Syntheses, structures, and Berry pseudorotation of ruthenium-phosphorane complexes

Article abstract of DOI:10.1021/om990044k

Ruthenium complexes containing a hypervalent phosphorus ligand, [Cp(CO)₂Ru{P-(OC₆H₄E)₂}] (E = NH (2a), NMe (2b), or O (4a)), [Cp(CO)₂Ru{P(OC₁₀H₆O)₂}] (4b), and [Cp-(CO)₂Ru{P(OC₇H₆O)₂}] (4c), were prepared in the reaction of [Cp(CO)₂Ru{P(OPh)₃}]BF₄ (1) with the corresponding aryl alcohol or arylamine and Et₃N or n-BuLi. The comparison of spectroscopic data of [Cp(CO)₂M{P(OC₆H₄E)₂}] (M = Ru, Fe) (E = NH, NMe, O) reveals that the Ru-P bonding is more polarized as M^δ+-P^δ- than the Fe-P bonding. During the course of preparation of 2b, a phosphite complex [Cp(CO)₂Ru{P(OC₆H₄NMe)(OC₆H ₄NMeH)}]-BF₄ (3) was isolated, which reacted with a Lewis base to give 2b. The X-ray structures of 2b, 4b, and 3 were determined. 2b and 4b have slightly distorted trigonal-bipyramidal geometries. From the variable-temperature ³¹P NMR study for 4c, the activation parameters for Berry pseudorotation around the pentacoordinate phosphorus were determined to be ΔH^? = 42.1 ± 0.5 kJ mol^-1, ΔH^? = -91.1 ± 1.6 J mol^-1 K^-1, and ΔG₃₄₀^? = 73.1 ± 0.7 kJ mol^-1. This constitutes the first determined activation parameters of Berry pseudorotation for a metallaphosphorane complex.

Full text of DOI:10.1021/om990044k

Organometallics 1999, 18, 2961-2969
2961
Syn th eses, Str u ctu r es, a n d Ber r y P seu d or ota tion of
Ru th en iu m -P h osp h or a n e Com p lexes
Hiroshi Nakazawa,* Kazumori Kawamura, Kazuyuki Kubo, and
Katsuhiko Miyoshi*
Department of Chemistry, Faculty of Science, Hiroshima University,
Higashi-Hiroshima 739-8526, J apan
Received J anuary 25, 1999
Ruthenium complexes containing a hypervalent phosphorus ligand, [Cp(CO)2Ru{P-
(OC6H4E)2}] (E ) NH (2a ), NMe (2b), or O (4a )), [Cp(CO)2Ru{P(OC10H6O)2}] (4b), and [Cp-
(CO)2Ru{P(OC7H6O)2}] (4c), were prepared in the reaction of [Cp(CO)2Ru{P(OPh)3}]BF4 (1)
with the corresponding aryl alcohol or arylamine and Et3N or n-BuLi. The comparison of
spectroscopic data of [Cp(CO)2M{P(OC6H4E)2}] (M ) Ru, Fe) (E ) NH, NMe, O) reveals
that the Ru-P bonding is more polarized as Mδ+-Pδ- than the Fe-P bonding. During the
course of preparation of 2b, a phosphite complex [Cp(CO)2Ru{P(OC6H4NMe)(OC6H4NMeH)}]-
BF4 (3) was isolated, which reacted with a Lewis base to give 2b. The X-ray structures of
2b, 4b, and 3 were determined. 2b and 4b have slightly distorted trigonal-bipyramidal
geometries. From the variable-temperature 31P NMR study for 4c, the activation parameters
for Berry pseudorotation around the pentacoordinate phosphorus were determined to be
q
∆Hq ) 42.1 ( 0.5 kJ mol-1, ∆Sq ) -91.1 ( 1.6 J mol-1 K-1, and ∆G340 ) 73.1 ( 0.7 kJ
mol-1. This constitutes the first determined activation parameters of Berry pseudorotation
for a metallaphosphorane complex.
In tr od u ction
transition-metal fragment at a phosphoranide6 (and the
Sb version7). Some other preparative methods8 and
review articles9 have been reported. We recently re-
ported an unprecedented method for the preparation of
iron-phosphorane complexes (Scheme 1), involving the
nucleophilic attack of an organic nucleophile at a
trivalent phosphorus coordinated to an iron.10 To expand
the scope of this preparative method, we examined
Metalated derivatives of pentacoordinate phosphorus
compounds, metallaphosphoranes, have received con-
siderable attention because they have a hypervalent
3-center 4-electron bond. Several kinds of methods for
the preparation of metallaphosphoranes have been
reported: (1) deprotonation1 and (2) protonation2 at a
nitrogen in polycyclic species with phosphine- and/or
amine-metal bonds, (3) oxidative addition of halogen
to transition-metal phosphide complexes3 (and Sb and
As versions4), (4) nucleophilic substitution at a phos-
phorane phosphorus atom by a transition-metal anion,5
and (5) electrophilic attack of an electron-deficient
reactions of
a
ruthenium complex, [Cp(CO)2Ru-
{P(OPh)3}]+. This paper reports preparations, proper-
ties, X-ray structures, and pseudorotation of ruthenium
phosphoranes, Cp(CO)2Ru{P(OC6H4E)2} (Cp ) η5-C5H5;
E ) NH, NMe, O; although the complex should be
described as Cp(CO)2Ru{P(OC6H4E)2}, the tie bar is
omitted hereafter for simplicity), and some related
complexes.
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nometallics 1995, 14, 3364.
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Organometallics 1986, 5, 677. (b) Burns, E. G.; Chu, S. S. C.; Meester,
P.; Lattman, M. Organometallics 1986, 5, 2383. (c) Lattman, M.; Burns,
E. G.; Chopra, S. K.; Cowley, A. H.; Arif, A. M. Inorg. Chem. 1987, 26,
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D. W. H. J . Chem. Soc., Chem. Commun. 1983, 484. (b) Ebsworth, E.
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10.1021/om990044k CCC: $18.00 © 1999 American Chemical Society
Publication on Web 07/03/1999

2962 Organometallics, Vol. 18, No. 16, 1999
Nakazawa et al.
