Structural insight into (2-Oxy-π-allyl)palladium and -platinum complexes as precursors of oxodimethylenemethane complexes

Article abstract of DOI:10.1021/om961108j

X-ray crystallographic structures of η³-allylpalladium and -platinum complexes bearing an acetal group at the 2-position {[M(η³-CH₂C(OCH₂OCH₃)CH ₂)(PPh₃)₂](PF₆) (M = Pd (1a), Pt (1b)) and [M(η³-CH₂C(O-2-C₅H₉O)CH ₂)(PPh₃)₂](PF₆) (M = pd (2a), Pt (2b))}) reveal that they have a large contribution of oxonium structure, regardless of the kind of metal. Depending on the structure of the acetal moiety, these η³-allyl complexes show different reactivities toward hydroxide and methoxide ion as nucleophiles. The generation mechanism of oxodimethylenemethane complexes {[M(η³-CH₂C(O)CH₂)(PPh₃) ₂](PF₆) (M = Pd (3a), Pt (3b))} from these acetal compounds was discussed on the basis of the X-ray crystallographic structures, the analysis of reaction products, and the ¹⁸O isotope-labeling technique. Nucleophilic displacement at the 2-position of η³-allylpalladium complexes was directly proved for the first time by the isotope technique.

Full text of DOI:10.1021/om961108j

3038
Organometallics 1997, 16, 3038-3043
Str u ctu r a l In sigh t in to (2-Oxy-π-a llyl)p a lla d iu m a n d
-p la tin u m Com p lexes a s P r ecu r sor s of
Oxod im eth ylen em eth a n e Com p lexes
Akihiro Ohsuka, Tjandra W. Wardhana, Hideo Kurosawa, and Isao Ikeda*
Department of Applied Chemistry, Faculty of Engineering, Osaka University,
Suita, Osaka 565, J apan
Received December 31, 1996X
X-ray crystallographic structures of η3-allylpalladium and -platinum complexes bearing
an acetal group at the 2-position {[M(η3-CH2C(OCH2OCH3)CH2)(PPh3)2](PF6) (M ) Pd (1a ),
Pt (1b)) and [M(η3-CH2C(O-2-C5H9O)CH2)(PPh3)2](PF6) (M ) Pd (2a ), Pt (2b))} reveal that
they have a large contribution of oxonium structure, regardless of the kind of metal.
Depending on the structure of the acetal moiety, these η3-allyl complexes show different
reactivities toward hydroxide and methoxide ion as nucleophiles. The generation mechanism
of oxodimethylenemethane complexes {[M(η3-CH2C(O)CH2)(PPh3)2](PF6) (M ) Pd (3a ), Pt
(3b))} from these acetal compounds was discussed on the basis of the X-ray crystallographic
structures, the analysis of reaction products, and the 18O isotope-labeling technique.
Nucleophilic displacement at the 2-position of η3-allylpalladium complexes was directly proved
for the first time by the isotope technique.
In tr od u ction
Unsubstituted (oxodimethylenemethane)palladium
(ODMM-palladium) and -platinum complexes (3a ,b)
were generated from the corresponding η3-allylmetal
complexes bearing an acetal group at the 2-position
(1a ,b, 2a ,b) through reaction with a base under mild
conditions,1,2 although it was known that acetal com-
pounds are generally stable in basic conditions.3
Meanwhile, alkyl 2-[(1-(butyloxy)ethyl)oxy]allylcar-
bonate (4) afforded the corresponding ODMM complexes
3a ,b only upon mixing with palladium(0) or platinum-
(0) via the η3-allyl complexes as intermediates.4
Since there are many possible reactive sites in
η3-allylpalladium and -platinum complexes bearing a
((methyloxy)methyl)oxy group at the 2-position (1a ,b),
namely the terminal methyl and the central methylene
carbons of the acetal group and the 1- and 2-position
carbons of the allyl moiety, it is very interesting to
clarify the electronic structures of these η3-allyl com-
plexes and the mechanism of their reaction with nu-
cleophiles and to learn the correlation between them.
F igu r e 1. ORTEP plot of 1b at the 50% probability level
(counterion PF6 and all hydrogen atoms are omitted).
-
Resu lts a n d Discu ssion
Str u ctu r e of η3-Allyl Com p lexes 1a ,b. Complexes
1a ,b1 readily crystallized in prisms from CH2Cl2/hexane.
Their structures were determined by X-ray diffraction.
The X-ray crystallographic structure of 1b is shown in
Figure 1 (the structures of both complexes are similar,
and therefore only one is shown here).
Selected bond lengths and angles of 1a ,b are given
in Table 1, the structural parameters in Table 2, and
the data for X-ray diffraction analysis of 1a ,b in Table
3.
In this paper, X-ray crystallographic structures of
these unique η3-allylpalladium and -platinum complexes
bearing a ((methyloxy)methyl)oxy group at the 2-posi-
tion (1a ,b) were determined, and the generation mech-
anism of ODMM complexes 3a ,b from these acetal
compounds was discussed on the basis of the X-ray
crystallographic structures, the analysis of reaction
products, and the results obtained by using the 18O
isotope-labeling technique.
