α,β-Unsaturated carbonyl compounds as hard/soft chelating ligands in methyl nickel phenolates and the structure of trans-methyl-2-(3- phenyl-2,3-η2-propenoyl)phenolatobis(trimethylphosphine) nickel(II)

Article abstract of DOI:10.1021/om050051a

Phenolato functions of chalcone type compounds may replace both methoxo bridges in dinuclear methyl nickel complexes without utilizing the aldehyde functions. Cleavage of phenolato-bridged nickel(II) centers in square planar coordination geometry by addition of trimethylphosphine affords mononuclear methylnickel complexes of coordination number five. The trimethylphosphine- supported trigonal bipyramidal methyl nickel(II) complex has a hard/soft chelating ligand with a phenolato oxygen atom and a π-coordinated olefin functional group. The chemical reactivity of complexes with these novel hard/soft chelating ligands remains to be clarified.

Full text of DOI:10.1021/om050051a

Organometallics 2005, 24, 4347-4350
4347
Articles
r,â-Unsaturated Carbonyl Compounds as Hard/Soft
Chelating Ligands in Methyl Nickel Phenolates and the
Structure of trans-Methyl-2-(3-phenyl-2,3-η2-
propenoyl)phenolatobis(trimethylphosphine)nickel(II)
Xiaoyan Li,† Hongjian Sun,*,† Ulrich Flo¨rke,‡ and Hans-Friedrich Klein§
School of Chemistry and Chemical Engineering, Shandong University, Shanda Nanlu 27,
250100 Jinan, People’s Republic of China, Anorganische und Analytische Chemie der
Universita¨t Paderborn, Warburger Strasse, 33098 Paderborn, Germany, and
Eduard-Zintl-Institut fu¨r Anorganische und Physikalische Chemie der Technischen
Universita¨t Darmstadt, Petersenstrasse 18, 64285 Darmstadt, Germany
Received January 25, 2005
Phenolato functions of chalcone type compounds may replace both methoxo bridges in
dinuclear methyl nickel complexes without utilizing the aldehyde functions. Cleavage of
phenolato-bridged nickel(II) centers in square planar coordination geometry by addition of
trimethylphosphine affords mononuclear methylnickel complexes of coordination number
five. The trimethylphosphine-supported trigonal bipyramidal methyl nickel(II) complex has
a hard/soft chelating ligand with a phenolato oxygen atom and a π-coordinated olefin
functional group. The chemical reactivity of complexes with these novel hard/soft chelating
ligands remains to be clarified.
Introduction
R,â-Unsaturated carbonyl compounds are useful re-
agents in organic synthesis. Few studies on the coordi-
nation chemistry of these multifunctional ligands have
been published. When they are coordinated to transition
metals, we expect several bonding modes of these
ligands (Figure 1).
Figure 1. Coordination alternatives of R,â-unsaturated
carbonyl ligands.
The coordination of cinnamate at cobalt(II) was
studied,1 showing a π-olefin bonding mode (form a),
without formation of a chelated complex. Dicarbonyl (η4-
cinnamaldehyde)triphenylphosphineiron(0) was shown
to attain coordination type b.2 No complex exhibiting
the coordination mode c has been reported so far.
Natarajan3 obtained metal complexes (M ) Co(II),
Ni(II), Cu(II)) with R,â-unsaturated carbonyl ligands
through ring-opening in the presence of pyridine or
water as supporting ligands. The metal coordination
occurs through a carbonyl oxygen atom and a phenolato
oxygen atom. The observed interaction without utilizing
the olefin function was believed to be due to the six-
membered chelate ring.
