Chelating phosphane-boranes as hemilabile ligands - Synthesis of [Mn(CO)3(η2-H3B·dppin)][BAr F4] and [Mn(CO)4(η1-H3B· dppm)][BArF4]

Article abstract of DOI:10.1002/ejic.200600526

Manganese complexes bearing the chelating phosphaneborane ligand H ₃B·dppm [dppm = bis(diphenylphosphanyl)-methane] have been prepared. Addition of H₃B·dppm to Mn(CO)₅Br using Na[BAr^F₄] as a halide-abstracting reagent affords [Mn(CO)₃(η²-H₃B·dppm)][BAr ^F₄] (1). This reacts with CO to open the bidentate borane to afford [Mn(CO)₄(η¹-H₃B·dppm)] [BAr^F₄] (2) in which the borane is now bound in a monodentate manner. The CO addition is reversible, and placing 2 under vacuum (hours) regenerates 1 quantitatively, demonstrating that the chelating phosphane-boranes can act as hemilabile ligands. The complexes 1 and 2 have been fully characterised by NMR spectroscopy and X-ray crystallography. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.

Full text of DOI:10.1002/ejic.200600526

FULL PAPER
DOI: 10.1002/ejic.200600526
Chelating Phosphane–Boranes as Hemilabile Ligands – Synthesis of
[Mn(CO)3(η2-H3B·dppm)][BArF ] and [Mn(CO)4(η1-H3B·dppm)][BArF ]
4
4
Nicolas Merle,[a] Christopher G. Frost,[a] Gabriele Kociok-Köhn,[a] Michael C. Willis,[a] and
Andrew S. Weller*[a]
Keywords: Boranes / Catalysis / Hemilabile ligands / Manganese / Phosphanes
Manganese complexes bearing the chelating phosphane–
borane ligand H3B·dppm [dppm = bis(diphenylphosphanyl)-
methane] have been prepared. Addition of H3B·dppm to
Mn(CO)5Br using Na[BArF4] as a halide-abstracting reagent
affords [Mn(CO)3(η2-H3B·dppm)][BArF4] (1). This reacts with
CO to open the bidentate borane to afford [Mn(CO)4(η1-
H3B·dppm)][BArF4] (2) in which the borane is now bound in
a monodentate manner. The CO addition is reversible, and
placing 2 under vacuum (hours) regenerates 1 quantitatively,
demonstrating that the chelating phosphane–boranes can act
as hemilabile ligands. The complexes 1 and 2 have been fully
characterised by NMR spectroscopy and X-ray crystallogra-
phy.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2006)
Introduction
Reactions catalysed by Lewis acid transition metal frag-
ments invariably rely on the generation of a vacant site on
a cationic metal centre. Often this is generated by dissoci- Scheme 1.
ation of a weakly bound ligand (e.g. solvent)[1] or anion.[2]
An alternative mechanism – when a suitable ligand set is
available – is one that involves a hemilabile ligand,[3–5] in
which one donor atom in a chelate ligand has the ability
One way of preventing borane loss would be to include
to reversibly decoordinate in a catalytic cycle to reveal a
coordinatively unsaturated metal centre. The design of hem-
ilabile ligands is often based on ligands in which one end is
a phosphane (which binds strongly) and the other a more
weakly ligating group that can move away to generate a
vacant site (Scheme 1). Examples of the weakly binding
group include phosphane oxides,[6] sulfides,[7,8] and ether
groups.[9] As pointed out nearly 30 years ago by Marks,[10]
[BH4]– can also potentially be a hemilabile ligand, by mov-
ing from η2- to η1-coordination modes (Scheme 1), thus
generating the vacant site needed for substrate coordina-
tion. Examples of borohydride acting in this way are rare
however, as on addition of ligand L loss of H3B·L often
occurs with the concomitant generation of a metal hy-
dride.[11,12] A recently reported observation of η2- to η1-
borohydride hemilability comes from the addition of Lewis
base (e.g. PMe2Ph) to Ru(PMe2Ph)2H(CO)(η2-BH4) to af-
ford Ru(PMe2Ph)3H(CO)(η1-BH4), although at tempera-
tures above 300 K H3B·PMe2Ph is irreversibly lost to gener-
ate Ru(PMe2Ph)3H2(CO).[13]