The dihedral angles θ′ between the P(1)-M-P(2) and
C(1)-C(2)-C(3) planes of 1a ,b were almost equal to or
a little smaller than those of typically reported η3-allyl
X Abstract published in Advance ACS Abstracts, J une 1, 1997.
(1) Ohsuka, A.; Fujimori, T.; Hirao, T.; Kurosawa, H.; Ikeda, I. J .
Chem. Soc., Chem. Commun. 1993, 1039.
(2) Ohsuka, A.; Hirao, T.; Kurosawa, H.; Ikeda, I. Organometallics
1995, 14, 2538.
(3) Gu, X.-P.; Nishida, N.; Ikeda, I.; Okahara, M. J . Org. Chem. 1987,
52, 3192.
(4) Ikeda, I.; Ohsuka, A.; Tani, K.; Hirao, T.; Kurosawa, H. J . Org.
Chem. 1996, 61, 4971-4974.
(5) η3-Allylpalladium and -platinum complexes (θ′ ) 61-72°): (a)
Mason, R.; Wheeler, A. G. J . Chem. Soc. A 1968, 2549. (b) Hartley, F.
R. In Comprehensive Organometallic Chemistry; Wilkinson, G., Stone,
F. G. A., Abel, E. W., Eds.; Pergamon: Oxford, 1982; Vol. 6, p 721.
S0276-7333(96)01108-9 CCC: $14.00 © 1997 American Chemical Society

Formation of Pd and Pt Oxodimethylenemethane Complexes
Organometallics, Vol. 16, No. 13, 1997 3039
Ta ble 1. Selected Bon d Len gth s (Å) a n d Bon d
An gles (d eg) for 1a ,b
somewhat shorter than ordinary single bonds. From
these data, it can be concluded that the η3-allyl com-
plexes 1a ,b are in resonance between the formal acetal
(A) and the oxonium ion (B) structures, as shown in eq
1.
bond
1a
1b
angle
1a
1b
P(1)-M
P(2)-M
C(1)-M
C(2)-M
C(3)-M
2.328(3) 2.292(4) P(2)-M-P(1)
2.331(4) 2.297(4) C(1)-M-P(1)
2.13(1) 2.17(2) C(1)-M-P(2)
2.24(1) 2.22(2) C(2)-M-P(1)
2.15(1) 2.15(2) C(2)-M-P(2)
102.3(1) 101.2(1)
163.5(4) 163.9(5)
93.3(5) 93.8(5)
130.9(5) 130.9(5)
124.7(4) 125.6(4)
36.4(6) 37.3(7)
98.1(4) 98.2(4)
159.4(4) 160.3(5)
66.1(6) 66.5(7)
37.0(5) 37.3(5)
C(2)-C(3) 1.39(2) 1.40(2) C(2)-M-C(1)
C(1)-C(2) 1.37(2) 1.41(3) C(3)-M-P(1)
O(1)-C(2) 1.33(2) 1.33(2) C(3)-M-P(2)
O(1)-C(4) 1.38(2) 1.39(3) C(3)-M-C(1)
O(2)-C(4) 1.37(3) 1.36(4) C(3)-M-C(2)
O(2)-C(5) 1.39(4) 1.46(7) C(3)-C(2)-C(1) 115(1)
C(11)-P(1) 1.83(1) 1.83(1) O(1)-C(2)-C(1) 117(1)
C(21)-P(1) 1.83(1) 1.84(1) O(1)-C(2)-C(3) 125(1)
C(31)-P(1) 1.83(1) 1.83(2) C(2)-O(1)-C(4) 120(1)
C(41)-P(2) 1.84(1) 1.83(1) O(1)-C(4)-O(2) 111(1)
C(51)-P(2) 1.83(1) 1.86(1) C(4)-O(2)-C(5) 110(2)
C(61)-P(2) 1.83(1) 1.85(1)
115(1)
118(1)
126(1)
120(1)
110(2)
112(2)
The fact that the C(2)-M bonds (2.24 Å (1a ), 2.22 Å
(1b)) are longer than C(1)-M and C(3)-M, as shown
in Table 1, may also support the contribution of oxonium
ion structure. Usually, the length of C(2)-M is almost
the same to the other two C-M lengths for an η3-allyl
complex, especially in the case of unsubstituted η3-allyl
complexes.7 In the case of 2-methyl-η3-allylpalladium
and -platinum complexes, however, C(2)-M was re-
ported to be slightly longer than the others.8
Ta ble 2. Str u ctu r a l P a r a m eter s of 1a ,b
structural parametera
1a (M ) Pd)
1b (M ) Pt)
M-P
2.330(4)
2.14(1)
2.24(1)
1.38(2)
1.33(2)
102.3(1)
115(1)
62.3
2.295(4)
2.16(3)
2.22(2)
1.41(3)
1.33(2)
101.2(1)
115(1)
66.5
M-C(1)
M-C(2)
C(1)-C(2)
C(2)-O
P(1)-M-P(2)
C(1)-C(2)-C(3)
θ
Rea ctivities of η3-Allyl Com p lexes w ith Nu cleo-
p h iles. Depending on the structure of the acetal group,
these η3-allylpalladium and -platinum complexes re-
vealed different reactivities toward hydroxide ion and
methoxide ion. Upon treating the η3-allylpalladium
complex bearing an acetal group with methoxide ion,
only 2a , which has â-hydrogen atoms on the acetal
centra carbon, gave ODMM-palladium complex (3a ) in
good yields (eq 2), while 1a , which has no â-hydrogen
atom, did not yield the same product. In the case of
the platinum complex, however, 3b was obtained by
reaction with methoxide ion, even from 1b which has
no â-hydrogen atom, though in a poor yield. On the
contrary, upon using hydroxide ion, the complexes 3a ,b
were afforded not only from 2a ,b but also from 1a ,b
which have no â-hydrogen atom on the acetal group (eq
2).
