Steric and electronic effects on arylphosphonate elimination from organopalladium complexes

Article abstract of DOI:10.1021/om060662i

To study the effects of electronic and steric manipulation of metal-bound aryl fragments on arylphosphonate formation, model organopalladium complexes have been prepared and investigated. While no phosphorus-carbon bond formation was observed at 25°C, all of the arylpalladium phosphonates underwent clean reductive elimination in C₆D₆ solutions at elevated temperatures. The incorporation of electron-donating groups into the metal-bound aryl fragments accelerated the elimination process, while palladium complexes containing aryl groups with electron-withdrawing or ortho substituents exhibited slower elimination rates. While the rate of arylphosphonate formation was dependent upon the nature of the metal-bound aryl fragment, it was rather insensitive to the identity of the phosphonate moiety. These results demonstrate the results of subtle changes in the electronic and steric composition of the eliminating species in P(O)-C bond-forming reactions.

Full text of DOI:10.1021/om060662i

5746
Organometallics 2006, 25, 5746-5756
Steric and Electronic Effects on Arylphosphonate Elimination from
Organopalladium Complexes
Mark C. Kohler,† Robert A. Stockland, Jr.,*,† and Nigam P. Rath‡
Department of Chemistry, Bucknell UniVersity, Lewisburg, PennsylVania 17837, and Department of
Chemistry and Biochemistry, UniVersity of Missouri - St. Louis, St. Louis, Missouri 63121
ReceiVed July 23, 2006
To study the effects of electronic and steric manipulation of metal-bound aryl fragments on
arylphosphonate formation, model organopalladium complexes have been prepared and investigated. While
no phosphorus-carbon bond formation was observed at 25 °C, all of the arylpalladium phosphonates
underwent clean reductive elimination in C6D6 solutions at elevated temperatures. The incorporation of
electron-donating groups into the metal-bound aryl fragments accelerated the elimination process, while
palladium complexes containing aryl groups with electron-withdrawing or ortho substituents exhibited
slower elimination rates. While the rate of arylphosphonate formation was dependent upon the nature of
the metal-bound aryl fragment, it was rather insensitive to the identity of the phosphonate moiety. These
results demonstrate the results of subtle changes in the electronic and steric composition of the eliminating
species in P(O)-C bond-forming reactions.
Introduction
The transition-metal-promoted coupling of aryl halides with
HP(O)(OR)2 is one of the most effective ways to prepare
arylphosphonates.1,2 Typically, NiCl2 or PdCl2 promotes these
transformations; however, high temperatures (100-200 °C) are
often needed to obtain high yields of the ArP(O)(OR)2 targets.1,2
As a result of the harsh conditions needed for an efficient
coupling reaction, difficulties have been encountered in extend-
ing this chemistry to sensitive substrates. One of the challenges
for the design of new protocols that proceed under mild
conditions is a limited understanding of the factors that
accelerate specific steps of the reaction.
A plausible mechanism for the coupling reaction is shown
in Figure 1. The first step in the process is oxidative addition
of an aryl halide to a low-valent metal species. This step and
the factors that accelerate or retard reactions of this type are
well-known in organometallic chemistry and have been the
subject of a number of investigations.3 The second step is base-
assisted phosphonylation of the intermediate generated from the
oxidative addition reaction. The final step is reductive elimina-
tion from the LnM(aryl)(P(O)(OR)2) intermediate to generate
Figure 1. Metal-catalyzed synthesis of arylphosphonates.
the desired C-P(O) bond and regenerate the low-valent metal
catalyst. Although the metal-promoted formation of C-C, C-O,
C-S, and C-N bonds has been studied in detail,4 analogous
investigations focused on understanding the factors that will
accelerate the generation of C-P(O) bonds are rare.5 To increase
the understanding of this important reaction, a detailed inves-
tigation of the phosphorus-carbon bond-forming step has been
carried out using model systems in order to probe the influence
of electronic and steric manipulation on the rate of the
elimination reaction.
* To whom correspondence should be addressed. E-mail:
rstockla@bucknell.edu.
† Bucknell University.
‡ University of Missouri at St. Louis.
(1) (a) Defacqz, N.; de Bueger, B.; Touillaux, R.; Cordi, A.; Marchand-
Brynaert, J. Synthesis 1999, 1368. (b) Beletskaya, I. P.; Kazankova, M. A.
Russ. J. Org. Chem. 2002, 38, 1391. (c) Huang, C.; Tang, X.; Fu, H.; Jiang,
Y.; Zhao, Y. J. Org. Chem. 2006, 71, 5020. (d) Hirao, T.; Masunaga, T.;
Ohshiro, Y.; Agawa, T. Synthesis 1981, 56. (e) Gelman, D.; Jiang, L.;
Buchwald, S. L. Org. Lett. 2003, 5, 2315. (f) Rao, H. H.; Jin, Y.; Fu, H.;
Jiang, Y. Y.; Zhao, Y. F. Chem. Eur. J. 2006, 12, 3636. (g) Bravo-
Altamirano, K.; Huang, Z. H.; Montchamp, J. L. Tetrahedron 2005, 61,
6315. (h) Beletskaya, I. P. Pure. Appl. Chem. 1997, 69, 471. (i) Kim, Y.
C.; Brown, S. G.; Harden, T. K.; Boyer, J. L.; Dubyak, G.; King, B. F.;
Burnstock, G.; Jacobson, K. A. J. Med. Chem. 2001, 44, 340.
(2) Coupling reactions involving aryl triflates have also been success-
ful: (a) Martorell, G.; Garcias, X.; Janura, M.; Saa, J. M. J. Org. Chem.
1998, 63, 3463. (b) Harper, B. A.; Knight, D. A.; George, C.; Brandow, S.
L.; Dressick, W. J.; Dalcey, C. S.; Schull, T. L. Inorg. Chem. 2003, 42,
516. (c) Ma, D.; Zhu, W. J. Org. Chem. 2001, 66, 348. (d) Petrakis, K. S.;
Nagabhushan, T. L. J. Am. Chem. Soc. 1987, 109, 2831.
Results
Palladium precursors of the type (bu2bipy)Pd(aryl)I (bu2bipy
) 4,4′-di-tert-butyl-2,2′-bipyridine) were prepared by treatment
(3) (a) Rendina, L. M.; Puddephatt, R. J. Chem. ReV. 1997, 97, 1735.
(b) Ariafard, A.; Lin, Z. Organometallics 2006, 25, 4030. (c) Casado, A.
L.; Espinet, P. Organometallics 1998, 17, 954. (d) Alcazar-Roman, L. M.;
Hartwig, J. F.; Rheingold, A. L.; Liable-Sands, L. M.; Guzei, I. A. J. Am.
Chem. Soc. 2000, 122, 4618. (e) Senn, H. M.; Ziegler, T. Organometallics
2004, 23, 2980. (f) Goossen, L. J.; Koley, D.; Hermann, H. L.; Thiel, W.
Organometallics 2005, 24, 2398. (g) Alcazar-Roman, L. M.; Hartwig, J. F.
Organometallics 2002, 21, 491. (h) Kozuch, S.; Amatore, C.; Jutand, A.;
Shaik, S. Organometallics 2005, 24, 2319.
10.1021/om060662i CCC: $33.50 © 2006 American Chemical Society
Publication on Web 10/24/2006

Arylphosphonate Elimination from Pd Complexes
Organometallics, Vol. 25, No. 24, 2006 5747
Table 1. Arylpalladium Precursors
Table 2. Arylpalladium Phosphonate Compoundsa
Ar
Ar
1
2
3
4
5
C6H5
6
7
8
9
2-C6H4OMe
2,6-C6H3Me2
4-C6H4CN
4-C6H4NO2
4-C6H4Cl
4-C6H4NH2
4-C6H4Me
2-C6H4Me
4-C6H4OMe
Ar
R′
yield, %b
31P NMR, ppmc
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
C6H5
C6H5
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
Et
Ph
90
98
79
70
90
71
79
73
91
84
67
93
93
78
95
94
74
93
86
73
69.6
67.8
69.7
68.4
70.1
68.3
70.2
68.6
69.4
67.8
69.1
67.0
71.3
69.4
65.5
63.6
64.4
63.0
68.9
65.9
of Pd2(dba)3 with aryl iodides and bu2bipy (Table 1).6 For
example, stirring a benzene solution of Pd2(dba)3 with 2
equiv of 4-iodotoluene and bu2bipy for 24 h at 25 °C followed
by filtration, concentration of the effluent, and trituration with
a 1:1 mixture of hexane/diethyl ether afforded (bu2bipy)-
Pd(4-C6H4Me)I as a yellow powder. Aryl iodides with bulky
substituents as well as electron-donating and -withdrawing
groups were well tolerated by this reaction, and moderate to
high yields of the desired complexes were obtained with minimal
purification. Compounds 1-10 were quite stable in the solid
state for extended periods of time. No decomposition or
elimination was observed from 1-10 in C6D6 or CDCl3 solvents.
The 1H and 13C{1H} NMR spectra of 1-10 displayed the
expected resonances for a Cs-symmetric species. No rotamers
were detected for species containing ortho-substituted aryl
groups (4, 6, 7).
4-C6H4NH2
4-C6H4NH2
4-C6H4Me
4-C6H4Me
2-C6H4Me
2-C6H4Me
4-C6H4OMe
4-C6H4OMe
2-C6H4OMe
2-C6H4OMe
2,6-C6H3Me2
2,6-C6H3Me2
4-C6H4CN
4-C6H4CN
4-C6H4NO2
4-C6H4NO2
4-C6H4Cl
4-C6H4Cl
a Reactions employing Ag[P(O)(OPh)2] were carried out in THF;
reactions using Ag[P(O)(OEt)2] were carried out in dichloromethane.
b Yields were based upon isolated material. c In CDCl3 solution.
Arylpalladium phosphonates of the type (bu2bipy)Pd(aryl)-
(P(O)(OR)2) (R ) phenyl, ethyl) were prepared by treatment
of the (bu2bipy)Pd(aryl)I precursors with Ag[P(O)(OR)2] (R )
Et, Ph) (Table 2). Diphenyl and diethyl phosphite were chosen
as prototypical alkyl and aryl phosphites, due to their widespread
use in synthetic applications. As a representative example,
treatment of 4 with Ag[P(O)(OEt)2] in CH2Cl2 for 2 h followed
by filtration, concentration, trituration with ether/hexane, and
drying afforded 17 as a light gray solid. Compounds 1-10 were
all successfully phosphonylated using variations of this general
procedure to afford 11-30 as white to pale yellow solids. Even
compounds containing two ortho substituents were readily
isolated in high yield (23 and 24). Compounds 11-30 ex-
hibited a single resonance in the 31P{1H} NMR spectrum,
with the chemical shift following the donor ability of the aryl
group (Table 2). The arylpalladium phosphonates containing
electron-donating substituents were found to higher frequency
1
than those containing electron-withdrawing groups. The H
and 13C{1H} NMR spectra of the arylpalladium phospho-
nate compounds without ortho substituents exhibited the ex-
pected resonances for a Cs-symmetric compound. For 17, 18,
21, and 22 the presence of the ortho substituent resulted in
inequivalence of the alkoxy groups of the phosphonate frag-
ment. Despite having the phosphonate group cis to the aryl
moiety, 11-30 were remarkably robust. No decomposition was
observed in the solid state for extended periods of time.
Additionally, no elimination or decomposition was observed
from solutions of 11-30 (CDCl3, acetone-d6, CD3CN, C6D6,
dmso-d6) at 25 °C.
While the arylpalladium phosphonates were quite stable in
solution at 25 °C, heating solutions of 11-30 (95-120 °C)
induced arylphosphonate formation. The (bu2bipy)Pd0 species
decomposed and released free bu2bipy.7 1H NMR spectroscopy
was a convenient way to monitor these phosphorus-carbon
bond-forming reactions, and the concentrations of the arylpal-
ladium phosphonates and other products were quantified using
hexamethylbenzene as an internal standard. Heating solutions
of 11-30 to 95 °C induced significant amounts of elimination
from substrates containing electron-donating groups in the para
position (13, 14, 19, and 20) of the aryl substituent, while
complexes containing electron-withdrawing groups or ortho
substituents only generated small amounts of arylphosphonate
(Figure 2, Tables 3 and 4) at this temperature. It was noteworthy
that the rates of reductive elimination showed little differences
(4) (a) Zuidema, E.; van Leeuwen, P. W. N. M.; Bo, C. Organometallics
2005, 24, 3703. (b) Culkin, D. A.; Hartwig, J. F. Organometallics 2004,
23, 3398. (c) Hartwig, J. F. Acc. Chem. Res. 1998, 31, 852. (d) Hartwig, J.
F.; Richards, S.; Baranano, D.; Paul, F. J. Am. Chem. Soc. 1996, 118, 3626.
