Palladium(II) complexes of monoaryliminophosphorane derivatives of 1,2-bis(diphenylphosphino)methane. Crystal structure of [Pd{κ2-C6H3(N=N-C6H 4Me-4′)-2-(C6H 4Me-4″)-5-C,N′}{κ2-PPh 2CH2P(=NC6H4Me-4)Ph 2-P,N}]

Article abstract of DOI:10.1021/om980445k

The complex [Pd(azoMe)(κ¹-dppm)(κ²-dppm)]TfO (azoMe = 2-(4′-tolylazo)-5-methylphenyl, dppm = bis(diphenylphosphino)methane, TfO - CF₃SO₃) reacts at room temperature with aryl azides N₃Ar to give, in moderate to high yields, iminophosphorane complexes Pd(κ²-azoMe-C,N′){κ²-PPh ₂CH₂P(=NAr)Ph₂-P,N}]TfO [Ar = C₆H₄R, R = H (1), MeO-2 (2a), Me-2 (2b), NO₂-2 (2c), MeO-3 (3a), NO₂-3 (3c), MeO-4 (4a), Me-4 (4b), NO₂-4 (4c)]. In all cases, there is a linear correlation between δ(P) (ppm) of both phosphorus atoms and temperature T (°C) [δ(P₁) = δ₁(0) + a₁T; δ(P₂) = δ₂(0) + a₂T]. In the ortho-subsututed complexes 2a-c and the nitro derivatives 3c and 4c, crossing of the two δ/T plots of each complex is not observed and the change in chemical shift with temperature is small or nil, |a₁|, |a₂| = (0-12) × 10^-3 ppm/°C. In the other complexes, the gradient of one of the straight lines is positive (a₁ ≈ 26 × 10^-3 ppm/°C) and that of the other is negative (a₂ ≈ -7.5 × 10^-3 ppm/°C). Both lines cross in the range 0-25°C. 4b reacts with [Au(acac)PPh₃] (1:2) to give [Pd(azoMe-C,N′){PPh₂C(AuPPh₃) ₂P(=NAr)Ph₂-P,N}] [Ar = Me-4 (5b)]. [Pd(azoMe-C,N′)(κ²-dppm)]TfO reacts with NaN₃ to give [Pd₂(azoMe)₂(μ₂-N₃)(μ ₂-dppm)₂]TfO (6). The crystal structure of 4b is reported.

Full text of DOI:10.1021/om980445k

4544
Organometallics 1998, 17, 4544-4550
Articles
P a lla d iu m (II) Com p lexes of Mon oa r ylim in op h osp h or a n e
Der iva tives of 1,2-Bis(Dip h en ylp h osp h in o)m eth a n e.
Cr ysta l Str u ctu r e of [P d {K2-C6H3(NdN-C6H4Me-4′)-2-
(C6H4Me-4′′)-5-C,N′}{K2-P P h 2CH2P (dNC6H4Me-4)P h 2-P ,N}]†
J ose´ Vicente,*,‡ Aurelia Arcas, Delia Bautista, and
M. Carmen Ram´ırez de Arellano
Grupo de Quı´mica Organometa´lica,§ Departamento de Quı´mica Inorga´nica, Facultad de
Quı´mica, Universidad de Murcia, Apartado 4021, Murcia, 30071 Spain
Received J une 1, 1998
The complex [Pd(azoMe)(κ1-dppm)(κ2-dppm)]TfO (azoMe ) 2-(4′-tolylazo)-5-methylphenyl,
dppm ) bis(diphenylphosphino)methane, TfO ) CF3SO3) reacts at room temperature with
aryl azides N3Ar to give, in moderate to high yields, iminophosphorane complexes [Pd(κ2-
azoMe-C,N′){κ2-PPh2CH2P(dNAr)Ph2-P,N}]TfO [Ar ) C6H4R, R ) H (1), MeO-2 (2a ), Me-2
(2b), NO2-2 (2c), MeO-3 (3a ), NO2-3 (3c), MeO-4 (4a ), Me-4 (4b), NO2-4 (4c)]. In all cases,
there is a linear correlation between δ(P) (ppm) of both phosphorus atoms and temperature
T (°C) [δ(P1) ) δ1(0) + a1T; δ(P2) ) δ2(0) + a2T]. In the ortho-substituted complexes 2a -c
and the nitro derivatives 3c and 4c, crossing of the two δ/T plots of each complex is not
observed and the change in chemical shift with temperature is small or nil, |a1|, |a2| ) (0-
12) × 10-3 ppm/°C. In the other complexes, the gradient of one of the straight lines is positive
(a1 ≈ 26 × 10-3 ppm/°C) and that of the other is negative (a2 ≈ -7.5 × 10-3 ppm/°C). Both
lines cross in the range 0-25 °C. 4b reacts with [Au(acac)PPh3] (1:2) to give [Pd(azoMe-
C,N′){PPh2C(AuPPh3)2P(dNAr)Ph2-P,N}] [Ar ) Me-4 (5b)]. [Pd(azoMe-C,N′)(κ2-dppm)]TfO
reacts with NaN3 to give [Pd2(azoMe)2(µ2-N3)(µ2-dppm)2]TfO (6). The crystal structure of
4b is reported.
