Hydrido-osmium(II), -osmium(IV) and -osmium(VI) complexes with functionalized phosphanes as ligands

Article abstract of DOI:10.1002/ejic.200900706

Reaction of five-coordinate [OsHCl(CO)(PiPr₃)₂] (1) with the chelating phosphane iPr₂PCH₂CO₂Me gave six-coordinate [OsHCl(CO)(PiPr₃)(K²(P,O)-.iPr ₂PCH₂C(=O)

Full text of DOI:10.1002/ejic.200900706

FULL PAPER
DOI: 10.1002/ejic.200900706
Hydrido-Osmium(II), -Osmium(IV) and -Osmium(VI) Complexes with
Functionalized Phosphanes as Ligands
Birgit Richter[a] and Helmut Werner*[a]
Dedicated to Professor Michael Lappert on the occasion of his 80th birthday
Keywords: Dioxygen ligands / Hydrido complexes / Hydrogen transfer / Osmium / Phosphane ligands
Reaction of five-coordinate [OsHCl(CO)(PiPr3)2] (1) with the
chelating phosphane iPr2PCH2CO2Me gave six-coordinate
[OsHCl(CO)(PiPr3){κ2(P,O)-iPr2PCH2C(=O)OMe}] (2), which
upon treatment with CO and O2 afforded the 1:1 adducts
[OsHCl(CO)(L)(PiPr3){κ(P)-iPr2PCH2CO2Me}] (3, 4) by partial
opening of the chelate ring. The vinyl complex [OsCl-
(VI) compounds [OsH6(PiPr2R)2] with R = CH2CH2OMe (12),
CH2CO2Me (13) and CH2CO2Et (14), and [OsH6(PiPr3){κ(P)-
iPr2PCH2CH2NMe2}] (16) were prepared from osmium(IV)
precursors and shown to rapidly react with O2 and primary
alcohols. Exploratory studies revealed that the catalytic ac-
tivity of the hexahydrido complexes in the hydrogen transfer
reaction from 2-propanol to cyclohexanone and aceto-
phenone depends on the type of the functionalized phos-
phane and is best for R = CH2CH2OMe.
(CH=CHPh)(CO)(PiPr3){κ2(P,O)-iPr2PCH2C(=O)OMe}]
(5)
was obtained from 2 and PhCϵCH by insertion of the alkyne
into the Os–H bond. Reaction of 2 with sodium acetate led to
metathesis of the anionic ligands and formation of [OsH(η2-
O2CCH3)(CO)(PiPr3){κ(P)-iPr2PCH2CO2Me}] (6). Osmium-
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
osmium complexes mainly with PiPr2CH2CO2Me and
PiPr2CH2CH2OMe as the coordinated phosphanes, which
were prepared by addition, substitution or insertion reac-
tions. The catalytic activity of some of the title compounds
in the hydrogen transfer from 2-propanol to cyclohexanone
and acetophenone has also been briefly investigated.
Introduction
In the course of studies to explore the catalytic potential
of coordinatively unsaturated hydrido-osmium complexes
having a 16-electron count, we reported that five-coordinate
[OsHCl(CO)(PiPr3)2] (1), in the presence of KOH or
NaBH4, serves as catalyst for hydrogen transfer from 2-pro-
panol to cyclohexanone, acetophenone,[1] benzylideneace-
tone, benzylideneacetophenone,[2] and phenylacetylene.[3]
Moreover, under a hydrogen atmosphere, complex 1 also
catalyzes the reduction of cyclohexene, 1,3- and 1,4-cyclo-
hexadiene, styrene and phenyl- and diphenylacetylene.[4,5]
After we observed that the PiPr3 ligands of 1 can easily be
replaced by chiral mono- and bisphosphanes such as
PiPr2NHCH(Me)Ph, (S,S)-Chiraphos and (S,S)-Diop,[6] we
became interested to find out whether a similar substitution
reaction would also occur with hemilabile, potentially che-
lating phosphanes. We note that the chemistry of a mani-
fold of osmium and ruthenium compounds with phosphane
ethers, phosphane esters and phosphaneamines as ligands
has recently been investigated in our laboratory as well as
by others.[7,8]
Results and Discussion
The reaction of the monohydrido-osmium(II) complex 1
(Scheme 1), which was prepared from OsCl3·3H2O and
PiPr3 in methanol,[9] with a threefold excess of PiPr2CH2-
CO2Me in pentane proceeded smoothly at room tempera-
ture and afforded the monosubstitution product 2 in almost
quantitative yield. The composition of the colorless, air-sen-
sitive solid was determined by elemental analyses and mass
spectrometry. The 1H NMR spectrum of 2 displays a
broadened signal for the hydrido ligand at room tempera-
ture, which resolves at –70 °C into a doublet-of-doublets
owing to coupling to two 31P nuclei. We assume that the
broadening of the signal is due to an equilibrium between
a five-coordinate species with a (P)-bonded and a six-coor-
dinate species with a (P,O)-bonded phosphane ester, which
is rapid on the NMR time scale at room temperature. The
chemical shift of the hydride resonance of 2 (δ –16.27 ppm)
is nearly identical to that of the analogous ruthenium com-
pound [RuHCl(CO)(PiPr3){κ2(P,O)-iPr2PCH2C(=O)OMe}]
(δ = –16.56 ppm).[7c]
As a continuation of our earlier work, we report here the
synthesis of a series of mono-, di-, tetra- and hexahydrido-
[a] Institut für Anorganische Chemie, Universität Würzburg,
Am Hubland, 97074 Würzburg, Germany
Fax: +49-931-888-4623
E-mail: helmut.werner@mail.uni-wuerzburg.de
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B. Richter, H. Werner
FULL PAPER
Scheme 1.