Figure 2. Coordination of chalcone ligands.
also phenolato-π-olefin coordination (Figure 2, e). In this
interaction the carbon-carbon double bond π-coordi-
nates to the metal center. This type of bonding was
confirmed by Li with an indirect method.5 Reaction of
a hydrido(acyl)phenolatocobalt(III) complex with eth-
ynyltrimethylsilane in THF afforded a π-olefin(enolato)-
cobalt(I) complex, which was identified by X-ray dif-
fraction (eq 1). It was proposed that the vinyl complex
after insertion is hydrolyzed.6 The last step consists of
Ligands of the chalcone type can provide not only (O,
O)-coordination (Figure 2, d) as in Natarajan’s work but
† Shandong University.
‡ Universita¨t Paderborn.
§ Technische Universita¨t Darmstadt.
(1) Hammerschmitt, B. I. Doctoral Thesis, Technische Hochschule
Darmstadt, 1991.
(4) Khadikar, P. V.; Kakkar, S.; Berge, D. D. Z. Phys. Chem., Leipzig
1976, 257 (4), 7698.
(5) Li, X. Doctoral Thesis, Technische Universita¨t Darmstadt, 1999.
(6) Klein, H.-F.; Li, X.; Flo¨rke, U.; Haupt, H.-J. Z. Naturforsch. 2000,
55b, 707.
(2) Sacerdoti, M.; Bertolasi, V.; Gilli, G. Acta Crystallogr. 1980, B36,
1061.
(3) Natarajan, C.; Shanthi, P.; Athappan, P.; Murugesan, R. Transi-
tion Met. Chem. 1992, 17 (1), 39.
10.1021/om050051a CCC: $30.25 © 2005 American Chemical Society
Publication on Web 08/04/2005

4348 Organometallics, Vol. 24, No. 18, 2005
Li et al.
a reductive elimination at the cobalt(III) center. The
coordination number is reduced from 6 to 5, and an R,â-
unsaturated carbonyl compound is formed as chelating
ligand. The coordination geometry is depicted in Figure
2, e.
(PMe3)2,12 with elimination of trimethylphosphonium
chloride (eq 3). The yields are 34% and 19%, respec-
tively.
π-Coordination with an olefinic fragment on a nickel-
(II) center is rare. Brookhart and co-workers reported
their studies on olefin polymerization with diimine
Ni(II) and Pd(II) catalysts.7 Mechanistic and theoretical
work for these catalytic polymerization reactions shows
that the π-interaction between the olefin fragment and
the nickel(II) center is a decisive step for the polymer-
ization.8 These Ni(II) and Pd(II) diimine based cata-
lysts have emerged as promising alternatives to both
Ziegler-Natta systems and metallocene catalysts for
olefin polymerization.
Previously we reported on the influence of hard/soft
chelating ligands on the reactivity of a metal center.9
Here we investigate the effect that a hard/soft chelating
ligand exerts on a methylmetal function. Methyl(phe-
nolato)nickel(II) complexes containing a π-coordinated
olefinic function were prepared. trans-Methyl-2-(3-phen-
yl-2,3-η2-propenoyl)phenolatobis(trimethylphosphine)-
nickel(II) 2 was characterized by single-crystal X-ray
diffraction.
Complex 1 in solution forms two isomers with cisoid
and transoid configuration (eq 4). The proportion of
these two configurations can be determined utilizing the
signal intensity of the Ni-CH3 group and trimethylphos-
phine ligands in the 1H NMR spectra. Solvents of
different polarity can shift the equilibrium concentra-
tions of isomers. The proportion in d6-acetone at 296 K
is 1:1 (cisoid:transoid), while in d8-THF it changes to
1:2. In 31P NMR experiments a solvent shift of reso-
nances was noticed. In d6-acetone two singlets at 0.28
and 1.12 ppm were found, while in d8-THF these
singlets were moved to 0.52 and 1.42 ppm, respectively.
Results and Discussion
As expected of dinuclear, O-bridged methyl(methoxo)-
nickel(II) compounds, [NiMe(OMe)(PMe3)]2 reacts with
substituted salicylaldehyde and enolated malondialde-
hyde derivatives,10,11 while 1-(2-hydroxyphenyl)-3-phen-
yl-2-propenone reacts with [NiMe(OMe)(PMe3)]2 in di-
ethyl ether according to eq 2 to afford bis[µ-2-oxo-(3-
phenyl-2-propenone)-1-phenolato]bis[methyl(trimeth-
ylphosphine)nickel(II)], 1.