(e) Ozawa, F.; Ito, T.; Yamamoto, A. J. Am. Chem. Soc. 1980, 102, 6457.
(f) Komiya, S.; Shibue, A. Organometallics 1985, 4, 684. (g) Shekhar, S.;
Ryberg, P.; Hartwig, J. F.; Mathew, J. S.; Blackmond, D. G.; Strieter, E.
R.; Buchwald, S. L. J. Am. Chem. Soc. 2006, 128, 3584. (h) Muci, A. R.;
Buchwald, S. L. Top. Curr. Chem. 2002, 219, 131. (i) Sawyer, J. S.
Tetrahedron 2000, 56, 5045. (j) Lira, R.; Wolfe, J. P. J. Am. Chem. Soc.
2004, 126, 13906. (k) Widenhoefer, R. A.; Buchwald, S. L. J. Am. Chem.
Soc. 1998, 120, 6504. (l) Singh, U. K.; Strieter, E. R.; Blackmond, D. G.;
Buchwald, S. L. J. Am. Chem. Soc. 2002, 124, 14104. (m) Canty, A. J.;
Denney, M. C.; Skelton, B. W.; White, A. H. Organometallics 2004, 23,
1122. (n) Canty, A. J.; Denney, M. C.; van Koten, G.; Skelton, B. W.;
White, A. H. Organometallics 2004, 23, 5432. (o) Widenhoefer, R. A.;
Zhong, H. A.; Buchwald, S. L. J. Am. Chem. Soc. 1997, 119, 6787. (p)
Mann, G.; Hartwig, J. F. J. Am. Chem. Soc. 1996, 118, 13109. (q) Driver,
M. S.; Hartwig, J. F. J. Am. Chem. Soc. 1997, 119, 8232. (r) Mann, G.;
Baranano, D.; Hartwig, J. F.; Rheingold, A. L.; Guzei, I. A. J. Chem. Soc.
1998, 120, 9205. (s) Kuniyasu, H.; Ohtaka, A.; Nakazano, T.; Kinomoto,
M.; Kurosawa, H. J. Am. Chem. Soc. 2000, 122, 2375. (t) Mann, G.; Shelby,
Q.; Roy, A. H.; Hartwig, J. F. Organometallics 2003, 22, 2775.
(5) (a) Levine, A. M.; Stockland, R. A., Jr.; Clark, R.; Guzei, I.
Organometallics 2002, 21, 3278. (b) Stockland, R. A., Jr.; Levine, A. M.;
Giovine, M. T.; Guzei, I. A.; Cannistra, J. C. Organometallics 2004, 23,
647. (c) Han, L.-B.; Choi, N.; Tanaka, M. Organometallics 1996, 15, 3259.
(d) Han, L.-B.; Zhao, C.-Q.; Onozawa, S.-Y.; Goto, M.; Tanaka, M. J. Am.
Chem. Soc. 2002, 124, 3842. For related studies of reductive elimination
of phosphines from metal phosphides see: (e) Moncarz, J. R.; Brunker, T.
J.; Jewett, J. C.; Orchowski, M.; Glueck, D. S.; Sommer, R. D.; Lam, K.
C.; Incarvito, C. D.; Concolino, T. E.; Ceccarelli, C.; Zakharov, L. N.;
Rheingold, A. L. Organometallics 2003, 22, 3205. (f) Blank, N. F.;
McBroom, K. C.; Glueck, D. S.; Kassel, W. S.; Rheingold, A. L.
Organometallics 2006, 25, 1742.
(6) Markies, B. A.; Canty, A. J.; de Graaf, W.; Boersma, J.; Janssen, M.
D.; Hogerheide, M. P.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. J.
Organomet. Chem. 1994, 482, 191.
(7) The decomposition of a similar species has been reported: de Graaf,
W.; Boersma, J.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. Organome-
tallics 1989, 8, 2907.

5748 Organometallics, Vol. 25, No. 24, 2006
Kohler et al.
Figure 2. Arylphosphonate elimination from 11-30 in C6D6 at 95 °C after 3 h.
Table 3. Arylphosphonate Elimination from
Table 4. Arylphosphonate Elimination from
(bu2bipy)Pd(Ar)(P(O)(OR)2) Speciesa
(bu2bipy)Pd(Ar)(P(O)(OR)2) Species Incorporating Ortho
Substituentsa
a Elimination reactions were carried out in C6D6 (0.5 mL) at 120 °C
using hexamethylbenzene as an internal standard.
Additionally, there was no indication in the 31P{1H} NMR
spectrum of phosphoryl oxygen coordination to palladium.
While sluggish elimination occurred from substrates contain-
ing electron-withdrawing groups at 95 °C, increasing the
temperature to 120 °C resulted in elimination from all model
compounds (Tables 3 and 4). Even substrates containing bulky
aryl groups such as 2-C6H4R (R ) Me, OMe) and 2,6-C6H3-
Me2 cleanly eliminated the arylphosphonate. The elimination
1
reactions were quite clean, as evidenced by the H and 31P-
a Elimination reactions were carried out in C6D6 (0.5 mL) at 120 °C
using hexamethylbenzene as an internal standard.
{1H} NMR spectra routinely showing only the resonances for
the starting palladium complex, bu2bipy, and the arylphospho-
nate (Figure 4 and the Supporting Information). The only
exceptions were 29 and 30. Analysis of the 31P{1H} NMR
spectrum revealed the presence of small amounts of secondary
between [Pd]-P(O)(OPh)2 and [Pd]-P(O)(OEt)2 species (Figure
3). The relative ease of elimination correlated with the donor
ability of the para substituent (e.g. NH2 > OMe > Me).

Arylphosphonate Elimination from Pd Complexes
Organometallics, Vol. 25, No. 24, 2006 5749
Table 5. Crystallographic Data for 1 and 29
1
29
formula
formula wt
cryst syst
space group
a (Å)
b (Å)
c (Å)
â (deg)
temp (K)
V (Å3)
C24H29IN2Pd
578.78
monoclinic
P21/c
9.9177(3)
12.0637(4)
19.3038(7)
101.295(2)
100(2)
C28H38ClN2O3PPd
623.42
monoclinic
P21/n
13.4268(4)
11.1315(3)
19.8695(6)
105.323(2)
100(2)
2264.85(13)
4
2864.13(14)
4
Z
θ
max (deg)
32.5
1.697
30.55
1.446
D(calcd) (Mg m-3
)
Figure 3. Elimination from arylpalladium phosphonates at 95 °C.
no. of rflns collected
no. of indep rflns
R (I > 2σ(I))
GOF
101081
8165 (R(int) ) 0.043)
0.0247
85376
8767 (R(int) ) 0.053)
0.0340
products (totaling less than 5%). These products could be
generated from small amounts of aryl chloride oxidative addition
to the generated Pd(0). Similar to the reactions carried out at
95 °C, there were no significant differences in the rates of
elimination of [Pd]-P(O)(OPh)2 and [Pd]-P(O)(OEt)2 species.
Arylphosphonate formation from model compounds containing
electron-withdrawing groups was sluggish and required extended
periods of time for complete elimination. For example, while
elimination from 13-16 was too fast at 120 °C for accurate
rate determination, the incorporation of a cyano group (25 and
26) required 18.1 and 18.3 h, respectively, at 120 °C to reach
50% conversion. The effect of different solvents on the rate of
elimination was probed using 12 as the model arylpalladium
phosphonate complex (Figure 5). While acetone-d6 and CD3-
CN solutions of 12 afforded similar conversions (37-47%; 120
°C, 1.5 h), thermolysis reactions carried out in dmso-d6 resulted
in increased consumption of 12 (69%). The effect of excess
free ligand on the elimination reaction was probed using 12
and 5 equiv of bu2bipy. Heating a C6D6 solution of pure 12
(120 °C; 5 h) resulted in the generation of PhP(O)(OPh)2 (80
( 5%). The analogous reaction carried out in the presence of 5
equiv of bu2bipy afforded a similar conversion (84 ( 5%),
showing that the free ligand neither accelerated nor retarded
the formation of the arylphosphonate.
1.012
1.035
molecules per unit cell. The palladium-carbon bond length in
1 (1.983(2) Å) is similar to that found in 29 (2.006(2) Å) and
similar to the Pd-C(Ar) bond lengths in bipyPd(C6F5)(CH2-
COMe) (2.009(2) Å),8 bipyPd(3,5-C6H3(CF3)2)I (1.990(5) Å),9
and bipyPd(C6H5)I (1.996(10) Å).6 Both of the Pd-C bond
lengths are shorter than the Pd-C bond length in the alkyl
derivative bipyPdMe(P(O)(OPh)2) (2.044(3) Å).5a The Pd-P
bond length in 29 (2.2316(5) Å) is similar to the metal-
phosphorus bond lengths found in bipyPdMe(P(O)(OPh)2)
(2.2203(8) Å)5a and bipyPd(P(O)(OPh)2)2 (2.2369(6) Å).5b The
N-Pd-N angles (1, 78.39(5)°; 29, 76.69(6)°) are smaller than
the C-Pd-X (X ) I, P) angles (1, 89.34(5)°; 29, 87.43(6)°)
due to the constraint of the chelate rings.
Discussion
The formation of carbon-carbon and carbon-heteroelement
bonds by reductive elimination from transition-metal centers is
one of the key steps in cross-coupling reactions, since this
process typically results in the formation of new bonds.4,5 Even
for well-known reactions, predicting the effect of electronic
manipulation of the metal-bound alkyl or aryl species on the
rate and outcome of the elimination process is often challenging.
In several experimental investigations of C-X (X ) N, O)
bond-forming reactions, metal-bound aryl groups containing
electron-withdrawing groups increased the rate of the elimination
The molecular structures of 1 and 29 were determined by
X-ray diffraction. The crystallographic data are presented in
Table 5, with the structure diagrams shown in Figure 6. Complex
1 crystallizes in the monoclinic space group P21/c, with four
molecules per unit cell, while 29 crystallizes in P21/n with four
Figure 4. Elimination from (bu2bipy)Pd(C6H5)(P(O)(OEt)2) in C6D6 for 3 h at 120 °C.

5750 Organometallics, Vol. 25, No. 24, 2006
Kohler et al.
Figure 5. Arylphosphonate elimination from 12 in different
solvents at 120 °C after 1.5 h.
Figure 7. Representative Hammett plot of elimination from (bu2-
bipy)Pd(Ar)(P(O)(OR)2) at 95 °C.
tion.4c,r Along these lines, heteroarylpalladium systems in which
the metal was attached to the more electron rich position of the
heteroaryl groups had slower rates of reductive elimination.10
In contrast, computational studies have predicted that reductive
eliminations should be faster from metal-bound aryl groups
bearing electron-donating groups.11 In a recent report, Hartwig
found that L2PtAr2 complexes incorporating electron-donating
substituents exhibited faster rates of reductive elimination.12
Thus, the overall effect of electronic manipulation on the
elimination rate is quite sensitive to subtle changes in the
electronic composition of the transition-metal complex.
The presence of electron-donating groups in the para position
of the metal-bound aryl fragment accelerated arylphosphonate
formation from our model compounds (13-16, 19, and 20),
while the incorporation of electron-withdrawing groups (25-
30) resulted in a slower elimination rate. The correlation of Ham-
mett parameters with reaction rates has been used in related
studies to explain the electronic effects of various functional
groups in the para or meta positions.13 Plotting the reaction rates
for the arylpalladium phosphonates that underwent elimination
at 95 °C (13-16, 19, and 20) against the σ parameters resulted
in a fair correlation (Figure 7, R2 ) 0.96). For the model systems
incorporating electron-withdrawing groups, the temperature was
increased to 120 °C in order to induce significant amounts of
elimination, and a representative Hammett plot is shown in Fig-
ure 8 for the diphenyl phosphonate containing compounds. The
correlation between σ- and the observed reaction rates has a
slightly better fit (σ, R ) 0.97; σ-, R ) 0.99), suggesting that
resonance effects may be important in the elimination
process.16
Figure 6. Molecular structures of 1 and 29. Thermal ellipsoids
are shown at 50% probability for both 1 and 29. Selected bond
distances (Å) and angles (deg) for 1: Pd(1)-C(19) ) 1.983(2),
Pd(1)-N(1) ) 2.1325(14), Pd(1)-N(2) ) 2.0730(15); C(19)-
Pd(1)-N(2) ) 93.84(7), C(19)-Pd(1)-N(1) ) 172.18(7), N(2)-
Pd(1)-N(1) ) 78.39(5). Selected bond distances (Å) and angles
(deg) for 29: Pd(1)-C(19) ) 2.006(2), Pd(1)-N(2) ) 2.1341(17),
Pd(1)-N(1) ) 2.1353(17), Pd(1)-P(1) ) 2.2316(5); C(19)-
Pd(1)-N(2) ) 95.34(7), C(19)-Pd(1)-N(1) ) 171.85(7), N(2)-
Pd(1)-N(1) ) 76.69(6), C(19)-Pd(1)-P(1) ) 87.43(6), N(2)-
Pd(1)-P(1) ) 169.88(5), N(1)-Pd(1)-P(1) ) 100.71(5).