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4NMe)2}] (2b) fr om
1. A solution of o-C6H4(NHMe)(OH) (200 mg, 1.62 mmol) in
THF (5 mL) was treated with n-BuLi (0.50 mL of n-BuLi, 1.61
M of hexane solution, 0.81 mmol) at -78 °C. After it had been
stirred at -78 °C for 20 min, the reaction mixture was treated
with 1 (502 mg, 0.81 mmol) and warmed to room temperature
and then stirred for 4 h. The solvent was removed under
reduced pressure, and the residue was washed with a small
amount of ether and then extracted with hot ether (20 mL ×
4). The ether extract was concentrated to ca. 3 mL and cooled
to -10 °C, yielding yellow crystals of 2b (99 mg, 0.20 mmol,
25%). Anal. Calcd for C21H19N2O4PRu: C, 50.91; H, 3.87; N,
5.65. Found: C, 51.03; H, 3.95; N, 5.72.
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4NMe)2}] (2b) fr om
3. A white suspension of 3 (100 mg, 0.17 mmol) in THF (2 mL)
was treated with Et3N (0.024 mL, 0.17 mmol) at room
temperature. The mixture was stirred for 8 h to give a yellow
solution. The solvent was removed under reduced pressure.
The resulting solid was extracted with hot ether (15 mL × 5),
and the ether extract was concentrated to ca. 3 mL. Cooling
to -10 °C yielded yellow crystals of 2b (65 mg, 0.13 mmol,
77%).
Sch em e 1
Exp er im en ta l Section
Gen er a l Rem a r k s. All reactions were carried out under
an atmosphere of dry nitrogen by using standard Schlenk tube
techniques. All solvents were purified by distillation: Ether,
THF, benzene, toluene, and p-xylene were distilled from
sodium/benzophenone, hexane and pentane were distilled from
sodium metal, and CH2Cl2 was distilled from P2O5. Acetone
was dried with anhydrous CaSO4 and distilled. They were
stored under an N2 atmosphere. Other reagents were used as
received. Cp(CO)2RuCl,11 HP(OC6H4NH)2,12 and o-C6H4(NHMe)-
(OH)13 were prepared according to the respective published
procedures.
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4NMe)(OC6H4NH-
Me)}]BF 4 (3). A solution of o-C6H4(NHMe)(OH) (505 mg, 4.10
mmol) in THF (5 mL) was treated with n-BuLi (1.27 mL of
n-BuLi, 1.61 M of hexane solution, 2.05 mmol) at -78 °C. After
it had been stirred at -78 °C for 20 min, the reaction mixture
was treated with 1 (1197 mg, 1.93 mmol), warmed to room
temperature, and then stirred for ca. 24 h until the yellow
solution was changed to a white suspension. A precipitate was
collected by filtration, washed with cold THF, and dissolved
in acetone (20 mL). After filtration to remove insoluble
materials, the solvent was removed in vacuo to give a white
IR spectra were recorded on Shimadzu FTIR-4000 and
FTIR-8100A spectrometers. 1H, 13C, and 31P NMR spectra were
measured on J EOL EX-270, EX-400, and LA-300 spectrom-
eters. 1H NMR and 13C NMR data were referenced to Si(CH3)4
as an internal standard. 31P NMR data were referenced to 85%
H3PO4 as an external standard. Elemental analyses were
performed on a Perkin-Elmer 2400CHN elemental analyzer.
P r ep a r a tion of [Cp (CO)2Ru {P (OP h )3}]BF 4 (1). A solu-
tion of Cp(CO)2RuCl (2860 mg, 11.10 mmol) and P(OPh)3 (3445
mg, 11.10 mmol) in CH2Cl2 (100 mL) was added to a suspen-
sion of AgBF4 (2162 mg, 11.10 mmol) in CH2Cl2 (20 mL). The
mixture was stirred for 24 h at room temperature. After
filtration to remove AgCl formed, the solvent was removed
from the filtrate under reduced pressure to give a yellow
powder, which was washed with benzene and then ether.
Recrystallization from CH2Cl2/hexane gave colorless crystals
of 1 (6145 mg, 9.92 mmol, 89%). Anal. Calcd for C25H20BF4O5-
PRu: C, 48.49; H, 3.26. Found: C, 48.29; H, 3.35.
powder of 3 (891 mg, 1.53 mmol, 79%). Anal. Calcd for C21H20
-
BF4N2O4PRu: C, 43.25; H, 3.46; N, 4.80. Found: C, 42.99; H,
3.44; N, 4.79.
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4O)2}] (4a ). A solu-
tion of 1 (520 mg, 0.84 mmol) in THF (5 mL) was added to a
solution of o-C6H4(OH)2 (185 mg, 1.68 mmol) and Et3N (0.12
mL, 0.84 mmol) in THF (3 mL). The mixture was stirred for 4
h at 60 °C, and the volatiles were removed under reduced
pressure. The yellow residue was extracted with hot ether (20
mL × 4), and the ether extract was evaporated to dryness.
The resulting solid was washed with ether (1 mL × 5) and
dried in vacuo to yield a white powder of 4a (304 mg, 0.65
mmol, 77%). Anal. Calcd for C19H13O6PRu: C, 48.62; H, 2.79.
Found: C, 48.54; H, 2.96.
P r epar ation of [Cp(CO)2Ru {P (OC10H6O)2}] (4b). A treat-
ment of 1 (329 mg, 0.53 mmol) with 2,3-C10H6(OH)2 (170 mg,
1.06 mmol) and Et3N (0.074 mL, 0.53 mmol) in a manner
similar to that of 4a gave a white powder of 4b (196 mg, 0.34
mmol, 65%). Anal. Calcd for C27H17O6PRu: C, 62.24; H, 4.66;
N, 5.18. Found: C, 62.09; H, 4.71; N, 5.04.
P r ep a r a tion of [Cp (CO)2Ru {P (OC7H6O)2}] (4c). A treat-
ment of 1 (596 mg, 0.96 mmol) with 3-methylcatechol (239 mg,
1.93 mmol) and Et3N (0.13 mL, 0.96 mmol) in a manner similar
to that of 4a gave a white powder of 4c (312 mg, 0.63 mmol,
66%). Anal. Calcd for C21H17O6PRu: C, 50.71; H, 3.44. Found:
C, 50.66; H, 3.44.
