Regiospecific cyclometalation of diphenyl(2-substituted phenyl)phosphane with methyltetrakis(trimethylphosphane)cobalt(I)

Article abstract of DOI:10.1002/ejic.200390115

The pre-chelate molecules 2-(diphenylphosphanyl)-N,N-dimethylaniline, [2-(diphenylphosphanyl)benzyl]dimethylamine, 1-(diphenylphosphanyl)-2-ethylbenzene, 1-(diphenylphosphanyl)-2-isopropylbenzene, and 2-(diphenylphosphanyl)benzonitrile, in a reaction with [CoMe(PMe₃)₄], eliminate methane to afford the selectively 6-ortho-metalated complexes 1-5 that contain four-membered metallacycles. The molecular structure of 3 shows a tbp-coordinated cobalt atom, with axial C and PMe₃ donor groups. Metalation in the aliphatic side-chain occurs with 2-(diphenylphosphanyl)toluene, giving complex 6 that contains a five-membered metallacycle. Benzyldiphenylphosphane is selectively orthometalated in the benzyl group, affording 7. As shown by the molecular structures, complex 7 is a true ligand isomer of 6. Substitution of a trimethylphosphane group in compounds 4 and 6 by ethene gives the pentacoordinate complexes 8 and 9, respectively. The ethene ligand is π-coordinated in the equatorial plane of a trigonal bipyramid. Under 1 bar of CO, complex 6 forms monocarbonyl complex 10. Carbonylation of complexes 3 and 4 proceeds by insertion of CO into the Co-C bond under ring expansion, affording the aroylcobalt complexes 11 and 12, respectively. Complex 6 reacts with iodomethane in an oxidative substitution reaction yielding a structurally characterized octahedral complex mer-13, which eliminates a methyl group in THF at 20 °C to form a pentacoordinate cobalt(II) complex 14. Complex 3 oxidatively adds iodomethane in a stereoselective cis addition to give the cobalt(III) complex mer-15, which retains its four-membered metallacycle and the CoCH₃ group. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.

Full text of DOI:10.1002/ejic.200390115

FULL PAPER
Regiospecific Cyclometalation of Diphenyl(2-substituted phenyl)phosphane with
Methyltetrakis(trimethylphosphane)cobalt( )
I
Hans-Friedrich Klein,*[a] Robert Beck,[a] Ulrich Flörke,[b] and Hans-Jürgen Haupt[b]
Keywords: Orthometalation / Cobalt / Coordination chemistry / Structure elucidation / Steric control
The pre-chelate molecules 2-(diphenylphosphanyl)-N,N-di-
methylaniline, [2-(diphenylphosphanyl)benzyl]dimethyl-
amine, 1-(diphenylphosphanyl)-2-ethylbenzene, 1-(diphenyl-
phosphanyl)-2-isopropylbenzene, and 2-(diphenylphosphan-
9, respectively. The ethene ligand is π-coordinated in the
equatorial plane of a trigonal bipyramid. Under 1 bar of CO,
complex 6 forms monocarbonyl complex 10. Carbonylation
of complexes 3 and 4 proceeds by insertion of CO into the
yl)benzonitrile, in a reaction with [CoMe(PMe3)4], eliminate Co−C bond under ring expansion, affording the aroylcobalt
methane to afford the selectively 6-ortho-metalated com- complexes 11 and 12, respectively. Complex 6 reacts with
plexes 1−5 that contain four-membered metallacycles. The
molecular structure of 3 shows a tbp-coordinated cobalt
atom, with axial C and PMe3 donor groups. Metalation in the
aliphatic side-chain occurs with 2-(diphenylphosphanyl)tol-
iodomethane in an oxidative substitution reaction yielding a
structurally characterized octahedral complex mer-13, which
eliminates a methyl group in THF at 20 °C to form a penta-
coordinate cobalt(II) complex 14. Complex 3 oxidatively adds
uene, giving complex 6 that contains a five-membered metal- iodomethane in a stereoselective cis addition to give the co-
lacycle. Benzyldiphenylphosphane is selectively ortho-
metalated in the benzyl group, affording 7. As shown by the
molecular structures, complex 7 is a true ligand isomer of 6.
Substitution of a trimethylphosphane group in compounds 4
balt(III) complex mer-15, which retains its four-membered
metallacycle and the CoCH3 group.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
and 6 by ethene gives the pentacoordinate complexes 8 and Germany, 2003)
Introduction
Cyclometalation reactions are among the oldest CϪH-
activation processes, and those involving phenylphosphanes
are well known in electron-rich complexes of the late trans-
ition metals.[1] In many cases cyclometalation has been
shown to be a reversible reaction involving an oxidative-
addition and a reductive-elimination step (Scheme 1).