(10) Hooper, M. W.; Hartwig, J. F. Organometallics 2003, 22, 3394.
(11) Tatsumi, K.; Hoffmann, R.; Yamamoto, A.; Stille, J. K. Bull. Chem.
Soc. Jpn. 1981, 54, 1857.
(12) Shekhar, S.; Hartwig, J. F. J. Am. Chem. Soc. 2004, 126, 13016.
(13) Ehrenson, S.; Brownlee, R. T. C.; Taft, R. W. Prog. Phys. Org.
Chem. 1973, 10, 1.
(14) (a) Winkler, P. P.; Peringer, P. Transition Met. Chem. 1982, 7, 313.
(b) Pidcock, A.; Waterhou, C. R. J. Chem. Soc. A 1970, 2080. (c) Hegedus,
L. S. In Organometallics in Synthesis, 2nd ed.; Schlosser, M., Ed.; Wiley:
London, 2002; p 1127.
process, while the metal-bound -NR2 and -OR fragments
containing electron-donating substituents accelerated the reac-
(15) (a) Kagayama, T.; Nakano, A.; Sakaguchi, S.; Ishii, Y. Org. Lett.
2006, 8, 407. (b) Kottman, H.; Skarzewski, J.; Effenberger, F. Synthesis
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2001, 20, 1087.

Arylphosphonate Elimination from Pd Complexes
Organometallics, Vol. 25, No. 24, 2006 5751
Conclusion
The effect of electronic and steric manipulation on arylphos-
phonate formation from model palladium complexes has been
studied. For these compounds, the incorporation of electron-
donating groups into the metal-bound aryl fragments accelerated
the elimination reaction. Electron-withdrawing groups as well
as aryl groups containing ortho substituents induced slower rates
of elimination. Little differences were observed in the elimina-
tion rates of diethyl and diphenyl phosphonate species.
Experimental Section
General Considerations. Diethyl ether, dichloromethane, and
hexane were dried using a Grubbs-style solvent purification system.
THF was dried by distillation from Na/benzophenone. The aryl
iodides, bu2bipy, and phosphites were obtained from Aldrich and
used as received. Pd2(dba)3, Ag[P(O)(OEt)2], and Ag[P(O)(OPh)2]
were prepared by following literature procedures.14 All yields are
based upon isolated material unless specified. Elemental analyses
were performed by Midwest Microlabs. 1H and 13C chemical shifts
were determined by reference to residual protonated solvent
resonances or Me4Si. All coupling constants are given in hertz.
31P{1H} NMR spectra were referenced to external H3PO4 (0 ppm).
Arylphosphonates were identified by comparison of the spectro-
scopic data to authentic samples or literature values.15 Previously
uncharacterized arylphosphonates were isolated from the thermol-
ysis reactions as described below. The reaction mixtures were
analyzed using H NMR spectroscopy as well as GC and GC-MS
for products resulting from secondary reactions. In all cases, less
than 1% unidentified material was found.
General Procedure for the Preparation of Arylpalladium
Iodides. A reactor vial was charged with Pd2(dba)3, aryl iodide (1
equiv per Pd), bu2bipy (1 equiv per Pd), a magnetic stirring bar,
and benzene. The reaction mixture was stirred at 23 °C for 48 h.
The mixture was filtered, concentrated under vacuum, and triturated
with hexane/ether to afford the arylpalladium iodide as a fine
powder.
Figure 8. Representative Hammett plot for elimination from
(bu2bipy)Pd(Ar)(P(O)(OPh)2) species at 120 °C.
The incorporation of ortho substituents into the metal-
bound aryl group resulted in a significant reduction in the
reaction rate. For example, the relative rate of elimination
from 11 was 3.0 times faster than when one o-methyl group
was added (17) and 18.0 times faster than when two o-methyl
groups were incorporated into the model system (23). While
heating 11 (120 °C) for 3 h resulted in 68% consumption,
23 required over 83 h for 50% conversion (120 °C). This
reduction in the rate when bulky groups were present is similar
to other reductive elimination reactions and could be due to
the relative stability of Pd(0) arene species generated from the
reaction.
1
The coordination number and geometry of the metal species
have a significant impact on the rate of reductive elimination.
The reaction is typically proposed to occur from three- or four-
coordinate Pd(II) T-shaped or square-planar species, with the
rate of elimination from the three-coordinate species being
faster.4q For the arylpalladium phosphonates studied, the zero-
order dependence upon added ligand, the insensitivity to
moderate changes in the solvent polarity, and the presence of
the strong chelating bipyridine ligand suggest that the elimina-
tion occurred from a four-coordinate Pd(II) species. However,
our kinetic studies cannot rule out dissociation of one end of
the chelate followed by rapid reductive elimination and either
trapping by the free end of the chelating ligand or direct
decomposition to Pd(0) and free bu2bipy. This dissociation
process is predicted to be unfavorable, due to the strongly
chelating bipyridine ligand and the noncoordinating solvent
(benzene). The accelerated rate of reductive elimination in
dmso-d6 could be due to the formation of three-coordinate
species that would be favored by the polar solvent. It is also
noteworthy to point out that these elimination reactions pro-
ceeded in high yield (as determined by NMR: Figure 4 and
the Supporting Information) in the absence of a trapping agent
for the generated Pd(0). This is in contrast to other carbon-
heteroelement bond-forming reactions where additional equiva-
lents of ligand were needed for a high-yielding process.12a It is
possible that the phosphoryl oxygen could act as a ligand and
stabilize the metal center prior to formation of free Pd(0);
however, no coordination was observed in the 31P{1H} NMR
spectrum of the thermolysis reactions, although the coordination/
release could be rapid.
Preparation of (bu2bipy)Pd(C6H5)I (1). The general procedure
was followed with iodobenzene (244 µL, 2.18 mmol), bu2bipy
(0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol) to afford
0.415 g (33%) of the title compound as a yellow powder. Anal.
Calcd for C24H29IN2Pd: C, 49.80; H, 5.05. Found: C, 49.97; H,
1
5.04. H NMR (CDCl3, 25 °C): δ 9.50 (d, 1H, J ) 5.7, Ar-H),
7.96 (s, 2H, Ar-H), 7.56 (d, 1H, J ) 5.9, Ar-H), 7.50 (dd, 1H, J )
5.8, 1.8, Ar-H), 7.40 (d, 2H, J ) 6.9, Ar-H), 7.32 (dd, 1H, J )
5.9, 1.9, Ar-H), 7.04 (t, 2H, J ) 7.4, Ar-H), 6.91 (t, 1H, J ) 7.3,
Ar-H), 1.42 (s, 9H, -CMe3), 1.38 (s, 9H, -CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.11 (s, quat), 163.08 (s, quat), 155.8 (s, quat),
153.8 (s, quat), 152.4 (s, Ar-CH), 149.7 (s, Ar-CH), 146.6 (s, quat),
136.5 (s, Ar-CH), 127.2 (s, Ar-CH), 123.8 (s, Ar-CH), 123.5 (s,
Ar-CH), 123.0 (s, Ar-CH), 118.3 (s, Ar-CH), 117.9 (s, Ar-CH),
35.5 (s, -CMe3), 35.4 (s, -CMe3), 30.4 (s, -CMe3), 30.2 (s,
-CMe3).
Preparation of (bu2bipy)Pd(4-C6H4NH2)I (2). The general
procedure was followed with 4-iodoaniline (0.478 g, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.455 g (35%) of the title compound as a yellow powder.
Anal. Calcd for C24H30IN3Pd: C, 48.54; H, 5.09. Found: C, 48.39;
H, 4.95. 1H NMR (CDCl3, 25 °C): δ 9.51 (d, 1H, J ) 5.7, Ar-H),
7.95 (s, 2H, Ar-H), 7.74 (d, 1H, J ) 5.9, Ar-H), 7.50 (dd, 1H,
J ) 5.8, 1.8, Ar-H), 7.36 (dd, 1H, 5.9, 1.9, Ar-H), 7.14 (m, 2H,
C6H4NH2), 6.58 (m, 2H, C6H4NH2), 3.39 (s, 2H, -NH2), 1.43 (s,
9H, -CMe3), 1.40 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3, 25
°C): δ 163.0 (s, quat), 162.9 (s, quat), 155.8 (s, quat), 153.8 (s,
quat), 152.4 (s, Ar-CH), 149.9 (s, Ar-CH), 142.1 (s, quat), 136.3
(s, Ar-CH), 131.8 (s, quat), 123.7 (s, Ar-CH), 123.4 (s, Ar-CH),

5752 Organometallics, Vol. 25, No. 24, 2006
Kohler et al.
118.2 (s, Ar-CH), 117.8 (s, Ar-CH), 115.8 (s, Ar-CH), 35.4 (s,
-CMe3), 35.4 (s, -CMe3), 30.4 (s, -CMe3), 30.2 (s, -CMe3).
Preparation of (bu2bipy)Pd(2,6-C6H3Me2)I (7). The general
procedure was followed with 2-iodo-m-xylene (315 µL, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.659 g (50%) of the title compound as a yellow powder.
Anal. Calcd for C26H33IN2Pd: C, 51.46; H, 5.48. Found: C, 51.42;
H, 5.49. 1H NMR (CDCl3, 25 °C): δ 9.50 (d, 1H, J ) 5.7, Ar-H),
7.97 (s, 2H, Ar-H), 7.53 (dd, 1H, J ) 5.8, 1.7, Ar-H), 7.33-7.26
(m, 2H, Ar-H), 6.80 (m, 3H, Ar-H), 2.65 (s, 6H, -Me), 1.43 (s,
9H, -CMe3), 1.39 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3, 25
°C): δ 162.98 (s, quat), 162.95 (s, quat), 156.0 (s, quat), 153.6 (s,
quat), 152.2 (s, Ar-CH), 148.8 (s, Ar-CH), 148.0 (s, quat), 141.1
(s, quat), 125.5 (s, Ar-CH), 123.9 (s, Ar-CH), 123.8 (s, Ar-CH),
123.7 (s, Ar-CH), 118.4 (s, Ar-CH), 117.8 (s, Ar-CH), 35.5 (s,
-CMe3), 35.4 (s, -CMe3), 30.4 (s, -CMe3), 30.2 (s, -CMe3), 27.4
(s, -Me).
Preparation of (bu2bipy)Pd(4-C6H4Me)I (3). The general
procedure was followed with 4-iodotoluene (0.476 g, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.357 g (28%) of the title compound as a yellow powder.
Anal. Calcd for C25H31IN2Pd: C, 50.65; H, 5.27. Found: C, 50.56;
H, 4.87. 1H NMR (CDCl3, 25 °C): δ 9.52 (d, 1H, J ) 5.7, Ar-H),
7.96 (s, 2H, Ar-H), 7.66 (AA′BB′, 1H, J ) 5.9, Ar-H), 7.50 (dd,
1H, J ) 5.7, 1.7, Ar-H), 7.34 (dd, 1H, J ) 5.9, 1.8, Ar-H), 7.28
(d, 2H, J ) 7.8, Ar-H), 6.90 (d, 2H, J ) 7.8, Ar-H), 2.30 (s, 3H,
-Me), 1.43 (s, 9H, CMe3), 1.39 (s, 9H, CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.04 (s, quat), 162.98 (s, quat), 155.8 (s, quat),
153.8 (s, quat), 152.5 (s, Ar-CH), 149.9 (s, Ar-CH), 141.7 (s, quat),
136.2 (s, Ar-CH), 132.1 (s, quat), 128.4 (s, Ar-CH), 123.8 (s,
Ar-CH), 123.5 (s, Ar-CH), 118.2 (s, Ar-CH), 117.8 (s, Ar-CH),
35.5 (s, -CMe3), 35.4 (s, -CMe3), 30.4 (s, -CMe3), 30.3 (s,
-CMe3), 20.7 (s, -Me).
Preparation of (bu2bipy)Pd(2-C6H4Me)I (4). The general
procedure was followed with 2-iodotoluene (278 µL, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.401 g (31%) of the title compound as a yellow powder.