X-r a y Str u ctu r e Deter m in a tion for 2b, 4b, a n d 3. Single
crystals of 2b grown from ether, 4b grown from toluene/
hexane, and 3 grown from CH2Cl2/hexane in a refrigerator
were individually mounted on an Enraf-Nonius CAD4 diffrac-
tometer and irradiated with graphite-monochromated Mo KR
radiation (λ ) 0.710 73 Å). Unit cell dimensions were obtained
by least-squares from the angular setting of 25 carefully
centered reflections with 23° < 2θ < 36° for 2b, from that of
15 such reflections with 20° < 2θ < 22° for 4b, and from that
of 24 such reflections with 21° < 2θ < 36° for 3. P2/c, P212121,
and P21/n were selected as the space groups for 2b, 4b, and 3,
respectively, which led to successful refinements. Reflection
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4NH)2}] (2a ) fr om
1. A solution of 1 (619 mg, 1.00 mmol) in THF (10 mL) was
added to a solution of o-C6H4(NH2)(OH) (218 mg, 2.00 mmol)
and Et3N (0.14 mL, 1.00 mmol) in THF (5 mL). The mixture
was stirred for 4 h at 60 °C, and the volatiles were removed
under reduced pressure. The yellow residue was extracted with
hot ether (50 mL × 4), and the ether extract was evaporated
to dryness. The resulting solid was washed with ether (2 mL
× 5) and dried in vacuo to yield a white powder of 2a (238
mg, 0.51 mmol, 51%). Anal. Calcd for C19H15N2O4PRu: C,
48.83; H, 3.23; N, 5.99. Found: C, 48.59; H, 3.36; N, 5.81.
P r ep a r a tion of [Cp (CO)2Ru {P (OC6H4NH)2}] (2a ) fr om
Cp (CO)2Ru Cl a n d HP (OC6H4NH)2. A solution of HP(OC6H4-
NH)2 (626 mg, 2.54 mmol) in THF (5 mL) was treated with
n-BuLi (2.37 mL of n-BuLi, 1.61 M hexane solution, 3.81 mmol)
at -78 °C. The colorless solution changed immediately to a
white suspension. After it had been stirred at -78 °C for 20
min, the reaction mixture was treated with Cp(CO)2RuCl (657
mg, 2.55 mmol) and was warmed to room temperature and
then stirred for 24 h to complete the reaction. The solvent was
removed under reduced pressure, and the residue was ex-
tracted with hot ether (50 mL × 4). After the ether extract
was dried in vacuo, the resulting white powder was washed
with a small amount of ether and dried in vacuo to give 2a
(224 mg, 0.48 mmol, 19%).
(11) Blockmore, T.; Cottton, J . D.; Bruce, M. I.; Stone, F. G. A. J .
Chem. Soc. A 1968, 2931.
(12) Malavaud, C.; Charbonnel, Y.; Barrans, J . Tetrahedron Lett.
1975, 497.
(13) Anderson, G. W.; Bell, F. J . Chem. Soc. 1949, 2668.

Ruthenium-Phosphorane Complexes
Organometallics, Vol. 18, No. 16, 1999 2963
Sch em e 2
Sch em e 3
Sch em e 4
intensities were collected in the usual manner at 20 ( 1 °C,
and 3 representative reflections checked after every 200
reflections showed no decrease in intensity.
The structure was solved by a heavy-atom Patterson method
with the PATTY program system14 for 2b and by direct
methods with the SHELXS86 program system15 for 4b and 3.
The positions of all hydrogen atoms were calculated by
1
directly bonded to it. (iii) In the H NMR spectrum, in
-
assuming idealized geometries. For 3, the counteranion, BF4
,
addition to a doublet due to Cp protons and multiplet
due to phenyl protons, a doublet assigned to NH protons
was observed at 5.27 ppm with J ) 17.6 Hz.
was refined as a disordered molecule. Absorption and extinc-
tion corrections were then applied, and several cycles of a full-
matrix least-squares refinement with anisotropic temperature
factors for non-hydrogen atoms led to final values of R ) 0.027
and Rw ) 0.036 for 2b, R ) 0.048 and Rw ) 0.035 for 4b, and
R ) 0.058 and Rw ) 0.047 for 3. All calculations were
performed using teXsan.16
Similarly, [Cp(CO)2Ru{P(OC6H4O)2}] (4a), [Cp(CO)2Ru-
{P(OC10H6O)2}] (4b), and [Cp(CO)2Ru{P(OC7H6O)2}]
(4c) were prepared from 1 and o-C6H4(OH)2, 2,3-C10H6-
(OH)2, and 3-methylcatechol, respectively (Scheme 2).
In all cases, the reactions proceeded cleanly, but the
yields of the isolated complexes were in the range of 51-
77%, depending on the solubility and crystallinity of the
respective complexes.
Resu lts a n d Discu ssion
P r ep a r a tion a n d Ch a r a cter iza tion of Ru th e-
n iu m -P h osp h or a n e Com p lexes. Ruthenium com-
plexes containing a phosphorane fragment were syn-
thesized according to the method reported previously
for the corresponding iron complexes10 with some modi-
fications. [Cp(CO)2Ru{P(OPh)3}]BF4 (1) was added to
a reaction mixture of 2 equiv of o-C6H4(NH2)(OH) and
1 equiv of Et3N in THF, and then the reaction mixture
was heated at 60 °C to give a white powder (Scheme 2).
We concluded that the product is a ruthenium-phos-
phorane, [Cp(CO)2Ru{P(OC6H4NH)2}] (2a ), from the
following spectroscopic data similar to those of the iron
analogue:10 (i) Two IR absorption bands due to νCO (2037
and 1983 cm-1) were observed in a terminal carbonyl
region of electrically neutral complexes. (ii) In the 31P
NMR spectrum, one resonance was observed at 0.66
ppm, which is at a higher field by 136 ppm than that of
the starting complex, as a singlet with proton irradiation
and as a triplet with J ) 18.0 Hz without proton
irradiation, indicating the formation of a pentavalent
pentacoordinate phosphorus with two NHR groups
The formation mechanism of the ruthenium phospho-
ranes can be considered to be the same as that of iron
phosphoranes.10 That is, it involves nucleophilic attacks
of an organic nucleophile such as -OR or -NR2 at a
trivalent phosphorus coordinated to a ruthenium and
the subsequent substitutions on the phosphorus.
In the reaction of 1 with o-C6H4(NHMe)(OH) and
n-BuLi at room temperature, a quantitative formation
of [Cp(CO)2Ru{P(OC6H4NMe)2}] (2b) is confirmed first
in the 31P NMR spectrum of the reaction mixture, and
then 2b changes to the corresponding phosphite com-
plex, [Cp(CO)2Ru{P(OC6H4NMe)(OC6H4NHMe)}]BF4 (3)
(Scheme 3). Preparation of 2b by this method leads to
the concomitant formation of 3 equiv of PhOH, which
reacts with the more basic N atom in 2b, compared with
that of 2a , to give a cationic complex 3. An equilibrium
between 2b and 3 may exist in solution, but 3 is readily
precipitated out from the solution, which makes 3 a
main product in this reaction. The reaction of isolated
3 with a base such as Et3N gives 2b in a good yield
(77%).