The 31P NMR spectrum of 2 displays two signals at δ = as [OsHCl(CO)(O2)(PCy3)2],[11] [OsHX(CO)(O2)(PR3)2] (X
47.0 and 35.8 ppm, which corresponds to an AB spin sys- = Cl, Br, I, N3, OPh; PR3 = PiPr3, PMetBu2),[4,5,12] and
tem. The large 31P,31P coupling constant of 256.8 Hz indi- [IrCl(CO)(O2)(PPh3)2].[13] This bonding mode is supported
cates that the two phosphorus atoms are trans-disposed.[7m] by a band at 853 cm–1 in the IR spectrum of 4, which ap-
Since the ν(C=O) stretching mode appears in the IR spec- pears at wavelengths that are characteristic for metal peroxo
trum of 2 at 1630 cm–1 in KBr and is thus shifted by derivatives.[14]
100 cm–1 to lower energy compared with free PiPr2CH2-
The reaction of 2 with phenylacetylene also proceeded at
CO2Me,[10] we conclude that in the solid state the function- room temperature and led to the insertion of the alkyne
alized phosphane is coordinated in a bidentate fashion. It into the Os–H bond. The yield of the insertion product 5,
is worth mentioning that even with a tenfold excess of the which like 3 and 4 is a colorless, slightly air-sensitive solid,
phosphane ester, neither the remaining PiPr3 nor the CO is virtually quantitative. Typical spectroscopic features of 5
ligand of 2 could be replaced by a second PiPr2CH2CO2Me are (1) the signals for the OsCH and =CHPh protons at δ
molecule.
= 8.35 and 6.32 ppm in the low-temperature 1H NMR spec-
Similar to the starting material 1,[4,9] the substitution trum, (2) the resonances of the vinylic carbon atoms at δ =
product 2 reacts with CO and O2 at room temperature to 140.0 and 133.8 in the 13C NMR spectrum, and (3) the
give the 1:1 adducts 3 and 4 in excellent yields. Both com- appearance of an AB spin system with signals at δ = 30.2
plexes were isolated as colorless, only slightly air-sensitive and 20.6 ppmin the 31P NMR spectrum. The H,1H cou-
1
solids, for which correct elemental analyses were obtained. pling constant for the vinyl protons is 16.1 Hz and indicates
The structures of 3 and 4 are related to the structure of 2 the formation of the E-isomer. We note that in the case of
insofar, as the entering ligand L (CO or O2) occupies the the vinyl osmium complex [OsCl(CH=CHPh)(CO)(PiPr3)2],
same coordination site which in the precursor is taken by the E-configuration of the OsCH=CHPh fragment was
the C=O oxygen of the ester group. In agreement with this, confirmed by an X-ray diffraction analysis.[15]
the 31P NMR spectra of 3 and 4 show two signals of an AB
spin system with 31P,31P coupling constants that are typical ment of chloride by acetate. The proposed structure of 6
for trans disposed phosphorus atoms.[7m]
(see Scheme 1) is mainly supported by the IR spectrum,
Treatment of 2 with NaOAc in THF led to the displace-
The IR spectra of 3 and 4 display one ν(C=O) stretching which shows two C-O stretching modes at 1520 and
mode at, respectively, 1728 cm–1 (for 3) and 1720 cm–1 (for 1470 cm–1, that are diagnostic for a bidentate OAc li-
4), confirming that the C=O oxygen atom of the ester unit gand.[16] The presence of the hydride ligand is substantiated
1
is not involved in the coordination to the metal.[10] In the by the appearance of a signal at δ –20.63 in the H NMR
IR spectrum of 3, two bands appear in the ν(CO) region, spectrum, the chemical shift being nearly identical to that
which indicates that the two carbonyl ligands are in cis dis- of [OsH(η2-O2CCH3)(CO)(PiPr3)2].[9] The 31P NMR spec-
position. The fact that the ν(CO) stretching mode of 4 (ob- trum of 6 shows the characteristics of a AB spin system
served at 1950 cm–1) is shifted by 70 cm–1 to higher wave with resonances at δ = 39.3 and 34.3. The large 31P,31P cou-
numbers compared with 1, is consistent with the well- pling constant of 264.5 Hz as well as the 31P,187Os coupling
known π-acceptor properties of the dioxygen unit. We as- constants of 188.2 (for δA) and 192.5 Hz (for δB) confirm
sume that the O2 ligand is coordinated to the metal in a the trans disposition of the two phosphorus atoms. The
side-on fashion, as was found in related compounds such 1H and 31P NMR spectra of 6 are independent of tempera-
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Eur. J. Inorg. Chem. 2009, 5433–5438

Hydrido-Osmium Complexes with Functionalized Phosphanes
ture, which proves that the molecule is not fluxional in solu- recognized, that even traces of oxygen in the solvents or test
tion.
tubes led to a facile deactivation of the catalyst. Thus, we
Following the observation, that the dihydrido- reacted 13 with an equimolar amount of O2 and isolated
osmium(IV) complex [OsH2Cl2(PiPr3)2] (7) reacts with the tetrahydrido(dioxygen) osmium(IV) compound 17
NaBH4 and methanol to give the hexahydrido-osmium(VI) (Scheme 3). In the presence of CH2=CHtBu, serving as a
derivative [OsH6(PiPr3)2] (8),[17] we prepared the analogues hydrogen acceptor, the yield of the dioxygen complex is vir-
of 8 with phosphane ethers and phosphane esters as ligands tually quantitative. The IR spectrum of 17 shows an ab-
on the same route. With 9, 10 and 11 as the starting materi- sorption for the side-on bonded O2 ligand at 875 cm–1 (see
als,[7m] we obtained the products 12, 13 and 14 either as a 4: 853 cm–1) as well as a C=O stretching mode at 1720 cm–1,
colorless air-sensitive solid (13) or air-sensitive oils (12, 14). i.e., at the same wave length as 4. The 31P NMR spectrum
The related complex 16 with one PiPr3 and one phospha- of 17 displays a singlet (split into a quintet in off-reso-
neamine ligand was obtained analogously (see Scheme 2). nance), which indicates that the two phosphane ligands oc-
The presence of six equivalent hydrido ligands in the os- cupy equivalent coordination sites.