A residual methylmetal function can utilize the new hyd-
rido ligand in an alternative reductive elimination reaction
and can also stabilize three-membered ZrϪNϪC rings.[2]
Scheme 1. Reversible and irreversible cyclometalation reactions
With [CoMe(PMe3)4], the subsequent elimination of meth-
ane, which proceeds at Ϫ70 °C, renders the formation of a
metallacycle practically irreversible, since methane does not of possible isomers. We have recently found an unusually
react in the same manner as dihydrogen at 20 °C in a hydro- high selectivity in the reaction of [CoMe(PMe3)4] with 2-
genolytic cleavage reaction.[3] Given a selective course of (diphenylphosphanyl)-N,N-dimethylaniline,[4] and report
such cyclometalation reactions, we do not expect the kin- here on our investigation of substituent effects on the select-
etically favored product complex to undergo equilibration ivity of cyclometalation reactions. Our strategy was firstly
to generate gradual steric and electronic changes in the vi-
[a]
Eduard-Zintl-Institut für Anorganische und Physikalische
Chemie, Technische Universität Darmstadt
Petersenstr. 18, 64287 Darmstadt, Germany
Fax: (internat.) ϩ 49-6151/16-4173
cinity of the anchoring PPh2 group in order to favor attack
at the available four sites in the unsubstituted phenyl
groups, and secondly to provide 2-substituents that would
favor an attack at the side-chain. Investigation of molecular
structures with respect to ring size and bite-angle of chelat-
ing ligands are warranted because these parameters have
E-mail: hfklein@hrz2.hrz.tu-darmstadt.de
Anorganische und Analytische Chemie der Universität
Paderborn,
[b]
Warburger Straße, 33098 Paderborn, Germany
Eur. J. Inorg. Chem. 2003, 853Ϫ862  2003 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim 1434Ϫ1948/03/0305Ϫ0853 $ 20.00ϩ.50/0
853

H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt
FULL PAPER
been shown in homogeneous catalysis to be among the
most sensitive steering devices within the metal coordina-
tion sphere.[5]
Results and Discussion
a) The ArNMe2 Ǟ ArCH2NMe2 Ǟ ArCH2Me Ǟ
ArCHMe2 Line
A side-chain in one of the six ortho positions of triphenyl-
phosphane containing an N-donor function and activated
aliphatic CϪH bonds was provided in the pre-chelate mole-
cules 2-(diphenylphosphanyl)-N,N-dimethylaniline, [2-(di-
phenylphosphanyl)benzyl]dimethylamine, 1-(diphenylphos-
phanyl)-2-ethylbenzene, and 1-(diphenylphosphanyl)-2-iso-
propylbenzene. Reactions with [CoMe(PMe3)4] proceeded
at Ϫ70 °C in THF [Equation (1)], and afforded the select-
ively ortho-metalated complexes 1,[4] and 2Ϫ4.
Figure 1. Molecular structure of 3 (ORTEP plot with hydrogen
˚
atoms omitted); selected bond lengths [A] and angles [°]: CoϪC12
1.984(5), CoϪP1 2.2103(14), CoϪP2 2.1639(17), CoϪP3
2.1691(17), CoϪP4 2.1857(17), P1ϪC11 1.796(6), C11ϪC12
1.401(7); C12ϪCoϪP1 71.02(15), C12ϪCoϪP2 90.96(16),
C12ϪCoϪP3 90.89(15), C12ϪCoϪP4 166.25(15), P1ϪCoϪP2
119.25(7),
P1ϪCoϪP3
121.97(7),
P1ϪCoϪP4
95.23(6),
P2ϪCoϪP3 115.56(7), P2ϪCoϪP4 95.79(7), P3ϪCoϪP4 96.95(7)
(1)
phanyl)aniline were compared with the P,C-donor group in
2-(diphenylphosphanyl)toluene. Reaction of this type of
weak CϪH acid with [CoMe(PMe3)4] at Ϫ70 °C produces
methane [Equation (2)].
The 31P NMR spectra at 233 K most clearly show three
resonances with chemical shifts and a coupling pattern
which are characteristic of an ortho-metalated tris(trime-
thylphosphane)cobalt complex.[3] As no other signals are
detected, the absence of possible isomers in solution (Ͻ ca.
2%) is demonstrated in all four compounds.
(2)
The dominant feature in the molecular structure of 3 is
a four-membered cobaltacycle (Figure 1), in which the che-
lating ligand spans the C-axial and P-equatorial positions
From a red-brown solution in pentane, complex 6 is ob-
tained as black prismatic crystals. In the 1H NMR spectrum
at 296 K, a broad resonance at δ ϭ 1.80 ppm (2 H) con-
taining multiple phosphorus coupling is assigned to a
CoCH2 group. Doublet and pseudotriplet PCH3 resonances
with intensity ratios of 1:2 also indicate little ligand mobil-
ity. Complex 6 remains pentacoordinate, which differs from
the rapidly exchanging trimethylphosphane from [P,O]-che-
late and [P,N]-chelate systems on the NMR time scale.