Sch em e 1
In tr od u ction
Iminophosphoranes [also called phosphoranimines,
phosphinimines, or phosphazenes; (A) in Scheme 1] are
interesting intermediates in the synthesis of natural
products1-3 and of nitrogen-containing organic com-
pounds.4
Metallic derivatives of iminophosphoranes can be
classified into three groups: phosphiniminates (R′ )
metallic moiety in A, Scheme 1), N-coordinated imino-
phosphorane complexes (M ) metallic moiety in B), and
mixed complexes (M and M′ metallic moieties in C).4-7
In this paper, we describe palladium(II) complexes of
type B. Most of these complexes are prepared starting
from the ligand (see Scheme 2 to see this and other8-13
methods of synthesis). We have reported the synthesis
of iminophosphorane platinum complexes by reacting
ylides with nitrile complexes.14,15 In this paper, we
report a new method which uses the attack of organic
azides on the noncoordinated phosphorus atom of a
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1989, 111, 8007.
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(13) Daporto, P.; Denti, G.; Dolcetti, G.; Ghedini, M. J . Chem. Soc.,
Dalton Trans. 1983, 779.
† Dedicated to Professor Pascual Royo on the occasion of his 60th
birthday.
‡ E-mail: jvs@fcu.um.es.
§ WWW: http://www.scc.um.es/gi/gqo/.
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S0276-7333(98)00445-2 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 09/12/1998

Crystal Structure of Palladium(II) Complexes
Organometallics, Vol. 17, No. 21, 1998 4545
Sch em e 2
Sch em e 3
Sch em e 4
monocoordinated 1,2-bis(diphenylphosphino)methane
palladium(II) complex (Staudinger reaction).
The reported iminophosphorane complexes can be
classified into two groups depending on the number of
P atoms of the ligand. Those from monophosphines are
known for Mo,16 W,9,12 Os,10 Co,11,17,18 Rh,19-23 Ir,13,20,21
Ni,8 Pd,23,24 Pt,14,15 Zn, Cd, Hg,23 and B.25 With only a
few exceptions,26-29 most complexes containing imino-
phosphorane ligands with two phosphorus atoms are
bis(diphenylphosphino)methane (dppm) derivatives. Of
this family, complexes of Mo,12 Rh,30-35 Ir,30-32,36
Pd,7,27,37,38 and Pt37-39 have been reported. The different
(16) Fourquet, J . L.; Leblanc, M.; Saravanamuthu, A.; Bruce, M. R.
M.; Bruce, A. E. Inorg. Chem. 1991, 30, 3241.
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528.
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1979, 41, 667.
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175, 209.
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C. H. Organometallics 1991, 10, 1421.
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Barluenga, J . Polyhedron 1987, 6, 1999.
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A.; Wiesemann, F.; Cavell, R. G. Inorg. Chem. 1996, 35, 5684.
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Inorg. Chem. 1990, 29, 808.
types of coordination of these ligands are shown in
Scheme 3. The most abundant are those from diphos-
phinodiimine derivatives (I-III). In this paper, we
report the synthesis of a family of palladium complexes
of type IV containing N,P-diphosphinomonoimine ligands.
In most cases, the reported synthesis of these complexes
requires two or three steps from dppm to prepare first
the ligand. In addition, the nature of the N-substituent
is limited to H,27 aryl groups containing several F, CN,
or NO2 substituents, a polyfluoropyridyl group, or
8-quinoline (Schemes 4 and 5).12,33-35 Only one pal-
ladium complex of this type has previously been re-
ported, [PdCl2(PPh2CH2P(dNH)Ph2-P,N)].27 During the
preparation of this article, a new derivative of the type
[PdCl2(PPh2CH2P(dNR)Ph2-P,N)], where R is a group
containing a ferrocenyl unit, was reported.40
(28) Liu, C.-Y.; Chen, D.-Y.; Cheng, M.-C.; Peng, S.-M.; Liu, S.-T.
Organometallics 1995, 14, 1983.
(29) Reed, R. W.; Santarsiero, B.; Cavell, R. G. Inorg. Chem. 1996,
35, 4292.
(30) Imhoff, P.; Elsevier: C. J . J . Organomet. Chem. 1989, 361, C61.
(31) Imhoff, P.; van Asselt, R.; Elsevier: C. J .; Zoutberg, M. C.; Stam,
C. H. Inorg. Chim. Acta 1991, 184, 73.
(32) Imhoff, P.; Vanasselt, R.; Ernsting, J . M.; Vrieze, K.; Elsevier:
C. J .; Smeets, W. J . J .; Spek, A. L.; Kentgens, A. P. M. Organometallics
1993, 12, 1523.
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15, 1033.
(34) Katti, K. V.; Cavell, R. G. Organometallics 1989, 8, 2147.
(35) Katti, K. V.; Santarsiero, B. D.; Pinkerton, A. A.; Cavell, R. G.
Inorg. Chem. 1993, 32, 5919.
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L.; Elsevier: C. J . Inorg. Chim. Acta 1995, 235, 77.
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J .; Spek, A. L. J . Organomet. Chem. 1997, 527, 263.
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Veldman, N.; Spek, A. L.; Katti, K. V.; Barnes, C. L. Organometallics
1996, 15, 2376.
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L.; Elsevier: C. J . Inorg. Chem. 1995, 34, 4092.
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Tetrahedron Lett. 1997, 38, 7613.

4546 Organometallics, Vol. 17, No. 21, 1998
Vicente et al.
obtain 2c as a yellow solid. Yield: 101 mg, 75%. Anal. Calcd
for C46H39F3N4O5P2PdS: C, 56.08; H, 3.99; N, 5.69; S, 3.25.