the borohydride ligand in a chelate ring, allowing this po-
tentially useful η2- to η1-transformation to occur without
decomposition. Others[14,15] and we[16–18] have recently re-
ported on the coordination chemistry of chelating phos-
phane–boranes XH2B·dppm (X
= H, Cl, dppm =
PPh2CH2PPh2) in which one end of the ligand is valence-
isoelectronic with borohydride while the other provides a
firm phosphane anchor to the metal centre. These ligands
show promise for hemilabile behaviour as the cationic com-
plexes [RuCp*(η2-XH2B·dppm)][Y] [X = H (I), Cl (II); Cp*
= η5-C5Me5; Y = BArF4; PF6] react with Lewis bases (CO,
PMe3) to open the borane from η2 to η1, thus forming
[RuCp*(L)(η1-XH2B·dppm)]+ (Scheme 2).[16,18] With these
strong ligands the reaction is not reversible, and the ligand
cannot be removed. The η2-precursors I and II can thus
be considered as being operationally unsaturated, effectively
acting as a source of a reactive cationic 16-electron
{RuCp*(η1-XH2B·dppm)}+ fragment. The lack of borane
loss on reaction with Lewis bases can be contrasted both
with borohydride complexes, as discussed earlier, and also
complexes of the monodentate phosphane–boranes devel-
oped by Shimoi, such as MnCp*(CO)2(η1-H3B·PMe3),
which react with weak Lewis bases to displace the bo-
rane.[19–21]
[a] Department of Chemistry, University of Bath,
Bath, BA2 7AY, UK
Fax: +44-1225-386231
E-mail: a.s.weller@bath.ac.uk
4068
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 4068–4073

Chelating Phosphane–Boranes as Hemilabile Ligands
FULL PAPER
Scheme 2.
Scheme 3.
The BH3 fragment binds to the manganese atom through
two B–H–Mn 3-centre-2-electron interactions. The hydro-
gen atoms associated with the BH3 group were located in
the final difference map and freely refined. Within the limits
of confidence associated with the location of hydrides by
X-ray crystallography the two hydrogen atoms that bridge
to the metal atom have B–H bonds that can be considered
longer than that to the terminal hydride [B1–H1a 1.07(3) Å,
B1–H1b 1.30(4) Å, B1–H1c 1.24(3) Å], consistent with the
3c–2e bond description. The Mn–B distance is short
We report here the synthesis of some new cationic man-
ganese complexes with the H3B·dppm ligand. In these com-
plexes the phosphane–borane opens and closes reversibly
(i.e. shows true hemilabile behaviour) on the addition/re-
moval of carbon monoxide.
Results
Treatment of Mn(CO)5Br with H3B·dppm using [2.146(4) Å] mirroring that observed in the ruthenium com-
Na[BArF4] as a halide-abstracting reagent results in the iso- plexes I and II,[16,18] being slightly longer than that found
lation of analytically pure (46% yield) [Mn(CO)3(η2- in three-coordinate boryl complexes of Mn such as (CO)5-
H3B·dppm)][BArF4] (1) (Scheme 3). The equivalent reac- MnB(O2C6H4) [2.108(6) Å][22] and comparable with the σ-
tions with ClH2B·dppm or BrH2B·dppm[18] only resulted in borane complex Mn(η5-C5H4Me)(CO)2(HB{O2C4Me4})
mixtures of intractable products. Complex 1 has been fully [2.149(2) Å].[23] It is significantly shorter than in the four-
characterised by NMR spectroscopy and X-ray crystal- coordinate boryl complex Mn(CO)4(PMe2Ph)(BH2·PMe3)
lography, which all show that the chelating phosphane–bo- [2.314(2) Å]
rane adopts a bidentate (η2) bridging mode of the BH3 [BH2(PMe3)]+ bonding description is suggested.[19] A sim-
group. Figure 1 shows the solid-state structure of 1.
ilar short distance is observed in [Cr(CO)4(η2-BH4)][PPN]
for
which
an
[Mn(CO)4(PMe2Ph)]–-
Figure 1. Solid-state structure of complex 1. Thermal ellipsoids are shown at the 50% probability level; hydrogen atoms are omitted apart
form those associated with the boron atom.