Anal. Calcd for C25H31IN2Pd: C, 50.65; H, 5.27. Found: C, 51.00;
H, 5.38. 1H NMR (CDCl3, 25 °C): δ 9.51 (d, 1H, J ) 5.7, Ar-H),
7.97 (s, 2H, Ar-H), 7.52 (dd, 1H, J ) 5.7, 1.8, Ar-H), 7.42 (m,
1H, Ar-H), 7.40 (d, 1H, J ) 5.9, Ar-H), 7.30 (dd, 1H, J ) 5.9, 1.9,
Ar-H), 6.99 (m, 1H, Ar-H), 6.87 (m, 2H, Ar-H), 2.61 (s, 3H, -Me),
1.44 (s, 9H, -CMe3), 1.40 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3,
25 °C): δ 163.1 (s, quat), 163.0 (s, quat), 155.9 (s, quat), 153.7 (s,
quat), 152.4 (s, Ar-CH), 149.3 (s, Ar-CH), 147.3 (s, quat), 141.3
(s, quat), 136.2 (s, Ar-CH), 128.7 (s, Ar-CH), 124.0 (s, Ar-CH),
123.9 (s, Ar-CH), 123.7 (s, Ar-CH), 123.2 (s, Ar-CH), 118.3 (s,
Ar-CH), 117.8 (s, Ar-CH), 35.5 (s, -CMe3), 35.4 (s, -CMe3), 30.4
(s, -CMe3), 30.3 (s, -CMe3), 26.9 (s, -Me).
Preparation of (bu2bipy)Pd(4-C6H4OMe)I (5). The general
procedure was followed with 4-iodoanisole (0.511 g, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.310 g (23%) of the title compound as a yellow powder.
Anal. Calcd for C25H31IN2OPd: C, 49.32; H, 5.13. Found: C, 49.23;
H, 5.73. 1H NMR (CDCl3, 25 °C): δ 9.52 (d, 1H, J ) 5.7, Ar-H),
7.96 (s, 2H, Ar-H), 7.64 (d, 1H, J ) 5.9, Ar-H), 7.51 (dd, 1H, J )
5.7, 1.7, Ar-H), 7.34 (dd, 1H, J ) 5.9, 1.9, Ar-H), 7.27 (d, 2H, J
) 7.1, Ar-H), 6.76 (d, 2H, J ) 7.0, Ar-H), 3.79 (s, 3H, -OMe),
1.43 (s, 9H, -CMe3), 1.40 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3,
25 °C): δ 163.09 (s, quat), 163.05 (s, quat), 156.6 (s, quat), 155.9
(s, quat), 153.8 (s, quat), 152.5 (s, Ar-CH), 149.8 (s, Ar-CH), 136.3
(s, Ar-CH), 134.1 (s, quat), 123.8 (s, Ar-CH), 123.5 (s, Ar-CH),
118.2 (s, Ar-CH), 117.9 (s, Ar-CH), 113.6 (s, Ar-CH), 55.1 (s,
-OMe), 35.5 (s, -CMe3), 35.4 (s, -CMe3), 30.4 (s, -CMe3), 30.2
(s, -CMe3).
Preparation of (bu2bipy)Pd(2-C6H4OMe)I (6). The general
procedure was followed with 2-iodoanisole (284 µL, 2.18 mmol),
bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09 mmol)
to afford 0.489 g (37%) of the title compound as a yellow powder.
Anal. Calcd for C25H31IN2OPd: C, 49.32; H, 5.13. Found: C, 48.93;
H, 5.01. 1H NMR (CDCl3, 25 °C): δ 9.55 (d, 1H, J ) 5.7, Ar-H),
7.95 (s, 2H, Ar-H), 7.57 (d, 1H, J ) 5.9, Ar-H), 7.49 (dd, 1H, J )
5.7, 1.6, Ar-H), 7.42 (dd, 1H, J ) 7.2, 1.4, Ar-H), 7.29 (dd, 1H, J
) 6.0, 1.9, Ar-H), 6.97 (dt, 1H, J ) 8.0, 1.4, Ar-H), 6.73 (dt, 1H,
J ) 7.1, 1.0, Ar-H), 6.68 (dt, 1H, J ) 8.0, 1.0, Ar-H), 3.81 (s, 3H,
-OMe), 1.42 (s, 9H, -CMe3), 1.38 (s, 9H, -CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.05 (s, quat), 162.94 (s, quat), 156.0 (s, quat),
154.1 (s, quat), 152.7 (s, Ar-CH), 149.8 (s, Ar-CH), 138.1 (s,
Ar-CH), 132.5 (s, quat), 128.9 (s, quat), 124.3 (s, Ar-CH), 123.7
(s, Ar-CH), 123.4 (s, Ar-CH), 120.3 (s, Ar-CH), 118.3 (s, Ar-CH),
117.8 (s, Ar-CH), 111.6 (s, Ar-CH), 56.3 (s, -OMe), 35.42 (s,
-CMe3), 35.39 (s, -CMe3), 30.3 (s, -CMe3), 30.2 (s, -CMe3).
Preparation of (bu2bipy)Pd(4-C6H4CN)I (8). The general
procedure was followed with 4-iodobenzonitrile (0.500 g, 2.18
mmol), bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09
mmol) to afford 0.653 g (49%) of the title compound as a yellow
powder. Anal. Calcd for C25H28IN3Pd: C, 49.73; H, 4.67. Found:
1
C, 49.68; H, 4.58. H NMR (CDCl3, 25 °C): δ 9.50 (d, 1H, J )
5.7, Ar-H), 7.98 (d, 1H, J ) 1.8, Ar-H), 7.97 (d, 1H, J ) 1.8,
Ar-H), 7.61 (AA′BB′, 2H, Ar-H), 7.53 (dd, 1H, J ) 5.7, 1.8,
Ar-H), 7.45 (d, 1H, J ) 5.9, Ar-H), 7.37 (dd, 1H, J ) 6.0, 1.9,
Ar-H), 7.28 (AA′BB′, 2H, Ar-H), 1.43 (s, 9H, -CMe3), 1.41 (s,
9H, -CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.8 (s, quat),
163.6 (s, quat), 158.1 (s, quat), 156.0 (s, quat), 153.8 (s, quat),
152.6 (s, Ar-CH), 149.3 (s, Ar-CH), 137.7 (s, Ar-CH), 128.9 (s,
Ar-CH), 124.1 (s, Ar-CH), 123.7 (s, Ar-CH), 120.2 (s, quat), 118.7
(s, Ar-CH), 118.2 (s, Ar-CH), 106.4 (s, quat), 35.6 (s, -CMe3),
35.5 (s, -CMe3), 30.3 (s, -CMe3), 30.2 (s, -CMe3).
Preparation of (bu2bipy)Pd(4-C6H4NO2)I (9). The general
procedure was followed with 4-iodonitrobenzene (0.543 g, 2.18
mmol), bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09
mmol) to afford 0.541 g (40%) of the title compound as a yellow
powder. Anal. Calcd for C24H28IN3O2Pd: C, 46.21; H, 4.52.
1
Found: C, 46.46; H, 4.41. H NMR (CDCl3, 25 °C): δ 9.50 (d,
1H, J ) 5.8, Ar-H), 8.00 (d, 1H, J ) 1.8, Ar-H), 7.98 (d, 1H, J )
1.7, Ar-H), 7.89 (AA′BB′, 2H, Ar-H), 7.69 (AA′BB′, 2H, Ar-H),
7.54 (dd, 1H, J ) 5.8, 1.7, Ar-H), 7.44 (d, 1H, J ) 5.9, Ar-H),
7.36 (dd, 1H, J ) 5.9, 1.8, Ar-H), 1.44 (s, 9H, -CMe3), 1.40 (s,
9H, -CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.9 (s, quat),
163.7 (s, quat), 162.7 (s, quat), 156.0 (s, quat), 153.8 (s, quat),
152.8 (s, Ar-CH), 149.3 (s, Ar-CH), 145.3 (s, quat), 137.2 (s,
Ar-CH), 124.1 (s, Ar-CH), 123.8 (s, Ar-CH), 120.6 (s, Ar-CH),
118.7 (s, Ar-CH), 118.2 (s, Ar-CH), 35.6 (s, -CMe3), 35.5 (s,
-CMe3), 30.4 (s, -CMe3), 30.2 (s, -CMe3).
Preparation of (bu2bipy)Pd(4-C6H4Cl)I (10). The general
procedure was followed with 4-iodochlorobenzene (0.521 g, 2.18
mmol), bu2bipy (0.586 g, 2.18 mmol), and Pd2(dba)3 (1.00 g, 1.09
mmol) to afford 0.526 g (39%) of the title compound as a yellow
powder. Anal. Calcd for C24H28ClIN2Pd: C, 47.00; H, 4.60.
1
Found: C, 47.33; H, 4.72. H NMR (CDCl3, 25 °C): δ 9.48 (d,
1H, J ) 5.7, Ar-H), 7.97 (s, 2H, Ar-H), 7.58 (d, 1H, J ) 5.9,
Ar-H), 7.51 (dd, 1H, J ) 5.6, 1.3, Ar-H), 7.35 (m, 3H, Ar-H),
7.04 (d, 2H, J ) 8.15, Ar-H), 1.43 (s, 9H, Ar-H), 1.40 (s, 9H,
Ar-H). 13C{1H} NMR (CDCl3, 25 °C): δ 163.4 (s, quat), 163.3 (s,
quat), 155.9 (s, quat), 153.8 (s, quat), 152.6 (s, Ar-CH), 149.6 (s,
Ar-CH), 144.1 (s, quat), 137.5 (s, Ar-CH), 129.4 (s, quat), 126.9
(s, Ar-CH), 123.9 (s, Ar-CH), 123.6 (s, Ar-CH), 118.4 (s, Ar-CH),
118.0 (s, Ar-CH), 35.5 (s, -CMe3), 35.4 (s, -CMe3), 30.4 (s,
-CMe3), 30.2 (s, -CMe3).
General Procedure for the Preparation of the Arylpalladium
Phosphonates. A 10 mL reactor vial was charged with the
arylpalladium iodide, Ag[P(O)(OR)2], solvent, and a magnetic
stirring bar. The reaction mixture was stirred for 2 h in the dark
and filtered to remove the silver salts. After purification by column

Arylphosphonate Elimination from Pd Complexes
Organometallics, Vol. 25, No. 24, 2006 5753
chromatography (Et2O/CH2Cl2), the residue was triturated with
ether/hexane to afford the aryl palladium phosphonates as fine
powders.
(AA′BB′, 2H, Ar-H), 3.49 (s, 2H, -NH2), 1.51 (s, 9H, -CMe3),
1.44 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.7 (s,
quat), 163.1 (s, quat), 155.1 (s, quat), 154.3 (s, quat), 153.6 (d, J
) 153.6, Ar-CH), 152.9 (d, J ) 8.08, quat), 150.1 (s, quat), 136.1
(d, J ) 5.5, Ar-CH), 129.6 (s, quat), 128.8 (s, Ar-CH), 123.7 (s,
Ar-CH), 123.2 (s, Ar-CH), 122.3 (s, Ar-CH), 121.2 (d, J ) 5.6,
Ar-CH), 117.8 (s, Ar-CH), 117.6 (d, J ) 2.1, Ar-CH), 115.5 (s,
Ar-CH), 35.39 (s, -CMe3), 35.35 (s, -CMe3), 30.34 (s, -CMe3),
30.29 (s, -CMe3). 31P{1H} NMR (CDCl3, 25 °C): δ 69.4 (s).
Synthesis of (bu2bipy)Pd(4-C6H4Me)(P(O)(OEt)2) (15). The
general procedure was followed using (bu2bipy)Pd(4-C6H4Me)I
(0.257 g, 0.433 mmol), Ag[P(O)(OEt)2] (0.106, 0.433 mmol), and
CH2Cl2 (5 mL). After purification by column chromatography, the
title compound was isolated as a white solid (0.234 g, 90%). Anal.
Calcd for C29H41N2O3PPd: C, 57.76; H, 6.85. Found: C, 57.83;
H, 6.89. 1H NMR (CDCl3, 25 °C): δ 9.96 (d, 1H, J ) 5.7, Ar-H),
7.87 (s, 2H, Ar-H), 7.45 (m, 2H, Ar-H), 7.36 (m, 2H, Ar-H), 7.18
(m, 1H, Ar-H), 6.83 (AA′BB′, 2H, Ar-H), 3.85 (m, 4H, -OCH2-
CH3), 2.20 (s, 3H, ArMe), 1.33 (s, 9H, -CMe3), 1.28 (s, 9H,
-CMe3), 1.06 (t, 6H, J ) 7.0, -OCH2CH3). 13C{1H} NMR (CDCl3,
25 °C): δ 163.4 (s, quat), 162.8 (s, quat), 155.1 (d, J ) 1.7, quat),
154.4 (d, J ) 1.7, quat), 153.8 (s, Ar-CH), 150.5 (s, quat), 149.9
(d, J ) 1.9, Ar-CH), 136.1 (d, J ) 5.3, Ar-CH), 131.9 (s, quat),
127.9 (d, J ) 3.5, Ar-CH), 123.5 (s, Ar-CH), 123.1 (d, J ) 3.0,
Ar-CH), 117.7 (s, Ar-CH), 117.5 (d, J ) 3.0, Ar-CH), 57.7 (d, J )
4.5, -OCH2CH3), 35.35 (s, -CMe3), 35.29 (s, -CMe3), 30.33 (s,
-CMe3), 30.29 (s, -CMe3), 21.0 (s, -ArMe), 16.6 (d, J ) 7.3,
-OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ 70.1 (s).