Found: C, 56.22; H, 4.08; N, 5.54; S, 3.06. Mp (°C): 216. ΛM
(Ω-1 cm2 mol-1) ) 124. 1H NMR: δ, 7.93-6.23 (m, aromatic
protons), 4.6-3.6 (m, CH2), 2.25, 1.79 (s, 3H, Me). 31P{1H}
Sch em e 5
2
NMR: δ, 44.93 (d, J PP ) 22.5 Hz), 31.32 (d).
3a . The solid was washed with diethyl ether (5 mL) and
then recrystallized three times from dichloromethane (1 mL)/
diethyl ether (20 mL). The resulting solid was dissolved in
dichloromethane and chromatographed on a silica gel TLC
plate (ca. 30 × 30 cm) with a dichloromethane/diethyl ether
(1:3) mixture. The elution gave only one yellow wide band,
which was collected to give a solution that was evaporated to
give complex 3a as an orange solid. Yield: 40 mg, 24%. Anal.
Calcd for C47H42F3N3O4P2PdS: C, 58.18; H, 4.36; N, 4.33; S,
3.30. Found: C, 57.16; H, 4.45; N, 4.11; S, 3.73. Although
this complex was spectroscopically pure, the elemental ana-
lyzer always gave a low C content (1.75% relative error). Mp
(°C): 125. 1H NMR: δ, 7.81-5.90 (m, aromatic protons), 4.21
2
[t, CH2, J PH ) 9.00 Hz], 3.30 [s, 3H, MeO], 2.15, 1.81 [s, 3H,
Me (azoMe)]. 31P{1H} NMR: δ, 35.08 (s) (see Discussion).
3c. The solid was washed with diethyl ether (4 × 4 mL)
and the oily residue was stirred with diethyl ether (4 mL) to
obtain 3c as an orange solid. Yield: 44 mg, 30%. Anal. Calcd
for C46H39F3N4O5P2PdS: C, 56.08; H, 3.99; N, 5.69; S, 3.25.
Found: C, 56.19; H, 4.19; N, 5.72; S, 3.07. Mp (°C): 119. 1H
Exp er im en ta l Section
1H and 31P{1H} NMR spectra (CDCl3 solutions, room tem-
perature) were measured on a Varian Unity 300 spectrometer.
Chemical shifts are referred to TMS (1H) and H3PO3 (31P). All
solvents were distilled before use, and unless otherwise stated,
the reactions were carried out under normal laboratory condi-
tions. [Pd(azoMe)(κ1-dppm)(κ2-dppm)]TfO, [Pd(κ2-azoMe-C,N′)-
(κ2-dppm)]TfO, and [Pd(azoMe)Cl(κ1-dppm)2] were prepared as
previously reported.15
NMR: δ, 8.2-6.21 (m, aromatic protons), 4.31 (t, CH2, 2J PH
)
9.3 Hz), 2.14, 1.87 [s, 3H, Me (azoMe)]. 31P{1H} NMR: δ, 39.10
(d, J PP ) 17.85 Hz), 34.29 (d).
2
4a . The orange solid was treated as for 1. Yield: 150 mg,
91%. Anal. Calcd for C47H42F3N3O4P2PdS: C, 58.18; H, 4.36;
N, 4.33; S, 3.30. Found: C, 58.13; H, 4.44; N, 4.28; S, 3.18.
Mp (°C): 290. ΛM (Ω-1 cm2 mol-1) ) 131. 1H NMR: δ, 7.89-
7.26 (m, aromatic protons), 6.97 (d, 1 H, aromatic protons, 3J HH
) 8.1 Hz), 6.85 (d, 2 H, aromatic protons, 3J HH ) 8.1 Hz), 6.50
[P d (K2-a zoMe-C,N′)(P P h 2CH2P (dNAr )P h 2-P ,N] [Ar
)
C6H4R, R ) H (1), MeO-2 (2a ), Me-2 (2b), NO2-2 (2c), MeO-3
(3a ), NO2-3 (3c), MeO-4 (4a ), Me-4 (4b), NO2-4 (4c)]. To a
suspension of [Pd(azoMe)(κ1-dppm)(κ2-dppm)]TfO in THF was
added the corresponding R-phenyl azide [Pd:azide ) 1 (R )
p-Me), 2 (R ) p-MeO, o-Me, o-MeO, m-MeO), and 2.5 (R ) H,
p-NO2, o-NO2, m-NO2)]. The solution was stirred for 15 (4b),
30 (2c), 90 (2a , 4c) min or 4 (4a , 3a ), 5 (1, 2b, 3c) h. The
resulting solutions were evaporated to dryness. Complexes
were isolated as follows.
3
4
(dd, aromatic protons, J HH ) 8.1, J HH ) 1.5 Hz), 6.26-6.18
(m, 3H, aromatic protons), 4.17 [dd, CH2, 2J PH ) 11 Hz, 9 Hz],
3.57 [s, 3H, MeO], 2.25, 1.88 [s, 3H, Me (azoMe)]. 31P{1H}
2
NMR: δ, 35.65, 35.14 (AB, J PP ) 20.15 Hz).
4b. The orange solid was treated as for 1. Yield: 270 mg,
94%. Anal. Calcd for C47H42F3N3O3P2PdS: C, 59.15; H, 4.44;
N, 4.40; S, 3.36. Found: C, 59.47; H, 4.56; N, 4.47; S, 3.39.