Eur. J. Inorg. Chem. 2006, 4068–4073
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4069

N. Merle, C. G. Frost, G. Kociok-Köhn, M. C. Willis, A. S. Weller
FULL PAPER
[2.29(1) Å] which is valence-isoelectronic with 1.[24] As for I be frozen out at low temperature. For 2, cooling to 190 K
and II,[16,18] this interaction in 1 is best described as being (CD2Cl2) results in the observation of two broad signals in
like borohydride and not a dihydridoboryl complex, as the the ratio 2:1 at δ = 1.99 (fwhm = 160 Hz) ppm and δ =
1
B–Mn–H and H–Mn–H angles are far more compressed –15.52 (fwhm = 250 Hz) ppm in the H{11B} NMR spec-
than expected for a complex with two hydrides and a boryl trum, assigned to the terminal and bridging hydrides,
ligand.[25] As expected for a relatively weakly bound BH3 respectively, showing that the exchange process has been
group, the M–C bond lengths associated with the carbonyl halted. This difference between neutral III and cationic 2
ligands trans to the bridging hydrides [Mn–C2 1.803(4) Å can be attributed to the increased electrostatic attraction
and Mn–C3 1.817(4) Å] are shorter than that trans to the between the cationic manganese centre and the polarised
phosphane group [Mn–C1 1.849(4) Å].
Hδ––Bδ+ group. At low temperature, the methylene protons
In solution, the 11B NMR spectrum of 1 demonstrates for 2 are observed as a single integral 2 H broadened peak
the Mn···B interaction by a significant downfield shift of (fwhm = 50 Hz) centred at δ = 3.5 ppm in the 1H{11B}
the signal of the H3B·dppm ligand on coordination, from δ NMR spectrum, suggesting Cs symmetry for the molecule
= –37.1 ppm in the free ligand to δ = 16.7 ppm (∆δ = at low temperature. In the solid-state structure (see below)
+53.8 ppm) in 1, consistent with η2-coordination of the bo- the molecule adopts C1 symmetry, resulting in the methyl-
rane and a significant M···B interaction. In the 1H{11B} ene protons and the B–H protons being all inequivalent,
NMR spectrum two signals observed at δ = –9.08 (2 H) contrary to the observation of just two signals for the B–H
ppm and δ = 4.99 (1 H) ppm are assigned to the bridging protons and one for the methylene group. However, due to
and terminal BH groups, respectively, indicating that ex- the broadness of these signals at 190 K and the inherent
change between the terminal and bridging hydrides does difficulty associated with reliably integrating such broad
not occur at room temperature. The methylene backbone in signals, it is not possible to say whether inequivalent envi-
the dppm group is observed as an integral 2 H doublet of ronments are present for each group, or instead if a low-
doublets, indicating time-averaged Cs symmetry in solution. energy libration of the bridging hydride around the Mn–B
The 31P{1H} NMR spectrum displays two peaks, a sharp vector is occurring to make both the dppm methylene and
doublet at δ = 73.7 ppm and a broad signal as δ = 15.6 ppm, BH2 protons each equivalent.
the latter assigned to the boron-bound phosphorus atom.