However, the 31P NMR chemical shifts at 233 K are found
in similar positions to those of the [P,N] and [P,O] com-
plexes, and are in no way related to those in complexes 1Ϫ4.
Therefore, a selective attack appears to be directed at the
ortho-methyl group to form a five-membered metallacycle,
which is known to form with platinum.[7] The molecular
structure (Figure 2) is entirely consistent with the config-
uration of 6 derived from the solution data. A cobalt atom
is centered in a trigonal bipyramid with axial CH2 and
PMe3 groups and a five-membered metallacycle occupying
of
a
trigonal bipyramid. The small bite-angle
[C12ϪCoϪP1 ϭ 71.02(15)°], which falls just outside the
range of Rh and Ir complexes (67Ϫ69°),[6] causes bending
between the axial positions [C12ϪCoϪP4 ϭ 166.25(15)°].
Bond lengths and angles do not substantially deviate from
those in the unsubstituted molecule.[3]
b) The ArNMe2 Ǟ ArCH2Me Ǟ ArCN Line
Electron-donating dimethylamino and ethyl groups were
replaced by the strong electron-accepting cyano group.
However, reaction of [CoMe(PMe3)4] with 2-(diphenylphos-
phanyl)benzonitrile followed the same route as in Equa-
tion (1), affording 5 as a single ortho-metalated isomer. The
31P NMR spectrum at 233 K closely resembles those of
1Ϫ4. Thus, there is little chance for the electronic steering
of the ortho-metalation reaction.
c) The ArOH Ǟ ArNH2 Ǟ ArCH3 Line
The isoelectronic donor functions of the pre-chelate sys- C-axial and P-equatorial positions with a narrow bite-angle
tems in 2-(diphenylphosphanyl)phenol or 2-(diphenylphos- [C10ϪCoϪP1 ϭ 77.77(17)°] and considerable ring bending
854
Eur. J. Inorg. Chem. 2003, 853Ϫ862

Cyclometalation of Diphenyl(2-substituted phenyl)phosphans
FULL PAPER
(sum of internal angles ϭ 518.8°). The CoϪC10 distance
3
˚
[2.080(5) A] is within the range of CoϪC(sp ) bonds
[8]
˚
(2.03Ϫ2.15 A), and CoϪP distances are typical and
appear unaffected by the trans influence of the distant CH2
group. We note here an unexpected and complete switching
of the cyclometalation reaction on changing from a 2-
methyl to a 2-ethyl group.
Figure 3. Molecular structure of 7 (molecule A) (ORTEP plot with
˚
hydrogen atoms omitted); selected bond lengths [A] and angles [°]:
CoϪC11 2.011(4), CoϪP11 2.1625(12), CoϪP12 2.2197(13),
CoϪP13 2.1994(12), CoϪP14 2.1833(13), P11ϪC17 1.830(4),
C16ϪC17 1.501(5), C11ϪC16 1.415(6); C11ϪCoϪP11 83.08(12),
C11ϪCoϪP12
88.51(12),
C11ϪCoϪP13
177.17(12),
C11ϪCoϪP14 84.22(12), P11ϪCoϪP12 120.47(5), P11ϪCoϪP13
94.83(5), P11ϪCoϪP14 119.37(5), P12ϪCoϪP13 94.21(5),
P12ϪCoϪP14 118.13(5), P13ϪCoϪP14 95.19(5), CoϪC11ϪC16
120.6(3), C11ϪC16ϪC17 118.0(4), C16ϪC17ϪP11 106.2(3)
Figure 2. Molecular structure of 6 (ORTEP plot with hydrogen
[8,9]
˚
˚
(1.97Ϫ2.01 A).
The approximation to an ideal tbp geo-
atoms omitted); selected bond lengths [A] and angles [°]: CoϪC10
2.080(5), CoϪP1 2.1646(18), CoϪP2 2.206(2), CoϪP3 2.186(2),
CoϪP4 2.180(2), P1ϪC11 1.827(7), C10ϪC16 1.494(8), C11ϪC16
1.399(8); C10ϪCoϪP1 77.77(17), C10ϪCoϪP2 87.15(17),
C10ϪCoϪP3 88.10(18), C10ϪCoϪP4 172.48(18), P1ϪCoϪP2
metry is better in 7, and the sum of the internal angles in
the cobaltacycle (532.7°) is closer to planarity (540°) than
in 6 (518.8°).
132.14(8),
P1ϪCoϪP3
114.22(8),
P1ϪCoϪP4
95.86(7),
P2ϪCoϪP3 110.29(7), P2ϪCoϪP4 94.36(8), P3ϪCoϪP4 98.26(8)
d) Reactions with Ethene
π-Olefin coordination in aryl(trimethylphosphane)co-
balt() complexes is an expected phenomenon.[4] The steric
limitations of pentacoordination will be modified by the an-
gular strain of the four- and five-membered metallacycles
on the preferred equatorial binding site. A spontaneous
substitution reaction is not feasible with complex 4. When
complex 4 is kept at 100 °C for 3 h under vacuum, a vacant
coordination site is formed by dissociation of 1 mol-equiv.
of trimethylphosphane that is necessary for subsequent co-
ordination of olefin to occur [Equation (4)].