A dark red solution of the dinuclear methylnickel
complex 1 in diethyl ether when combined with molar
equivalent amounts of trimethylphosphine at 213 K
(8) (a) Wang, C. M.; Friedrich, S.; Younkin, T. R.; Li, R. T.; Grubbs,
R. H. Bansleben, D. A.; Day, M. W. Organometallics 1998, 17, 3149.
(b) Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. Rev. 2000, 100,
1169. (c) Deng, L.; Woo, T. K.; Cavallo, L.; Margl, P. M.; Zieler, T. J.
Am. Chem. Soc. 1997, 119, 6177. (d) Froese, R. D. J.; Musaev, D. G.;
Morokuma, K. J. Am. Chem. Soc. 1998, 120, 1581.
(9) Klein, H.-F.; Lemke, U.; Lemke, M.; Brand, A. Organometallics
1998, 17, 4196.
Complex 1 can also be obtained through reaction of
(10) Klein, H.-F.; Hammerschmitt, B.; Bickelhaupt, A. Organome-
tallics 1994, 13, 2944.
1-(2-hydroxyphenyl)-3-phenyl-2-propenone with NiClMe-
(11) Sun, H. Doctoral Thesis, Technische Universita¨t Darmstadt,
1999.
(12) Klein, H.-F.; Karsch, H. H. Chem. Ber. 1973, 106, 1433.
(7) Johnson, L. K.; Killian, C. M.; Brookhart, M. J. Am. Chem. Soc.,
1995, 117, 6414.

R,â-Unsaturated Carbonyl Compounds as Ligands
Organometallics, Vol. 24, No. 18, 2005 4349
1
Table 1. Selected H NMR Data (δ/ppm, J/Hz) of
Complex 2 at Lower Temperatures
296 K
233 K
223 K
213 K
olefin-CH
PCH3
δ
3.58 (s)
5.91 (s)
3.53 (s)
5.03 (s)
3.51 (s)
5.00 (d)
5.6
3.49 (s)
4.95 (d)
5.6
3J(HH)
δ
1.22 (d)
6.4
1.13 (d)
7.0
1.20 (t′)
1.16 (t′)
2J(PH)
2
| J(PH) +
8.9
9.7
4J(PH)|
δ
NCH3
-0.44 (s) -0.36 (t) -0.35 (t) -0.34 (t)
10.4 11.1 11.0
3J(PH)
forms scarlet cubic crystals with 58% yield. From these
observations it was evident that the dinuclear complex
1 is cleaved into the mononuclear methylnickel complex
2 (eq 5). The coordination of the olefinic fragment is
achieved by addition of an extra trimethylphosphine
ligand. At 296 K the signals of the olefinic protons were
observed as two broad singlets at 3.58 and 5.91 ppm.
In comparison with the resonance of the uncoordinated
olefin ligand at 7.9 ppm, these protons experience a
coordination shift to higher field. 1H NMR measure-
ments at lower temperatures (Table 1) confirmed this
observation. While all chemical shifts were recorded at
higher field with lower temperatures, those of olefinic
protons were especially large. At 223 and 213 K the
singlets were split into doublets with coupling constants
3J(HH) ) 5.6 Hz, which could not be resolved at higher
temperature due to exchange broadening.