Other spectroscopic data are also in full accord with the for the phosphane–borane ligand, which forms a δ-agostic
solid-state structure. Mn–H–B interaction (Figure 2). The structural metrics are
The solid-state structure of 2 shows an η1-binding mode
Addition of CO (1 atm) to 1 results in the rapid for- similar to those already discussed for III,[16] as expected for
mation of the tetracarbonyl complex [Mn(CO)4(η1- this isoelectronic pair and are consistent with a relatively
H3B·dppm)][BArF4] (2) and the opening of the phosphane– weak δ-agostic Mn–H–B interaction [Mn···H 1.71(3) Å,
borane ligand form η2 to η1 (Scheme 4). The NMR spectro- Mn···B 2.748(3) Å]. Notably the Mn···B bond is long – be-
scopic data for 2 are very similar to those for the isoelec- ing similar to that calculated for [Mn(CO)4(PH3)(η1-
tronic complex Cr(CO)4(η1-H3B·dppm) (III).[16] A diagnos- H3B·PMe3)]+ [2.780 Å][19] and slightly shorter than ob-
tic high-field chemical shift change for the BH3 signal in served for neutral Cr(CO)5(η1-H3B·PMe3) [2.79(1) Å].[21]
the 11B{1H} NMR spectrum to δ = –37.5 ppm (similar to The Mn–H–B angle of 134(2)° means that the molecule
the free ligand[16,26]) indicates the η1-binding mode and loss does not have Cs symmetry in the solid state, in contrast to
1
of a significant M···B interaction. In the H NMR spec- the solution NMR spectroscopic data (vide supra). This an-
trum, the BH3 group is observed as a quadrupolar, broad- gle is far more open than those observed in 1 [viz. 91(1),
ened integral 3 H signal at δ = –3.74 ppm, which sharpens 93(1)°], consistent with move from didentate to mono-
on decoupling of 11B. The observation of one integral 3 H dentate coordination modes. The carbonyl ligand trans to
BH3 signal at room temperature shows that the BH3 group the weakly bound H3B group has the shortest Mn–C dis-
is rapidly spinning around the P–B bond at this tempera- tance, as expected. The Mn···H distance in 2 is significantly
ture, exchanging terminal and bridging hydrides. Consistent shorter than that found in γ-agostic complex [Mn(CO)3-
with this fluxional process, the methylene group on the (PCy3)2][BArF4] [2.01(9) Å],[27] in part a consequence of the
dppm ligand is observed as an integral 2 H doublet of dou- polarised Bδ+···Hδ– group interacting with the cationic
blets. In III this fluxional process also occurs but cannot metal centre.
Scheme 4.
4070
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 4068–4073

Chelating Phosphane–Boranes as Hemilabile Ligands
FULL PAPER
Figure 2. Solid-state structure of complex 2. Thermal ellipsoids are shown at the 50% probability level; hydrogen atoms are omitted apart
form those associated with the boron atom.
The addition of CO to 2 is reversible. Placing 2 under a bases. For [Mn(CO)3(η1-H3B·dppm)][BArF4] this opening is
dynamic vacuum (minutes) or under argon (days) regener- reversible, and this observation of hemilabile behaviour sug-
ates 1 quantitatively in both the solid state and solution. gests that, with suitable systems and substrates, they have
For this reason, crystals of 2 are best obtained under CO the potential for application in catalysis.
and good microanalytical data could not be obtained. Ad-
dition of Lewis bases other than CO to 2 (MeCN, PR3)
resulted in decomposition. Addition of the weaker Lewis
base H2 did not displace the borane, and addition of D2 did
not result in H/D exchange. This is contrary to complexes I
Experimental Section
General: All manipulations were carried out under argon, using
standard Schlenk-line and glove-box techniques, unless otherwise
and II in which H/D exchange occurs, via a putative dihy-
stated. Glassware was pre-dried in an oven at 130 °C and flamed
dride intermediate that results from the opening of the bo-
with a blowtorch under vacuum prior to use. Solvents were dried
with activated alumina, copper or molecular sieves columns by
using an MBraun solvent purification system and stored under
rane to η1.[16,18] Presumably, the cationic {Mn(CO)3}+ frag-
ment is reluctant to undergo oxidative addition of H2 and
thus no H/D exchange is observed in 1.
slight vacuum in ampoules equipped with Young’s taps. CD2Cl2
was distilled under vacuum from CaH2. Mn(CO)5Br,[30] Na-
Interestingly, the complex isoelectronic with 2, Mn-
(CO)5(η1-BH4), has only been briefly reported as a possible
intermediate in the formation of Mn3(CO)10(BH3)3H from
Al[BH4] and Mn(CO)5Br,[28] while the borohydride complex
equivalent to 1, Mn(CO)4(η2-BH4), has not been reported
apart from a calculated structure.[29] Related complexes
[BArF [31] and H3B·dppm[26] were prepared according to published
]
4
routes. All other chemicals were used as received from Aldrich and
Strem. Microanalyses were performed by Elemental Microanalysis
Ltd, Devon, UK.
NMR Spectroscopy: 1H, 1H{11B}, 11B{1H}, 11B and 31P{1H} NMR
with monodentate phosphanes such as [Mn(CO)4- spectra were recorded with Bruker Avance 300 MHz or 400 MHz
[19]
(PMe2Ph)(η1-H3B·PMe3)][BArF
]
and MnCp*(CO)2(η2-
spectrometers. Resonances were referenced to residual hydrogen
4
from the solvent for H and H{11B} NMR spectra (CD2Cl2: δ =
5.30 ppm). 11B, 11B{1H} and 31P{1H} spectra were referenced
against BF3·OEt2 (external) and 85%% H3PO4 (external), respec-
tively. Values are quoted in ppm. Coupling constants are quoted in
Hz.