θ′
57.5
61.1
a
θ is the fold angle between the C(1)-M-C(3) and C(1)-C(2)-
C(3) planes. θ′ is the dihedral angle between the P(1)-M-P(2)
and C(1)-C(2)-C(3) planes.
Ta ble 3. Da ta for X-r a y Diffr a ction An a lysis
of 1a ,b
1a
1b
A.Crystal Data
monoclinic
P21/n
cryst syst
space group
lattice parameters
a, Å
b, Å
c, Å
monoclinic
P21/n
16.552(4)
22.378(4)
11.126(2)
90.72(2)
4120(1)
877.07
1.414
4
6.27
0.71069
16.518(4)
22.396(4)
11.117(3)
90.83(2)
4112(1)
965.76
1.560
â, deg
V, Å3
fw
D(calcd), g/cm3
Z value
4
µ, cm-1
35.76
0.71069
λ (Mo KR), Å
B.Data Collection and Analysis Summary
cryst dimens, mm
2θ range for centered 22.11 e 2θ e 26.60° 27.19 e 2θ e 27.49°
reflns
0.70 × 0.25 × 0.25
0.60 × 0.25 × 0.25
total no. of reflns
measd
no. of unique data
10549
9724
10034
9711
Gen er a tion Mech a n ism of ODMM Com p lexes
fr om th e Rea ction of 2a ,b w ith Meth oxid e Ion .
Upon considering the synthetic utilization of complexes
3a ,b, it would be very important to clarify the multiplic-
ity of the mechanisms of these reactions. In a previous
paper,4 we reported that alkyl 2-[(1-(butyloxy)ethyl)oxy]-
allylcarbonate (4) afforded complexes 3a ,b only upon
mixing with M(PPh3)4 (M ) Pd, Pt). Thus, in an NMR
experiment, the appearance of signals due to the
used
max transm factor
min transm factor
0.9993
0.9533
0.071
0.088
1784.00
0.9997
0.8743
0.060
0.078
1912.00
R
Rw
F(000)
complexes (61-72°),5 while the C(2)-O(1) bonds of 1a ,b
(1.33 Å) were shorter than a typical C-O single bond
(1.43 Å) and almost equal to the mean of this length
and the C-O bond length of ODMM complexes (1.22 Å
(7) For palladium complexes, see: (a) De Munno, G.; Bruno, G.;
Rotondo, E.; Giordano, G.; Lo Schiavo, S.; Piraino, P.; Tresoldi, G. Inorg.
Chim. Acta 1993, 208, 67. (b) Canty, A. J .; J in, H.; Roberts, A. S.;
Traill, P. R.; Skelton, B. W.; White, A. H. J . Organomet. Chem. 1995,
489, 153.
2,6
(3a ), 1.257 Å (3b)),
though the result shows that the
C(4)-O(1), C(4)-O(2), and C(5)-O(2) bonds were also
(6) Chen, J .-T.; Huang, T.-M.; Cheng, M.-C.; Lin, Y.-C.; Wang, Y.
Organometallics 1992, 11, 1761.
(8) Ozawa, F.; Son, T.-i.; Ebina, S.; Osakada, K.; Yamamoto, A.
Organometallics 1992, 11, 171.

3040 Organometallics, Vol. 16, No. 13, 1997
Ohsuka et al.
Sch em e 1
Ta ble 4. In ten sity of [M + 1]+ P ea k s of ODMM
complexes 3a ,b9 and butyl vinyl ether10 was confirmed.
On the other hand, alkyl allylcarbonate, having no
â-hydrogen at the central carbon of the acetal moiety
on the 2-position of the allyl group, did not afford end
products 3a ,b, even when mixed with M(PPh3)4 (M )
Pd, Pt), although generation of the corresponding η3-
Com p lexes 3a ,b
intensity
intensity
(3a )
(3b)
63%
76%
[M + 1] from from 18O-labeled [M + 1] from from 18O-labeled
(m/e) KOH K18OH
(calcd)
(m/e) KOH K18OH
(calcd)
682
683
684
685
686
1.15
4.11
6.33
38.07 18.07
80.06 36.86
0.73
1.81
3.13
0.93
2.28
3.30
772
773
774
775
0.84
3.21
10.86
75.35 24.70
39.19
85.53 91.33
32.44 100
21.58 82.34
7.84 30.67
1.87 19.74
0.43
0.21
0.15
0.47
1.32
3.86
0.46
1.27
3.87
1
allyl complex was confirmed in H NMR.
