5H5)(Cl)(l3-CO)2(l-dppm)2]
2.86(1)
2.63(1)
This work
This work
[26]
2.779(1)
2.783(1)
2.803(1)
2.781(1)
2.832(1)
2.788(1)
2.774(3)
2.758(2)
[Pd2Mo(g5-C5H5)2(CO)3(PiPr3)2]
[34]
[{PdNMe2CH2C6H4}2l{Mo(CO)3(g5-C5H5}2l-Cl]
[(g5-C5H5)Mo(l3-CO)2(l-MeN{P(OPh)2}2)2Pd2Cl] Æ CH2Cl2, 5b
[35]
This work
Table 9
Bond parameters related to semibridging carbonyls in 5b and 6aa
ab
h (ꢁ)
w (ꢁ)
˚
a (A)
˚
b (A)
˚
c (A)
˚
d (A)
˚
e (A)
Complex
5b
Pd(2), C(1)
Pd(2), C(2)
Pd(1), C(1)
Pd(1), C(2)
6a
0.23
0.25
0.27
0.30
0.23
2.00
1.98(2)
2.00
2.46(2)
2.479(14)
2.54(2)
2.758(2)
2.758(2)
2.774(3)
2.774(3)
2.629(2)
3.18(1)
3.19(1)
3.19(1)
3.22(1)
3.12(1)
1.14(2)
1.18(2)
1.14(2)
1.18(2)
1.14(1)
164.0(1)
167.1(1)
164.0(1)
167.1(1)
171.8(1)
59.9(4)
60.4(4)
61.8(5)
63.1(4)
62.1(4)
1.98(2)
1.993(14)
2.579(14)
2.445(13)
a
The parameters a, b, c, d, e, h and w are defined as shown below [43]:
O
e
θ
d
C
c
b
a
M1
M2
b
a is defined as (b ꢀ a)/a [40].
the strong p-acceptor capability of the diphosphazane li-
gand. The P(1)–Mo–P(2) [63.4(1)ꢁ] angle is smaller than
the corresponding P(1)–Mo(1)–P(2) angle [75.3ꢁ] found
in the dppe complex, but is comparable to that observed
for the Diphosphazane complex, [Mo(CO)4(PhN-
{P(OPh)2}2)] [P(1)–Mo–P(2) = 64.8(1)ꢁ] [7]. The P(1)–
N(1)–P(2) angle [97.5(1)ꢁ] is close to that observed for
the diphosphazane chelate complexes, [Mo(CO)4(PhN-
{P(OPh)2}2)] [7] and [WI2(CO)3(PhN{P(OPh)2}2)] [37].
The solid state structure of the trimetallic complex 5b
reveals the presence of two independent molecules in the
asymmetric part of the unit cell. The two molecules do
not differ in their bond lengths and bond angles but dif-
fer in the orientation of the phenyl groups. The mole-
cules consist of a triangulo Pd(1)–Pd(2)–Mo(1) unit, of
which the edges Pd(1)–Pd(2) and Pd(2)–Mo(1) are
spanned by the diphosphazane ligand. The Pd(1)–
Pd(2), Pd(1)–Mo(1), Pd(2)–Mo(1) distances are slightly
shorter than those in the related trinuclear clusters (Ta-
ble 8). The two carbonyl ligands are semi-bridging with
respect to the two Pd centers and are slightly closer to
Pd(2) than to Pd(1). One CO is located above and the
other below the Pd2Mo plane [distances from this plane
˚
to C(1) and C(2) are 1.670(6) and 1.676(6) A, respec-
tively] These two carbonyl ligands are slightly
bent [Mo(1)–C(1)–O(1) = 164(1)ꢁ, Mo(1)–C(2)–O(2) =
167(1)ꢁ]. The P(4)–Mo(1)–Pd(2) angle [81.2(1)ꢁ] is less
than the P(3)–Pd(2)–Mo(1), P(2)–Pd(2)–Pd(1) and
P(1)–Pd(1)–Pd(2) angles presumably because of the
steric interaction between the C5H5 ligand and the
phenyl groups at P(4). The Pd(1)–Cl distance [2.402(4)
˚
A] is comparable to that found in [Pd2Cl2(PhN-
{P(OPh)2}2)2]; however, the Pd–Pd distance is shorter
˚
(by 0.082 A) [8].