1
1
H3B·PMe3)[20] are also unstable in solution. The stability of
2 is doubtlessly associated with the chelate ring, as we have
commented on previously.[16]
X-ray Crystallography: The crystal structure data for compounds
1 and 2 were collected with a Nonius KappaCCD diffractometer
(Tables 1 and 2). Structure solution, followed by full-matrix least-
squares refinement was performed using the SHELX suite of pro-
Conclusions
As with our earlier studies,[16,18] the results we report
here show that the chelating phosphane–borane ligand
H3B·dppm can open from η2 to η1 on addition of Lewis grams throughout.[32] Hydrogen atoms were included at calculated
Eur. J. Inorg. Chem. 2006, 4068–4073
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4071

N. Merle, C. G. Frost, G. Kociok-Köhn, M. C. Willis, A. S. Weller
Table 1. Details of crystallographic data collection and refinement for complexes 1 and 2.
FULL PAPER
Compound
1
2
Empirical formula
Mr [gmol1]
Crystal size [mm]
Crystal colour
Crystal system
Space group
a [Å]
C60H37B2F24MnO3P2
1400.40
0.70×0.40×0.30
orange
monoclinic
C2/c
25.4630(3)
12.37800(10)
38.1190(4)
91.98
C61H37B2F24MnO4P2·0.35CH2Cl2·0.65 C5H12
1505.02
0.35×0.28×0.23
yellow
orthorhombic
Pbca
13.3490(2)
26.4730(5)
38.1720(7)
90
13489.5(4)
8
b [Å]
c [Å]
β [°]
V [Å3]
12007.2(2)
8
1.549
Z
Dcalcd. [gcm–3]
µ [mm–1]
1.482
0.383
0.393
F(000)
T [K]
5616
150(2)
6064
150(2)
λ [Å]
Θ range [°]
Reflections collected
Data/parameters
Goodness-of-fit on F2
Final R indices [IϾ2σ(I)]
Largest diff. peak/hole [e·Å–3]
0.71073
3.22 to 28.68
34057
10178/913
1.078
R1 = 0.0602, wR2 = 0.1308
0.588/–0.670
0.71073
3.53 to 28.26
52244
14338/936
1.020
R1 = 0.0515, wR2 = 0.1154
0.532/–0.416
Table 2. Selected bond lengths [Å] and angles [°] for complexes 1 and 2.
Compound 1
Mn–C(1)
Mn–B(1)
Mn–H(1B)
B(1)–H(1B)
C(2)–Mn–B(1)
B(1)–Mn–H(1C)
1.849(4)
2.146(4)
1.68(4)
1.30(4)
129.67(15)
35(1)
Mn–C(2)
Mn–P(2)
Mn–H(1C)
B(1)–H(1C)
C(3)–Mn–B(1)
B(1)–Mn–H(1B)
1.803(4)
2.3428(9)
1.69(3)
1.24(3)
139.74(16)
37(1)
Mn–C(3)
B(1)–P(1)
B(1)–H(1A)
1.817(4)
1.944(4)
1.07(3)
C(1)–Mn–B(1)
H(1B)–Mn–H(1C)
87.24(15)
72(2)
Compound 2
Mn–C(26)
Mn–C(29)
Mn–H(1)
B–H(3)
1.883(3)
1.871(3)
1.71(3)
1.26(3)
Mn–C(27)
Mn–P(1)
B–H(1)
1.868(3)
2.3321(8)
1.08(3)
Mn–C(28)
B(1)–P(2)
B–H(2)
1.816(3)
1.929(3)
1.05(3)
134(2)
Mn–B(1)
2.748(3)
B–H(3)–Mn
positions throughout apart from those associated with the borane
which were located in the final Fourier difference map and refined
without constraints. For complex 2 two, partial occupancy, solvent
molecules (CH2Cl2 and pentane) were included in the refinement.