mium(VI) compounds is confirmed by the 31P NMR spec-
tra, which for 12, 13 and 14 display a singlet and for 16
two doublets at room temperature. In off-resonance, these
1
signals transform into symmetrical septets owing to H,31P
coupling. The 1H NMR spectra of 12, 13, 14 and 16 display
a high-field resonance at, respectively, δ –9.86 (12), –9.61
(13), δ –9.64 (14) and δ –9.94 (16), which is split into a
triplet (12, 13, 14) or a doublet-of-doublets (16) through
1H,31P coupling. This illustrates that the two phosphorus
atoms of the functionalized phosphanes are in trans-dispo-
sition. At –80 °C in [D8]toluene, the 31P NMR signals of
12, 13, 14 and 16 become broader which could be due to an
intramolecular rearrangement. For other polyhydrido metal
complexes with the coordination number eight, it was pre-
viously postulated that the eight ligands can be arranged
either in a dodecahedral or square-antiprismatic fashion;
Scheme 3.
the difference in energy probably being small.[18] In the case
of [OsH6(PiPr2Ph)2], the molecular structure was deter-
The results of the hydrogen transfer experiments, where
mined by X-ray and neutron diffraction methods at low the hexahydrido complexes were prepared in situ from the
temperature and shown to be dodecahedral.[19]
dihydrides [OsH2Cl2(PR3)2] and NaBH4 in 2-propanol,[17]
are listed in Table 1. They indicate that replacing one iso-
propyl unit of PiPr3 for the ether moiety CH2CH2OMe has
only a minor effect. If one isopropyl group of PiPr3 is re-
placed by a CH2CO2R unit, the corresponding osmium
compounds 13 and 14 are significantly less active than 8
and 12. We assume that the main reason for the difference
is that with iPr2PCH2CO2Me and iPr2PCH2CO2Et as li-
gands the proposed intermediate [OsH4(PR3)2] is much
faster deactivated by 2-propanol than the corresponding
tetrahydrido species with PR3 = PiPr3 and iPr2PCH2CH2-
OMe. Support for this argument comes from the observa-
tion that we were unable to identify the osmium containing
product formed during the decomposition of 13 and 14 in
methanol. With 12 as the precursor, we found that if a solu-
tion of this compound in methanol is stirred at 60 °C, the
Scheme 2.
In comparison with 8, the catalytic activity of 12, 13 and coordinatively and electronically saturated complex cis,cis,-
14 was probed for the hydrogen transfer reaction from 2- trans-[OsH2(CO)2(iPr2PCH2CH2OMe)2] (19) is obtained. It
propanol to cyclohexanone and acetophenone. Taken the is catalytically inactive in the hydrogen transfer reaction. A
proposal into account,[17] that the osmium(VI) precursor more convenient procedure for the synthesis of 19 consists
[OsH6(PR3)2] initiate the catalytic cycle by generating an in the substitution of chloride in 18 for hydride (see
active osmium(IV) intermediate [OsH4(PR3)2] via elimi- Scheme 3), which affords the dihydrido-osmium(II) com-
nation of H2, we were tempted to find out whether the func- pound in excellent yield. The spectroscopic data of 19 are
tionalized phosphane could temporarily stabilize the tetra- quite similar to those of cis,cis,trans-[OsH2(CO)2(PiPr3)2],
hydrido-osmium(IV) species and thus facilitate the re- prepared from [OsH(η2-BH4)(CO)(PiPr3)2] and CO in
duction of the ketone. In the course of these studies we first methanol.[20]
Eur. J. Inorg. Chem. 2009, 5433–5438
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5435

B. Richter, H. Werner
FULL PAPER
2
3
(100.6 MHz, CDCl3): δ = 185.9 (dd, JP,C = 13.4, JP,C = 4.9 Hz,
Table 1. Results of the hydrogen transfer reactions from 2-propanol
to cyclohexanone (Cy) and acetophenone (Ac) with the hexahyd-
rido-osmium(VI) complexes 8 and 12–14 as the catalyst precursor.
The conversion of the ketones (Cy and Ac) into the alcohols (CyH2
and AcH2) are given in prozent (%) at a particular reaction time
(see the first horizontal line). Reactions conditions are described in
the Exp. Section.
2
CO2Me), 183.1 (dd, JP,C
=
2JPЈ,C = 8.5 Hz, OsCO), 54.9 (s,
CO2CH3), 33.0 (d, 1JP,C = 23.2 Hz, PCH2), 25.2 (d, 1JP,C = 25.6 Hz,
1
PCHCH3 of iPr2P), 24.4 (d, JP,C = 23.2 Hz, PCHCH3 of PiPr3),
23.6 (d, JP,C = 25.6 Hz, PCHCH3 of iPr2P), 19.8, 19.2 (both s,
1
PCHCH3 of PiPr3), 19.4, 18.9, 18.8, 18.4 (all s, PCHCH3 of iPr2P)
ppm. 31P NMR (162.0 MHz, CDCl3): AB spin system: δA = 47.0
(1JOs,P = 181.8, JP,P = 256.8 Hz, d in off-resonance), δB = 35.8
2
Catalyst t [min]:
5
15
98
30
60
180
360
(1JOs,P = 192.9, JP,P = 256.8 Hz, d in off-resonance) ppm.