(14) PATTY: Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bos-
man, W. P.; Garcia-Granda, S.; Gould, R. O.; Smits, J . M. M.; Smykalla,
C. The DIRDIF program system; Technical Report of the Crystal-
lography Laboratory, University of Nijmegen: Nijmegen, The Neth-
erlands, 1992.
(15) SHELXS86: Sheldrick, G. M. In Crystallographic Computing
3; Sheldrick, G. M., Kruger, C., Goddard, R., Eds.; Oxford University
Press: New York, 1985; pp 175-189.
(16) teXsan: Crystal Structure Analysis Package; Molecular Struc-
ture Corp.: The Woodlands, TX, 1985, 1992.
Another method for the preparation of metallaphos-
phoranes, which has been reported for an iron analogue,
is a replacement of chloride on a transition metal by
phosphoranide.6,10 This method was applied for the
preparation of 2a and 4a (Scheme 4). The reaction of
Cp(CO)2RuX (X ) Cl, I) with hydridophosphorane HP-
(OC6H4E)2 (E ) NH, O) in the presence of a base gave

2964 Organometallics, Vol. 18, No. 16, 1999
Ta ble 1. Sp ectr oscop ic Da ta
Nakazawa et al.
complex IR (THF): νCO (cm-1
)
1H NMR (CDCl3): δ (ppm)
13C NMR (CDCl3): δ (ppm)
31P NMR (CDCl3): δ (ppm)
1
2083
2037
5.21 (s, 5H, C5H5)
7.18-7.25 (m, 9H, OC6H5)
7.37-7.42 (m, 6H, OC6H5)
89.41 (s, C5H5)
120.88 (d, J PC ) 5.0 Hz, o-C6H5)
126.84 (s, p-C6H5)
136.50 (s)
130.73 (s, m-C6H5)
149.72 (d, J PC ) 8.1 Hz, ꢀ-C6H5)
191.56 (d, J PC ) 21.8 Hz, CO)
88.59 (s, C5H5)a
108.88 (d, J PC ) 12.9 Hz, OC6H4N)
109.03 (s, OC6H4N)
2a
2037
1983
5.27 (d, J PH ) 17.6 Hz, 2H, NH)
5.38 (s, 5H, C5H5)
6.59-6.67 (m, 8H, OC6H4N)
0.66 (s)
119.07 (s, OC6H4N)
119.64 (s, OC6H4N)
132.79 (d, J PC ) 14.7 Hz, OC6H4N)
149.21 (d, J PC ) 3.7 Hz, OC6H4N)
197.98 (d, J PC ) 22.1 Hz, CO)
198.20 (d, J PC ) 22.0 Hz, CO)
32.81 (d, J PC ) 3.7 Hz, NCH3)
87.40 (d, J PC ) 2.5 Hz, C5H5)
2b
2036
1983
3.27 (d, J PH ) 8.9 Hz, 6H, NCH3)
5.38 (d, J PH ) 1.3 Hz, 5H, C5H5)
-6.93 (s)
6.61 (d, J HH ) 7.9 Hz, 2H, OC6H4N) 107.51 (s, OC6H4N)
6.70-6.87 (m, 6H, OC6H4N)
107.58 (d, J PC ) 9.8 Hz, OC6H4N)
118.15 (s, OC6H4N)
119.01 (s, OC6H4N)
136.43 (d, J PC ) 18.2 Hz, OC6H4N)
148.45 (d, J PC ) 7.3 Hz, OC6H4N)
197.04 (d, J PC ) 20.8 Hz, CO)
197.82 (d, J PC ) 23.2 Hz, CO)
29.50 (d, J PC ) 11.8 Hz, PNCH3)b
30.73 (s, NHCH3)
91.98 (d, J PC ) 1.9 Hz, C5H5)
110.17 (d, J PC ) 6.8 Hz, OC6H4N)
112.66 (d, J PC ) 6.2 Hz, OC6H4N)
112.92 (d, J PC ) 1.8 Hz, OC6H4N)
117.20 (s, OC6H4N)
3
2084
2038
2.85 (s, 3H, NHCH3)b
3.43 (d, J PH ) 12.0 Hz, 3H, PNCH3)
4.88 (s, 1H, NHCH3)
6.16 (d, J PH ) 0.8 Hz, 5H, C5H5)
6.36-7.20 (m, 8H, OC6H4N)
147.71 (s)b
121.89 (s, OC6H4N)
122.20 (d, J PC ) 4.4 Hz, OC6H4N)
125.27 (s, OC6H4N)
128.59 (d, J PC ) 1.9 Hz, OC6H4N)
136.67 (d, J PC ) 6.8 Hz, OC6H4N)
139.44 (d, J PC ) 13.7 Hz, OC6H4N)
142.58 (d, J PC ) 3.7 Hz, OC6H4N)
148.97 (d, J PC ) 9.3 Hz, OC6H4N)
193.79 (d, J PC ) 22.4 Hz, CO)
194.03 (d, J PC ) 21.8 Hz, CO)
87.89 (d, J PC ) 2.5 Hz, C5H5)
110.31 (d, J PC ) 9.8 Hz, OC6H4O)
120.99 (s, OC6H4O)
4a
4b
2052
2001
5.41 (d, J PH ) 1.3 Hz, 5H, C5H5)
6.80-6.94 (m, 8H, OC6H4O)
47.82 (s)
47.35 (s)
144.72 (s, OC6H4O)
195.43 (d, J PC ) 23.1 Hz, CO)
87.94 (d, J PC ) 2.4 Hz, C5H5)
105.53 (d, J PC ) 9.8 Hz, OC10H6O)
124.04 (s, OC10H6O)
126.97 (s, OC10H6O)
130.01 (s, OC10H6O)
2055
2004
5.44 (d, J PH ) 1.7 Hz, 5H, C5H5)
7.26 (s, 4H, OC10H6O)
7.28-7.36 (m, 4H, OC10H6O)
7.64-7.74 (m, 4H, OC10H6O)
144.60 (s, OC10H6O)
195.06 (d, J PC ) 24.4 Hz, CO)
4cc
2051
1999
2.28 (s, CH3)
2.29 (s, CH3)
15.20 (s, CH3)
46.40 (s)
47.11 (s)
15.26 (s, CH3)
5.40 (d, J PH ) 1.7 Hz, C5H5)
5.41 (d, J PH ) 1.7 Hz, C5H5)
6.65-6.85 (m, OC6H3(CH3)O)
87.89 (d, J PC ) 2.4 Hz, C5H5)
107.76 (d, J PC ) 9.8 Hz, OC6H3(CH3)O)
108.02 (d, J PC ) 11.0 Hz, OC6H3(CH3)O)
119.86 (s, OC6H3(CH3)O)
120.13 (s, OC6H3(CH3)O)
120.19 (d, J PC ) 8.5 Hz, OC6H3(CH3)O)
120.40 (d, J PC ) 9.8 Hz, OC6H3(CH3)O)
122.48 (s, OC6H3(CH3)O)
122.88 (s, OC6H3(CH3)O)
143.14 (s, OC6H3(CH3)O)
143.45 (s, OC6H3(CH3)O)
143.86 (d, J PC ) 2.4 Hz, OC6H3(CH3)O)
144.29 (d, J PC ) 2.4 Hz, OC6H3(CH3)O)
195.75 (d, J PC ) 23.2 Hz, CO)
195.78 (d, J PC ) 23.2 Hz, CO)
195.80 (d, J PC ) 23.1 Hz, CO)
a
b
In CD2Cl2. In acetone-d6. c 4c is comprised of at least two isomers, and spectral assignment to a particular isomer is not attempted.