1090
M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
The solid state structure of 6a consists of two inde-
prepared generally by the reactions of the (chloro)palla-
dium(I) dimer, [PdCl(L–L)]2 with metal carbonylate an-
ions, [M(CO)n]ꢀ or [CpM(CO)n]ꢀ [6,26,46]. The present
study demonstrates that a direct thermal reaction be-
tween metal–metal bonded dipalladium and dimolybde-
num complexes leads to Mo–Pd dinuclear, MoPd2
trinuclear and mononuclear molybdenum chelate com-
plexes [47]. While trinuclear complexes of type 5 are
not unprecedented and the formation of dinuclear com-
plexes of type 3 is not unexpected, dinuclear complexes
of type 6 with chloro and carbonyl bridges are unusual.
Given the range of diphosphazane ligands in which the
substituents on both phosphorus and nitrogen can be
varied readily [3a], it would be interesting to investigate
systematically the ‘‘metathesis’’ reactions of metal–metal
bonded systems to enlarge the scope of the synthetic
strategy developed in the present study and also to unra-
vel the mechanism(s) involved in the formation of trinu-
clear and unusual dinuclear complexes from these
reactions.
pendent molecules in the asymmetric part of the unit
cell. The bond lengths and bond angles in the two mol-
ecules do not differ significantly. The two molecules dif-
fer in the orientation of trifluoroethoxy groups. The
coordination geometry around the Mo atom (ignoring
the M–M bond) is that of a four-legged piano stool with
the two chlorides adopting a cisoid orientation. The for-
mal oxidation state of Mo is +2.5 and that of Pd is +1.5
and hence there is a dative bond between palladium and
molybdenum. An interesting feature of the complex is
the presence of a semibridging CO as well as a bridging
chloride. If the bridging chloride is considered as a one
electron donor, the total number of valence electrons
for this compound would be 30 which implies a formal
double bond between Mo and Pd. This is reflected in
˚
˚
the Mo–Pd distance [2.63(1) A] which is 0.23 A shorter
˚
than that for 3a [2.86(1) A] having a Mo–Pd single bond
˚
and also 0.20–0.29 A shorter than that found in several
Mo–Pd heteronuclear complexes containing dppm and
other ligands (Table 8). Casey et al. [38] have concluded
that there is a double bond between two Re atoms in
[Cp*(CO)2Re@Re(CO)2Cp*] based on the Re–Re bond
distance and the linear nature of the semi-bridging car-
5. Supplementary material
Crystallographic data for structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 244244–244248 for com-
pounds 1a, 3a, 4b, 5b and 6a, respectively. 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 http://www.ccdc.cam.ac.uk.
˚
bonyl ligand. The Mo–P [2.437(3) A] and Pd–P
˚
[2.150(3) A] distances in 6a are shorter than the Mo–P
and Pd–P distances for the dppm complexes. The
P(1)–N(1)–P(2), P(1)–Pd(1)–Mo(1) and P(2)–Mo(1)–
Pd(1) angles are wider than the corresponding angles
˚
for 3a. The Cl(3)–Pd(1)–Mo(1) angle [162.9(1) A] devi-
ates from linearity probably because of the tilt of one
of the CF3 groups towards the chloride ligand.
The description of bonding of semi-bridging carbo-
nyls to transition metals has been the subject of several
investigations [39–44]. Following the approach of Crab-
tree and Lavin [43], the various parameters ꢀa, b, c, d, e, h
and Wꢁ for the semi-bridging carbonyls in 5b and 6a are
listed in Table 9. The value of the parameter a as defined
by Curtis and coworkers [40] is also included in Table 9.
These values for both 5b and 6a fall within the range
found for type II linear semi-bridging carbonyls. Theo-
retical studies have shown that linear semi-bridging car-
bonyls would be associated with strong M–M bonding
interactions [45]. Both the carbonyls in 5b have shorter
distances with Pd(2) than with Pd(1). Consequently,
Acknowledgements
We thank the Department of Science and Technol-
ogy, New Delhi for financial support and Professor
T.N. Guru Row for useful discussions on the refinement
of the crystal structures. Thanks are also due to Sophis-
ticated Instrument Facility, IISc., Bangalore and Spec-
trospin, Fallanden, Switzerland for the 31P NMR
spectra.
References
˚
[1] P. Braunstein, L.A. Oro, P.R. Raithby, Metal Clusters in
Chemistry, vol. 2, Wiley-VCH, Weinheim, 2000.
[2] E.W Abel, F.G.A. Stone, G. Wilkinson, Comprehensive Organo-
metallic Chemistry II, vol. 10, Pergamon, Oxford, 1995.
[3] (a) M.S. Balakrishna, V.S. Reddy, S.S. Krishnamurthy, J.F.