A possible mechanism for this reaction is illustrated
in Scheme 1. During the first step of the reaction, the
transition metal (0) adds to the carbonate 4 oxidatively
to result in the formation of carbon dioxide and a
17.95
36.17
65.63
73.31
100
46.83
70.93
31.00
28.99
11.35
2.94
24.50
38.50
92.85
100
83.76
31.67
20.11
7.23
776 100
687 100
67.27
777
778
779
780
781
782
783
784
688
689
690
691
692
693
694
695
47.79 75.60
80.85 100
cationic complex paired with a methoxide ion (5).11,12
A
36.24 47.27
40.45 71.79
16.14 32.37
3.93 30.16
1.02 11.58
â-hydrogen atom is abstracted from the acetal moiety
by the generated methoxide ion, resulting in the elimi-
nation of the ODMM complex, i.e., the η3-(2-oxyallyl)
complex moiety.
In the case of the reaction of 2a ,b with methoxide ion,
this mechanism is also likely.
7.09
1.63
0.37
1.76
0.43
0.69
2.64
resulting complexes 3a ,b enriched with 18O were further
treated with water saturated in benzene at room tem-
perature for a day, and the unlabeled complexes 3a ,b
were treated wth K18OH in 2-propanol/THF for 1 h.
However, the degree of 18O enrichment in both cases
was not changed, as confirmed in the mass spectra,
suggesting no exchange of hydroxide group with water
under neutral conditions at ambient temperature, which
are the same conditions as in the workup process, nor
with OH- under the conditions of the preparation
reaction.
A possible mechanism for the generation reaction is
illustrated in Scheme 2. During the first step of the
reaction, nucleophilic attack by a hydroxide ion takes
place at the 2-position carbon atom of allyl moiety to
generate η2-metallacyclobutane complex 6 as a reaction
intermediate. The proton of the hydroxy group in this
intermediate is transferred, then, to the ((methyloxy)-
methyl)oxy group as the result of a four-centered
reaction, to result in the elimination of a hemiacetal
molecule and the formation of the ODMM complexes
3a ,b. In the case of the reaction of 1a ,b with methoxide
ion, even if the intermediate of η2-metallacyclobutane
complex is generated, ODMM complexes 3a ,b are
considered not to be generated, due to the impossibility
of the methyl group transfer via the four-centered
reaction.
One important factor by which this reaction proceeded
smoothly with these acetal compounds was supposed to
be the easy elimination of the η3-(2-oxyallyl) complex
moiety, assisted by a large contribution of oxonium ion
structure (B in eq 1), as shown in 1a ,b. The difference
of reactivity toward methoxide ion between palladium
and platinum complexes is obvious (1b afforded 3b,
though in a poor yield, while 1a did not afford 3a at
all) but is left unexplained at present.
Gen er a tion Mech a n ism of ODMM Com p lexes
fr om th e Rea ction of 1a ,b a n d 2a ,b w ith Hyd r oxid e
Ion . For the purpose of clarifying this difference, the
formation mechanism was investigated by analyzing the
ODMM complex generated from the reaction of 1a ,b
with hydroxide ion labeled with 18O (ca. 80% enriched)13
using mass spectrum.
As a result, both of the generated ODMM complexes
3a ,b were found to be 18O atom enriched, by 63% for
the palladium complex and 76% for the platinum
complex, as calculated from their mass spectra (Table
4). To find out why the 18O enrichment decreased, the
(9) 1H NMR (25 °C, 400 MHz) signals of methylene protons are as
follows. Pd complex (3a ): in CD2Cl2, δ 2.39 (s, br). Pt complex (3b):
in CD2Cl2, δ 2.19 (s, J (PtH) ) 48 Hz).
(10) 1H NMR (CD2Cl2, 25 °C, 400 MHz) signals are δ 0.92 (t, 3H),
1.38 (sext, 2H), 1.60 (quint, 2H), 3.65 (t, 2H), 3.39 (d, 1H), 4.13 (d,
1H), 6.45 (dd, 1H).
(11) Tsuji, J .; Shimizu, I.; Minami, I.; Ohashi, Y. Tetrahedron Lett.
1982, 23, 4809.
(12) Ikeda, I.; Gu, X.-P.; Okuhara, T.; Okahara, M. Synthesis 1990,
32.
One of the reasons why nucleophilic attack by hy-
droxide ion at the 2-position of the η3-allyl complexes
(13) Enrichment of 18O was confirmed by mass spectrum of the
product ([intensity of fragment (m/e ) 150)/intensity of fragment (m/e
) 148)]; 18O-enriched cinnamic acid, M ) 150) from the reaction of
methyl cinnamate with potassium hydroxide prepared from H218O
(purchased as 96.9 atom %-enriched reagent from Isotec Inc., Dayton,
OH) and t-BuOK (purified by sublimation before use) in absolute
2-propanol and followed by neutralization with hydrochloric acid.