CCDC-284481 (1) and -284482 (2) contain the supplementary crys-
tallographic data for this paper. These data can be obtained free
of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
PPh2], 15.6 (br., 1 P, PBH3) ppm. 11B{1H} NMR (CD2Cl2): δ =
16.7 (br. s, 1 B, BH3), –5.9 (s, 1 B, BArF4). C60H37B2F24MnP2
(1400): calcd. C 51.46, H 2.66; found C 51.60, H 2.74. IR (KBr):
ν
= 2519 (m, BH), 2070 (s, CO), 2010 (s, CO), 1975 (s, CO)
˜
max
cm–1.
F
[(CO)4Mn(η1-BH3·dppm)][BAr4
]
(2):
A CH2Cl2 solution of
[(CO)3Mn(η2-BH3·dppm)][BArF
] (0.100 g, 0.074 mmol) was
4
stirred under CO for 15 min to give a yellow solution. The com-
(0.267 g, pound loses a carbonyl group in vacuo to give 2. Crystals suitable
[(CO)3Mn(η2-BH3·dppm)][BArF
]
4
(1):
NaBArF
4
0.301 mmol) was dissolved in 10 mL of diethyl ether and added
to a mixture of (CO)5MnBr (0.083 g, 0.301 mmol) and dppm·BH3
(0.120 g, 0.301 mmol) in 20 mL of CH2Cl2. The solution was
stirred for 2 d with regular degassing of the solution to remove
the released CO. The reaction mixture was filtered to remove the
insoluble NaBr to give an orange solution. Solvent was removed
in vacuo to leave an orange solid. Crystals suitable for an X-ray
diffraction study were grown by dissolving the solid in a minimum
for an X-ray diffraction study were grown by layering the CO-satu-
rated CH2Cl2 solution with CO-saturated pentane to yield yellow
1
crystals. H NMR (CD2Cl2): δ = 7.78–7.30 (m, 32 H, Ph, BAr4F),
3.54 [dd, J(PH) = 11.5 Hz, J(P(BH3)H) = 11.9 Hz, 2 H, CH2], –3.74
1
[br., J(BH) 61.4 Hz, 3 H, BH3]. Selected H{11B} NMR (CD2Cl2)
data: δ = –3.74 [br. d, J(PH) = 8 Hz, 3 H, BH3] ppm. 31P{1H}
NMR (CD2Cl2): δ = 55.2 [d, 1 P, J(PP) = 54.7 Hz, PPh2], 16.0 (br.,
1 P, PBH3) ppm. 11B{1H} NMR (CD2Cl2): δ = –5.9 (s, 1 B,
of CH2Cl2 and layering with pentane to yield orange crystals
BAr4F), –37.5 (br. s, 1 B, BH ) ppm. IR (KBr): ν
= 2498 (m,
˜
3
max
1
(0.183 g, 46% yield). H{11B} NMR (CD2Cl2): δ = 7.79–7.24 (m, BH), 2440 (m, BH) 2112 (s, CO), 2053 (s, CO), 2028 (s, CO), 2000
32 H, Ph, BAr4F), 4.99 (s, 1 H, BH), 2.90 [dd, J(PH) = 10.5 Hz,
J(P(BH3)H) = 12.5 Hz, 2 H, CH2], –9.08 [br. d, J(PH) = 6 Hz, 2 H,
BH2] ppm. 31P{1H} (CD2Cl2): δ = 73.7 [d, J(PP) = 102.1 Hz, 1 P,
(s, CO) cm–1. Selected low-temperature NMR spectroscopic data
1
(190 K): H{11B} NMR (CD2Cl2): δ = 3.50 (br., 2 H, CH2), 1.99
(v br., 2 H, BH), –15.52 (br., 1 H, BH) ppm.
4072
www.eurjic.org
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2006, 4068–4073

Chelating Phosphane–Boranes as Hemilabile Ligands
FULL PAPER
[16] N. Merle, G. Koicok-Köhn, M. F. Mahon, G. D. Ruggerio,
C. G. Frost, A. S. Weller, M. C. Willis, Dalton Trans. 2004,
3883.
Acknowledgments
[17] M. Ingleson, N. J. Patmore, G. D. Ruggiero, C. G. Frost, M. F.
Mahon, M. C. Willis, A. S. Weller, Organometallics 2001, 20,
4434.
The EPSRC (GR/R90475/01) and the Royal Society are thanked
for support.