2
8
% CyH2
% CyH2
% CyH2
% CyH2
C19H41ClO3OsP2 (605.1): calcd. C 37.71, H 6.83; found C 37.43, H
6.90.
12
13
14
98
5
4
7
6
9
8
16
16
25
27
[OsHCl(CO)2(PiPr3){κ(P)-iPr2PCH2CO2Me}] (3): A slow stream
of CO was passed through a solution of 2 (179 mg, 0.30 mmol) in
benzene (5 mL) for 10 min at room temperature. The solvent was
evaporated in vacuo, and the oily residue suspended in pentane
(2 mL). After the suspension was stirred for 5 min, a colorless solid
precipitated, which was filtered, washed three times with 10-mL
portions of pentane and dried; yield 165 mg (88%); m.p. 86 °C
Catalyst t [min]:
5
10
53
15
24
45
47
120
240
8
% AcH2
% AcH2
% AcH2
% AcH2
10
21
2
60
63
12
13
14
4
17
2
(dec.). IR (KBr): ν = 2040 [ν(OsH)], 1970, 1910 [ν(CO)], 1730
˜
[ν(C=O)] cm–1. 1H NMR (400 MHz, CDCl3): δ = 3.63 (s, 3 H,
OCH3), 3.20 (AB part of an ABX spin system, iPr2PCH2CO2Me,
In summary, the present work has shown that the six-
coordinate complex 2, containing the functionalized phos-
phane ester iPr2PCH2CO2Me as ligand, is a useful starting JA,B = 14.3, JA,X = JB,X = 9.1 Hz, 2 H, A and B = H, X = P of
iPr2P, δA = 3.22, δB = 3.19), 2.50 (m, 5 H, PCHCH3 of PiPr3 and
material for the preparation of a series of monohydrido and
monovinyl osmium(II) derivatives. Several hexahydrido-
osmium(VI) complexes with ether-, ester- and amine-substi-
tuted phosphanes were obtained from dihydrido-os-
mium(IV) precursors. They are rather labile and readily re-
act with oxygen and primary alcohols. The catalytic activity
of the hexahydrido compounds [OsH6(PiPr2R)2] (12–14) in
the hydrogen transfer reaction from 2-propanol to cyclo-
hexanone and acetophenone depends on the type of the
phosphane ligand and is best for R = CH2CH2OMe.
3
iPr2P), 1.24 (dvt, JH,H = 6.7, N = 13.6 Hz, 18 H, PCHCH3 of
PiPr3), 1.15 (m, 12 H, PCHCH3 of iPr2P), –5.17 (dd, 2JP,H = 2JPЈ,H
= 21.2 Hz, 1 H, OsH) ppm. 13C NMR (100.6 MHz, CDCl3): δ =
2
2
2
2
186.6 (dd, JP,C = JPЈ,C = 5.4 Hz, OsCO), 178.5 (dd, JP,C = JPЈ,C
2
3
= 8.2 Hz, OsCO), 171.6 (dd, JP,C = 8.2, JP,C = 2.3 Hz, CO2Me),
52.5 (s, CO2CH3), 28.8 (d, JP,C = 16.7 Hz, PCH2), 26.0 (d, JP,C
1
1
=
1
27.9 Hz, PCHCH3 of iPr2P), 25.2 (d, JP,C = 25.9 Hz, PCHCH3 of
PiPr3), 25.0 (d, 1JP,C = 27.0 Hz, PCHCH3 of iPr2P), 19.6, 19.5 (both
4
s, PCHCH3 of PiPr3), 18.3 (d, JP,C = 2.0 Hz, PCHCH3 of iPr2P),
4
18.2 (d, JP,C = 2.5 Hz, PCHCH3 of iPr2P), 17.7, 17.6 (both s,
PCHCH3 of iPr2P) ppm. 31P NMR (162.0 MHz, CDCl3) AB spin
system: δA = 30.2 (1JOs,P = 169.3, JP,P = 220.8 Hz, d in off-reso-
2
nance), δB = 20.6 (1JOs,P = 169.0, JP,P = 220.8 Hz, d in off-reso-
2
Experimental Section
nance) ppm. C20H41ClO4OsP2 (633.1): calcd. C 37.94, H 6.53;
found C 38.12, H 6.80.
General: All operations were carried out under argon using Schlenk
techniques. The osmium complexes 1,[9] 7, 8,[17] 9–11, 15 and 18[7m]
were prepared as described in the literature. – NMR: Jeol FX 90
Q, Bruker AC 200 and AMX 400. IR: Perkin–Elmer 397 and
1320. – Mass spectra: Varian CH 7 MAT (70 eV). Melting points
determined by DTA. Abbreviations used: s, singlet; d, doublet; t,
triplet; q, quartet; quint, quintet; sept, septet; m, multiplet; vt, vir-
[OsHCl(CO)(O2)(PiPr3){κ(P)-iPr2PCH2CO2Me}] (4):
A
slow
stream of O2 was passed through a solution of 2 (236 mg,
0.41 mmol) in CH2Cl2 (5 mL) for 2 min at room temperature. After
the solvent was evaporated in vacuo, the oily residue was worked
up as described for 3. Colorless solid; yield 230 mg (88%); m.p.
tual triplet; br, broadened signal; N = 3JP,H + 5JP,H or 2JP,C + 4JP,C
.