Figure 3. Molecular structure14 of complex 2 and selected
bond parameters (Å, deg): Ni-O(1) 1.9359 (18), Ni-C(8)
2.075(3), Ni-C(9) 2.127(2), Ni-C(16) 1.975(3), Ni-P(1)
2.2443(10), Ni-P(2) 2.2477(10), C(6)-C(7) 1.473(4), C(7)-
C(8) 1.468(4), C(8)-C(9) 1.393(4), C(9)-C(10) 1.476(3),
C(1)-C(6) 1.412(4), C(1)-O(1) 1.308(3); O(1)-Ni-C(16)
170.77(12), O(1)-Ni-C(9) 91.22(9), C(16)-Ni-C(9) 97.19-
(12), O(1)-Ni-P(1) 88.88(6), C(8)-Ni-P(1) 104.76(8), C(16)-
Ni-P(2) 89.87(12), P(1)-Ni-P(2) 117.99(4), C(7)-C(8)-
C(9) 123.2(2), O(1)-Ni-C(8) 95.05(9), C(16)-Ni-C(8)
93.89(13), C(8)-Ni-C(9) 38.69(10), C(16)-Ni-P(1) 86.65-
(12), O(1)-Ni-P(2) 85.11(6), C(9)-Ni-P(2) 98.57(7), C(8)-
C(9)-C(10) 125.9(2).
the cobalt(I) complex (1.451(11) Å), the π-coordination
in complex 2 appears to be weaker. The packing does
not show significant intermolecular contacts.
In a one-pot synthesis (eq 6) starting from [NiMe-
(OMe)(PMe3)]2 and 1-(2-hydroxyphenyl)-3-(3,4,5-tri-
methoxyphenyl)-2-propenone in the presence of excess
trimethylphosphine in diethyl ether/THF (1:1) the
methyl(phenolato)nickel(II) complex 3 was obtained in
64% yield.
From a diethyl ether solution complex 2 crystallized
at 245 K as red cubes, which were suitable for X-ray
diffraction. The nickel is found in a trigonal bipyramidal
coordination (Figure 3). Two trimethylphosphine ligands
are held at relatively long distances, Ni-P(1) ) 2.2443-
(10) Å and Ni-P(2) ) 2.2477(10) Å, and the olefin
function C(8)-C(9) lies in the equatorial plane NiP(1)-
P(2). Methyl carbon and phenolato oxygen atoms are
oriented in the axial direction. In comparison with an
isoelectronic cobalt(I) complex5,6 the distance of 1.982(3)
Å between nickel and the center of the CdC bond is
significantly larger than that of the cobalt complex
(1.899(8) Å). The olefinic double bond, C(8)-C(9) )
1.393(4) Å, lies close to the average value (1.40 Å) for
olefin ligands in transition metal complexes.13 Since the
CdC bond in the nickel complex is shorter than that of
Conclusion
Phenolato functions of chalcone type compounds may
replace both methoxo bridges in dinuclear methyl nickel
complexes without utilizing the aldehyde functions.
Cleavage of phenolato-bridged nickel(II) centers in
square planar coordination geometry by addition of
trimethylphosphine affords mononuclear methylnickel
complexes of coordination number 5. The trimeth-
ylphosphine-supported trigonal bipyramidal methyl nick-
el(II) complex has a hard/soft chelating ligand with a
phenolato oxygen atom and a π-coordinated olefin
functional group. The chemical reactivity of complexes
(13) Carmona, E.; Gutierrez-Puebla, E.; Monge, A.; Marin, J. M.;
Paneque, M.; Poveda, M. L. Organometallics 1989, 8, 967.

4350 Organometallics, Vol. 24, No. 18, 2005
Li et al.
2
Hz), 1.37 (d, cisoid-18H, J(PH) ) 9.9 Hz); CHOlefin, 6.37 (dt,
4H, 3J(HH) ) 7.8 Hz, 4J(HH) ) 0.89 Hz); 6.54 (d, 2H,
3J(HH) ) 8.7 Hz); 6.72 (d, 2H, 3J(PH) ) 8.7 Hz); CHbenzol, 7.10-
7.95 (m, 36 H). 13C NMR (50.3 MHz, d6-acetone, 296 K, ppm):
NiCH3, -10.30 s, -9.45 s; PCH3, 13.53 (d, 1J(PC) ) 29.0 Hz),
with these novel hard/soft chelating ligands remains to
be clarified.