Formation of a five-membered cobaltacycle with reversed
ring positions of Co(PMe3)3 and PPh2 groups can be ex-
pected from a reaction of [CoMe(PMe3)4] with benzyldi-
phenylphosphane [Equation (3)].
(3)
When the reactants are combined at Ϫ70 °C, the color
changes to red-brown and the evolution of gas commences.
Eventually, red crystals of 7, which are air-sensitive and de-
compose under argon above 75 °C, were obtained from
pentane. The 31P NMR spectrum contains a doublet of
triplets (δ ϭ 63 ppm, PPh2) and two doublets of doublets
(δ ϭ Ϫ4 and 22 ppm, PMe3), with couplings that suggest
a five-membered cobaltacycle in the C(axial)/P(equatorial)
(4)
On dissolution of 4 in diethyl ether under 1 bar of ethene,
positions of a trigonal bipyramid. The expected configura- complex 8 is obtained as orange crystals. In the 31P NMR
tion is observed in the molecular structure of 7 (Figure 3).
spectrum of 8, three doublets of doublets are seen at δ ϭ
All bond lengths in 7 are similar to those in the ligand Ϫ12, 9, and 17 ppm. These signals are in the same region
isomer 6 (Figure 2). In particular, the distance [CoϪC11 ϭ as those of a four-membered cobaltacycle, as expected from
2
˚
2.011(4) A] falls in the range reported for CoϪC(sp ) bonds the data of compounds 1Ϫ5.
Eur. J. Inorg. Chem. 2003, 853Ϫ862
855

H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt
FULL PAPER
When heated under argon, decomposition of 8 occurs
When carbonylation reactions of complexes 3 and 4,
with the release of ethene, and no alteration of the four- which contain four-membered cobaltacycles, take place un-
membered metallacycle is indicated (IR) prior to the depos- der the same conditions, monosubstitution is accompanied
ition of cobalt.
by insertion of CO into the CoϪC bond under ring expan-
Without thermal pretreatment of complex 6, which con- sion [Equation (7)], thus affording the aroylcobalt com-
tains a five-membered cobaltacycle, substitution of trime- plexes 11 and 12, respectively.
thylphosphane by ethene occurs [Equation (5)].
(5)
(7)
The orange-yellow needles of 9 (from pentane, decomp.
Ͼ 87 °C) exhibit a better thermal stability than π-ethene
The lustrous red crystals of 11 and 12 have narrow melt-
ing ranges (11: 152Ϫ153 °C; 12: 161Ϫ162 °C) and melt
without decomposing. The IR spectra contain two con-
spicuous new bands which are assigned to the terminal car-
complexes containing five-membered cobaltacycles with
(P,N) and (P,O) ligands,[4,10] which are isoelectronic. From
the 31P NMR spectrum, the doublet of doublets pattern,
with characteristic shifts at δ ϭ 66, 18, and 11 ppm, indic-
ates that the π-ethene ligand occupies an equatorial posi-
tion.
bonyl ligand and to the benzoylcobalt group [11: ν˜ ϭ 1913
Ϫ1
(CϵO), 1542 cmϪ1 (CϭO); 12: ν ϭ 1906 (CϵO), 1513 cm
˜
(CϭO)].
In the 31P NMR spectra, the ring expansion causes a low-
field shift of the chelating phosphorus resonance by
85 ppm, which appears as a triplet by coupling to two
equatorial trimethylphosphane groups. The observed doub-
let and triplet pattern is only compatible with the acyl and
carbonyl ligands arranged in the axial positions.
e) Reactions with Carbon Monoxide
Carbonylated methylcobalt() compounds, [CoCH3-
(CO)(PMe3)3] or [Co(CH3CO)(CO)2(PMe3)2],[11] are unre-
active towards diphenyl(2-substituted phenyl)phosphanes
and do not undergo a cyclometalation reaction of the pro-
scribed type. However, CO ligands are smoothly introduced
into metallacyclic product complexes. In solution under 1
bar of CO at 20 °C, 6 forms the monocarbonyl complex
10 [Equation (6)].
f) Reactions with Iodomethane
Complex 6 reacts with excess iodomethane in diethyl
ether by dissociation and quaternization of a trimethylphos-
phane [Equation (8)], thus undergoing an oxidative substi-
tution reaction.