90 °C (dec.). IR (KBr): ν = 2110 [ν(OsH)], 1950 [ν(CO)], 1720
˜
[ν(C=O)], 855 [ν(O2)] cm–1. 1H NMR (200 MHz, CDCl3): δ = 3.71
(s, 3 H, OCH3), 3.58 (AB part of an ABX spin system, A and B =
H, X = P of iPr2P, correct coupling constants not determined due
to overlap of respective signals, 2 H, iPr2PCH2CO2Me), 2.92 (m, 5
1
The coupling constants JOs,P were determined from the satellites
that belongs to the 31P NMR signals.[21]
[OsHCl(CO)(PiPr3){κ2(P,O)-iPr2PCH2C(=O)OMe}] (2): A sus-
pension of 1 (207 mg, 0.31 mmol) in pentane (20 mL) was treated
with iPr2PCH2CO2Me (211 µL, 1.08 mmol) and stirred for 4 h at
room temperature. A colorless, air-sensitive solid precipitated,
which was filtered, washed three times with 10-mL portions of pen-
tane and dried; yield 199 mg (91%); m.p. 96 °C (dec.). MS: m/z(Ir)
H, PCHCH3 of PiPr3 and iPr2P), 1.43 (m, 30 H, PCHCH3 of iPr2P
2
and PiPr3), –2.95 (dd, JP,H
=
2JPЈ,H = 31.0 Hz, 1 H, OsH) ppm.
31P NMR (81.0 MHz, CDCl3) AB spin system: δA = 28.7 (2JP,P
=
90.8 Hz, d in off-resonance), δB = 18.2 (2JP,P = 90.8 Hz, d in off-
resonance) ppm. C19H41ClO5OsP2 (637.1): calcd. C 35.82, H 6.49;
found C 35.72, H 6.76.
= 606 (3.4) [M+]; 570 (3.3) [M+ – Cl]. IR (KBr): ν = 2125 [ν(OsH)],
˜
1880 [ν(CO)], 1630 [ν(C=O)] cm–1. 1H NMR (400 MHz, CDCl3,
25 °C): δ = 3.74 (s, 3 H, OCH3), 3.05 (AB part of an ABX spin
system, iPr2PCH2CO2Me, JA,B = 16.8, JA,X = JB,X = 8.6 Hz, 2 H,
A and B = H, X = P of iPr2P, δA = 3.07, δB = 3.03), 2.57 (m, 3 H,
PCHCH3 of PiPr3), 2.75, 2.32 (both m, 1 H each, PCHCH3 of
[OsCl(CH=CHPh)(CO)(PiPr3){κ2(P,O)-iPr2PCH2C(=O)OMe}] (5):
A solution of 2 (150 mg, 0.25 mmol) in benzene (10 mL) was
treated with phenylacetylene (45 µL, 0.30 mmol) and stirred for
30 min at room temperature. The solvent was evaporated in vacuo
iPr2P), 1.30 (br. m, 27 H, PCHCH3 of PiPr3 and iPr2P), 1.17 (dd, and the residue dissolved in pentane (10 mL). After the solution
3
3JP,H = 15.2, JH,H = 6.9 Hz, 3 H, PCHCH3 of iPr2P), –17.86 (br.,
was stored for 2 h, a colorless solid precipitated. It was filtered,
washed three times with 5-mL portions of pentane and dried; yield
1
1 H, OsH) ppm. H NMR (90 MHz, CDCl3, –70 °C): δ = –16.27
2
(dd, JP,H
=
2JPЈ,H = 14.9 Hz, 1 H, OsH) ppm. 13C NMR 156 mg (89%); m.p. 110 °C (dec.). MS: m/z(Ir) = 708 (0.2) [M+];
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Hydrido-Osmium Complexes with Functionalized Phosphanes
2
604 (0.2) [M+ – CH=CHPh], 540 (10.7) [M+ – CO – PhCH=CHCl]. H, PCHCH3), –9.86 (t, JP,H = 9.6 Hz, 6 H, OsH) ppm. 31P NMR
IR (KBr): ν = 1880 [ν(CO)], 1625 [ν(C=O)] cm–1. 1H NMR
(81.0 MHz, C6D6): δ = 38.4 (s; sept in off-resonance) ppm.
C18H48O2OsP2 (548.72): calcd. C 39.40, H 8.82; found C 40.10, H
9.29.
˜
(200 MHz, C6D6): δ = 8.64 (br., 1 H, OsCH=CHPh), 7.12, 6.96,
3
6.67 (all m, 5 H, C6H5), 6.61 (br. d, JH,H = 16.0 Hz, 1 H,
OsCH=CHPh), 2.93 (s, 3 H, OCH3), 2.65, 2.50 (both m, 7 H, PCH2
and PCHCH3), 1.05 (dvt, 3JH,H = 7.4, N = 12.3 Hz, 18 H, PCHCH3
of PiPr3), 0.75 (m, 12 H, PCHCH3 of iPr2P) ppm. 1H NMR
[OsH6{κ(P)-iPr2PCH2CO2Me}2] (13): This compound was pre-
pared as described for 12, with 10 (68 mg, 0.11 mmol), an excess
of NaBH4 (ca. 0.5 g) and methanol (1 mL) as starting materials.
After the solution was filtered and the filtrate evaporated in vacuo,
a grey residue remained, which was recrystallized from hexane
(1 mL) at –78 °C to give a colorless air-sensitive solid; yield 22 mg
3
(200 MHz, CDCl3, –60 °C): δ = 8.35 (d, JH,H = 16.1 Hz, 1 H,
OsCH=CHPh), 6.32 (d, 3JH,H = 16.1 Hz, 1 H, OsCH=CHPh) ppm.