(14) Direct observation of nucleophilic displacement reaction at the
2-position of η3-allylplatinum complex and indirect observation (deduc-
tion from organic products analysis) for nucleophilic displacement
reaction at the 2-position of η3-allylpalladium complex: Ohe, K.;
Matsuda, H.; Morimoto, T.; Ogoshi, S.; Chatani, N.; Murai, S. J . Am.
Chem. Soc. 1994, 116, 4125.

Formation of Pd and Pt Oxodimethylenemethane Complexes
Organometallics, Vol. 16, No. 13, 1997 3041
Sch em e 2
solution of 2.53 g (2.03 mmol) of Pt(PPh3)4 in 30 mL of benzene
at room temperature. The solution was stirred for 15 min,
and then 200 mL of hexane was added. After removal of the
solvent by filtration, solid materials containing 2b (counterion,
Cl-) were dried under reduced pressure and were again
dissolved in CH2Cl2/acetone (40 mL + 40 mL). A solution of
342 mg (2.10 mmol) of ammonium hexafluorophosphate in 20
mL of acetone was added to the CH2Cl2/acetone solution. After
the solution was stirred for 15 min, the solvent was evaporated
to dryness. Thus obtained, 2b was purified by recrystallization
from CH2Cl2/hexane (1/4 v/v) as colorless prisms. Yield: 1540
mg (70%); mp 135-137 °C. 1H NMR (600 MHz, CDCl3): δ
7.38-7.36 (m, 6H, Ph), 7.30-7.26 (m, 18H, Ph), 7.22-7.18 (m,
6H, Ph), 5.08 (t, J ) 2.87 Hz, 1H, OCHO), 3.72 (m, 1H, OCH2),
3.33-3.29 (m, 3H, OCH2 and allyl H), 2.77 (m, J PtH ) 40.3
Hz, 1H, allyl H), 2.60 (m, J PtH ) 44 Hz, 1H, allyl H), 1.88-
1.87 (m, 1H, 3-CH2), 1.80-1.61 (m, 5H, 3-CH2 and 4,5-CH2).
13C NMR (600 MHz, CDCl3): δ 18.7, 24.6, 29.8 (3,4,5-carbons
of tetrahydropyran-2-yl ring), 53.6 (C1-position), 63.6 (s, OCH2),
97.7 (s, OCHO), 128.2-134.9 (phenyl carbons), 153.5 (C2-position).
proceeded smoothly may also be the large contribution
of oxonium ion structure (B in eq 1), that is, the high
density of positive charge on the 2-position carbon atom
connected to the oxonium-characteristic oxygen atom.
The isolation of ODMM complexes 3a ,b enriched with
18O is the first direct observation of nucleophilic dis-
placement reaction at the 2-position of η3-allylpalladium
complexes.14-16
Recently, nucleophilic attack at the 2-position of η3-
propargyl/allenyl complexes was reported.17 While the
nucleophilic substitution in our studies presumedly
proceeds via the η2-metallacyclobutane intermediate 6,
these reports showed an addition of pronucleophile
toward the triple-bonded η3-allenyl intermediate moiety,
with the hydrogen atom (or possibly transferred as a
hydride ion) selectively adding to the terminal carbon.
The reason for about 4-17% loss of 18O enrichment
during the preparation of 3a ,b from 1a ,b and 18OH-
remained unknown.
31P NMR (400 MHz, CDCl3): δ 17.9 (d, J PP ) 11.0 Hz, J PtP
)
3684 Hz), 17.8 (d, J PP ) 11.0 Hz, J PtP ) 3757 Hz). Anal. Calcd
for C44H43O2F6P3Pt‚CH2Cl2: C, 49.55; H, 4.16. Found: C,
49.77; H, 4.18.
Con clu sion
It was clarified that, concerning the generation mech-
anism of ODMM-palladium and -platinum complexes
from η3-allyl complexes bearing an acetal group at the
2-position, there are at least two different paths leading
to the ODMM complexes, and their reactivities toward
bases were based on the high positive charge density
on the 2-position carbon atom and the oxygen atom
connected to this carbon, i.e., a large contribution of
oxonium ion structure, which was confirmed by the
X-ray crystallographic analysis.