Mp (°C): 260. ΛM (Ω-1 cm2 mol-1) ) 135. 1H NMR: δ, 7.89-
1. The solid was washed with diethyl ether (4 mL) and the
oily residue was stirred with diethyl ether (4 mL) to obtain 1
as an orange solid. Yield: 112 mg, 58%. Anal. Calcd for
C46H40F3N3O3P2PdS: C, 58.76; H, 4.29; N, 4.47; S, 3.41.
Found: C, 58.47; H, 4.31; N, 4.49; S, 3.72. Mp (°C): 154. ΛM
(Ω-1 cm2 mol-1) ) 136. 1H NMR: δ, 7.89-7.25 (m, aromatic
protons), 6.99-6.23 (m, aromatic protons), 4.21 (dd, CH2, 2J PH
) 10.8, 9.00 Hz), 2.23 (s, 3H, Me), 1.88 (s, 3H, Me). 31P{1H}
7.35 (m, aromatic protons), 7.25 (d, 2H, H22
6.97 (d, 1H, H14, J HH ) 8.15 Hz), 6.81 (d, 2H, H23
,
26, 3J HH ) 8.4 Hz),
3
3
,
25, J HH
)
8.4 Hz), 6.50, 6.44 (AB, 4H, Ar, J AB ) 8.4 Hz), 6.25 (d, 1H,
4
2
H
16, J HP ) 6.6 Hz), 4.21 [t, CH2, J PH ) 9.00 Hz], 2.24, 2.02,
1.88 [s, 3H, Me]. 31P{1H} NMR: δ, 35.17 (s, see Discussion).
Cr ysta l Str u ctu r e. A crystal of 4b was mounted in inert
oil on a glass fiber and transferred to the diffractometer
(Siemens P4). The crystal data are summarized in Table 1.
Unit cell parameters were determined from a least-squares
fit of 63 accurately centered reflections (5.6° < 2θ < 25.0°).
The structure was solved by the heavy atom method and
refined anisotropically on F2 (program SHELXL 93).41 Hy-
drogen atoms were included using a riding model. The final
R1 was 0.0344 [I > 2σ(I)], for 660 parameters. Maximum ∆/σ
2
NMR: δ, 31.39, 30.59 (AB, J PP ) 18.33 Hz).
2a . The solid was washed with n-hexane (15 mL) and the
oily residue was stirred with diethyl ether (4 mL) to obtain 1
as an orange solid. The mixture was stirred to obtain 2a as a
solid. Yield: 86 mg, 63%. Anal. Calcd for C47H42F3N3O4P2-
PdS: C, 58.18; H, 4.36; N, 4.33; S, 3.30. Found: C, 58.30; H,
4.56; N, 4.16; S, 3.13. Mp (°C): 220. ΛM (Ω-1 cm2 mol-1) )
124. 1H NMR: δ, 8.0-6.02 (m, aromatic protons), 3.87 [dd,
CH2, 2J PH ) 11.7, 8.7 Hz], 3.01 [s, 3H, MeO], 2.27, 1.84 [s, 3H,
) 0.036; maximum ∆F ) 0.30 e Å-3
.
2
Me (azoMe)]. 31P{1H} NMR: δ, 41.42 (d, J PP ) 22.95 Hz),
The programs use the neutral atom scattering factors, ∆f ′
and ∆f ′′ and absorption coefficients from International Tables
for Crystallography.42
4c. The orange solid was washed with dichloromethane (4
mL), the suspension was filtered, and to the resulting solution
were added diethyl ether (15 mL) and n-hexane (10 mL) to
give 4c. Yield: 84 mg, 72%. Anal. Calcd for C46H39F3N4O5P2-
33.80 (d).
2b. Dichloromethane (1 mL), diethyl ether (10 mL), and
n-hexane (5 mL) were successively added to the solid, and the
mixture was stirred to obtain 2b as an orange solid. Yield:
103 mg, 67%. Anal. Calcd for C47H42F3N3O3P2PdS: C, 59.15;
H, 4.44; N, 4.40; S, 3.36. Found: C, 59.67; H, 4.77; N, 3.93; S,
3.32. Mp (°C): 124. ΛM (Ω-1 cm2 mol-1) ) 121. 1H NMR: δ,
7.86-7.33 (m, aromatic protons), 7.03-6.85 (m, aromatic
protons), 6.63-6.26 (m, aromatic protons), 4.0-3.8 [m, CH2],
2.26 (s, 6H, Me), 1.82 (s, 3H, Me). 31P{1H} NMR: δ, 40.67 (d,
2J PP ) 24.65 Hz), 32.12 (d).
(41) Sheldrick, G. M. SHELXL 93; University of Go¨ttingen: Go¨t-
tingen, Germany, 1994.
(42) International Tables for Crystallography; Wilson, A. J . C., Ed.;
Kluwer Academic Publishers: Dordrecht, The Netherlands, 1992; Vol.
C, Tables 6.1.1.4 (pp 500-502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp
193-199).