Synthesis of (bu2bipy)Pd(4-C6H4Me)(P(O)(OPh)2) (16). The
general procedure was followed using (bu2bipy)Pd(4-C6H4Me)I
(0.250, 0.422 mmol), Ag[P(O)(OPh)2] (0.144 g, 0.422 mmol), and
THF (5 mL). After purification by column chromatography, the
title compound was isolated as a white solid (0.210 g, 71%). Anal.
Calcd for C37H41N2O3PPd: C, 63.56; H, 5.91. Found: C, 63.41;
H, 5.92. 1H NMR (CDCl3, 25 °C): δ 10.08 (d, 1H, J ) 5.7,
Ar-H), 7.95 (s, 2H, Ar-H), 7.53 (dd, 1H, J ) 5.8, 1.8, Ar-H), 7.42
(dd, 1H, J ) 5.8, 3.5, Ar-H), 7.30-7.13 (m, 11H, Ar-H), 6.94 (t,
2H, J ) 7.05, Ar-H), 6.86 (d, 2H, J ) 7.7, Ar-H), 2.28 (s, 3H,
-Me), 1.42 (s, 9H, -CMe3), 1.35 (s, 9H, -CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.7 (s, quat), 163.1 (s, quat), 155.2 (d, J )
1.7, quat), 154.2 (d, J ) 2.0, quat), 153.6 (s, Ar-CH), 152.9 (d, J
) 8.3, quat), 149.9 (d, J ) 1.9, Ar-CH), 149.6 (s, quat), 135.7 (d,
J ) 5.4, Ar-CH), 132.2 (s, quat), 128.7 (s, Ar-CH), 127.9 (d, J )
3.6, Ar-CH), 123.6 (s, Ar-CH), 123.2 (d, J ) 3.2, Ar-CH), 122.3
(s, Ar-CH), 121.2 (d, J ) 5.5, Ar-CH), 117.8 (s, Ar-CH), 117.7 (d,
J ) 3.0, Ar-CH), 35.4 (s, -CCH3), 35.3 (s, -CCH3), 30.33 (s,
-CMe3), 30.25 (s, -CMe3), 21.0 (s, -CH3). 31P{1H} NMR (CDCl3,
25 °C): δ 68.3 (s).
Synthesis of (bu2bipy)Pd(2-C6H4Me)(P(O)(OEt)2) (17). The
general procedure was followed using (bu2bipy)Pd(2-C6H4Me)I
(0.383 g, 0.646 mmol), Ag[P(O)(OEt)2] (0.158 g, 0.646 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as a gray solid (0.306 g, 79%).
Anal. Calcd for C29H41N2O3PPd: C, 57.76; H, 6.85. Found: C,
57.52; H, 6.92. 1H NMR (CDCl3, 25 °C): δ 9.99 (d, 1H, J ) 5.7,
Ar-H), 7.96 (s, 2H, Ar-H), 7.59-7.54 (m, 2H, Ar-H), 7.32 (m, 1H,
Ar-H), 7.24 (m, 1H, Ar-H), 7.03-6.87 (m, 3H, Ar-H), 3.86 (m,
4H, -OCH2CH3), 2.60 (s, 3H, Ar Me), 1.43 (s, 9H, -CMe3), 1.37
(s, 9H, -CMe3), 1.17 (t, 3H, J ) 7.0, -OCH2CH3), 1.09 (t, 3H, J
) 7.0, -OCH2CH3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.3 (s,
quat), 162.8 (s, quat), 156.4 (d, J ) 2.3, quat), 155.1 (d, J ) 1.7,
quat), 154.2 (d, J ) 1.6, quat), 153.5 (s, Ar-CH), 149.1 (d, J )
2.0, Ar-CH), 142.04 (s, quat), 142.00 (s, quat), 136.3 (d, J ) 6.5,
Ar-CH), 127.9 (s, Ar-CH), 123.5 (d, J ) 5.2, Ar-CH), 123.4 (s,
Ar-CH), 123.2 (d, J ) 3.0, Ar-CH), 122.9 (s, Ar-CH), 117.6 (s,
Ar-CH), 117.5 (d, J ) 3.2, Ar-CH), 57.6 (d, J ) 5.1, -OCH2-
CH3), 57.4 (d, J ) 6.3, -OCH2CH3), 35.3 (s, -CMe3), 35.2 (s,
Synthesis of (bu2bipy)PdPh(P(O)(OEt)2) (11). The general
procedure was followed using (bu2bipy)PdPhI (0.215 g, 0.371
mmol), Ag[P(O)(OEt)2] (0.0910 g, 0.371 mmol), and CH2Cl2 (5
mL). After purification by column chromatography, the title
compound was isolated as a tan solid (0.196 g, 90%). Anal. Calcd
for C28H39N2O3PPd: C, 57.10; H, 6.67. Found: C, 56.84; H, 6.45.
1H NMR (CDCl3, 25 °C): δ 10.01 (d, 1H, J ) 5.7, Ar-H), 7.96 (s,
2H, Ar-H), 7.60-7.53 (m, 3H, Ar-H), 7.48 (dd, 1H, Ar-H), 7.31-
7.24 (m, 1H, Ar-H), 7.08 (t, 2H, J ) 7.3, Ar-H), 7.00 (t, 1H,
Ar-CH), 3.91 (m, 4H, -OCH2CH3), 1.42 (s, 9H, -CMe3), 1.37 (s,
9H, -CMe3), 1.13 (t, 6H, -OCH2CH3). 13C{1H} NMR (CDCl3,
25 °C): δ 163.5 (s, quat), 163.0 (s, quat), 155.3 (s, quat), 155.2 (d,
J ) 1.8, quat), 154.4 (d, J ) 1.7, quat), 153.8 (s, Ar-CH), 149.8
(d, J ) 1.9, Ar-CH), 136.5 (d, J ) 5.3, Ar-CH), 127.0 (d, J ) 3.2,
Ar-CH), 123.5 (s, Ar-CH), 123.1 (d, J ) 3.1, Ar-CH), 123.0 (s,
Ar-CH), 117.7 (s, Ar-CH), 117.6 (d, J ) 2.9, Ar-CH), 57.8 (d, J )
4.8, -OCH2CH3), 35.4 (s, -CMe3), 35.3 (s, -CMe3), 30.37 (s,
-CMe3), 30.32 (s, -CMe3), 16.6 (d, J ) 4.8, -OCH2CH3).
31P{1H} NMR (CDCl3, 25 °C): δ 69.6 (s).
Synthesis of (bu2bipy)PdPh(P(O)(OPh)2) (12). The general
procedure was followed using (bu2bipy)PdPhI (0.246 g, 0.425
mmol), Ag[P(O)(OPh)2] (0.145 g, 0.425 mmol), and THF (5 mL).
After purification by column chromatography, the title compound
was isolated as a white solid (0.285 g, 98%). Anal. Calcd for
C36H39N2O3PPd: C, 63.11; H, 5.74. Found: C, 63.46; H, 5.32. 1H
NMR (CDCl3, 25 °C): δ 10.01 (d, 1H, J ) 5.73, Ar-H), 7.98 (s,
2H, Ar-H), 7.55 (dd, 1H, J ) 5.8, 1.8, Ar-H), 7.40 (m, 3H, Ar-H),
7.23 (m, 8H, Ar-H), 7.02 (m, 6H, Ar-H), 1.44 (s, 9H, -CMe3),
1.37 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.8 (s,
quat), 163.2 (s, quat), 155.2 (d, J ) 1.8, quat), 154.4 (d, J ) 1.0,
quat), 154.2 (d, J ) 1.8, quat), 153.7 (s, Ar C), 152.9 (d, J ) 8.5,
quat), 149.9 (d, J ) 2.0, Ar C), 136.1 (d, J ) 5.3, Ar C), 128.8 (s,
Ar C), 127.0 (d, J ) 3.55, Ar C), 123.7 (s, Ar C), 123.3 (s, Ar C),
123.2 (s, J ) 3.1, Ar C), 122.3 (s, Ar C), 121.2 (d, J ) 5.5, Ar C),
117.8 (s, Ar C), 117.7 (d, J ) 3.0, Ar C), 35.4 (s, -CMe3), 35.3
(s, -CMe3), 30.4 (s, -CMe3), 30.3 (s, -CMe3). 31P{1H} NMR
(CDCl3, 25 °C): δ 67.8 (s).
Synthesis of (bu2bipy)Pd(4-C6H4NH2)(P(O)(OEt)2) (13). The
general procedure was followed using (bu2bipy)Pd(4-C6H4NH2)I
(0.232 g, 0.391 mmol), Ag[P(O)(OEt)2] (0.0958 g, 0.391 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as an orange solid (0.187 g, 79%).
Anal. Calcd for C28H40N3O3PPd: C, 55.68; H, 6.67. Found: C,
55.60; H, 6.51. 1H NMR (CDCl3, 25 °C): δ 10.25 (d, 1H, J ) 5.7,
Ar-H), 8.19 (s, 2H, Ar-H), 7.85 (dd, 1H, J ) 5.6, 3.1, Ar-H), 7.76
(dd, 1H, J ) 4.0, 5.8, Ar-H), 7.67-7.50 (m, 3H, Ar-H), 6.87 (m,
2H, Ar-H), 4.20 (m, 4H, -OCH2CH3), 3.67 (s, 2H, -NH2), 1.66
(s, 9H, -CMe3), 1.61 (s, 9H, -CMe3), 1.40 (t, 6H, -OCH2CH3).
13C{1H} NMR (CDCl3, 25 °C): δ 163.3 (s, quat), 162.8 (s, quat),
155.0 (d, J ) 1.7, quat), 154.4 (d, J ) 1.3, quat), 153.7 (s, Ar-
CH), 149.9 (d, J ) 1.9, Ar-CH), 136.4 (d, J ) 5.4, Ar-CH), 130.5
(s, quat), 123.4 (s, Ar-CH), 123.0 (d, J ) 2.9, Ar-CH), 117.6 (s,
Ar-CH), 117.5 (d, J ) 3.0, Ar-CH), 115.5 (s, Ar-CH), 57.7 (d, J )
4.5, -OCH2CH3), 35.32 (s, -CMe3), 35.26 (s, -CMe3), 30.32 (s,
-CMe3), 30.28 (s, -CMe3), 16.6 (d, J ) 7.3, -OCH2CH3).
31P{1H} NMR (CDCl3, 25 °C): δ 69.7 (s).
Synthesis of (bu2bipy)Pd(4-C6H4NH2)(P(O)(OPh)2) (14). The
general procedure was followed using (bu2bipy)Pd(4-C6H4NH2)I
(0.254 g, 0.428 mmol), Ag[P(O)(OPh)2] (0.146 g, 0.428 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as an orange solid (0.209 g, 70%).
Anal. Calcd for C36H40N3O3PPd: C, 61.76; H, 5.76. Found: C,
61.50; H, 5.51. 1H NMR (CDCl3, 25 °C): δ 10.16 (d, 1H, J ) 5.6,
Ar-H), 8.04 (s, 2H, Ar-H), 7.62-7.00 (m, 15H, Ar-H), 6.60

5754 Organometallics, Vol. 25, No. 24, 2006
Kohler et al.
-CMe3), 30.24 (s, -CMe3), 30.19 (s, -CMe3), 26.7 (s, -Me), 26.6
(s, -Me), 16.6 (d, J ) 7.3, -OCH2CH3), 16.5 (d, J ) 6.9,
-OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ 70.2 (s).
(0.257 g, 0.422 mmol), Ag[P(O)(OEt)2] (0.103 g, 0.422 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as a pale yellow solid (0.175 g,
67%). Anal. Calcd for C29H41N2O4PPd: C, 56.27; H, 6.68. Found:
C, 56.65; H, 6.69. 1H NMR (CDCl3, 25 °C): δ 10.02 (d, 1H, J )
5.0, Ar-H), 7.94 (s, 2H, Ar-H), 7.59-7.49 (m, 3H, Ar-H), 7.23
(m, 1H, Ar-H), 7.06 (dt, 1H, J ) 8.6, 1.5, Ar-H), 6.78 (t, 1H, J )
7.3, Ar-H), 6.69 (m, 1H, Ar-H), 3.90 (m, 4H, -OCH2CH3), 3.76
(s, 3H, -OMe), 1.42 (s, 9H, -CMe3), 1.36 (s, 9H, -CMe3), 1.13
(t, 3H, J ) 7.0, -OCH2CH3), 1.06 (t, 3H, J ) 7.0, -OCH2CH3).