the corresponding metallaphosphorane. However, this
method seems not to be appropriate for ruthenium
phosphoranes, because of formation of some byproducts
which makes the purification of ruthenium phospho-
ranes difficult. This made the yield of these ruthenium
phosphoranes less than 20%.
Sp ectr oscop ic Da ta . Table 1 summarizes the IR
(νCO), 1H NMR, 13C NMR, and 31P NMR data for

Ruthenium-Phosphorane Complexes
Organometallics, Vol. 18, No. 16, 1999 2965
Ta ble 2. Com p a r ison of Sp ectr oscop ic Da ta for F e a n d Ru Com p lexes
a
complexes
M
IR: ν(CO) (cm-1
)
1H NMR: Cp, δ (ppm)b
31P NMR: δ (ppm)b
Ru (2a )
2037
1983
5.38
0.66
[Cp(CO)2M{P(OC6H4NH)2}]
Fec
Ru (2b)
2026
2036
1977
1983
4.94
5.38
25.67
-6.93
[Cp(CO)2M{P(OC6H4NMe)2}]
[Cp(CO)2M{P(OC6H4O)2}]
Fec
Ru (4a )
2024
2052
1975
2001
4.86
5.41
15.95
47.35
Fec
2042
1996
5.04
73.43
a
b
In THF. In CDCl3. c Reference 10.
ruthenium complexes isolated in this study. A compari-
son of these data shows distinct differences between
complexes 2 and 4; the former contains two O substit-
uents in apical positions and two N substitutents in
equatorial positions on the P atom, while the latter
contains only four O substitutents. In the IR spectra, two
CO absorptions of 4 were observed at higher frequencies
both by ca. 15 cm-1 than those of 2. It is believed that
the π back-donation from the filled M (dπ) orbital to the
σ* orbital of apical P-O bonds is one of the most
important factors to stabilize the M-P bond in the
metallaphosphorane complexes.6 Therefore, the IR fre-
quency differences are considered to come from the π
acidity of the σ* orbital, as follows. Since 4 has four
electronegative O atoms on P, the electron density on
P is reasonably expected to be lower in 4. This is
supported by the 31P NMR spectra; the resonance is
observed at a lower field for 4. Thus, the stronger π
back-donation (stronger π acidity of the σ*) expected for
4 leads to lower electron density on Ru in 4, thereby
causing higher νCO frequencies for 4.
position as a pivotal group. The lower energy barrier of
the pseudorotation process for 4 is interpreted in this
way. Detailed arguments about the pseudorotation
process in 4 are described later.
To investigate the bond character between a transi-
tion metal and a hypervalent phosphorus atom in [Cp-
(CO)2Ru{P(OC6H4E)2}] (E ) O, NH, NMe), we compared
their spectroscopic data with those of the Fe analogues10
(see Table 2). The following observations suggest that
the Ru-P bond is more polarized as Mδ+-Pδ- than the
Fe-P bond: (i) In the 31P NMR spectra, the Ru
complexes exhibit a signal at a ca. 24 ppm higher
magnetic field than the iron complexes. It can be thus
considered that the electron density on the phosphorus
atom is higher in the Ru complexes. (ii) For the Ru
1
complexes, the signal due to the Cp protons in the H
NMR spectrum appears at a ca. 0.4 ppm lower magnetic
field, and the CO absorption bands in the IR spectrum
appear at a ca. 10 cm-1 higher frequency, than those of
the corresponding iron complexes. These results indicate
that the electron density on the central metal is lower
in Ru complexes. The same tendency has been reported
for the related phosphonate complexes [Cp(CO)2M{P(O)-
R1R2}] (M ) Ru, Fe; R1 and/or R2 ) OMe, NC4H8),17
which also have a metal-phosphorus(V) covalent bond.
Therefore, the larger Mδ+-Pδ- polarization for Ru than
for Fe seems to be general.
Cr ysta l Str u ctu r es of 2b, 4b, a n d 3. X-ray struc-
ture analyses of 2b, 4b, and 3 were undertaken. The
ORTEP drawings of them are displayed in Figures 1-3,
and the crystal data and the selected bond distances
and angles are listed in Tables 3-6.
The X-ray structures of 2b, 4b, and 3 show that the
ruthenium takes a normal piano stool configuration
with a cyclopentadienyl ligand in η5 fashion, two
terminal CO ligands, and a phosphorus ligand as a
pentacoordinate phosphorus for 2b and 4b and as a
normal phosphite for 3. For both 2b and 4b, the five-
coordinate phosphorus adopts a distorted trigonal-
bipyramidal (tbp) geometry, but the degree of the
distortion is different. With 2b, the two apical bonds
slightly bend away from the ruthenium fragment (the
Oap-P-Oap angle is 175.9°), and in the equatorial plane,
the angles of Ru-P-Neq (121.7 and 123.7°) are slightly
greater than the ideal angle (120°), though the sum of
the equatorial angles is 359.9°. Those structural fea-
tures are the same as those of the corresponding iron
complex, Cp(CO)2Fe{P(OC6H4NMe)2}.10b In contrast,
with 4b, the two apical bonds largely bend from 180°
(the Oap-P-Oap angle is 158.0°), and in the equatorial
The 13C NMR data provide information on the behav-
ior of phosphorane complexes in solution. For 2a , two
doublets due to carbonyl carbons at 197.98 and 198.20
ppm with a coupling constant of 22.1 and 22.0 Hz,
respectively, were observed, which indicates the two
carbonyls are diastereotopic. The similar results were
obtained for 2b. Since 2b is demonstrated to have a
trigonal-bipyramidal geometry around the phosphorus
by its X-ray analysis (vide infra), 2a is also expected to
have a trigonal-bipyramidal geometry with two oxygen
atoms in apical positions. It is highly likely that the
racemization of those phosphoranes, if possible, takes
place by Berry pseudorotation. If the pseudorotation on
the pentacoordinate phosphorus should not occur, the
phosphorane P would be a chiral center. Therefore, the
above-mentioned results indicate that the pseudorota-
tion does not take place either for 2a or 2b on the NMR
time scale. Complexes 2a ,b require five transformation
pathways to complete the racemization. During these
pathways some tbp configurations have to have an
equatophilic amino and/or ruthenium group in apical
position(s), and in addition, they have to have a five-
membered chelate ring connecting two equatorial posi-
tions. Therefore, when the rings contain N and O atoms
bonded to phosphorus, like in 2a ,b, high-energy inter-
mediates are encountered during racemization by an
intramolecular process.