(6)
(8)
The dark-red crystals of 10 are thermally more stable (by
30 K) and less air-sensitive than those of complexes con-
taining five-membered cobaltacycles with (P,N) and (P,O)
ligands.[4,10] The 31P NMR spectra in THF solutions show
All volatile materials were removed in vacuo as soon as
mixtures of isomers, with couplings consistent with a tbp the precipitation of white tetramethylphosphonium iodide
configuration where a terminal carbonyl ligand resides began. Extraction of the remaining solid with diethyl ether
either in an axial or in an equatorial position. In toluene at 20 °C and cooling of the red-brown solution gave a mod-
solutions, only the isomer with the CO ligand in the axial erate yield of short orange rods. Complex 13 is air-stable,
position is observed.
but decomposes above 82 °C. In tetrahydrofuran at 20 °C,
856
Eur. J. Inorg. Chem. 2003, 853Ϫ862

Cyclometalation of Diphenyl(2-substituted phenyl)phosphans
FULL PAPER
spontaneous evolution of ethane transforms hexacoordin- planarity. These differences could make mer-13 the thermo-
ate 13 into the pentacoordinate cobalt() complex 14 dynamically most stable isomer. Eventually, mer-13 is meta-
[Equation (8)]. More conveniently, 14 is obtained by per- stable with respect to a CϪC-coupling reaction forming 14.
forming the synthesis in THF.
A
Although the molecular geometry of 14 has not been cla-
31P{1H} NMR spectrum of 13 in [D8]THF at 213 K rified due to poor crystal quality and broad and overlap-
shows three multiplet signals, suggesting three P-donor ping NMR signals, the magnetic moment (µeff/µB ϭ 1.93)
functions in an octahedral coordination geometry, but al- is as expected for a tbp configuration of cobalt (d7).[13Ϫ15]
lows no clear distinction between the mer and fac config-
Under the same conditions, 3 oxidatively adds iodome-
urations. The molecular structure of mer-13 was revealed thane after substitution and quaternization of a trimethyl-
by a single-crystal X-ray diffraction analysis (Figure 4).
phosphane group [Equation (9)].
(9)
The dark-red crystals of 15 melt at 115Ϫ116 °C under
argon, and are stable for more than 1 d in air at 20 °C. The
IR spectrum resembles that of 3, except for an additional
band [ν˜ ϭ 1165 cmϪ1 (CoCH3)]. The 31P NMR spectrum
at 213 K shows a triplet resonance at δ ϭ Ϫ32 ppm, charac-
teristic of a PPh2 group in a four-membered cobaltacycle,
and a doublet at δ ϭ 10 ppm containing a typical cis coup-
ling (2J ϭ 23 Hz). The observed pattern is consistent with
two isochronic trimethylphosphane 31P nuclei in trans posi-
tions, and a meridional arrangement of the three P-donor
atoms which appears to result from a regioselective cis addi-
tion of iodomethane.[3] At variance with the spontaneous
transformation of mer-13 [Equation (8)], solutions of 15 in
THF at 20 °C remain stable for at least 1 d.
Figure 4. Molecular structure of mer-13 (ORTEP plot with hydro-
˚
gen atoms omitted); selected bond lengths [A] and angles [°]:
CoϪC101 2.016(5), CoϪC131 2.053(5), CoϪI 2.7250(9), CoϪP11
2.2749(17), CoϪP12 2.2581(19), CoϪP13 2.2301(18), C101ϪC102
1.515(8),
C102ϪC107
1.386(8),
P13ϪC107
1.818(5);
C101ϪCoϪP13
86.89(18),
C101ϪCoϪI
178.47(17),
C101ϪCoϪP12 94.70(18), P11ϪCoϪP12 95.82(7), P11ϪCoϪP13
98.31(6), P12ϪCoϪP13 165.85(6), C107ϪP13ϪCo 102.8(2),
P13ϪC107ϪC102
CoϪC101ϪC102 114.9(4)
112.4(4),
C101ϪC102ϪC107
122.3(5),
While cobalt() compounds containing five-membered
metallacycles in a reaction with iodomethane undergo oxid-
ative substitution, followed by reductive elimination of eth-
ane, those containing four-membered cobaltacycles attain
the cobalt() state without a subsequent CϪC-coupling re-
action. In both transformations the endocyclic CoϪC
bonds remain unaffected.
The iodide ion and one of the trimethylphosphane li-
gands are coplanar with the cobaltacycle, while the other
trimethylphosphane ligand and the CoCH3 group are below
and above the plane. While the CoϪP and CoϪC bond
lengths are as expected, the CoϪI bond is slightly elongated
by the benzylic CH2ϪCo interaction in trans position.