P r ep a r a tion of P a lla d iu m η3-2-[(Tetr a h yd r op yr a n -2-
yl)oxy]a llyl Hexa flu or op h osp h a te (2a ). To a solution of
343 mg (0.604 mmol) of palladium η3-2-[(tetrahydropyran-2-
yl)oxy]allyl chloride dimer in acetone/CH2Cl2 (50 mL + 40 mL)
at 0 °C was added a solution of 635 mg (2.42 mmol) of PPh3 in
5 mL of CH2Cl2. Ammonium hexafluorophosphate (200 mg,
1.23 mmol) dissolved in 10 mL of acetone was added to the
solution at 0 °C. The solution was stirred at room temperature
for 15 min, and then the solvent was evaporated. The residual
solid materials were washed with ether and dried under
reduced pressure. Thus obtained, the end product was purified
by recrystallization from CH2Cl2/hexane (1/4 v/v) as yellow
needles. Yield: 960 mg (79%); mp 173-176 °C dec. 1H NMR
(600 MHz, CDCl3): δ 7.39-7.37 (m, 6H, Ph), 7.32-7.24 (m,
18H, Ph), 7.19-7.16 (m, 6H, Ph), 4.98 (t, 1H, J ) 2.72 Hz,
OCHO), 3.66 (dt, J ) 5.83, 10.80 Hz, 1H, OCH2), 3.46 (m, 2H,
allyl H), 3.24 (dt, J ) 4.72, 10.80 Hz, 1H, OCH2), 3.19 (d, J )
10.18 Hz, 1H, allyl H), 3.03 (d, J ) 9.75 Hz, 1H, allyl H), 1.90-
1.87 (m, 1H, 3-CH2), 1.80-1.76 (m, 1H, 3-CH2), 1.70-1.58 (m,
4H, 4,5-CH2). 13C NMR (600 MHz, CDCl3): δ 19.2, 24.7, 30.0
(3,4,5-carbons of tetrahydropyran-2-yl ring), 51.7 (C1-position),
63.7 (s, OCH2), 97.4 (s, OCHO), 128.7-133.7 (phenyl carbons),
154.6 (C2-position). 31P NMR (400 MHz, CDCl3): δ 26.0 (d, J PP
) 36.8 Hz), 25.3 (d, J PP ) 36.8 Hz). Anal. Calcd for C44H43O2-
F6P3Pd‚CH2Cl2: C, 53.94; H, 4.53. Found: C, 53.85; H, 4.58.
Nucleophilic displacement at the 2-position of the η3-
allylpalladium complex was first directly proved by the
isotope technique.
Exp er im en ta l Section
P r ep a r a tion of P la tin u m η3-2-[(Tetr a h yd r op yr a n -2-yl)-
oxy]a llyl Hexa flu or op h osp h a te (2b). In an argon atmo-
sphere, a solution of 377 mg (2.13 mmol) of 2-[(tetrahydropyran-
2-yl)oxy]allyl chloride in 3 mL of benzene was added to a
(15) Direct observation of nucleophilic addition reaction at the
2-position of η3-allylpalladium complex: Hoffmann, H. M. R.; Otte, A.
R.; Wilde, A.; Menzer, S.; Williams, D. J . Angew. Chem., Int. Ed. Engl.
1995, 34, 1.
(16) Indirect observation (deduction from organic products analysis)
for nucleophilic addition reaction at the 2-position of η3-allylpalladium
complex: (a) Trost, B. M. Angew. Chem., Int. Ed. Engl. 1989, 28, 1173.
(b) Hoffmann, H. M. R.; Otte, A. R.; Wilde, A. Angew. Chem., Int. Ed.
Engl. 1992, 31, 234. (c) Wilde, A.; Otte, A. R.; Hoffmann, H. M. R. J .
Chem. Soc., Chem. Commun. 1993, 615. (d) Otte, A. R.; Wilde, A.;
Hoffmann, H. M. R. Angew. Chem., Int. Ed. Engl. 1994, 33, 1280.
(17) (a) Baize, M. W.; Furilla, J . L.; Wojcicki, A. Inorg. Chim. Acta
1994, 223, 1. (b) Huang, T.-M.; Hsu, R.-H.; Yang, C.-S.; Chen, J .-T.;
Lee, G.-H.; Wang, Y. Organometallics 1994, 13, 3657. (c) Tsai, F.-Y.;
Hsu, R.-H.; Huang, T.-M.; Chen, J .-T.; Lee, G.-H.; Wang, Y. J .
Organomet. Chem. 1996, 520, 85.
P r ep a r a tion of P a lla d iu m η3-2-[(Tetr a h yd r op yr a n -2-
yl)oxy]allyl Ch lor ide Dim er . Pd2(dba)3‚CHCl3 (dba ) diben-
zylideneacetone) (1520 mg, 1.47 mmol) and 2-[(tetrahydropyran-
2-yl)oxy]-3-chloroprop-1-ene (1000 mg, 5.66 mmol) in acetone
(100 mL) were stirred for 24 h at room temperature. The deep
purple color turned to yellow upon completion of the reaction.
The precipitation was filtered off. The yellow solution was
evaporated to dryness and the residue washed with diethyl
ether until the washing was no longer tinted. Thus obtained,

3042 Organometallics, Vol. 16, No. 13, 1997
Ohsuka et al.
the end product was purified by recrystallization from CH2-
Cl2/hexane (1/4 v/v) as yellow needles. Yield: 634 mg (75%);
mp 134-137 °C dec. 1H NMR (600 MHz, CDCl3): δ 5.30 (t, J
) 7.3 Hz, 1H, OCHO), 4.09 (br, 1H, allyl H), 3.92 (t, J ) 3.0
Hz, 1H, OCH2), 3.72 (br, 1H, allyl H), 3.71 (t, J ) 3.4 Hz, 1H,
OCH2), 2.66 (br, 1H, allyl H), 2.52 (br, 1H, allyl H), 1.87-1.26
(m, 6H, 3,4,5-CH2). Anal. Calcd for C16H26O4Cl2Pd2: C, 33.83;
H, 4.97; Cl, 12.48. Found: C, 33.46; H, 4.58; Cl, 12.85.