2c. Dichloromethane (1 mL) and diethyl ether (10 mL) were
successively added to the solid and the mixture was stirred to

Crystal Structure of Palladium(II) Complexes
Organometallics, Vol. 17, No. 21, 1998 4547
Ta ble 1. Cr ysta l Da ta for 4b
Sch em e 6
molecular formula
source
crystal habit
a (Å)
b (Å)
c (Å)
C47H42F3N3O3P2PdS
slow diffusion Et2O/n-hexane
orange cube
18.439(2)
14.505(1)
18.754(2)
117.019(7)
4
â (deg)
Z
λ (Å)
T (K)
0.71073
298(2)
radiation used
monochromator
space group
crystal size (mm)
Mo KR
graphite
P21/n
0.46 × 0.36 × 0.33
µ (mm-1
)
0.590
abs correction
max/min transmission (%)
diffractometer
data collection method
2θ range (deg)
reciprocal lattice segment
reflns measd
ψ scans
0.82/0.75
Siemens P4
ω scans
6.1-50.0
+h, +k, (l
18 750
independent reflns
Rint
7858
0.024
0.0344
0.0785
R1a
wR2b
a
b
R1 ) ∑||Fo| - |Fc||/∑|Fo| for reflections with I > 2σ(I). wR2
) [∑[w(Fo2 - Fc2)2]/∑[w(Fo2)2]]0.5 for all reflections; w-1 ) σ2(F2) +
(aP)2 + bP, where P ) (2Fc + Fo2)/3 and a and b are constants
set by the program.
2
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for Com p ou n d 4b
Lengths (Å)
N(1)-N(2)
N(2)-C(11)
Pd-N(2)
1.267(3)
1.446(3)
2.104(2)
2.2303(8)
1.430(3)
N(1)-C(2)
1.396(3)
1.988(3)
2.159(2)
1.607(2)
Pd-C(1)
Pd-N(3)
P(2)-N(3)
Pd-P(1)
N(3)-C(61)
Angles (deg)
sion of [Pd(azoMe)(κ2-dppm)]TfO (165 mg, 0.19 mmol) in
acetone (15 mL) was added NaN3 (14 mg, 0.215 mmol), and
the reaction mixture stirred for 8 h. The solvent was removed,
and dichloromethane (10 mL) added. Concentration (2 mL)
and addition of diethyl ether (20 mL) and n-hexane (10 mL)
gave 6 as an orange solid. Yield: 126 mg, 83%. Anal. Calcd
for C79H70F3N7O3P4Pd2S: C, 59.63; H, 4.43; N, 6.16; S, 2.01.
Found: C, 59.34; H, 4.40; N, 6.11; S, 2.19. Mp (°C): 186. IR
N(2)-N(1)-C(2)
N(1)-N(2)-Pd
C(1)-Pd-N(2)
C(1)-Pd-P(1)
112.8(2)
117.1(2)
78.62(10) N(2)-Pd-N(3)
97.71(8)
N(1)-N(2)-C(11) 114.6(2)
C(11)-N(2)-Pd
128.3(2)
100.71(8)
84.33(6)
117.0(2)
111.4(2)
N(3)-Pd-P(1)
C(61)-N(3)-Pd
C(61)-N(3)-P(2) 122.0(2)
P(2)-N(3)-Pd
N(1)-C(2)-C(1)
120.71(12) C(2)-C(1)-Pd
120.0(2)
PdS: C, 56.08; H, 3.99; N, 5.69; S, 3.25. Found: C, 55.89; H,
4.14; N, 5.67; S, 3.17. Mp (°C): 290. ΛM (Ω-1 cm2 mol-1) )
130. 1H NMR: δ, 8.0-7.26 (m, aromatic protons), 7.00 (d,
(cm-1): νasymmetric(N3), 2070 cm-1 1H NMR: δ, 7.54-6.83 (m,
.
aromatic protons), 6.34 (d, 2 H aromatic protons, J ) 8.1 Hz),
4.25-3.57 [dm, 4H, CH2], 2.46, 1.94 (s, 6H, Me). 31P{1H}
NMR: δ, 9.79 (s).
3
aromatic protons, J HH ) 7.5 Hz), 6.80-6.71 (m, aromatic
3
4
protons), 6.19 (dd, aromatic protons, J HH ) 8.7 Hz, J HH
)
2
0.9 Hz), 4.38 [dd, CH2, J PH ) 11.4, 9 Hz], 2.17, 1.87 [s, 3H,
2
Me]. 31P{1H} NMR: δ, 38.27 (d, J PP ) 15.2 Hz), 34.46 (d).
Resu lts a n d Discu ssion
[P d (K2-a zoMe-C,N′)(P P h 2C(Au P P h 3)2P (dNAr )P h 2-P ,N]-
TfO (Ar ) C6H4Me-4) (5b). To a suspension of [Pd(κ2-azoMe-
C,N′)(PPh2CH2P(dNAr)Ph2-P,N]TfO [Ar ) C6H4Me-4 (4b)] (90
mg, 0.09 mmol) in dichloromenthane (10 mL) was added [Au-
(acac)PPh3] (106 mg, 0.19 mmol). The suspension was stirred
for 36 h and then concentrated (2 mL). Addition of diethyl
ether (5 mL) and n-hexane (5 mL) gave 3 as a red solid.