Nixon, J.C.T.R. Burckett St. Laurent, Coord. Chem. Rev. 129
(1994) 1;
the Pd(2)–Mo distance [2.758(2) A] is shorter than the
˚
Pd(1)–Mo distance [2.774(3) A], which in turn implies
that the Pd(2)–Mo bond is slightly stronger than
Pd(1)–Mo bond.
(b) M. Ganesan, S.S. Krishnamurthy, M. Nethaji, J. Organomet.
Chem. 570 (1998) 247;
4. Conclusions
(c) K. Raghuraman, S.S. Krishnamurthy, M. Nethaji, J. Chem.
Soc., Dalton Trans. (2002) 4289;
Heterometallic complexes of palladium with other
transition metals bearing bidentate phosphorus ligands
such as Ph2PXPPh2 [X = CH2 or NH] (L–L) have been
(d) S.K. Mandal, S.S. Krishnamurthy, G.A.N. Gowda, M.
Nethaji, Dalton Trans. (2003) 1016;

M. Ganesan et al. / Journal of Organometallic Chemistry 690 (2005) 1080–1091
1091
(e) K. Raghuraman, S.S. Krishnamurthy, M. Nethaji, J. Organo-
met. Chem. 669 (2003) 79;
bicyclic 1,3,2k3,4k3-diazadiphosphetidines, Ph.D. Thesis, Indian
Institute of Science, Bangalore, 1990, pp. 79–80.
[23] R.J. Haines, R.S. Nyholm, M.H.B. Stiddard, J. Chem. Soc. A
(1968) 43.
(f) S.K. Mandal, S.S. Krishnamurthy, M. Nethaji, J. Organomet.
Chem. 676 (2003) 22;
(g) T.S. Venkatakrishnan, M. Nethaji, S.S. Krishnamurthy,
Current Sci. 85 (2003) 969;
[24] P. Braunstein, B. Oswald, A. DeCian, J. Fischer, J. Chem. Soc.,
Dalton Trans. (1991) 2685.
(h) S.K. Mandal, G.A.N. Gowda, S.S. Krishnamurthy, T. Stey,
D. Stalke, J. Organomet. Chem. (in press).
[25] K. Starker, M.D. Curtis, Inorg. Chem. 24 (1985) 3006.
[26] P. Braunstein, M. Ries, C. de Meric deBellefon, Y. Dusausoy,
J.-P. Mangeot, J. Organomet. Chem. 355 (1988) 533.
[27] Z.-Z. Zhang, H.-K. Wang, H.-G. Wang, R.-J. Wang, J. Organo-
met. Chem. 314 (1986) 357.
[4] Part of this work was presented at the XIV International
Conference on Phosphorus Chemistry, Cincinnati, Ohio, USA,
July 12–17, 1998 M. Ganesan, S.S. Krishnamurthy, M. Nethaji,
K. Raghuraman, Phosphorus Sulfur Silicon 147 (1999) 355.
[5] (a) J.T. Mague, Organometallics 10 (1991) 513;
(b) J.T. Mague, Z. Lin, Organometallics 11 (1992) 4139.
[6] (a) I. Bachert, P. Braunstein, R. Hasselbring, New J. Chem. 20
(1996) 993;
[28] W. Klaui, H. Hamers, M. Pfeffer, A. de Cian, J. Fischer,
J. Organomet. Chem. 394 (1990) 213.
[29] A.L. Balch, B.C. Noll, M.M. Olmstead, D.V. Toronto, Inorg.
Chem. 32 (1993) 3613.
[30] P. Braunstein, E. de Jesus, A. Tiripicchio, M.T. Camellini,
J. Organomet. Chem. 368 (1989) C5.
(b) I. Bachert, P. Braunstein, M.K. McCart, F. Fabrizi de Biani,
F. Laschi, P. Zanello, G. Kickelbick, U. Schubert, J. Organomet.
Chem. 573 (1999) 47;
[31] S.J. Loeb, H.A. Taylor, L. Gelmini, D.W. Stephan, Inorg. Chem.
25 (1986) 1977.
(c) I. Bachert, I. Bartusseck, P. Braunstein, E. Guillon, J. Rose,
G. Kickelbic, J. Organomet. Chem. 588 (1999) 144.
[7] M.S. Balakrishna, T.K. Prakasha, S.S. Krishnamurthy, U. Siri-
wardane, N.S. Hosmane, J. Organomet. Chem. 390 (1990) 203.
[8] M.S. Balakrishna, S.S. Krishnamurthy, R. Murugavel, M. Neth-
aji, I.I. Mathews, J. Chem. Soc., Daltan Trans. (1993) 477.
[9] M.D. Curtis, M.S. Hay, M. Gunchoi, R.J. Angelici, Inorg. Synth.