Experimental Section
1
13.0 (d, J(PC) ) 30.1 Hz); C and CH, 102,9 s, 114.3 s, 121.6
General Procedures and Materials. Standard vacuum
techniques were used in manipulations of volatile and air-
sensitive materials. 1-(2-Hydroxyphenyl)-3-phenyl-2-prope-
none (Aldrich) was used without purification. 1-(2-Hydroxy-
phenyl)-3-(3,4,5-trimethoxyphenyl)-2-propenone,15 [NiMe(OMe)-
(PMe3)]2,12and NiMeCl(PMe3)212 were synthesized according to
literature procedures. Microanalyses were carried out by
Kolbe, Microanalytical Laboratory, Mu¨lheim (FRG). Infrared
spectra (4000-400 cm-1), as obtained from Nujol mulls
between KBr windows, were recorded on a Perkin-Elmer, type
397, spectrophotometer. 1H NMR spectra were obtained from
a Bruker 300 spectrometer equipped with a low-temperature
unit that was calibrated with a standard methanol sample.
Melting points were measured in capillaries sealed under
argon and are uncorrected.
s, 123.2 s, 124.1 s, 126.1 s, 126.2 s, 129.0 s, 129.2 s, 129.8 s,
130.1 s, 130.7 s, 131.1 s, 131.3 s, 135.6 s, 136.5 s, 142.3 s, 142.7
s; C-O, 172.5 s, 172.7 s; C)O, 184.6 s, 185.3 s. 31P NMR: (81.0
MHz, 296 K, ppm): in d6-acetone, PCH3, 0.28 s, 1.12 s; in d8-
THF, PCH3, 0.52 s, 1.42 s.
trans-Methyl-2-(3-phenyl-2,3-η2-propenoyl)phenolato-
bis(trimethylphosphine)nickel(II) (2). To a clear solution
of 1.10 g (1.47 mmol) of complex 1 in 60 mL of diethyl ether
was condensed trimethylphosphine (1.0 g, 12.5 mmol), causing
a pale red color. After 2 h at room temperature the mixture
was filtered. This filtrate at 246 K afforded 0.77 g of scarlet
cubes (58%). Dec > 376 K. Anal. Calcd for C22H32NiO2P2
(449.1): C, 58.83; H, 7.18; P, 13.79. Found: C, 58.79; H, 7.35;
P, 13.71. IR (Nujol mull, 2000-1500 cm-1): 1601 (sst), 1591
(st) ν(CdO); 1541 (m), 1500 s, ν(CdC). 1H NMR (300 MHz,
d6-acetone, ppm): δ, 296 K, NiCH3 -0.44 (s, 3H); PCH3, 1.22
(d, 18H, 2J(PH) ) 6.4 Hz); CHOlefin, 3.58 (s, 1H); 5.91 (s, br,
1H); CHbenzol, 6.28-7.44 (m, 9 H). 233 K, NiCH3 -0.36 (t, 3H,
3J(PH) ) 10.4 Hz); PCH3, 1.13 (d, 18H, 2J(PH) ) 7.0 Hz);
CHOlefin, 3.53 (s, 1H); 5.03 (s, 1H); CHbenzol, 6.25-7.44 (m, 9
H). 223 K, NiCH3 -0.35 (t, 3H, 3J(PH) ) 11.1 Hz); PCH3, 1.20
Preparation of Bis(µ-2-(3-phenylpropenoyl)phenola-
to)bis(methyl(trimethylphosphine)nickel(II)) (1). Method
a: A sample of 1.17 g (3.23 mmol) of [NiMe(OMe)(PMe3)]2 and
1.45 g (6.46 mmol) of 1-(2-hydroxyphenyl)-3-phenyl-2-prope-