Yield: 146 mg, 88%. Anal. Calcd for C83H70Au2F3N3O3P4-
PdS: C, 53.28; H, 3.78; N, 2.25; S, 1.71. Found: C, 52.96; H,
3.96; N, 2.14; S, 1.82. Mp (°C): 143. ΛM (Ω-1 cm2 mol-1) )
125 Ω-1 mol-1 cm2. 1H NMR (300 MHz): 8.09-8.02 (m,
aromatic protons), 7.75-7.64 (m, aromatic protons), 7.5-6.9
(m, aromatic protons), 6.77-6.64 (m, aromatic protons), 6.42-
6.30 (m, aromatic protons), 2.23, 1.98, 1.83 [s, 2Me (azoMe)
and 1Me (p-methylphenyl)]. 31P NMR (121 MHz): 60.3 [dt,
Syn th esis a n d Rea ctivity of Com p lexes. The
complex [Pd(azoMe)(κ1-dppm)(κ2-dppm)]TfO (azoMe )
2-(4′-tolylazo)-5-methylphenyl, dppm ) bis(diphenylphos-
phino)methane, TfO ) CF3SO3)43 reacts, at room tem-
perature, with aryl azides N3Ar to give moderate to high
yields of iminophosphorane complexes [Pd(κ2-azoMe-
C,N′){PPh2CH2P(dNAr)Ph2-P,N}]TfO [Ar ) C6H4R, R
) H (1), MeO-2 (2a ), Me-2 (2b), NO2-2 (2c), MeO-3 (3a ),
NO2-3 (3c), MeO-4 (4a ), Me-4 (4b), NO2-4 (4c)] (Scheme
6). The reaction with N3C6H4Me-3 gives the corre-
sponding complex, but we were unable to separate it
from traces of bis(diphenylphosphino)methane dioxide
(by 31P NMR).
2
2
2
PV, J AM ) 33.0 Hz, J AX ) 11.4 Hz], 43.3 [d, PIII, J AM ) 33.0
We propose a reaction pathway (see Scheme 6) that
assumes formation of the iminophosphorane A through
the classical Staudinger reaction.4 A chelating N,P-
2
Hz], 37.1 [d, PPh3, J AX ) 11.4 Hz)].
[P d 2(µ2-N3)(a zoMe)2(µ2-d p p m )2]TfO (6). To a suspen-

4548 Organometallics, Vol. 17, No. 21, 1998
Vicente et al.
Sch em e 7
Sch em e 8
iminophosphorane is formed by replacement of the
P-Pd bond trans to the aryl group in A. Finally, the
resulting intermediate (B) gives complexes 1-4 by
replacement of the monocoordinate dppm by the N atom
of the aryl ligand. The formation of the iminophospho-
rane A requires the presence of the uncoordinated P
atom, as the complex [Pd(κ2-azoMe-C,N′)(κ2-dppm)]TfO43
does not react with N3C6H4Me-4. In the only process
reported in the literature similar to our reaction, the
dissociation of one of the phosphorus atoms of a chelat-
ing diphosphine was proposed as an essential step in
the reaction mechanism (Scheme 5).12 In this case, the
previous coordination of the 8-azidoquinoline could help
the cleavage of the P-Mo bond. The A f B process is
facilitated by (i) the strained nature of the four-
membered ring of dppm compared to the very stable
five-membered ring that results in B and (ii) the
destabilizing effect that an aryl group exerts on the
trans P-Pd bond (transphobia).43 Finally, the chelate
effect can explain the transformation of B into 1-4.
Complex 4b reacts with KOBut to give a mixture of
two compounds (observed by 31P NMR) that could not
be separated. However, it does not react with Et2NH
(neat or in a dichloromethane solution, room tempera-
ture, 3 days). The behavior of the N,P-diphosphino-
monoimine ligand in 4a contrasts with that of the free
diphosphinodiimine ligands ArNdPPh2CH2P(dNAr)-
Ph2. These react with [PdCl2L2] (L ) PhCN, MeCN, L2
) COD) to give products resulting from the migration
of one of the methylene protons to one of the nitrogen
atoms and coordination through the other nitrogen and
the methine carbon atoms (Scheme 7).37 The acidic
character of the CH2 group in 4b was shown by its
reaction with [Au(acac)PPh3]. The 1:2 reaction gives
complex [Pd(κ2-azoMe-C,N′){PPh2C(AuPPh3)2P(dNAr)-
Ph2-P,N}] [Ar ) Me-4 (5b); Scheme 8]. The 1:1 reaction
gives a mixture that contains 4b, the starting palladium
complex, and another complex that, according to 31P
NMR, could be the monoaurated complex [Pd(κ2-azoMe-
C,N′)(PPh2CH(AuPPh3)P(dNAr)Ph2-P,N]. Many at-
tempts to separate this mixture were unsuccessful. We
have shown the synthetic utility of [Au(acac)PPh3] to
prepare gold(I) complexes with C-,44-52 N-,53-55 and S-56
donor ligands. This reagent has also been used to
prepare other gold(I) complexes containing the moiety
Ph2PC(AuPPh3)2PPh2.57-61
We also attempted to prepare phosphiniminates of
palladium (R′ ) metallic moiety in A, Scheme 1) by
reacting NaN3 with [Pd(azoMe)(κ1-dppm)(κ2-dppm)]TfO,
[Pd(azoMe)Cl(κ1-dppm)2], or [Pd(κ2-azoMe-C,N′)(κ2-
dppm)]TfO.43 The starting materials were recovered in
the first two cases, but in the last reaction, the complex
[Pd2(azoMe)2(µ2-N3)(µ2-dppm)2]TfO (6) was isolated
(Scheme 9). This complex does not decompose after
being refluxed in THF for 1 h. Traces of 6 were also
obtained in the reaction between [Pd(azoMe)(κ1-dppm)(κ2-
dppm)]TfO and N3SiMe3. This result can be explained
if formation of TfOSiMe3 is asumed.
(43) Vicente, J .; Arcas, A.; Bautista, D.; J ones, P. G. Organometallics
1997, 16, 2127.