[18] N. Merle, C. G. Frost, G. Kociok-Kohn, M. C. Willis, A. S.
Weller, J. Organomet. Chem. 2005, 690, 2829.
[19] T. Yasue, K. Kawano, M. Shimoi, Angew. Chem. Int. Ed. 2003,
42, 1727.
[1]
R. H. Crabtree, The Organometallic Chemistry of the Transition
Elements, Wiley, New York, 2001.
A. Macchioni, Chem. Rev. 2005, 105, 2039.
P. Braunstein, F. Naud, Angew. Chem. Int. Ed. 2001, 40, 680.
P. Espinet, K. Soulantica, Coord. Chem. Rev. 1999, 195, 499.
C. S. Slone, D. A. Weinberger, C. A. Mirkin, Prog. Inorg. Chem.
1999, 48, 233.
V. V. Grushin, Chem. Rev. 2004, 104, 1629.
a) J. W. Faller, J. C. Wilt, J. Parr, Org. Lett. 2004, 6, 1301; b)
J. W. Faller, J. Lloret-Fillol, J. Parr, New J. Chem. 2002, 26, 883.
[2]
[3]
[4]
[5]
[20] T. Kakizawa, K. Kawano, M. Shimoi, Organometallics 2001,
20, 3211.
[21] M. Shimoi, S. Nagai, M. Ichikawa, K. Kawano, Y. Katoh, M.
Uruichi, H. Ogino, J. Am. Chem. Soc. 1999, 121, 11704.
[22] K. M. Waltz, C. N. Muhoro, J. F. Hartwig, Organometallics
1999, 18, 3383.
[23] S. Schlecht, J. F. Hartwig, J. Am. Chem. Soc. 2000, 122, 9435.
[24] M. Y. Darensbourg, R. Bau, M. W. Marks, R. R. Burch Jr,
J. C. Deaton, S. Slater, J. Am. Chem. Soc. 1982, 104, 6961.
[6]
[7]
[8] C. J. Chapman, C. G. Frost, M. P. Gill-Carey, G. Kociok- [25] J. F. Hartwig, S. R. De Gala, J. Am. Chem. Soc. 1994, 116,
Köhn, M. F. Mahon, A. S. Weller, M. C. Willis, Tetrahedron:
Asymmetry 2003, 14, 705.
3661.
[26] D. R. Martin, C. M. Merkel, J. P. Ruiz, Inorg. Chim. Acta 1986,
[9] B. J. Holliday, P. A. Ulmann, C. A. Mirkin, C. L. Stern, Orga-
nometallics 2004, 23, 1671.
[10] T. J. Marks, J. R. Kolb, Chem. Rev. 1977, 77, 263.
115, L29.
[27] A. Toupadakis, G. J. Kubas, W. A. King, B. L. Scott, J.
Huhmann-Vincent, Organometallics 1998, 17, 5315.
[11] S. C. P. Joseph, F. G. N. Cloke, C. J. Cardin, P. B. Hitchcock, [28] P. H. Bird, M. G. H. Wallbridge, J. Chem. Soc. Chem. Com-
Organometallics 1995, 14, 3566.
[12] R. J. Hamilton, C. G. Leong, G. Bigman, M. Miskolzie, S. H.
Bergens, J. Am. Chem. Soc. 2005, 127, 4152.
mun. 1968, 687.
[29] Y. Oishi, T. A. Albright, Polyhedron 1995, 14, 2603.
[30] M. H. Quick, R. J. Angelici, Inorg. Synth. 1979, 19, 160.
[13] B. Chamberlain, S. B. Duckett, J. P. Lowe, R. J. Mawby, J. C. [31] W. E. Buschmann, J. S. Miller, Inorg. Synth. 2002, 33, 85.
Stott, Dalton Trans. 2003, 2603.
[14] R. Macias, N. P. Rath, L. Barton, Angew. Chem. Int. Ed. 1999,
38, 162.
[15] O. Volkov, R. Macías, N. P. Rath, L. Barton, Inorg. Chem.
2002, 41, 5837.
[32] G. M. Sheldrick, SHELX-97, A Computer Program for Refine-
ment of Crystal Structures, University of Göttingen, Germany,
1997.
Received: June 6, 2006
Published Online: August 10, 2006
Eur. J. Inorg. Chem. 2006, 4068–4073
© 2006 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4073