In contrast, only one signal assigned to carbonyl
carbons was observed for 4a ,b in the 13C NMR, and this
result suggests that the pseudorotation does occur in 4
on the NMR time scale. This is because the racemization
of 4 is attained by only one transformation pathway
where the ruthenium fragment retains an equatorial
(17) (a) Nakazawa, H.; Fujita, T.; Kubo, K.; Miyoshi, K. J . Orga-
nomet. Chem. 1994, 473, 243. (b) Nakazawa, H., Kubo, K.; Tanisaki,
K.; Kawamura, K.; Miyoshi, K. Inorg. Chim. Acta 1994, 222, 123.

2966 Organometallics, Vol. 18, No. 16, 1999
Nakazawa et al.
F igu r e 3. ORTEP drawing of 3 (50% probability el-
lipsoids), showing the numbering system. All hydrogen
-
atoms and the BF4 counterion are omitted for clarity.
F igu r e 1. ORTEP drawing of 2b (50% probability el-
lipsoids), showing the numbering system. All hydrogen
atoms are omitted for clarity.
ideal tbp geometry corresponds to 0%, and an ideal sp
geometry corresponds to 100%). Application of this
method9a to our ruthenium phosphorane complexes
provides 20.0% and 36.5% for 2b and 4b, respectively,
indicating that 4b is distorted from tbp approximately
twice as much as 2b. The difference may arise from a
strong equatophilicity of an amino group (vide infra).
The geometries around nitrogens in 2b are both
planar (sums of the angles around N1 and N2 are 359.7
and 358.9°, respectively). The O3-P1-O4 bond is
almost in both of the planes. Therefore, each nitrogen
assumes sp2 hybridization and the lone-pair electrons
lie on the equatorial plane, implying favorable π dona-
tion of the lone-pair electrons to equatorial σ* orbitals
on the phosphorus. This interaction is proposed also for
the corresponding iron phosphorus complexes10 and is
responsible for equatophilicity of an amino group and
presumably for a smaller deviation from a tbp structure
in terms of a phosphorane phosphorus.
The Ru-P bonds in 2b and 4b are 2.377(1) and 2.311-
(4) Å long, respectively. They are longer than the
corresponding Fe-P bonds simply due to a large Ru van
der Waals radius. The interesting point is that the
Ru-P bond is clearly longer (by 0.066 Å) in 2b than in
4b. This is consistent with the suggestion reported
previously that, in terms of an M(transition metal)-
P(phosphorane) bond, π back-donation from M to P is a
more important contributor than σ donation from P to
M.10b This is supported by the fact that the 0.066 Å
difference in M-P bond distance between 2b and 4b is
larger than the corresponding 0.020 Å difference be-
tween an iron phosphorane complex containing two
amino and two alkoxy groups and an iron complex
containing one amino and three alkoxy groups. That is,
the difference in π acidity of the P fragment is larger
between 2b and 4b than between the two iron com-
plexes. Another support comes from the IR data. The
νCO stretching bands of 4b (2055 and 2004 cm-1) are at
a ca. 20 cm-1 higher frequency than those of 2b (2036
and 1983 cm-1), while those of the former iron complex
F igu r e 2. ORTEP drawing of 4b (40% probability el-
lipsoids), showing the numbering system. All hydrogen
atoms are omitted for clarity.
plane, the angles of Ru-P-Oeq (113.5 and 117.6°) are
slightly smaller (not greater) than the ideal angle (120°),
though the sum of the equatorial angles is 360.0°.
The structures for many spiro-phosphorane com-
pounds of the type RP(C6H4E2)2 (R, E ) main-group
moiety) have been reported, and the degree of distortion
from tbp to square pyramidal (sp) has been estimated
by Holmes et al.18 The difference between the ideal and
observed structures is described as a percent value (an
(18) (a) Holmes, R. R. Acc. Chem. Res. 1979, 12, 257. (b) Holmes, R.
R.; Deiters, J . A. J . Am. Chem. Soc. 1977, 99, 3318.