P r ep a r a tion of 2-[(Tetr a h yd r op yr a n -2-yl)oxy]-3-ch lo-
r op r op -1-en e. A mixture of 30.2 g (0.265 mol) of 2-[(tetrahy-
dropyran-2-yl)oxy]-1,3-dichloropropane, 4.6 g (0.0135 mol) of
tetrabutylammonium hydrogen sulfate, 11.6 g (0.291 mol) of
sodium hydroxide, and 5.3 g of water was placed in a round-
bottomed flask and stirred for 2 h at 80 °C. The end product
was isolated directly from the reaction mixture by distillation
under reduced pressure. Yield: 30.4 g (65%); bp 60 °C/2.0
mmHg. 1H NMR (600 MHz, CDCl3): δ 5.24 (t, J ) 3.12 Hz,
1H, OCHO), 4.48 (d, J ) 2.08 Hz, 1H, dCH2), 4.42 (d, J )
2.08 Hz, 1H, dCH2), 4.00 (s, 2H, CH2Cl), 3.88 (m, 1H, OCH2),
3.59 (m, 1H, OCH2), 1.93 (m, 1H, 3-CH2), 1.79 (m, 1H, 3-CH2),
1,67-1.57 (m, 4H, 4,5-CH2). Anal. Calcd for C8H13O2Cl: C,
54.40; H, 7.42; Cl, 20.01. Found: C, 54.20; H, 7.64; Cl, 19.74.
P r ep a r a t ion of 2-[(Tet r a h yd r op yr a n -2-yl)oxy]-1,3-
d ich lor op r op a n e. Into a round-bottomed flask fitted with
a stopper carrying a glass tube reaching nearly to the bottom
of the flask was placed 105 g (1.25 mol) of 3,4-dihydro-2H-
pyran. A rapid stream of hydrogen chloride gas was run into
the liquid at 0-5 °C. After about 3 h, no more hydrogen
chloride gas was absorbed. The stream of hydrogen chloride
gas was continued to run for about additionally 15 min.
Nitrogen gas was then bubbled through the glass tube for 15
min. The reaction mixture was slowly added to a solution of
123 g (1.33 mol) of epichlorohydrin and 16.3 g (0.062 mol) of
dodecyltrimethylammonium chloride in 100 mL of CH2Cl2
cooled in an ice bath and stirred for 1 h. After removal of the
solvent by evaporation, the dichloride was extracted with 500
mL of ether and isolated by distillation under reduced pres-
sure. Overall yield: 242 g (91%); bp 83 °C/1.8 mmHg. 1H
NMR (600 MHz, CDCl3): δ 4.79 (t, J ) 3.66 Hz, 1H, OCHO),
4.06 (m, 1H, OCH2), 3.93 (m, 1H, OCH2), 3.80 (dd, J ) 11.25,
4.10 Hz, 1H, CH2Cl), 3.77 (dd, J ) 11.57, 4.80 Hz, 1H, CH2-
Cl), 3.71 (dd, J ) 11.25, 6.18 Hz, 1H, CH2Cl), 3.67 (dd, J )
11.57, 5.28 Hz, 1H, CH2Cl), 3.54 (m, 1H, CH2Cl), 1.84 (m, 1H,
3-CH2), 1.75 (m, 1H, 3-CH2), 1.66-1.54 (m, 4H, 4,5-CH2). Anal.
Calcd for C8H14O2Cl2: C, 45.09; H, 6.62; Cl, 33.27. Found: C,
44.93; H, 6.75; Cl, 33.39.
data collection. Corrections for Lorentz and polarization
effects were applied to the intensity data. The structure was
solved by direct methods18 and expanded using Fourier
techniques.19 Non-hydrogen atoms were refined anisotropi-
cally, and hydrogen atoms were included but not refined. The
final cycle of refinement was based on 4016 observed reflec-
tions (I > 3.00 σ(I)).
(M ) P t). The ω scan of several intense reflections, made
prior to data collection, had an average width at half-height
of 0.36° with a take-off angle of 6.0°. Scans of (1.52 + 0.35
tan θ)° were made at a speed of 10.0 deg/min (in ω). The
intensities of three representative reflections which were
measured after every 150 reflections remained constant
throughout the data collection. Corrections for Lorentz and
polarization effects were applied to the intensity data. The
structure was solved by direct methods, and non-hydrogen
atoms were refined anisotropically. The final cycle of refine-
ment was based on 5665 observed reflections (I > 3.00σ(I)).
Fractional atomic coordinates for 1a and 1b are given in
the Supporting Information.
Isotop e Exp er im en t for In vestiga tion of th e Mech a -
n ism of Gen er a tion of ODMM Com p lexes fr om 1a ,b. A
solution of 0.10 mmol of the complex 1a or 1b in 2 mL of THF
was added to 1.5 mL of 0.1 N K18OH (ca. 80% 18O-enriched)14
in 2-propanol. The mixture was stirred for 1 h at room
temperature in an argon atmosphere. After removal of the
solvent by evaporation, the resulting solid materials were
washed with hexane and dried under reduced pressure to give
ODMM complex 3a or 3b, respectively, as the sample for mass
spectral analysis.