13C NMR (50.3 MHz, C6D6): δ = 187.6, 185.4 (both br, Os(CO)
and CO2Me), 143.6 (s, ipso-C of C6H5), 140.0 (br., CH=CHPh),
133.8 (s, CH=CHPh), 128.6, 124.2, 123.4 (all s, C6H5), 55.9 (s,
CO2CH3), 33.4 (d, 1JP,C = 24.0 Hz, PCH2), 25.8 (d, 1JP,C = 27.9 Hz,
(36%); m.p. 50 °C (dec.). IR (pentane): ν = 1980, 1895 [ν(OsH)],
˜
1
1725 [ν(C=O)] cm–1. H NMR (200 MHz, C6D6): δ = 3.29 (s, 6 H,
OCH3), 2.90 (vt, N = 8.1 Hz, 4 H, PCH2), 1.92 (m, 4 H, PCHCH3),
1
PCHCH3 of iPr2P), 24.9 (d, JP,C = 23.4 Hz, PCHCH3 of PiPr3),
3
1.13 (dvt, N = 16.5, JH,H = 6.9 Hz, 12 H, PCHCH3), 1.05 (dvt, N
20.0, 19.6 (both s, PCHCH3 of PiPr3), 19.8, 19.4, 18.9, 18.6 (all s,
PCHCH3 of iPr2P) ppm. 31P NMR (81.0 MHz, C6D5CD3, –40 °C)
AB spin system: δA = 31.4 (2JP,P = 253.4 Hz, d in off-resonance), δB
= 16.5 (2JP,P = 253.4 Hz, d in off-resonance) ppm. C27H47ClO3OsP2
(707.2): calcd. C 45.86, H 6.70; found C 45.33, H 7.01.
3
2
= 15.0, JH,H = 6.7 Hz, 12 H, PCHCH3), –9.61 [t, JP,H = 9.6 Hz,
6 H, OsH] ppm. 31P NMR (81.0 MHz, C6D6): δ = 44.6 (s; sept in
off-resonance) ppm. C18H44O4OsP2 (576.7): calcd. C 37.49, H 7.69;
found C 37.06, H 7.75.
[OsH6{κ(P)-iPr2PCH2CO2Et}2] (14): This compound was prepared
as described for 12, with 11 (33 mg, 0.05 mmol), an excess of
NaBH4 (ca. 0.5 g) and methanol (1 mL) as starting materials. A
colorless air-sensitive oil was obtained; yield 28 mg (96%). IR (pen-
[OsH(η2-O2CCH3)(CO)(PiPr3){κ(P)-iPr2PCH2CO2Me}] (6):
A
solution of 2 (105 mg, 0.17 mmol) in THF (10 mL) was treated
with an excess of sodium acetate (ca. 1 g) and stirred for 15 min
under reflux. After the solution was cooled to room temperature,
the solvent was evaporated in vacuo. The residue was extracted
twice with benzene (10 mL each) and the combined extracts were
dried in vacuo. A colorless solid was obtained, which was washed
three times with 5-mL portions of pentane and dried; yield 81 mg
tane): ν = 1965, 1880 [ν(OsH)], 1720 [ν(C=O)] cm–1. 1H NMR
˜
3
(200 MHz, C6D6): δ = 3.81 (q, JH,H = 6.9 Hz, 4 H, OCH2CH3),
2.91 (vt, N = 7.9 Hz, 4 H, PCH2), 1.96 (m, 4 H, PCHCH3), 1.13
3
(m, 24 H, PCHCH3), 1.04 (t, JH,H = 6.9 Hz, 6 H, OCH2CH3),
2
–9.64 (t, JP,H = 9.6 Hz, 6 H, OsH) ppm. 31P NMR (81.0 MHz,
(74%); m.p. 71 °C (dec.). IR (KBr): ν = 2120 [ν(OsH)], 1880
˜
1
C6D6): δ = 44.75 (s, JOs,P = 138.0 Hz; sept in off-resonance) ppm.
[ν(CO)], 1715 [ν(C=O)], 1520, 1470 [ν(O2CCH3)] cm–1. 1H NMR
(400 MHz, C6D6): δ = 3.29 (s, 3 H, OCH3), 2.96 (AB part of an
C20H48O4OsP2 (604.8): calcd. C 39.72, H 8.00; found C 39.64, H
8.35.
ABX spin system, iPr2PCH2CO2Me, JA,B = 13.9, JA,X = JB,X
=
[OsH6(PiPr3){κ(P)-iPr2PCH2CH2NMe2}] (16): This compound
was prepared as described for 12, with 15 (60 mg, 0.10 mmol), an
excess of NaBH4 (ca. 0.5 g) and methanol (1 mL) as starting mate-
7.4 Hz, 2 H, A and B = H, X = P of iPr2P, δA = 3.01, δB = 2.92),
2.62, 2.50 (both m, 1 H each, PCHCH3 of iPr2P), 2.30 (m, 3 H,
3
PCHCH3 of PiPr3), 1.56 (s, 3 H, O2CCH3), 1.45 (dd, JP,H = 15.5,
3
3JH,H = 7.1 Hz, 3 H, PCHCH3 of iPr2P), 1.32 (dd, JP,H = 14.6,
rials. A colorless air-sensitive oil was obtained; yield 41 mg (76%).