Ruthenium-Phosphorane Complexes
Organometallics, Vol. 18, No. 16, 1999 2967
Ta ble 3. Su m m a r y of Cr ysta l Da ta for 2b, 4b, a n d 3
2b
4b
3
formula
fw
cryst syst
spece group
cell constants
a, Å
C
21H19N2O4PRu
C27H17O6PRu
569.47
orthorhombic
P212121
C21H20BF4N2O4PRu
583.25
monoclinic
P21/n
495.44
monoclinic
P2/c
13.185(2)
7.278(2)
20.987(2)
16.033(5)
7.019(2)
20.277(5)
12.716(2)
15.028(4)
13.221(3)
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
90.38(1)
107.49(2)
2014(1)
2282(1)
2410(1)
Z
D
4
1.63
8.89
4
1.66
8.01
4
1.61
7.78
calcd, g cm-3
µ, cm-1
cryst size, mm
radiation (λ, Å)
scan technique
scan range, deg
scan rate, deg min-1
no. of unique data
no. of unique data with Fo > 3σ(Fo)
R
0.75 × 0.63 × 0.45
0.60 × 0.13 × 0.07
0.12 × 0.10 × 0.10
Mo KR (0.710 73)
Mo KR (0.710 73)
Mo KR (0.710 73)
ω
ω
ω
3 < 2θ < 55
3 < 2θ < 53
3 < 2θ < 55
6.0
6.0
6.0
5048
3963
0.027
0.036
4476
1877
0.048
0.035
5753
1656
0.058
0.047
Rw
Ta ble 4. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 2b
Ta ble 5. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 4b
Bond Distances
Bond Distances
Ru1-P1
Ru1-C1
Ru1-C2
P1-O3
P1-O4
P1-N1
P1-N2
O1-C1
O2-C2
2.377(1)
1.869(3)
1.878(3)
1.771(2)
1.752(2)
1.721(2)
1.716(2)
1.142(3)
1.134(4)
O3-C8
1.357(2)
1.365(3)
1.399(3)
1.450(3)
1.397(3)
1.459(3)
1.390(3)
1.389(3)
Ru1-P1
Ru1-C26
Ru1-C27
P1-O1
2.311(4)
1.89(2)
1.87(2)
1.758(9)
1.659(8)
1.734(7)
1.673(9)
1.36(1)
O2-C10
O3-C11
O4-C20
O5-C26
O6-C27
C1-C10
C11-C20
1.38(1)
1.35(1)
1.39(1)
1.12(2)
1.15(2)
1.42(2)
1.39(1)
O4-C15
N1-C13
N1-C14
N2-C20
N2-C21
C8-C13
C15-C20
P1-O2
P1-O3
P1-O4
O1-C1
Bond Angles
Bond Angles
P1-Ru1-C26
P1-Ru1-C27
C26-Ru1-C27
Ru1-P1-O1
Ru1-P1-O2
Ru1-P1-O3
Ru1-P1-O4
O1-P1-O2
90.1(5)
90.3(5)
91.5(6)
101.8(3)
113.5(3)
100.2(3)
117.6(3)
87.6(4)
158.0(4)
81.6(4)
82.5(4)
O2-P1-O4
O3-P1-O4
P1-O1-C1
P1-O2-C10
P1-O3-C11
P1-O4-C20
O1-C1-C10
O2-C10-C1
O3-C11-C20
O4-C20-C11
128.9(4)
89.3(4)
114.5(8)
115.2(9)
113.6(7)
113.8(7)
109(1)
112(1)
111(1)
112(1)
P1-Ru1-C1
P1-Ru1-C2
C1-Ru1-C2
Ru1-P1-O3
Ru1-P1-O4
Ru1-P1-N1
Ru1-P1-N2
O3-P1-O4
O3-P1-N1
O3-P1-N2
O4-P1-N1
O4-P1-N2
N1-P1-N2
91.47(8)
87.04(8)
91.8(1)
P1-O3-C8
114.2(1)
113.2(1)
114.7(1)
127.4(2)
117.6(2)
114.1(2)
128.0(2)
116.8(2)
112.2(2)
111.2(2)
112.3(2)
110.6(2)
P1-O4-C15
P1-N1-C13
P1-N1-C14
C13-N1-C14
P1-N2-C20
P1-N2-C21
C20-N2-C21
O3-C8-C13
N1-C13-C8
O4-C15-C20
N2-C20-C15
89.57(5)
94.50(6)
121.65(7)
123.65(7)
175.92(8)
87.25(8)
90.46(9)
90.38(9)
87.51(8)
114.63(9)
O1-P1-O3
O1-P1-O4
O2-P1-O3
rane ligand revealed by the X-ray analyses are favorable
for the σ* orbital of the 3c-4e bond to accept electron
density from the HOMO of the Cp(CO)2Ru fragment.
The X-ray structure of 3 (Figure 3) reveals that 3 is
a normal ruthenium complex containing an amino-
substituted phosphite. In this complex, no transannular
interaction is observed between N2 and P1.
Ber r y P seu d or ot a t ion P r ocess of R u t h en iu m
P h osp h or a n e. To investigate a pseudorotation process
of a transition-metalated phosphorane in more detail,
we prepared 4c, which has two 3-methylcatecholate
substituents in addition to a Cp(CO)2Ru fragment on a
phosphorane phosphorus. Scheme 5 shows a graph for
possible isomers of 4c and the relationship among them
through Berry pseudorotation according to the conven-
tion.20 A brief explanation about Scheme 5 may be
pertinent. The phosphorus in 4c is surrounded by Ru
and two kinds of oxygens (O1 and O2, which are close
are at a ca. 10 cm-1 higher frequency than those of the
latter iron complex.10b
Another interesting structural feature is the orienta-
tion of the phosphorane ligand in crystals of 2b and 4b.
The Ru1-P1-O3-O4 least-squares mean plane in 2b
is situated between Cp and two COs, and torsion angles
are 30.3° for C1-Ru1-P1-O3 and 57.7° for C2-Ru1-
P1-O4 (Figure 4a). Similar values are observed for 4b,
33.3° for C26-Ru1-P1-O1 and 56.7° for C27-Ru1-
P1-O3 (Figure 4b). The σ* orbital of the apical 3-center
4-electron bond on the P is situated such that it nicely
overlaps with the HOMO of the Cp(CO)2Ru fragment
which is expected to be similar in shape to that of the
Cp(CO)2Fe fragment reported by Hoffmann et al. (Fig-
ure 4c).19 As a result, the orientations of the phospho-
(19) (a) Schilling, B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J .
Am. Chem. Soc. 1979, 101, 585. (b) Schilling, B. E. R.; Hoffmann, R.;
Faller, J . W. J . Am. Chem. Soc. 1979, 101, 592.
(20) Emsley, J .; Hall, D. In The chemistry of Phosphorus; Harper &
Row: New York, 1976.

2968 Organometallics, Vol. 18, No. 16, 1999
Nakazawa et al.
Ta ble 6. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for 3
Sch em e 5
Bond Distances
Ru1-P1
Ru1-C1
Ru1-C2
P1-O3
P1-O4
P1-N1
O1-C1
O2-C2
2.265(4)
1.89(2)
1.84(2)
1.618(8)
1.594(8)
1.66(1)
1.14(2)
1.18(2)
O3-C8
1.39(2)
1.42(1)
1.39(2)
1.47(2)
1.40(2)
1.45(2)
1.39(2)
1.39(2)
O4-C15
N1-C13
N1-C14
N2-C20
N2-C21
C8-C13
C15-C20
Bond Angles
P1-Ru1-C1
P1-Ru1-C2
C1-Ru1-C2
Ru1-P1-O3
Ru1-P1-O4
Ru1-P1-N1
O3-P1-O4
O3-P1-N1
O4-P1-N1
P1-O3-C8
94.8(6)
89.0(5)
90.3(8)
114.4(3)
109.7(4)
124.1(3)
105.4(4)
92.8(5)
P1-O4-C15
P1-N1-C13
P1-N1-C14
C13-N1-C14
C20-N2-C21
O3-C8-C13
N1-C13-C8
O4-C15-C20
N2-C20-C15
122.3(8)
113.8(8)
126(1)
120(1)
120(1)
114(1)
107(1)
120(1)
118(1)
108.2(4)
111.4(7)
F igu r e 4. (a) Newman projection along the P1-Ru1 bond
for 2b. (b) Newman projection along the P-Ru bond for
4b. (c) HOMO of the Cp(CO)2Fe fragment.