none in 60 mL of diethyl ether changed color from yellow-
brown to dark red. After 20 h at 293 K the volatiles were
removed in vacuo and the residue was extracted with pentane
over a glass-sinter disk (G3). Freezing at 246 K afforded 0.83
g of dark red sticks (34%). Method b: 1.60 g (6.47 mmol) of
NiClMe(PMe3)2 and 1.45 g (6.46 mmol) of 1-(2-hydroxyphenyl)-
3-phenyl-2-propenone in 60 mL of diethyl ether at 213 K gave
an orange-red solution. Warming to room temperature and
removing the volatiles afforded a red-brown residue, which was
extracted with pentane. At 246 K 0.75 g of dark red crystals
(19%) were generated. Dec > 375 K. Anal. Calcd for C38H46-
Ni2O4P2 (745.8): C, 61.17; H, 6.21; P, 8.30. Found: C, 61.13;
H, 6.34; P, 8.35. IR (Nujol mull, 2000-1600 cm-1): 1626 (sst),
1609 (st) ν(CdO). 1H NMR (300 MHz, d6-acetone, 296 K, ppm,
cisoid:transoid ) 1:1): δ NiCH3 -0.59 (d, transoid-6H,
3J(PH) ) 4.0 Hz); -0.48 (d, cisoid-6H, 3J(PH) ) 6.8 Hz); PCH3,
1.32 (d, transoid-18H, 2J(PH) ) 10.4 Hz), 1.39 (d, cisoid-18H,
2J(PH) ) 9.8 Hz); CHOlefin, 6.44 (m, 4H); 6.58 (dd, 2H,
2
(t′, 18H, | J(PH) + 4J(PH)| ) 8.9 Hz); CHOlefin, 3.51 (s, 1H);
3
5.00 (d, 1H, J(HH) ) 5.6 Hz); CHbenzol, 6.25-7.29 (m, 9 H).
213 K, NiCH3 -0.34 (t, 3H, 3J(PH) ) 11.0 Hz); PCH3, 1.16 (t′,
2
4
18H, | J(PH) + J(PH)| ) 9.7 Hz); CHOlefin, 3.49 (s, 1H); 4.95
(d, 1H, 3J(HH) ) 5.6 Hz); CHbenzol, 6.25-7.27 (m, 9 H). 13C
NMR (50.3 MHz, d6-acetone, 296 K, ppm): NiCH3, -3.36 s,
PCH3, 13.63 s, C and CH, 113,3 s, 124.8 s, 128.1 s, 128.7 s,
129.4 s, 130.7 s, 134.0 s, 139.1 s. 31P NMR (81.0 MHz,
d6-acetone, ppm): PCH3, 296 K, -8.53 s; 213 K, 3.24 s.
trans-Methyl-2-(3-(3,4,5-trimethoxyphenyl)-2,3-η2-pro-
penoyl)phenolatobis(trimethylphosphine)nickel(II) (3).
[NiMe(OMe)(PMe3)]2 (0.31 g, 0.84 mmol) and 1-(2-hydroxy-
phenyl)-3-(3,4,5-trimethoxyphenyl)-2-propenone (0.53 g, 1.69
mmol) in a mixture of 30 mL of diethyl ether and 30 mL of
THF were stirred for 2 h at 293 K. Onto the clear solution
was condensed trimethylphosphine (0.32 g, 4.21 mmol). After
16 h the volatiles were removed in vacuo and the residue was
extracted with pentane over a glass-sinter disk (G3). Freezing
at 246 K afforded 0.58 g of red cubes (64%). Dec > 351 K. Anal.
Calcd for C25H38NiO5P2 (539.2): C, 55.69; H, 7.10; P, 11.49.
Found: C, 55.74; H, 7.03; P, 11.59. IR (Nujol mull, 2000-1500
cm-1): 1600 (sh), 1581 (sst) ν(CdO). 1544 (m), 1511 s, ν(CdC).