1
IR (pentane): ν = 1965, 1890 [ν(OsH)] cm–1. H NMR (400 MHz,
3
3JH,H = 6.7 Hz, 3 H, PCHCH3 of iPr2P), 1.27 (dd, JP,H = 13.1,
˜
3
3JH,H = 7.0 Hz, 3 H, PCHCH3 of PiPr3), 1.23 (br. d, JH,H
=
=
=
=
C6D6): δ = 2.98 (m, 2 H, CH2NMe2), 2.09 (s, 6 H, NCH3), 2.02,
1.72, 1.56 (all m, 7 H, PCH2 and PCHCH3), 1.08 (dd, 3JP,H = 13.9,
3
3
7.1 Hz, 3 H, PCHCH3 of iPr2P), 1.20 (dd, JP,H = 12.4, JH,H
3
3JH,H = 7.1 Hz, 18 H, PCHCH3 of PiPr3), 1.00 (dd, JP,H = 14.4,
3
3
7.1 Hz, 9 H, PCHCH3 of PiPr3), 1.15 (dd, JP,H = 12.5, JH,H
2
2
3JH,H = 6.9 Hz, 6 H, PCHCH3 of iPr2P), –9.94 (dd, JP,H = JPЈ,H
2
7.0 Hz, 3 H, PCHCH3 of iPr2P), –20.63 (dd, JP,H
=
2JPЈ,H
16.0 Hz, 1 H, OsH) ppm. 13C NMR (100.6 MHz, C6D6): δ = 184.1
= 10.0 Hz, 6 H, OsH), one signal for PCHCH3 of iPr2P not exactly
2
located ppm. 31P NMR (162.0 MHz, C6D6): δ = 57.2 (d, JP,P
=
=
(s, O2CCH3), 183.7 (dd, 2JP,C = 16.3, 2JPЈ,C = 8.9 Hz, OsCO), 170.8
1
2
2
3
134.9, JOs,P = 131.0 Hz; sept in off-resonance), 41.15 (d, JP,P
(dd, JP,C = 8.5, JP,C = 2.4 Hz, CO2Me), 51.3 (s, CO2CH3), 26.7
134.9, 1JOs,P = 128.8 Hz; sept in off-resonance) ppm. C19H51NOsP2
(545.7): calcd. C 41.81, H 9.42, N 2.57; found C 41.61, H 10.01, N
2.32.
1
1
3
(d, JP,C = 9.0 Hz, PCH2), 25.8 (dd, JP,C = 24.0, JP,C = 2.0 Hz,
PCHCH3 of PiPr3), 25.7 (dd, 1JP,C = 22.6, 3JP,C = 1.5 Hz, PCHCH3
of iPr2P), 25.3 (s, O2CCH3), 20.3, 19.4 (both s, PCHCH3 of PiPr3),
2
18.6 (d, JP,C = 3.2 Hz, PCHCH3 of iPr2P), 18.5 (s, PCHCH3 of
[OsH4(O2){κ(P)-iPr2PCH2CO2Me}2] (17): A solution of 13 (81 mg,
0.14 mmol) in benzene (5 mL) was treated with CH2=CHtBu (ca.
0.5 g) and, after a trace of air was passed through, was stirred for
2 h under reflux. The solution was brought to room temperature,
and the solvent was evaporated in vacuo. The remaining red-brown
oil was washed twice with hexane (1 mL) and dried; yield 80 mg
2
2
PiPr3), 18.0 (d, JP,C = 3.6 Hz, PCHCH3 of PiPr3), 17.4 (d, JP,C
=
2.2 Hz, PCHCH3 of PiPr3) ppm. 31P NMR (162.0 MHz, C6D6):
AB spin system: δA = 39.3 (1JOs,P = 188.2, JP,P = 264.5 Hz, d in
2
off-resonance), δB = 34.3 (1JOs,P = 192.5, 2JP,P = 264.5 Hz, d in off-
resonance) ppm. C21H44O5OsP2 (628.7): calcd. C 40.12, H 7.05;
found C 40.19, H 7.35.
(93%). IR (KBr): ν = 1935, 1875 [ν(OsH)], 1720 [ν(C=O)], 875
˜
[OsH6{κ(P)-iPr2PCH2CH2OMe}2] (12): A solution of 9 (66 mg, [ν(O2)] cm–1. 1H NMR (200 MHz, C6D6): δ = 3.25 (s, 6 H, OCH3),
0.11 mmol) in benzene (8 mL) was treated with an excess of NaBH4
(ca. 0.5 g) and methanol (1 mL). The mixture was stirred at room
temperature until the evolution of gaseous byproducts stopped.
The solution was filtered, and the filtrate was evaporated in vacuo.
An off-white air-sensitive oil was obtained; yield 54 mg (92%). IR
2.92 (d, 2JP,H = 8.4 Hz, 4 H, PCH2), 2.18 (m, 4 H, PCHCH3), 1.33
3
3
3
(dd, JP,H = 16.7, JH,H = 6.9 Hz, 12 H, PCHCH3), 1.23 (dd, JP,H
3
= 15.3, JH,H = 6.9 Hz, 12 H, PCHCH3), –12.78 (br., 4 H, OsH)
ppm. 13C NMR (50.3 MHz, C6D6): δ = 171.6 (dd, JP,C = 9.8 Hz,
2
1
CO2Me), 51.6 (s, CO2CH3), 41.2 (br. m, PCH2), 30.0 (d, JP,C
=
(pentane): ν = 1965, 1890 [ν(OsH)] cm–1. 1H NMR (200 MHz,
45.0 Hz, PCHCH3), 20.3, 20.1 (both s, PCHCH3) ppm. 31P NMR
˜
C6D6): δ = 3.59 (m, 4 H, OCH2), 3.13 (s, 6 H, OCH3), 2.01 (m, 4 (81.0 MHz, C6D6): δ = 43.2 (s; quint in off-resonance) ppm.
3
H, PCH2), 1.57 (m, 4 H, PCHCH3), 1.04 (dvt, N = 15.5, JH,H
=
C18H42O6OsP2 (606.7): calcd. C 35.64, H 6.98; found C 36.01, H
7.01.
3
7.1 Hz, 12 H, PCHCH3), 0.95 (dvt, N = 14.6, JH,H = 7.1 Hz, 12
Eur. J. Inorg. Chem. 2009, 5433–5438
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5437

B. Richter, H. Werner
FULL PAPER
1025–1027; b) B. Weber, P. Steinert, B. Windmüller, J. Wolf, H.