4 transformation pathways via two structures which
have a Ru fragment in an apical position. Therefore, the
two signals observed in the 31P NMR may be attributed
to 4c-O1O1/O2O2/O1O1/O2O2 and 4c-O1O2/O1O2.
The rotational feature mentioned above is further
supported by the 13C NMR data. The isolated 4c shows
three doublets due to CO carbons at 195.80, 195.78, and
195.75 ppm. Since the 4c-O1O2/O1O2 conversion ac-
companies disappearance of chirality at the phosphorus,
4c-O1O2/O1O2 gives one doublet assigned to CO. In
contrast, during the 4c-O1O1/O2O2 conversion and
equally the 4c-O1O1/O2O2 conversion, the phosphorus
chirality is not lost. Therefore, two carbonyl groups in
the Cp(CO)2Ru fragment are diastereotopic, giving rise
to two doublets in the 13C NMR spectra.
to and far from the methyl substituent, respectively).
A symbol in an oval is to denote a particular tbp
configuration by the apical atoms. An italicized symbol
shows the optical isomer of the parent compound. An
atom drawn between symbols next to each other shows
a pivot ligand about which pseudorotation converts one
isomer into another. For complex 4c, there are 10
possible configurations which can be linked by 11 Berry
pseudorotations.
A white powder isolated from the reaction of 1 with
3-methylcatechol in the presence of Et3N is a mixture
of some isomers of 4c. The 31P NMR spectrum at room
temperature shows two singlets with an integration
ratio of 1:1.17 at 47.11 and 46.40 ppm, respectively,
which are in the range of ruthenium-phosphorane
complexes. Because of equatophilicity of a transition-
metal fragment and no report of a metalated phospho-
rane with a transition-metal fragment in an apical
position, only six isomers, all of which have the ruthe-
nium fragment in an equatorial position, can be con-
sidered as possible isomers of the isolated 4c. 4c-O1O1
vs 4c-O2O2, 4c-O1O2 vs 4c-O1O2, and 4c-O2O2 vs 4c-
O1O1 are interconvertible by one transformation path-
way with the Ru fragment in an equatorial position as
a pivotal group. Therefore, two isomers in each pair are
not distinguished in NMR spectra at room temperature.
The interconversion between 4c-O1O2 and 4c-O1O2
corresponds to enantiomerization. 4c-O1O1/O2O2 is
enantiomeric to 4c-O1O1/O2O2, but they are not inter-
convertible to each other because the inversion requires
The variable-temperature 31P NMR data provide
further information on the isomerization. As mentioned
above, 4c-O1O1/O2O2 and 4c-O1O1/O2O2 show the
identical 31P NMR chemical shift, and 4c-O1O2/O1O2
shows another singlet at room temperature. Even at 183
K the 31P NMR spectrum shows two singlets, indicating
that energy barriers of pseudorotation between 4c-O1O1
and 4c-O2O2 (equally between 4c-O1O1 and 4c-O2O2),
and between 4c-O1O2 and 4c-O1O2 are very small. In
contrast, the two singlets coalesce into one broad
resonance at 340 K and then sharpened to one singlet
at higher temperatures (Figure 5). This means that
isomerization between 4c-O1O1/O2O2 and 4c-O1O2/
O1O2 (equally between 4c-O1O1/O2O2 and 4c-O1O2/
O1O2) takes place faster than the NMR time scale at
temperatures higher than 340 K.
The first-order rate constant for the isomerization
between 4c-O1O1/O2O2 and 4c-O1O2/O1O2 (equally

Ruthenium-Phosphorane Complexes
Organometallics, Vol. 18, No. 16, 1999 2969
tion of coalescence formulas,22 the activation parameters
were obtained: ∆Hq ) 42.1 ( 0.5 kJ mol-1; ∆Sq ) -91.1
( 1.6 J mol-1 K-1; ∆G340q ) 73.1 ( 0.7 kJ mol-1. These
small ∆Hq and ∆Sq values suggest that the isomeriza-
tion proceeds through the pseudorotation process but
not the mechanism involving cleavage of a P-O bond.
The activation parameters obtained here correspond to
the isomerization between 4c-O1O1/O2O2 and 4c-
O1O2/O1O2 (equally between 4c-O1O1/O2O2 and 4c-
O1O2/O1O2), which consists of two Berry pseudorota-
tion pathways. One involves the Ru fragment movement
from an equatorial to an apical position, and the other
involves the movement from an apical to an equatorial
position. Therefore, it can be said that the activation
parameters obtained here correspond to the former
pathway. This is, to our knowledge, the first report of
activation parameters of Berry pseudorotation for a
metallaphosphorane.
Ack n ow led gm en t. This work was supported by a
Grant-in-Aid for Science Research (Grant No. 10440195)
and a Grant-in Aid on Priority Area of Interelement
Chemistry (No. 09239235) from the Ministry of Educa-
tion, Science, Sports, and Culture of J apan.
F igu r e 5. 121.50 MHz variable-temperature experimental
(left) and simulated (right) 31P NMR spectra of 4c.
between 4c-O1O1/O2O2 and 4c-O1O2/O1O2) can be
estimated by a line-shape analysis.21 Simulation of VT-
NMR spectrum is displayed in Figure 5. From applica-
Su p p or tin g In for m a tion Ava ila ble: Tables giving posi-
tional and thermal parameters and bond distances and angles
for 2b, 4b, and 3 (20 pages). This material is available free of
charge via the Internet at http://pubs.acs.org.
(21) (a) DNMR5: Stephenson, D. S.; Binch, G. Program 365,
Quantum Chemistry Program Exchange, Indiana University, Bloom-
ington, IN 47405. (b) DNMR5 (IBM-PC version): LeMaster, C. B.;
LeMaster, C. L.; True, N. S. Program QCMP 059, Quantum Chemistry
Program Exchange, Indiana University, Bloomington, IN 47405.
OM990044K
(22) Sandstro¨m, J . In Dynamic NMR Spectroscopy; Academic
Press: New York, 1982; Chapters 2 and 7.