1H NMR (300 MHz, d8-THF, 296 K, ppm): δ, NiCH3 -0.50 (s,
3H); PCH3, 1.11 (s, 18H); para-OCH3, 3.71 (s, 3H); meta-OCH3,
3.80 (s, 6H); CHolefin, 6.05 (s, br, 2H); CHbenzol, 6.30 (t, 1H,
3J(HH) ) 7.4 Hz), 6.49 (d, 1H, 3J(HH) ) 8.5 Hz), 6.78 (m, 2H),
4
3
3J(HH) ) 8.8 Hz, J(HH) ) 1.3 Hz); 6.73 (dd, 2H, J(PH) )
8.8 Hz. 4J(PH) ) 1.7 Hz); CHbenzol, 7.22-7.80 (m, 36 H). 1H
NMR (300 MHz, d8-THF, 296 K, ppm, cisoid:transoid ) 1:2):
δ
NiCH3 -0.59 (s, transoid-6H); -0.48 (d, cisoid-6H,
3J(PH) ) 6.7 Hz); PCH3, 1.30 (d, transoid-18H, 2J(PH) ) 10.3
(14) Crystal structure analysis of 2: C22H32NiO2P2, Bruker AXS P4
diffractometer, Mo KR radiation (λ ) 0.71073 Å, graphite monochro-
mator), T ) 293(2) K, crystal size 0.18 × 0.30 × 0.58 mm3, triclinic,
space group P1h, a ) 8.672(1) Å, b ) 11.251(1) Å, c ) 13.458(2) Å, R )
68.88(1)°, â ) 74.54(1)°, γ ) 74.89(1)°, V ) 1160.6(2) Å3, Z ) 2, Dc )
1.258 g/cm3, µ(Mo KR) ) 0.987 mm-1, F(000) ) 476, 6299 reflections
collected 2.1° < θ < 27.5°, absorption correction via psi-scans, min./
3
4
7.02 (ddd, 1H, J(HH) ) 6.9 Hz, J(HH) ) 1.7 Hz), 7.50 (m,
1H). 13C NMR (75.4 MHz, d8-THF, 296 K, ppm): NiCH3, -6.5
s; PCH3, 11.88 s; OCH3, 54.5 s, 58.5; CH, 104.5 s, 111.3 s, 123.0
s, 128.9 s, 131.9 s, 152.7 s; C-O, 168.8 s. 31P NMR (121.5 MHz,
d8-THF, 296 K, ppm): PCH3, -21.26 s.
max. transmission 0.795/0.942, 5252 independent intensities (Rint
)
0.014), structure solution by direct and conventional Fourier methods,
full-matrix least-squares refinement based on F2 and 245 parameters,
all but hydrogen atoms refined anisotropically, H atoms at idealized
positions riding on their attached carbon atoms, refinement converged
at R1(I > 2σ(I)) ) 0.043, wR2 (all data) ) 0.107, S ) 1.008, max.
Acknowledgment. We thank the Fond der Chemis-
chen Industrie, the Deutsche Foschungsgemeinschaft,
and the project sponsored by SRF for ROCS, SEM.
∆/σ ) 0.0001, min./max. height in final ∆F map ) -0.38/0.39 e Å-3
.
Programs for solution and refinement were from the SHELX suite.16
Crystallographic data, excluding structure factors, have been deposited
with the Cambridge Crystallographic Data Centre, with deposition
number CCDC-269319. Data can be obtained free of charge on
application to the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK.
(e-mail: deposit@ccdc.cam.ac.uk).
Supporting Information Available: Tables containing
full X-ray crystallographic data for complex 2. This material
is available free of charge via the Internet at http://pubs.acs.org.
(15) Alcantara, A. R.; Marinas, J. M.; Sinistrra, J. V. Tetrahedron
Lett. 1987, 28, 1515.
(16) SHELXTL (Ver. 6.10); Bruker AXS Inc.: Madison, WI, 2002.
OM050051A