Conclusion
The reactivity in irreversible cyclometalation processes
with [CoMe(PMe3)4] appears to be controlled by a high
electron density on the metal atom, and is lost in the pres-
ence of a single strongly π-accepting ligand, e.g. in CoMe-
As the trans influences along Me3PϪCoϪCH3 would be (CO)(PMe3)3. The observed selectivity, which is based on
very similar to that of Me3PϪCoϪCH3 in the fac config- the orientation of the CϪH bonds that are in the proximity
uration, mer-13 would appear to be the product of a cis of the metal atom, is sterically controlled by the preferred
addition under kinetic control. However, when compared substrate conformation. The usual fan-type conformation
with 6, the chelate bite angle [C101ϪCoϪP13 ϭ 86.89(13)°] of a triphenylphosphane ligand is most effectively distorted
is augmented by 10°, while the CoϪC bond is shortened by by a 2-substituent, whereby the substituted phenyl group is
6.5 pm. The sum of the internal angles is 539.3°, indicating rotated in such a way that only this particular ortho-CH
considerable relaxation of the metallacycle towards group closes in on the metal atom (Scheme 2) and the four-
Eur. J. Inorg. Chem. 2003, 853Ϫ862
857

H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt
FULL PAPER
the solution cooled to 4 °C, affording dark-red rectangular crystals
of 1. Yield 270 mg (85%); m.p. 112Ϫ114 °C (dec.). 1H NMR
(300 MHz, [D8]THF, 296 K): δ ϭ 1.02 [d, J(PH) ϭ 5.6 Hz, 9 H,
membered cobaltacycle is formed. Thus,
hindered rotation of an aryl group renders the cyclo-
metalation reaction regiospecific.
a sterically
2
PCH3], 1.23 [s (br), 18 H, PCH3], 2.13 (s, 6 H, NCH3), 5.90Ϫ6.23
(m, 3 H, CH), 7.22Ϫ7.24 (m, 6 H, CH), 7.75Ϫ7.79 (m, 4 H, CH)
ppm. 13C NMR (75.4 MHz, [D8]THF, 296 K): δ ϭ 22.2Ϫ22.7 (m,
PCH3), 23.3 (m, PCH3), 43.3 (s, NCH3), 109.3 (s, CH), 125.9 [d,
3J(PC) ϭ 3.1 Hz, CH], 126.0 (s, CH), 126.3 [d, 3J(PC) ϭ 5.6 Hz,
CH], 126.9 (s, CH), 133.2 [d, 2J(PC) ϭ 7.6 Hz, CH], 133.3 [d,
2
2J(PC) ϭ 7.6 Hz, CH], 139.1 [d, J(PC) ϭ 9.2 Hz, CH], 171.3 (m,
CoC) ppm. 31P NMR (81 MHz, [D8]THF, 233 K): δ ϭ Ϫ24 [dt,
2J(PP) ϭ 89 and 68 Hz, 1 P, PPh2], Ϫ4 [dd, 2J(PP) ϭ 89 and 68 Hz,
2 P, PCH3], 22 [dt, 2J(PP) ϭ 68 and 47 Hz, 1 P, PCH3] ppm.
C29H46CoNP4 (591.5): calcd. C 58.89, H 7.84, N 2.37, P 20.95;
found C 58.92, H 7.82, N 2.27, P 20.83.
Scheme 2. Sterically controlled proximity conformation
A five-membered cobaltacycle is formed as the preferred
ring size, by activation of a benzylic CϪH bond only in the
absence of steric strain. In a monosubstituted triphenylpho-
sphane steric crowding is significant as the substituents are
changed from 2-methyl to the 2-ethyl substituents. Once
formed, the five-membered cobaltacycle does not insert a
CO ligand in a process that accompanies carbonylation of
complexes with four-membered cobaltacycles. Neither
metallacycle shows insertion of a π-ethene ligand.
While cobalt() compounds containing five-membered
metallacycles in a reaction with iodomethane undergo oxid-
ative substitution, followed by reductive elimination of eth-
ane, those containing four-membered cobaltacycles attain
the cobalt() state without a subsequent CϪC-coupling re-
action. In both transformations the endocyclic CoϪC
bonds remain unaffected.