13C{1H} NMR (CDCl3, 25 °C): δ 163.3 (s, quat), 162.9 (s, quat),
162.0 (s, quat), 155.3 (d, J ) 2.0, quat), 154.6 (d, J ) 2.0, quat),
153.8 (s, Ar-CH), 149.7 (d, J ) 2.0, Ar-CH), 142.2 (s, quat), 137.8
(d, J ) 5.1, Ar-CH), 124.1 (s, Ar-CH), 123.5 (s, Ar-CH), 123.0 (d,
J ) 3.2, Ar-CH), 120.1 (d, J ) 3.5, Ar-CH), 117.65 (s, Ar-CH),
117.62 (d, J ) 3.4, Ar-CH), 109.7 (s, Ar-CH), 57.8 (d, J ) 5.2,
-OCH2CH3), 57.7 (d, J ) 3.7, -OCH2CH3), 55.4 (s, -OMe), 35.33
(s, -CMe3), 35.29 (s, -CMe3), 30.33 (s, -CMe3), 30.29 (s,
-CMe3), 16.6 (d, J ) 5.2, -OCH2CH3), 16.5 (d, J ) 5.2,
-OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ 69.1 (s).
Synthesis of (bu2bipy)Pd(2-C6H4OMe)(P(O)(OPh)2) (22). The
general procedure was followed using (bu2bipy)Pd(2-C6H4OMe)I
(0.316 g, 0.519 mmol), Ag[P(O)(OPh)2] (0.177 g, 0.519 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.346 g, 93%).
Anal. Calcd for C37H41N2O4PPd: C, 62.14; H, 5.78. Found: C,
62.11; H, 5.73. 1H NMR (CDCl3, 25 °C): δ 10.02 (d, 1H, J ) 5.4,
Ar-H), 7.95 (s, 1H, Ar-H), 7.94 (s, 1H, Ar-H), 7.51-7.43 (m, 3H,
Ar-H), 7.26-7.03 (m, 10H, Ar-H), 6.94-6.87 (m, 2H, Ar-H), 6.77
(t, 1H, J ) 7.2, Ar-H), 6.59 (d, 1H, J ) 8.1, Ar-H), 3.50 (s, 3H,
-OMe), 4.41 (s, 9H, -CMe3), 1.34 (s, 9H, -CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.6 (s, quat), 163.0 (s, quat), 161.8 (s, quat),
155.3 (d, J ) 2.3, quat), 154.4 (d, J ) 2.3, quat), 153.5 (s,
Ar-CH), 152.9 (d, J ) 8.6, quat), 152.7 (d, J ) 9.2, quat), 149.8
(d, J ) 2.0, Ar-CH), 141.1 (s, quat), 137.3 (d, J ) 5.1, Ar-CH),
128.7 (s, Ar-CH), 128.5 (s, Ar-CH), 124.4 (s, Ar-CH), 123.5 (s,
Ar-CH), 123.1 (d, J ) 3.3, Ar-CH), 122.3 (s, Ar-CH), 121.9 (s,
Ar-CH), 121.3 (d, J ) 5.1, Ar-CH), 120.9 (d, J ) 5.5, Ar-CH),
120.1 (d, J ) 3.8, Ar-CH), 117.8 (d, J ) 3.1, Ar-CH), 117.7 (s,
Ar-CH), 109.7 (s, Ar-CH), 55.1 (s, -OMe), 35.31 (s, -CMe3),
35.26 (s, -CMe3), 30.3 (s, -CMe3), 30.2 (s, -CMe3). 31P{1H}
NMR (CDCl3, 25 °C): δ 67.0 (s).
Synthesis of (bu2bipy)Pd(2,6-C6H3Me2)(P(O)(OEt)2) (23). The
general procedure was followed using (bu2bipy)Pd(2,6-C6H3Me2)I
(0.531 g, 0.875 mmol), Ag[P(O)(OEt)2] (0.214, 0.875 mmol), and
CH2Cl2 (5 mL). After purification by column chromatography, the
title compound was isolated as a pale yellow solid (0.501 g, 93%).
Anal. Calcd for C30H43N2O3PPd: C, 58.39; H, 7.02. Found: C,
58.65; H, 6.63. 1H NMR (CDCl3, 25 °C): δ 9.86 (d, 1H, J ) 5.8,
Ar-H), 7.97 (s, 2H, Ar-H), 7.56 (dd, 1H, J ) 5.7, 1.9, Ar-H), 7.31-
7.21 (m, 2H, Ar-H), 6.92-6.82 (m, 3H, Ar-H), 3.78 (m, 4H,
-OCH2CH3), 2.64 (s, 6H, Ar Me), 1.43 (s, 9H, -CMe3), 1.37 (s,
9H, -CMe3), 1.10 (t, 6H, J ) 7.0, -OCH2CH3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.4 (s, quat), 162.9 (s, quat), 157.5 (d, J )
3.7, quat), 155.4 (d, J ) 1.7, quat), 154.3 (d, J ) 1.7, quat), 153.4
(s, Ar-CH), 148.9 (d, J ) 2.0, Ar-CH), 142.3 (s, quat), 142.2 (s,
quat), 124.9 (d, J ) 1.1, Ar-CH), 123.7 (s, Ar-CH), 123.5 (s,
Ar-CH), 123.3 (d, J ) 3.0, Ar-CH), 117.8 (d, J ) 2.9, Ar-CH),
117.7 (s, Ar-CH), 57.6 (d, J ) 6.8, -OCH2CH3), 35.4 (s, -CMe3),
35.3 (s, -CMe3), 30.33 (s, -CMe3), 30.28 (s, -CMe3), 26.94 (s,
-Me3), 26.87 (s, -Me), 16.6 (d, J ) 6.4, -OCH2CH3). 31P{1H}
NMR (CDCl3, 25 °C): δ 71.3 (s).
Synthesis of (bu2bipy)Pd(2-C6H4Me)(P(O)(OPh)2) (18). The
general procedure was followed using (bu2bipy)Pd(2-C6H4Me)I
(0.456, 0.769 mmol), Ag[P(O)(OPh)2] (0.262 g, 0.769 mmol), and
THF (5 mL). After purification by column chromatography, the
title compound was isolated as a white solid (0.395 g, 73%). Anal.
Calcd for C37H41N2O3PPd: C, 63.56; H, 5.91. Found: C, 63.83;
H, 5.99. 1H NMR (CDCl3, 25 °C): δ 10.04 (d, 1H, J ) 5.7,
Ar-H), 7.98 (s, 2H, Ar-CH), 7.52 (dd, 1H, J ) 5.8, 1.9, Ar-H),
7.43 (m, 1H, Ar-H), 7.32 (m, 1H, Ar-H), 7.26-6.87 (m, 14H,
Ar-H), 2.47 (s, 3H, Ar Me), 1.43 (s, 9H, -CMe3), 1.36 (s, 9H,
-CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.8 (s, quat), 163.1
(s, quat), 155.7 (d, J ) 3.0, quat), 155.4 (d, J ) 1.7, quat), 154.2
(d, J ) 2.1, quat), 153.5 (s, Ar-CH), 152.9 (d, J ) 8.5, quat), 152.7
(d, J ) 11.1, quat), 149.4 (d, J ) 2.0, Ar-CH), 142.00 (d, J ) 2.8,
quat), 136.0 (d, J ) 7.02, Ar-CH), 128.8 (s, Ar-CH), 128.6 (s,
Ar-CH), 128.4 (s, Ar-CH), 123.8 (d, J ) 4.0, Ar-CH), 123.7 (s,
Ar-CH), 123.37 (d, J ) 3.2, Ar-CH), 123.35 (s, Ar-CH), 122.4 (s,
Ar-CH), 122.3 (s, Ar-CH), 121.3 (d, J ) 5.6, Ar-CH), 121.2 (d, J
) 5.1, Ar-CH), 117.9 (d, J ) 3.2, Ar-CH), 117.8 (s, Ar-CH), 35.42
(s, -CMe3), 35.36 (s, -CMe3), 30.34 (s, -CMe3), 30.28 (s,
-CMe3), 26.44 (s, -Me), 26.37 (s, -Me). 31P{1H} NMR (CDCl3,
25 °C): δ 68.6 (s).
Synthesis of (bu2bipy)Pd(4-C6H4OMe)(P(O)(OEt)2) (19). The
general procedure was followed using (bu2bipy)Pd(4-C6H4OMe)I
(0.218 g, 0.358 mmol), Ag[P(O)(OEt)2] (0.0877 g, 0.358 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as a off-white solid (0.201 g, 91%).
Anal. Calcd for C29H41N2O4PPd: C, 56.27; H, 6.68. Found: C,
56.20; H, 6.56. 1H NMR (CDCl3, 25 °C): δ 10.04 (d, 1H, J ) 5.7,
Ar-H), 7.96 (s, 1H, Ar-H), 7.95 (s, 1H, Ar-H), 7.53 (m, 2H,
Ar-H), 7.45 (m, 2H, Ar-H), 7.26 (m, 1H, Ar-H), 6.75 (AA′BB′,
2H, Ar-H), 3.94 (m, 4H, -OCH2CH3), 3.80 (s, 3H, -OMe), 1.42
(s, 9H, -CMe3), 1.37 (s, 9H, -CMe3), 1.15 (t, 6H, -OCH2CH3).
13C{1H} NMR (CDCl3, 25 °C): δ 163.4 (s, quat), 162.9 (s, quat),
156.4 (d, J ) 1.8, quat), 155.1 (d, J ) 1.7, quat), 154.4 (s, quat),
153.8 (s, Ar-CH), 149.9 (d, J ) 1.5, Ar-CH), 143.7 (s, quat), 136.4
(d, J ) 5.5, Ar-CH), 123.5 (s, Ar-CH), 123.1 (d, J ) 3.0, Ar-CH),
117.7 (s, Ar-CH), 117.5 (d, J ) 3.0, Ar-CH), 113.1 (d, J ) 3.6,
Ar-CH), 57.7 (d, J ) 4.5, -OCH2CH3), 55.0 (s, -OMe), 35.4 (s,
-CMe3), 35.3 (s, -CMe3), 30.33 (s, -CMe3), 30.30 (s, -CMe3),
16.6 (d, J ) 7.3, -OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ
69.4 (s).
Synthesis of (bu2bipy)Pd(4-C6H4OMe)(P(O)(OPh)2) (20). The
general procedure was followed using (bu2bipy)Pd(4-C6H4OMe)I
(0.304 g, 0.499 mmol), Ag[P(O)(OPh)2] (0.170 g, 0.499 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.301 g, 84%).
Anal. Calcd for C37H41N2O4PPd: C, 62.14; H, 5.78. Found: C,
62.11; H, 5.73. 1H NMR (CDCl3, 25 °C): δ 10.08 (d, 1H, J ) 5.7,
Ar-H), 7.96 (s, 2H, Ar-H), 7.54 (dd, 1H, J ) 5.9, 1.9, Ar-H), 7.41
(dd, 1H, J ) 5.8, 3.4, Ar-H), 7.26-7.14 (m, 11H, Ar-H), 6.95 (t,
2H, J ) 7.15, Ar-H), 6.69 (AA′BB′, 2H, Ar-H), 3.79 (s, 3H,
-OMe), 1.42 (s, 9H, -CMe3), 1.36 (s, 9H, -CMe3). 13C{1H} NMR
(CDCl3, 25 °C): δ 163.8 (s, quat), 163.2 (s, quat), 156.6 (s, quat),
155.2 (d, J ) 1.7, quat), 154.3 (d, J ) 1.8, quat), 153.6 (s,
Ar-CH), 152.9 (d, J ) 8.4, quat), 149.9 (d, J ) 1.8, Ar-CH), 142.7
(s, quat), 136.1 (d, J ) 5.8, Ar-CH), 128.8 (s, Ar-CH), 123.7 (s,
Ar-CH), 123.2 (d, J ) 3.2, Ar-CH), 122.3 (s, Ar-CH), 121.2 (d, J
) 5.6, Ar-CH), 117.8 (s, Ar-CH), 117.7 (d, J ) 3.2, Ar-CH), 113.1
(d, J ) 3.8, Ar-CH), 55.1 (s, -OMe), 35.4 (s, -CMe3), 35.3 (s,
-CMe3), 30.33 (s, -CMe3), 30.27 (s, -CMe3). 31P{1H} NMR
(CDCl3, 25 °C): δ 67.8 (s).
Synthesis of (bu2bipy)Pd(2,6-C6H3Me2)(P(O)(OPh)2) (24). The
general procedure was followed using (bu2bipy)Pd(2,6-C6H3Me2)I
(0.412 g, 0.679 mmol), Ag[P(O)(OPh)2] (0.232 g, 0.679 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.377 g, 78%).