(44) Vicente, J .; Chicote, M. T.; Cayuelas, J . A.; Ferna´ndez-Baeza,
J .; J ones, P. G.; Sheldrick, G. M.; Espinet, P. J . Chem. Soc., Dalton
Trans. 1985, 1163.
(45) Vicente, J .; Chicote, M. T.; Saura-Llamas, I.; Turp´ın, J .;
Ferna´ndez-Baeza, J . J . Organomet. Chem. 1987, 333, 129.
(46) Vicente, J .; Chicote, M. T.; Saura-Llamas, I.; J ones, P. G.;
Meyer-Ba¨se, K.; Erdbru¨gger, C. F. Organometallics 1988, 7, 997.
(47) Vicente, J .; Chicote, M. T.; Saura-Llamas, I. J . Chem. Soc.,
Dalton Trans. 1990, 1941.
We have attempted unsuccessfully to react 4b with
H2O2, PPh3, or 2,2′-bipyridine.
Sp ectr oscop ic P r op er ties. The 31P{1H} NMR spec-
tra of complexes 1-4 show an AB system (1, 4a ), two
(48) Vicente, J .; Chicote, M. T.; Lagunas, M. C.; J ones, P. G. J . Chem.
Soc., Dalton Trans. 1991, 2579.
(49) Vicente, J .; Chicote, M. T.; Lagunas, M. C.; J ones, P. G. J . Chem.
Soc., Chem. Commun. 1991, 1730.
(50) Vicente, J .; Chicote, M. T.; Lagunas, M. C. Inorg. Chem. 1993,
32, 3748.
(51) Vicente, J .; Chicote, M. T.; Abrisqueta, M. D. J . Chem. Soc.,
Dalton Trans. 1995, 497.
(52) Vicente, J .; Chicote, M. T.; Abrisqueta, M. D.; J ones, P. G.
Organometallics 1997, 16, 5628.
(56) Vicente, J .; Chicote, M. T.; Rubio, C. Chem. Ber. 1996, 129, 327.
(57) Ferna´ndez, E. J .; Gimeno, M. C.; J ones, P. G.; Laguna, A.;
Laguna, M.; Lopez de Luzuriaga, J . M. Angew. Chem., Int. Ed. Engl.
1994, 33, 87.
(58) Ferna´ndez, E. J .; Gimeno, M. C.; J ones, P. G.; Laguna, A.;
Laguna, M.; Lopez de Luzuriaga, J . M. Organometallics 1995, 14, 2918.
(59) Ferna´ndez, E. J .; Gimeno, M. C.; J ones, P. G.; Laguna, A.;
Laguna, M.; Lopez de Luzuriaga, J . M. J . Chem. Soc., Dalton Trans.
1992, 3365.
(53) Vicente, J .; Chicote, M. T.; Guerrero, R.; J ones, P. G. J . Chem.
Soc., Dalton Trans. 1995, 1251.
(54) Vicente, J .; Chicote, M. T.; Guerrero, R.; J ones, P. G. J . Am.
Chem. Soc. 1996, 118, 699.
(55) Vicente, J .; Chicote, M. T.; Guerrero, R.; J ones, P. G.; Ram´ırez
de Arellano, M. C. Inorg. Chem. 1997, 36, 4438.
(60) Gimeno, M. C.; Laguna, A.; Laguna, M.; Sanmartin, F. Orga-
nometallics 1993, 12, 3984.
(61) Gimeno, M. C.; Laguna, A.; Laguna, M.; Sanmartin, F.; J ones,
P. G. Organometallics 1994, 13, 1538.

Crystal Structure of Palladium(II) Complexes
Organometallics, Vol. 17, No. 21, 1998 4549
Sch em e 9
doublets (2a , 2b, 2c, 3c, 4c) or a singlet (3a , 4b) in the
3
range 30-45 ppm with J PP ) 15-25 Hz. The 31P
chemical shifts of Ph3PdNC6H4R-4 (R ) H, NO2, CN,
CF3, Cl, F, Me, OMe, NMe2) are in the range 2.6-7.8
ppm and follow the expected order δ(NO2) > δ(CN) >
δ(CF3) > δ(Cl) > δ(F) > δ(H) > δ(Me) > δ(OMe) > δ-
(NMe2).62 Therefore, N-coordination leads to deshield-
ing of the PV nucleus. When we prepared the first
complex of this family (4b), we were surprised to find a
singlet for the two different phosphorus atoms. In the
only family of related complexes, [RhCl(CO)(PPh2CH2P-
(dNAr)Ph2-P,N] [Ar ) C6Fn(CN)m(NO2)pHq], the PIII and
PV resonances were unequivocally assigned because of
the different J PRh values.33-35 In all cases, the PV
resonance appeared at a lower field (2-4 ppm; range,
42-44 ppm) than the PIII resonance (range, 39-40 ppm)
F igu r e 1. Correlation between δ(P) (ppm) of both phos-
phorus nuclei and temperature T (°C) of complexes 1 (R )
H), 3a (R ) OMe-3), 4a (R ) OMe-4), and 4b (R ) Me-4).
found in the above-mentioned Rh complexes, the low-
field resonance in the range 37-45 ppm should be
assigned to the PV atom and those in the range 31-35
ppm to the PIII atom. In the second group of complexes,
there is a crossing of the two straight lines of each
complex (Figure 1). Of the two straight lines corre-
sponding to each complex, one is of a positive gradient
and the other is negative. Those with a positive
gradient have a1 ≈ 26 × 10-3 ppm/°C, while those with
a negative gradient have a2 ≈ -7.5 × 10-3 ppm/°C. The
crossing points are in the range 0-25 °C. This behavior
is similar to that found for the Me or CH2 and OH
protons of methanol or ethylene glycol, respectively, and
is used to measure the temperature within the sample
NMR tube.63 Correspondingly, our complexes could also
have the same application in 31P NMR spectroscopy.