{3-[(Dimethylamino)methyl]-2-(diphenylphosphanyl)phenyl-C1,P}-
tris(trimethylphosphane)cobalt (2): [2-(Diphenylphosphanyl)benzyl-
]dimethylamine (608 mg, 1.90 mmol) in 50 mL of diethyl ether was
combined at Ϫ70 °C with [CoMe(PMe3)4] (720 mg, 1.90 mmol) in
30 mL of diethyl ether. The reaction was accompanied by the evolu-
tion of a gas. After keeping the red-brown mixture at 20 °C for
16 h, the volatiles were removed in vacuo and the solid residue was
extracted with two 70-mL portions of pentane. When the solution
was kept at Ϫ27 °C, dark-red crystals of 2 were obtained. Yield
967 mg (84%); m.p. 107Ϫ109 °C (dec.). 1H NMR (300 MHz,
2
[D8]THF, 296 K): δ ϭ 0.90 [d, J(PH) ϭ 6.2 Hz, 9 H, PCH3], 1.28
[s (br), 18 H, PCH3], 1.73 (s, 6 H, NCH3), 2.78 (s, 2 H, NCH2),
6.68Ϫ6.77 (m, 3 H, CH), 7.24Ϫ7.26 (m, 6 H, CH), 7.72Ϫ7.78 (m,
4 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF, 296 K): δ ϭ
1
22.1Ϫ22.5 (m, PCH3), 23.3 [d, J(PC) ϭ 20.1 Hz, PCH3], 27.3 (s,
3
NCH3), 58.1 (s, NCH2), 118.5 [d, J(PC) ϭ 3.1 Hz, CH], 126.4 (s,
CH), 126.5 [d, 3J(PC) ϭ 5.6 Hz, CH], 126.9 (s, CH), 134.8 (s, CH),
2
2
135.6 [d, J(PC) ϭ 7.6 Hz, CH], 135.7 [d, J(PC) ϭ 7.6 Hz, CH],
138.1 [d, 2J(PC) ϭ 9.2 Hz, C], 151.1 [d, 2J(PC) ϭ 10.7 Hz, C],
Experimental Section
1511.5 [d, J(PC) ϭ 10.7 Hz, C], 169.9 (m, CoC) ppm. 31P NMR
2
2
(81 MHz, [D8]THF, 233 K): δ ϭ Ϫ26 [dt, J(PP) ϭ 89 and 70 Hz,
General Procedures and Materials: All air-sensitive and volatile
materials were handled using standard vacuum techniques and
were kept under argon. Microanalyses: Kolbe Microanalytical
Laboratory, Mülheim/Ruhr, FRG. Melting points/decomposition
temperatures: Sealed capillaries, uncorrected values. Chemicals
(Merck/Schuchardt) were used as purchased. Literature methods
were applied for the preparation of 2-(diphenylphosphanyl)-N,N-
1 P, PPh2], Ϫ4 [dd, 2J(PP) ϭ 89 and 48 Hz, 2 P, PCH3], 21 [dt,
2J(PP) ϭ 70 and 48 Hz, 1 P, PCH3] ppm. C30H48CoNP4 (605.5):
calcd. C 59.50, H 7.99, N 2.31, P 20.46; found C 59.36, H 8.10, N
2.18, P 20.38.
[2-(Diphenylphosphanyl)-3-ethylphenyl-C1,P]tris(trimethylphos-
phane)cobalt (3): 1-(Diphenylphosphanyl)-2-ethylbenzene (590 mg,
2.03 mmol) in 50 mL of THF was combined at Ϫ70 °C with [CoMe-
(PMe3)4] (770 mg, 2.03 mmol) in 30 mL of THF. As the solution
warmed up, the slow evolution of a gas was observed. After keep-
ing the dark-red mixture at 20 °C for 16 h, the volatiles were re-
moved in vacuo and the solid residue was extracted with two 50-
mL portions of pentane. Reduction of the volume to 60 mL and
keeping of the red solution at 4 °C afforded dark-red rectangular
crystals of 3, which were suitable for X-ray diffraction. Yield
809 mg (69%); m.p. 120Ϫ121 °C. 1H NMR (300 MHz, [D8]THF,
dimethylaniline,[16]
[2-(diphenylphosphanyl)benzyl]dimethylam-
ine,[17] 1-(diphenylphosphanyl)-2-ethylbenzene, 1-(diphenylphos-
phanyl)-2-isopropylbenzene,[18] 2-(diphenylphosphanyl)benzonitr-
ile,[19] 2-(diphenylphosphanyl)toluene,[20] benzyldiphenylphos-
phane,[21] and [CoMe(PMe3)4].[11] IR: Nujol mulls between KBr
discs, Bruker spectrophotometer type FRA 106. 1H and 13C NMR
spectra (300 MHz and 75 MHz, respectively) were recorded with a
Bruker ARX-300 spectrometer, 31P NMR spectra (81 MHz) with a
Bruker AM-200 instrument. 13C and 31P resonances were obtained
with proton decoupling. Magnetic susceptibility data were obtained
by the Faraday method using a Cahn D 200 torsion balance
(Bruker) at 1.5 Tesla.