Synthesis of (bu2bipy)Pd(2-C6H4OMe)(P(O)(OEt)2) (21). The
general procedure was followed using (bu2bipy)Pd(2-C6H4OMe)I

Arylphosphonate Elimination from Pd Complexes
Organometallics, Vol. 25, No. 24, 2006 5755
Anal. Calcd for C38H43N2O3PPd: C, 64.00; H, 6.08. Found: C,
64.14; H, 6.13. 1H NMR (CDCl3, 25 °C): δ 9.92 (d, 1H, J ) 5.7,
Ar-H), 8.00 (s, 2H, Ar-H), 7.51 (dd, 1H, J ) 5.8, 1.8, Ar-H), 7.33
(dd, 1H, J ) 5.7, 3.5, Ar-H), 7.23 (m, 1H, Ar-H), 7.09 (m, 4H,
Ar-H), 7.00 (m, 4H, Ar-H), 6.91 (m, 3H, Ar-H), 6.81 (d, 2H, J )
7.2, Ar-H), 2.58 (s, 6H, Ar Me), 1.43 (s, 9H, -CMe3), 1.38 (s,
9H, -CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.8 (s, quat),
163.1 (s, quat), 157.0 (d, J ) 5.4, quat), 155.5 (d, J ) 1.7, quat),
154.2 (d, J ) 1.9, quat), 153.4 (s, Ar-CH), 152.8 (d, J ) 11.7,
quat), 149.1 (d, J ) 2.3, Ar-CH), 141.9 (s, quat), 141.8 (s, quat),
128.7 (s, Ar-CH), 125.4 (d, J ) 1.2, Ar-CH), 123.8 (d, J ) 3.7,
Ar-CH), 123.5 (d, J ) 3.2, Ar-CH), 122.3 (s, Ar-CH), 121.4 (d, J
) 4.7, Ar-CH), 118.0 (d, J ) 3.2, Ar-CH), 117.9 (s, Ar-CH), 35.4
(s, -CMe3), 35.3 (s, -CMe3), 30.33 (s, -CMe3), 30.27 (s, -CMe3),
26.7 (s, -Me), 26.6 (s, -Me). 31P{1H} NMR (CDCl3, 25 °C): δ
69.4 (s).
(s, quat), 136.9 (d, J ) 5.0, Ar-CH), 123.8 (s, Ar-CH), 123.4 (d, J
) 3.2, Ar-CH), 120.6 (d, J ) 3.5, Ar-CH), 118.00 (s, Ar-CH),
117.98 (d, J ) 2.0, Ar-CH), 58.1 (d, J ) 5.2, -OCH2CH3), 35.5
(s, -CMe3), 35.4 (s, -CMe3), 30.35 (s, -CMe3), 30.30 (s, -CMe3),
16.6 (d, J ) 5.2, -OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ
64.4 (s).
Synthesis of (bu2bipy)Pd(4-C6H4NO2)(P(O)(OPh)2) (28). The
general procedure was followed using (bu2bipy)Pd(4-C6H4NO2)I
(0.447 g, 0.717 mmol), Ag[P(O)(OPh)2] (0.244 g, 0.717 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.485 g, 93%).
Anal. Calcd for C36H38N3O5PPd: C, 59.22; H, 5.25. Found: C,
1
58.82; H, 5.18. H NMR (CDCl3, 25 °C): δ 10.10 (d, 1H, Ar-H),
8.01 (s, 2H, Ar-CH), 7.85 (AA′BB′, 2H, Ar-H), 7.59 (m, 3H,
Ar-H), 7.28-7.15 (m, 10H, Ar-H), 6.98 (m, 2H, Ar-CH), 1.44 (s,
9H, -CMe3), 1.37 (s, 9H, -CMe3). 13C{1H} NMR (CDCl3, 25
°C): δ 169.8 (s, quat), 164.5 (s, quat), 163.8 (s, quat), 155.3 (d, J
) 2.1, quat), 154.3 (d, J ) 1.8, quat), 153.6 (s, Ar-CH), 152.4 (d,
J ) 8.6, quat), 149.4 (d, J ) 1.7, Ar-CH), 145.1 (s, quat), 136.7
(d, J ) 5.4, Ar-CH), 129.0 (s, Ar-CH), 124.0 (s, Ar-CH), 123.5 (d,
J ) 3.4, Ar-CH), 122.8 (s, Ar-CH), 120.9 (d, J ) 5.5, Ar-CH),
120.5 (d, J ) 3.4, Ar-CH), 118.1 (s, Ar-CH), 35.5 (s, -CMe3),
35.4 (s, -CMe3), 30.3 (s, -CMe3), 30.2 (s, -CMe3). 31P{1H} NMR
(CDCl3, 25 °C): δ 63.0 (s).
Synthesis of (bu2bipy)Pd(4-C6H4Cl)(P(O)(OEt)2) (29). The
general procedure was followed using (bu2bipy)Pd(4-C6H4Cl)I
(0.251 g, 0.409 mmol), Ag[P(O)(OEt)2] (0.100 g, 0.409 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as an off-white solid (0.219 g, 86%).
Anal. Calcd for C28H38ClN2O3PPd: C, 53.94; H, 6.14. Found: C,
54.18; H, 6.08. 1H NMR (CDCl3, 25 °C): δ 9.94 (d, 1H, J ) 5.3,
Ar-H), 7.98 (s, 2H, Ar-H), 7.57-7.44 (m, 4H, Ar-H), 7.28 (m, 1H,
Ar-H), 7.08 (AA′BB′, 2H, Ar-H), 3.93 (m, 4H, -OCH2CH3), 1.42
(s, 9H, -CMe3), 1.38 (s, 9H, -CMe3), 1.13 (d, 6H, J ) 7.0,
-OCH2CH3). 13C{1H} NMR (CDCl3, 25 °C): δ 163.8 (s, quat),
163.3 (s, quat), 155.2 (d, J ) 1.7, quat), 154.4 (d, J ) 1.7, quat),
153.6 (s, Ar-CH), 153.0 (s, quat), 149.6 (d, J ) 1.7, Ar-CH), 137.3
(d, J ) 5.4, Ar-CH), 129.2 (s, quat), 126.9 (d, J ) 3.3, Ar-CH),
123.7 (s, Ar-CH), 123.2 (d, J ) 3.1, Ar-CH), 117.9 (s, Ar-CH),
117.8 (d, J ) 2.9, Ar-CH), 58.0 (d, J ) 7.3, -OCH2CH3), 35.4 (s,
-CMe3), 35.3 (s, -CMe3), 30.31 (s, -CMe3), 30.28 (s, -CMe3),
16.52 (d, J ) 7.3, -OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ
68.9 (s).
Synthesis of (bu2bipy)Pd(4-C6H4CN)(P(O)(OEt)2) (25). The
general procedure was followed using (bu2bipy)Pd(4-C6H4CN)I
(0.418, 0.692 mmol), Ag[P(O)(OEt)2] (0.170, 0.692 mmol), and
CH2Cl2 (5 mL). After purification by column chromatography, the
title compound was isolated as a white solid (0.402 g, 95%). Anal.
Calcd for C29H38N3O3PPd: C, 56.73; H, 6.24. Found: C, 56.72;
H, 5.96. 1H NMR (CDCl3, 25 °C): δ 10.03 (d, 1H, J ) 5.4,
Ar-H), 7.98 (s, 1H, Ar-H), 7.97 (s, 1H, Ar-H), 7.76 (m, 2H,
Ar-H), 7.57 (dd, 1H, J ) 5.9, 1.9, Ar-H), 7.38-7.29 (m, 4H,
Ar-H), 3.94 (m, 4H, -OCH2CH3), 1.43 (s, 9H, -CMe3), 1.39 (s,
9H, -CMe3), 1.14 (t, 6H, J ) 7.0, -OCH2CH3). 13C{1H} NMR
(CDCl3, 25 °C): δ 167.1 (s, quat), 164.1 (s, quat), 163.4 (s, quat),
155.1 (d, J ) 2.0, quat), 154.4 (d, J ) 1.6, quat), 153.8 (s, Ar-
CH), 149.4 (d, J ) 1.7, Ar-CH), 137.4 (d, J ) 4.9, Ar-CH), 129.3
(d, J ) 3.2, Ar-CH), 123.7 (s, Ar-CH), 123.3 (d, J ) 3.3, Ar-CH),
120.6 (s, quat), 117.9 (s, Ar-CH), 117.9 (d, J ) 3.6, Ar-CH), 106.2
(s, quat), 58.0 (d, J ) 5.3, -OCH2CH3), 35.5 (s, -CMe3), 35.4 (s,
-CMe3), 30.31 (s, -CMe3), 30.28 (s, -CMe3), 16.5 (d, J ) 7.2,
-OCH2CH3). 31P{1H} NMR (CDCl3, 25 °C): δ 65.5 (s).
Synthesis of (bu2bipy)Pd(4-C6H4CN)(P(O)(OPh)2) (26). The
general procedure was followed using (bu2bipy)Pd(4-C6H4CN)I
(0.274 g, 0.454 mmol), Ag[P(O)(OPh)2] (0.155 g, 0.454 mmol),
and THF (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.303 g, 94%).
Anal. Calcd for C37H38N3O3PPd: C, 62.58; H, 5.39. Found: C,
62.71; H, 5.42. 1H NMR (CDCl3, 25 °C): δ 10.09 (d, 1H, J ) 5.7,
Ar-H), 8.00 (s, 2H, Ar-H), 7.55 (m, 3H, Ar-H), 7.30-7.14 (m, 12H,
Ar-H), 6.97 (m, 2H, Ar-H), 1.44 (s, 9H, -CMe3), 1.38 (s, 9H,
-CMe3). 13C{1H} NMR (CDCl3, 25 °C): δ 165.3 (s, quat), 164.4
(s, quat), 163.7 (s, quat), 155.3 (d, J ) 1.8, quat), 154.3 (d, J )
1.8, quat), 153.7 (s, Ar-CH), 152.5 (d, J ) 8.6, quat), 149.5 (d, J
) 1.7, Ar-CH), 137.1 (d, J ) 5.2, Ar-CH), 129.3 (d, J ) 3.3,
Ar-CH), 129.0 (s, Ar-CH), 123.9 (s, Ar-CH), 123.5 (d, J ) 3.2,
Ar-CH), 22.7 (s, Ar-CH), 120.9 (d, J ) 5.5, Ar-CH), 120.4 (s, quat),
118.1 (s, Ar-CH), 118.1 (d, J ) 2.0, Ar-CH), 106.6 (s, quat), 35.5
(s, -CMe3), 35.4 (s, -CMe3), 30.31 (s, -CMe3), 30.25 (s, -CMe3).
31P{1H} NMR (CDCl3, 25 °C): δ 63.6 (s).
Synthesis of (bu2bipy)Pd(4-C6H4Cl)(P(O)(OPh)2) (30). The
general procedure was followed using (bu2bipy)Pd(4-C6H4Cl)I
(0.152 g, 0.248 mmol), Ag[P(O)(OPh)2] (0.085, 0.248 mmol), and
THF (5 mL). After purification by column chromatography, the
title compound was isolated as a white solid (0.130 g, 73%). Anal.
Calcd for C36H38N3O5PPd: C, 60.08; H, 5.32. Found: C, 59.98;
H, 5.25. 1H NMR (CDCl3, 25 °C): δ 10.09 (d, 1H, J ) 5.5,
Ar-H), 7.98 (s, 2H, Ar-H), 7.55 (dd, 1H, J ) 5.7, 1.9, Ar-H), 7.38
(dd, 1H, J ) 5.8, 3.5, Ar-H), 7.31-7.14 (m, 11H, Ar-H), 7.01-
6.93 (m, 4H, Ar-H), 1.43 (s, 9H, -CMe3), 1.36 (s, 9H, -CMe3).
13C{1H} NMR (CDCl3, 25 °C): δ 164.1 (s, quat), 163.4 (s, quat),
155.2 (d, J ) 1.8, quat), 154.3 (d, J ) 1.7, quat), 153.6 (s,
Ar-CH), 152.7 (d, J ) 8.3, quat), 152.0 (s, quat), 149.7 (d, J )
2.0, Ar-CH), 137.1 (d, J ) 5.5, Ar-CH), 129.4 (s, quat), 128.8 (s,
Ar-CH), 126.7 (d, J ) 3.6, Ar-CH), 123.8 (s, Ar-CH), 123.3 (d, J
) 3.2, Ar-CH), 122.5 (s, Ar-CH), 121.0 (d, J ) 5.7, Ar-CH), 117.9
(s, Ar-CH), 117.8 (d, J ) 3.1, Ar-CH), 35.44 (s, -CMe3), 35.36
(s, -CMe3), 30.3 (s, -CMe3), 30.2 (s, -CMe3). 31P{1H} NMR
(CDCl3, 25 °C): δ 65.9 (s).