Werner, J. Chem. Soc., Chem. Commun. 1994, 2595–2596; c) H.
Werner, A. Stark, P. Steinert, C. Grünwald, J. Wolf, Chem. Ber.
1995, 128, 49–62; d) H. Werner, G. Henig, U. Wecker, N. Mahr,
K. Peters, H. G. von Schnering, Chem. Ber. 1995, 128, 1175–
1181; e) J. Bank, O. Gevert, W. Wolfsberger, H. Werner, Orga-
nometallics 1995, 14, 4972–4974; f) T. Braun, P. Steinert, H.
Werner, J. Organomet. Chem. 1995, 488, 169–176; g) J. Bank,
P. Steinert, B. Windmüller, W. Wolfsberger, H. Werner, J. Chem.
Soc., Dalton Trans. 1996, 1153–1159; h) M. Martín, O. Gevert,
H. Werner, J. Chem. Soc., Dalton Trans. 1996, 2275–2283; i) G.
Henig, M. Schulz, H. Werner, Chem. Commun. 1997, 2349–
2350; j) G. Henig, H. Werner, Z. Naturforsch., Teil B 1998, 53,
540–544; k) H. Werner, G. Henig, B. Windmüller, O. Gevert,
C. Lehmann, R. Herbst-Irmer, Organometallics 1999, 18, 1185–
1195; l) H. Werner, J. Bank, B. Windmüller, O. Gevert, W.
Wolfsberger, Helv. Chim. Acta 2001, 84, 3162–3177; m) B. We-
ber, H. Werner, Eur. J. Inorg. Chem. 2007, 2072–2082.
[8] Reviews: a) A. Bader, E. Lindner, Coord. Chem. Rev. 1991, 108,
27–110; b) E. Lindner, S. Pautz, M. Haustein, Coord. Chem.
Rev. 1996, 155, 145–162; c) C. S. Slone, D. A. Weinberger, C. A.
Mirkin, Prog. Inorg. Chem. 1999, 48, 233–250; d) P. Braunstein,
J. Organomet. Chem. 2004, 689, 3953–3967; e) P. Braunstein,
Chem. Rev. 2006, 106, 134–159.
cis,cis,trans-[OsH2(CO)2{κ(P)-iPr2PCH2CH2OMe}2] (19): A solu-
tion of 18 (45 mg, 0.07 mmol) in diethyl ether (10 mL) was treated
with an excess of LiAlH4 (ca. 0.3 g) and stirred for 2 d under reflux.
After the solution was cooled to room temperature, the solvent
was evaporated in vacuo, and the residue was extracted twice with
benzene (10 mL each). The combined extracts were dried in vacuo,
the colorless oily residue was washed with hexane (1 mL) and dried;
yield 31 mg (78%). IR (pentane): ν = 1995, 1975 [ν(CO)], 1915,
˜
1855 [ν(OsH)] cm–1. 1H NMR (200 MHz, C6D6): δ = 3.70 (m, 4 H,
OCH2), 3.16 (s, 6 H, OCH3), 2.10 (m, 4 H, PCH2), 1.77 (m, 4 H,
3
PCHCH3), 1.10 (dvt, N = 16.1, JH,H = 7.1 Hz, 12 H, PCHCH3),
3
0.97 (dvt, N = 14.2, JH,H = 6.9 Hz, 12 H, PCHCH3), –9.64 (t,
2JP,H = 22.7 Hz, 2 H, OsH) ppm. 13C NMR (50.3 MHz, C6D6): δ
2
= 186.8 (t, JP,C = 6.3 Hz, OsCO), 71.2 (s, OCH2), 58.2 (s, OCH3),
28.2 (vt, N = 16.1 Hz, PCH2), 20.2 (vt, N = 12.9 Hz, PCHCH3),
19.0, 18.4 (both s, PCHCH3) ppm. 31P NMR (81.0 MHz, C6D6): δ
1
=
23.5 (s, JOs,P
=
162.8 Hz;
t
in off-resonance) ppm.
C20H44O4OsP2 (600.7): calcd. C 40.00, H 7.38; found C 40.37, H
7.71.
Catalytic Studies: The reactions were carried out under argon with
magnetic stirring, in a 25 mL round-bottom flask fitted with a con-
denser and provided with a serum cap. In a typical procedure, a
solution of the catalyst precursor [OsH6(PR3)2] (8, 12–14) prepared
in situ from [OsH2Cl2(PR3)2] (7, 9–11) (0.02 mmol) and NaBH4
(1.0 mmol) in 5 mL of 2-propanol, was stirred for 1 h under reflux,
and then a solution of cyclohexanone or acetophenone (2.0 mmol)
in 3 mL of 2-propanol was injected. The progress of the reactions
were monitored by a Perkin–Elmer 8900 gas chromatograph with
a flame ionization detector and an FFAP on Chromosorb GHP
80/100 mesh column (3.6ϫ1/8 in.) at 160 °C. The results are sum-
marized in Table 1.
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Acknowledgments
[15] H. Werner, M. A. Esteruelas, H. Otto, Organometallics 1986,
This work was supported by the Deutsche Forschungsgemeinschaft
(DFG) and the Fonds der Chemischen Industrie. We thank Mrs.
R. Schedl and Mr. C. P. Kneis for elemental analyses and DTA
measurements, Dr. G. Lange and Mr. F. Dadrich for mass spectra,
and Professors Luis A. Oro and Miguel Esteruelas for providing
their gas chromatographic equipment.
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Received: July 23, 2009
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Published Online: November 5, 2009
5438
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Eur. J. Inorg. Chem. 2009, 5433–5438