Since palladium and platinum each consist of a complicated
isotope mixture, the 18O enrichments in 3a ,b were determined
by comparing the intensity of the peaks in the [M + 1] vicinity.
Natural abundance of 16O is more than 99%; thus, in the [M
+ 1] vicinity, a 100% 18O-labeled product is assumed to have
peaks with an intensity pattern similar to that of the peaks
of an unlabeled product (Table 4, from KOH), except that the
peaks of the labeled product are shifted farther along the m/e
axis by 2 units, due to the difference in the atomic weights of
18O and 16O (eq 3).
[intensity of peak (m/e) of 100% 18O-labeled product] )
[intensity of peak (m/e - 2) of unlabeled product] (3)
Here, the intensity pattern of peaks in the [M + 1] vicinity
of the mass spectrum of a partially labeled product is simu-
lated by adding fractions of the observed peak intensities of
the unlabeled product and the estimated peak intensities of a
100% 18O-labeled product (eq 4; N% for an arbitrary enrich-
ment level).
Preparation of 1a and 1b is described in our previous
report.1 Here, we add the 13C and 31P NMR measurements.
1a 13C NMR (600 MHz, CDCl3): δ 57.1 (s, OCH3), 61.5
(C1-position), 94.3 (s, OCH2O), 128.9-133.6 (phenyl carbons),
155.0 (C2-position). 31P NMR (400 MHz, CDCl3): δ 25.7. 1b 13C
NMR (600 MHz, CDCl3): δ 53.2 (C1-position), 57.3 (s, OCH3), 94.5
[intensity of peak (m/e) of N% 18O-enriched product] )
[estimated intensity of peak (m/e) of
(s, OCH2O), 127.8-134.8 (phenyl carbons), 153.8 (C2-position); 31
NMR (400 MHz, CDCl3): δ 17.6 (J PtP ) 3720 Hz).
P
100% 18O-labeled product] × N% + [intensity of peak
X-r a y Da ta Collection a n d Str u ctu r e An a lysis of 1a ,b.
A well-shaped colorless prismatic crystal of 1a or 1b was
mounted on a glass fiber. All measurements were made on a
Rigaku AFC-5R diffractometer with graphite-monochromated
MO KR radiation and a 12 kW rotating anode generator. Cell
constants and an orientation matrix for data collection ob-
tained from a least-squares refinement using the setting angles
of 25 centered reflections in the range 22.11 < 2θ < 26.60° (M
) Pd) or 27.19 < 2θ < 27.49° (M ) Pt) corresponded to a
monoclinic cell. The data were collected at 23 ( 1 °C using
the ω-2θ scan technique to a maximum 2θ value of 55.0°. The
data and experimental conditions were as follows:
(m/e - 2) of unlabeled product] × (100 - N)% (4)
By trial and error, several intensity patterns of various 18O-
enrichment levels were simulated, and their deviations from
the observed pattern (Table 4, from K18OH) were calculated.
From the intensity pattern with the least deviation, the most
probable 18O-enrichment level was found to be 63% for M )
Pd and 76% for M ) Pt (Table 4).
Since the mass analysis method applied was FAB-MAS,
besides the peaks of [M + 1], peaks of the [M] and [M - 1]
(M ) P d ). The ω scan of several intense reflections, made
prior to data collection, had an average width at half-height
of 0.32° with a take-off angle of 6.0°. Scans of (1.10 + 0.35
tan θ)° were made at a speed of 10.0 deg/min (in ω). The
intensities of three monitor reflections which were measured
after every 150 reflections remained constant throughout the
(18) SAPI91: Fan, H.-F. Structure Analysis Programs with Intel-
ligent Control; Rigaku Corp.: Tokyo, J apan, 1991.
(19) DIRDIF92: Beurskens, P. T.; Admiraal, G.; Beurskens, G.;
Bosman, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.;
Smykalla, C. The DIRDIF program system. Technical Report of the
Crystallography Laboratory; University of Nijmegen: Nijmegen, The
Netherlands, 1992.

Formation of Pd and Pt Oxodimethylenemethane Complexes
Organometallics, Vol. 16, No. 13, 1997 3043
ionization modes are also observed, although in small amount,
depending on the sample and measurement conditions, causing
a slight gap between the theoretical pattern and the actually
observed pattern. MS spectra were measured on a J MS-
DX303 mass spectrometer (J EOL Ltd., Tokyo, J apan). MS
spectroscopic parameters: scan range, 20-2050; scan slope,
10 s; scan type, Mf, LI, UP, DA; ionization mode; Xe FAB; tic
range, 50-2050; cycle time, 10 s; acceleration voltage, 3.0 kV/
DAC; matrix, 3-NBA.
supported by Grants-in-Aid for Scientific Research on
Priority Area of Reactive Organometallics No. 05236104
from the Ministry of Education, Science, and Culture
of J apan.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and Beq, anisotropic displacement parameters,
bond lengths and bond angles, and least-squares planes for
1a ,b (40 pages). Ordering information is given on any current
masthead page.
Ack n ow led gm en t. Thanks are due to Analytical
Center, Faculty of Engineering, Osaka University, for
the use of NMR and MS instruments. This work was
OM961108J