28 (1990) 150.
[32] Z. He, N. Lugan, D. Neibecker, R. Mathieu, J.-J. Bonnet,
J. Organomet. Chem. 426 (1992) 247.
[33] A. Macchioni, P.S. Pregosin, P.F. Engel, S. Mecking, M. Pfeffer,
J.-C. Daran, J. Vaissermann, Organometallics 14 (1995)
1637.
[34] H. Werner, P. Thometzek, C. Krueger, H.-J. Kraus, Chem. Ber.
119 (1986) 2777.
[35] M. Pfeffer, J. Fischer, A. Mitschler, L. Ricard, J. Am. Chem. Soc.
102 (1980) 6338.
[10] D. Drew, J.R. Doyle, Inorg. Synth. 28 (1990) 346.
[11] G.M. Sheldrick, SHELXS-86 and SHELXL-93, Universitat Gottin-
gen, 1986 and 1993.
[36] M.A Bush, A.D.U. Hardy, L. Manojlovic-Muir, G.A. Sim,
J. Chem. Soc. A (1971) 1003.
[12] Two other products are formed in this reaction as shown by the
31P NMR spectrum of the reaction mixture; the singlet observed at
76.5 ppm is assigned to the chelate complex, [PdCl2(j2-MeN{-
P(OCH2CF3)2}2)] (based on the 31P chemical shift for the
analogous complex [PdCl2(j2-MeN{P(OC6H5)2}2)]) [8] and the
multiplets at 98.4 and 0.8 ppm are assigned to the P-coordinated
[37] M.S. Balakrishna, S.S. Krishnamurthy, H. Manohar, Organo-
metallics 10 (1991) 2522.
[38] C.P. Casey, H. Sakaba, P.N. Hazin, D.R. Powell, J. Am. Chem.
Soc. 113 (1991) 8165.
[39] F.A. Cotton, Prog. Inorg. Chem. 21 (1976) 1.
[40] R.J. Klingler, W.M. Butler, M.D. Curtis, J. Am. Chem. Soc. 100
(1978) 5034.
diphosphazane-monoxide
MeN{P(OCH2CF3)2}{P(O)(OCH2CF3)2})2].
complex,
[PdCl2(j1-
[41] R. Colton, M.J. McCormick, Coord. Chem. Rev. 31 (1980) 1.
[42] E.D. Jemmis, A.R. Pinhas, R.J. Hoffmann, J. Am. Chem. Soc.
102 (1980) 2576.
[13] L.S. Benner, A.L. Balch, J. Am. Chem. Soc. 100 (1978) 6099.
[14] C. Amatore, E. Carre, A. Jutand, M.A. MꢁBarki, Organometallics
14 (1995) 1818.
[43] R.H. Crabtree, M. Lavin, Inorg. Chem. 25 (1986) 805.
[44] M. Benard, A. Dedieu, S. Nakamura, Nouv. J. Chim. 8 (1984)
149.
[15] V.V. Grushin, H. Alper, Organometallics 12 (1993) 1890.
[16] C. Amatore, A. Jutand, M.J. Medeiros, New J. Chem. 20 (1996)
1143.
[45] C.Q. Simpson, M.B. Hall, J. Am. Chem. Soc. 114 (1992) 1641.
[46] (a) P. Braunstein, C. de Meric de Bellefon, M. Ries, J. Fischer,
S.-E. Bouaoud, D. Grandjean, Inorg. Chem. 27 (1988) 1327;
(b) P. Braunstein, C. de Meric de Bellefon, M. Ries, Inorg. Chem.
27 (1988) 1338;
[17] M.R. Mason, J.G. Verkade, Organometallics 11 (1992) 2212.
[18] P.A. McLaughlin, J.G. Verkade, Organometallics 17 (1998) 5937.
[19] Z. Csakai, R. Skoda-Foeldes, L. Kollar, Inorg. Chim. Acta 286
(1999) 93.
[20] R. Uson, J. Fornies, R. Navarro, M. Tomas, C. Fortuno, J.I.
Cebollada, Polyhedron 8 (1989) 1045.
(c) P. Braunstein, C. de Meric de Bellefon, M. Ries, J. Fischer,
Organometallics 7 (1988) 332.
[47] Chelate complexes of the type 4 have been obtained by
[21] R.B. King, J. Gimeno, Inorg. Chem. 17 (1978) 2396.
[22] T.K. Prakasha, Transition metal organometallic complexes and
related derivatives of bis(diphenylphosphino)isopropylamine and
the reactions of [Mo(g5-C5H5)(CO)3Cl] with diphosphines
[25].