Synthesis of (bu2bipy)Pd(4-C6H4NO2)(P(O)(OEt)2) (27). The
general procedure was followed using (bu2bipy)Pd(4-C6H4NO2)I
(0.161 g, 0.258 mmol), Ag[P(O)(OEt)2] (0.063 g, 0.258 mmol),
and CH2Cl2 (5 mL). After purification by column chromatography,
the title compound was isolated as a white solid (0.121 g, 74%).
Anal. Calcd for C28H38N3O5PPd: C, 53.04; H, 6.04. Found: C,
53.20; H, 5.96. 1H NMR (CDCl3, 25 °C): δ 10.06 (d, 1H, J ) 6.0,
Ar-H), 7.99 (s, 2H, Ar-H), 7.94-7.92 (m, 2H, Ar-H), 7.86-7.81
(m, 2H, Ar-CH), 7.58 (dd, 1H, J ) 5.2, 1.8, Ar-H), 7.37-7.33 (m,
1H, Ar-H), 7.30-7.26 (m, 1H, Ar-H), 3.95 (m, 4H, -OCH2CH3),
1.43 (s, 9H, -CMe3), 1.38 (s, 9H, -CMe3), 1.15 (t, 6H, J ) 7.0,
-OCH2CH3). 13C{1H} NMR (CDCl3, 25 °C): δ 172.0 (s, quat),
164.2 (s, quat), 163.5 (s, quat), 155.2 (d, J ) 1.8, quat), 154.4 (d,
J ) 1.2, quat), 153.8 (s, Ar-CH), 149.4 (d, J ) 1.8, Ar-CH), 145.0
Thermolysis Reactions. A 5 mm NMR tube was charged with
the arylpalladium phosphonate (7.1 µmol), hexamethylbenzene (7.1
µmol), and C6D5 (0.5 mL). After an initial 1H NMR spectrum was
collected for standardization, the tube was sealed and placed in an
oil bath at the desired temperature (95 or 120 °C). At regular

5756 Organometallics, Vol. 25, No. 24, 2006
Kohler et al.
intervals, the NMR tube was removed and immediately immersed
into ice water. After collection of a H NMR spectrum, the tube
Preparation of (4-C6H4Cl)P(O)(OPh)2. The general procedure
was followed using 30 (0.05 g, 0.069 mmol) to afford the title
compound as a waxy solid (0.019 g, 79%). Anal. Calcd for
1
was placed back into the oil bath for further heating. No elimination
was observed from 1-30 at 25 °C. The arylpalladium phosphonates,
arylphosphonates (where discernible from 11-30 and bu2bipy), and
bu2bipy concentrations were readily obtained by comparison of the
integral values for the individual species relative to the internal
standard. Errors in the rate constants were calculated at 10%. For
almost all thermolysis reactions, the only signals in the 31P{1H}
NMR spectrum after heating were small amounts of remaining
11-30 and the desired arylphosphonate (Supporting Information).
General Procedure for the Isolation of Arylphosphonates. A
10 mL reaction vial was charged with the arylpalladium phospho-
nate and toluene (3.0 mL). After it was heated in an oil bath for 20
h at 150 °C, the reaction mixture was cooled to 25 °C, filtered,
and evaporated to dryness. The free bu2bipy was trapped with 1.0
equiv of Pd(cod)Cl2 in CH2Cl2. After removal of the volatiles, the
residue was extracted with hexane and the extract filtered and dried
to afford the desired arylphosphonate.
Preparation of (2-C6H4Me)P(O)(OPh)2. The general procedure
was followed using 18 (0.05 g, 0.071 mmol) to afford the title
compound as a waxy solid (0.020 g, 87%). Anal. Calcd for
C19H17O3P: C, 70.37; H, 5.28. Found: C, 70.32; H, 5.41. 1H NMR
(CDCl3, 25 °C): δ 8.01 (m, 1H, Ar-H), 7.43 (t, 1H, J ) 7.6,
Ar-H), 7.28-7.04 (m, 12H, Ar-H), 2.70 (s, 3H, Ar Me). 13C{1H}
NMR (CDCl3, 25 °C): δ 150.4 (d, J ) 7.9, quat), 142.1 (d, J )
10.9, quat), 134.5 (d, J ) 11.0, Ar-CH), 133.3 (d, J ) 3.0,
Ar-CH), 131.5 (d, J ) 15.8, Ar-CH), 129.7 (s, Ar-CH), 125.7 (d,
J ) 188.6, quat), 125.7 (d, J ) 15.9, Ar-CH), 125.0 (d, J ) 1.1,
Ar-CH), 120.4 (d, J ) 4.8, Ar-CH), 21.5 (d, J ) 3.6, Ar Me).
31P{1H} NMR (CDCl3, 25 °C): δ 11.7 (s).
1
C18H14O3PCl: C, 62.71; H, 4.09. Found: C, 62.38; H, 4.25. H
NMR (CDCl3, 25 °C): δ 7.93-7.85 (m, 2H, Ar-H), 7.51-7.46
(m, 2H, Ar-H), 7.32-7.25 (m, 4H, Ar-H), 7.20-7.12 (m, 6H, Ar-
H). 13C{1H} NMR (CDCl3, 25 °C): δ 150.2 (d, J ) 7.5, quat),
139.9 (d, J ) 4.2, quat), 133.7 (d, J ) 11.1, Ar-CH), 129.8 (s,
Ar-CH), 129.1 (d, J ) 16.5, Ar-CH), 125.3 (d, J ) 1.1, Ar-CH),
125.3 (d, J ) 195.9, quat), 120.5 (d, J ) 4.8, Ar-CH). 31P{1H}
NMR (CDCl3, 25 °C): δ 9.7 (s).
Preparation of (4-C6H4NH2)P(O)(OPh)2. The general procedure
was followed using 14 (0.05 g, 0.071 mmol) to afford the title
compound as a waxy solid (0.010 g, 43%). Anal. Calcd for
1
C18H16NO3P: C, 66.46; H, 4.96. Found: C, 66.10; H, 4.68. H
NMR (CDCl3, 25 °C): δ 7.65-7.60 (m, 2H, Ar-H), 7.36-6.99
(m, 10H, Ar-H), 6.64-6.60 (m, Ar-H), 4.00 (s, 2H, -NH2).
13C{1H} NMR (CDCl3, 25 °C): δ 151.2 (d, J ) 5.5, quat), 150.6
(d, J ) 7.3, quat), 134.3 (d, J ) 12.1, Ar-CH), 129.6 (s, Ar-CH),
124.8 (d, J ) 1.1, Ar-CH), 120.7 (d, J ) 4.6, Ar-CH), 114.2 (d, J
) 16.9, Ar-CH), 113.8 (d, J ) 203.2, quat). 31P{1H} NMR (CDCl3,
25 °C): δ 13.1 (s).
Preparation of (2,6-C6H3Me2)P(O)(OPh)2. The general pro-
cedure was followed using 24 (0.10 g, 0.14 mmol) to afford the
title compound as a waxy solid (0.030 g, 64%). Anal. Calcd for
C20H19O3P: C, 71.00; H, 5.66. Found: C, 70.85; H, 5.69. 1H NMR
(CDCl3, 25 °C): δ 7.31 (m, 13H, Ar-H), 2.77 (d, 6H, J ) 1.7, Ar
Me). 13C{1H} NMR (CDCl3, 25 °C): δ 150.4 (d, J ) 7.7, quat),
144.2 (d, J ) 12.2, quat), 132.5 (d, J ) 3.2, Ar-CH), 129.9
(d, J ) 16.4, Ar-CH), 129.7 (d, J ) 0.8, Ar-CH), 124.9 (d, J )
0.9, Ar-CH), 124.2 (d, J ) 182.9, quat), 120.4 (d, J ) 4.8,
Ar-CH), 23.5 (d, J ) 2.9, Ar Me). 31P{1H} NMR (CDCl3, 25 °C):
δ 11.4 (s).
Molecular Structures of 1 and 29. Crystals of 1 and 29 were
grown by slow diffusion of pentane into saturated CDCl3 solutions.
Suitable crystals were selected and mounted on glass fibers.
Preliminary examination and data collection were performed using
a Bruker SMART 1K charge coupled device (CCD) detector system
single-crystal X-ray diffractometer using graphite-monochromated
Mo KR radiation. SMART and SAINT software packages were
used for data collection and data integration.16 Structure solution
and refinement were carried out using the SHELXTL-PLUS
software package.17
In the molecular structure of 29, there is a positional disorder in
one of the tert-butyl groups that was refined using partial occupancy.
In the structure of 1, there is a minor cocrystallized component
(∼2%) that is refined well as bu2bipyPdI2, which could be formed
by small amounts of aryl-aryl exchange between two molecules
of 1.
Preparation of (2-C6H4OMe)P(O)(OPh)2. The general proce-
dure was followed using 22 (0.05 g, 0.070 mmol) to afford the
title compound as a waxy solid (0.018 g, 75%). Anal. Calcd for
C19H17O4P: C, 67.06; H, 5.04. Found: C, 67.43; H, 5.37. 1H NMR
(CDCl3, 25 °C): δ 7.96 (m, 1H, Ar-H), 7.55 (t, 1H, J ) 9.0,
Ar-H), 7.32-6.93 (m, 12H, Ar-H), 3.88 (s, 3H, -OMe). 13C{1H}
NMR (CDCl3, 25 °C): δ 161.4 (d, J ) 2.5, quat), 150.7 (d, J )
7.5, quat), 135.8 (d, J ) 7.9, Ar-CH), 135.3 (d, J ) 2.3, Ar-CH),
129.5 (s, Ar-CH), 124.8 (d, J ) 1.1, Ar-CH), 120.7 (d, J ) 4.8,
Ar-CH), 114.9 (d, J ) 192.1, quat), 111.2 (d, J ) 9.9, Ar-CH),
55.8 (s, -OMe). 31P{1H} NMR (CDCl3, 25 °C): δ 9.7 (s).
Preparation of (4-C6H4NO2)P(O)(OPh)2. The general procedure
was followed using 28 (0.05 g, 0.068 mmol) to afford the title
compound as a waxy solid (0.014 g, 58%). Anal. Calcd for
1
C18H14NO5P: C, 60.85; H, 3.97. Found: C, 61.00; H, 4.54. H
NMR (CDCl3, 25 °C): δ 8.37-8.32 (m, 2H, Ar-CH), 8.20-8.13
(m, 2H, Ar-CH), 7.35-7.27 (m, 4H, Ar-CH), 7.21-7.16 (m, 6H,
Ar-CH). 13C{1H} NMR (CDCl3, 25 °C): δ 149.9 (d, J ) 7.9,
quat), 133.9 (d, J ) 191.8, quat), 133.6 (d, J ) 11.2, Ar-CH), 130.0
(s, Ar-CH), 125.6 (d, J ) 1.1, Ar-CH), 123.5 (d, J ) 16.0,
Ar-CH), 120.5 (d, J ) 4.7, Ar-CH). 31P{1H} NMR (CDCl3, 25
°C): δ 6.8 (s).
Acknowledgment. We thank the donors of the Petroleum
Research Fund, administered by the American Chemical Society,
for financial support of this work (Grant No. 43494-B10).
Preparation of (4-C6H4CN)P(O)(OPh)2. The general procedure
was followed using 26 (0.05 g, 0.070 mmol) to afford the title
compound as a waxy solid (0.012 g, 51%). Anal. Calcd for
Supporting Information Available: Figures giving selected
31P{1H} NMR spectra from the thermolysis reactions and CIF files
giving crystallographic data for 1 and 29. This material is available
free of charge via the Internet at http://pubs.acs.org.
1
C19H14NO3P: C, 68.06; H, 4.21. Found: C, 67.73; H, 4.10. H
NMR (CDCl3, 25 °C): δ 8.11-8.04 (m, 2H, Ar-H), 7.81-7.72
(m, 2H, Ar-H), 7.43-7.29 (m, 4H, Ar-H), 7.15 (m, 6H, Ar-H).
13C{1H} NMR (CDCl3, 25 °C): δ 149.9 (d, J ) 7.9, quat), 132.8
(d, J ) 10.3, Ar-CH), 132.2 (d, J ) 15.8, Ar-CH), 132.1 (d, J )
192.1, quat), 129.9 (s, Ar-H), 125.5 (d, J ) 1.1, Ar-CH), 120.5 (d,
J ) 4.8, Ar-CH), 117.6 (d, J ) 1.0, quat), 116.9 (d, J ) 3.6, quat).
31P{1H} NMR (CDCl3, 25 °C): δ 7.20 (s).
OM060662I
(17) Sheldrick, G. M. SHELXTL-PLUS; Bruker Analytical X-ray
Division, Madison, WI, 2002.