Although we cannot assign the PV and PIII resonances
in the second group of complexes, the observed order
δ(PVNO2-4) > δ(PVMe-4) ≈ δ(PVOMe-4) > δ(H) at room
temperature means that, in this case, the chemical shift
is dependent on other more important contributions
than the electronic one.
3
with J PP in the range 28-32 Hz. Therefore, we
undertook a variable-temperature 31P{1H} NMR study
to see if a scrambling process was making both phos-
phorus atoms in 4b equivalent. At -60 °C two doublets
were observed that changed to an AB quartet when the
temperature was raised to give a singlet at 24 °C and
again an AB quartet at 30 °C. No coalescence was
observed. Therefore, the conclusion was that both
resonances were temperature dependent. To see if this
phenomenon had some electronic and/or steric origin,
we prepared the rest of the family containing substit-
uents of different electronic effects in the three possible
positions on the aryl group. The data are represented
in Figures 1 and 2. In all cases, a linear correlation
between δ(P) (ppm) of both phosphorus atoms and
temperature T (°C) was observed [δ(P1) ) δ1(0) + a1T;
δ(P2) ) δ2(0) + a2T]. Complexes 1-4 can be divided into
two groups. In the first one, including the ortho-
substituted complexes 2a -c and the nitro derivatives
3c and 4c (Figure 2), there is no crossing of the two δ/T
plots of each complex. In addition, the changes in
chemical shift with temperature are small or nil, |a1|,
|a2| ) (0-12) × 10-3 ppm/°C. According to the data
Iminophosphorane complexes related to 1-4 exhibit
an IR band in the range 1230-1285 cm-1 assigned to
the ν(PdN) mode.14,19,26,31,37 The IR spectra of com-
plexes 1-4 in such a region are not different from that
in the complex [Pd(κ2-azoMe-C,N′)(κ2-dppm)]+.43 Prob-
ably, in our complexes the band assigned to the ν(Pd
N) mode is overlapped by others due to the azophenyl
group.
(62) Pomerantz, M.; Marynick, D. S.; Rajeshwar, K.; Chou, W.-N.;
Throckmorton, L.; Tsai, E. W.; Chen, P. C. Y.; Cain, T. J . Org. Chem.
1986, 51, 1223.
(63) Gu¨nter, H. NMR Spectroscopy. An Introduction; J ohn Wiley &
Sons: New York, 1980.

4550 Organometallics, Vol. 17, No. 21, 1998
Vicente et al.
F igu r e 3. ORTEP plot of 4b with the labeling scheme.
Cr yst a l St r u ct u r e of [P d (K2-a zoMe-C,N′)(P P h 2-
CH2P (dNC6H4Me-4)P h 2-P ,N)] (4b). There are only
two reported crystal structures of iminophosphorane
complexes of Pd, [PdCl2(PPh2CH2P(dNR)Ph2-P,N)], with
R being H,27 or Fe(η5-C5H5)(η5-C5H4CHdC(CO2Et).40 In
4b, the coordination plane is strongly distorted because
the Pd-C(1)-C(2)-N(1)-N(2) plane forms an angle of
13.9° with the Pd-N(3)-P(1) plane (see Figure 3). This
distortion seems necessary to avoid contact between the
aryl groups bonded to the cis nitrogen atoms. The Pd-
Nimine bond distance [2.159(2) Å] is longer than the Pd-
N
azo bond length [2.104(2) Å]. Both distances are much
F igu r e 2. Correlation between δ(P) (ppm) of both phos-
phorus nuclei and temperature T (°C) of complexes 2a (R
) OMe-2), 2b (R ) Me-2), 2c (R ) NO2-2), 3c (R ) NO2-3),
and 4c (R ) NO2-4).
Complex 6 shows a singlet in the 31P{1H} NMR
spectrum, suggesting the symmetrical structure shown
in Scheme 9. When the azido ligand bridges two metal
centers, there are two coordination modes for this
ligand: through a single N atom (1,1 mode) or through
the two terminal N atoms (1,3 mode). IR spectroscopy
can be used to distinguish between these modes.64 The
longer than Pd-Nimine in [PdCl2(PPh2CH2P(dNH)Ph2-
P,N)] [2.021(6) Å].27 The different Pd-Nimine and Pd-
Nazo distances could reflect the greater strength of the
Pd-NH bond compared to the Pd-NAr bond and/or be
due to a difference in the trans influence [C(1) versus
P(1)].
Ack n ow led gm en t . We thank DGES for financial
support. D.B. and M.C.R.A. thank the Ministerio de
Educacio´n y Ciencia (Spain) for a grant and a contract,
respectively.
ν
sym(NNN) mode appears as a band of medium intensity
Su p p or tin g In for m a tion Ava ila ble: An X-ray crystal-
lographic file in CIF format for compound 4b is available on
the Internet only. Access information is given on any current
masthead page.
at around 2060 cm-1 for the 1,1-N3 mode. In complex
6, a strong band at 2070 cm-1 indicates the 1,1-
coordination mode for the N3 ligand.
(64) Nelson, J .; Nelson, S. M. J . Chem. Soc., A 1969, 1597.
OM980445K