3
2
296 K): δ ϭ 0.53 (t, J ϭ 7.5 Hz, 3 H, CCH3), 1.09 [d, J(PH) ϭ
6.3 Hz, 9 H, PCH3], 1.25 [tЈ, |2J(PH) ϩ 4J(PH)| ϭ 4.5 Hz, 18 H,
PCH3], 2.43 (q, 3J ϭ 7.5 Hz, 2 H, CH2), 6.29 (d, J ϭ 6.4 Hz, 1 H,
3
[3-(Dimethylamino)-2-(diphenylphosphanyl)phenyl-C1,P]tris(tri-
CH), 6.67 (t, 3J ϭ 7.1 Hz, 1 H, CH), 6.73 (m, 1 H, CH), 7.21Ϫ7.27
methylphosphane)cobalt
(1):
2-(Diphenylphosphanyl)-N,N-di-
(m, 6 H, CH), 7.72Ϫ7.80 (m, 4 H, CH) ppm. 13C NMR (75.4 MHz,
methylaniline (549 mg, 1.79 mmol) in 50 mL of diethyl ether was [D8]THF, 296 K): δ ϭ 22.1 (s, CH3), 22.1Ϫ22.9 (m, PCH3), 23.7 (s,
combined at Ϫ70 °C with [CoMe(PMe3)4] (680 mg, 1.79 mmol) in
30 mL of diethyl ether. The reaction was accompanied by the evolu-
tion of a gas. After the solution had warmed up, the red-brown
mixture was kept at 20 °C for 16 h. The volatiles were removed in
vacuo, the solid residue was extracted with 80 mL of pentane, and
CH2), 117.9 [d, 2J(PC) ϭ 11.5 Hz, CH], 126.9 (s, CH), 128.6 [d,
4
3J(PC) ϭ 9.0 Hz, CH], 129.3 [d, J(PC) ϭ 3.1 Hz, CH], 130.1 [d,
1J(PC) ϭ 15.1 Hz, CH], 131.5 [d, 2J(PC) ϭ 12.3 Hz, CH], 137.9 [d,
2J(PC) ϭ 10.5 Hz, CH], 138.2 (s, C), 145.5 (m, C), 171.5 (m, CoC)
ppm. 31P NMR (81 MHz, [D8]THF, 233 K): δ ϭ Ϫ26 [dt, 2J(PP) ϭ
858
Eur. J. Inorg. Chem. 2003, 853Ϫ862

Cyclometalation of Diphenyl(2-substituted phenyl)phosphans
FULL PAPER
87 and 69 Hz, 1 P, PPh2], Ϫ4 [dd, 2J(PP) ϭ 87 and 47 Hz, 2 P, stirred at 20 °C for 16 h. The volatiles were removed in vacuo, and
PCH3], 21 [dt, 2J(PP) ϭ 69 and 47 Hz, 1 P, PCH3] ppm. the solid residue was extracted with three 80-mL portions of pent-
C29H45CoP4 (576.5): calcd. C 60.42, H 7.87, P 21.49; found C
60.51, H 8.13, P 21.19.
ane. At 4 °C, black crystals of 6, which were suitable for X-ray
diffraction, were obtained. Yield 806 mg (81%); m.p. 124Ϫ126 °C
(dec.). 1H NMR (300 MHz, [D8]THF, 296 K): δ ϭ 0.93 [d,
2J(PH) ϭ 6.5 Hz, 9 H, PCH3], 1.19 [tЈ, |2J(PH) ϩ 4J(PH)| ϭ 4.3 Hz,
[2-(Diphenylphosphanyl)-3-isopropylphenyl-C1,P]tris(trimethylphos-
phane)cobalt (4): 1-(Diphenylphosphanyl)-2-isopropylbenzene
(732 mg, 2.40 mmol) in 50 mL of THF was combined at Ϫ70 °C
with [CoMe(PMe3)4] (910 mg, 2.40 mmol) in 50 mL of THF. After
the solution had warmed up, the dark-red mixture was kept at 20
°C for 16 h. The volatiles were removed in vacuo and the solid
residue was extracted with two 80-mL portions of pentane. When
the solution was kept at 4 °C, dark-red rectangular crystals of 4
were obtained. Yield 1040 mg (73%); m.p. 95Ϫ98 °C. 1H NMR
(300 MHz, [D8]THF, 296 K): δ ϭ 0.61 [d, 3J ϭ 6.8 Hz, 6 H,
3
18 H, PCH3], 1.80 [m (br), 2 H, CoCH2], 6.71 (t, J ϭ 7.2 Hz, 1
3
4
3
H, CH), 6.80 (tt, J ϭ 7.2, J ϭ 1.4 Hz, 1 H, CH), 6.92 (d, J ϭ
3
7.2 Hz, 1 H, CH), 7.08 (t, J ϭ 6.3 Hz, 1 H, CH), 7.22Ϫ7.24 (m,
6 H, CH), 7.56Ϫ7.65 (m, 4 H, CH) ppm. 13C NMR (75.4 MHz,
[D8]THF, 296 K): δ ϭ 21.1Ϫ22.9 (m, PCH3), 24.8 (m, CoCH2),
108.2 (m, C), 117.3 (m, CH), 120.4 (s, CH), 122.9 [d, 2J(PC) ϭ
13.0 Hz, CH], 125.1 (s, CH), 125.9 [d, 4J(PC) ϭ 3.1 Hz, CH], 130.1
[d, 1J(PC) ϭ 15.1 Hz, CH], 131.5 [d, 2J(PC) ϭ 12.3 Hz, CH], 137.9
[d, 2J(PC) ϭ 13.1 Hz, CH], 126.4 [d, 1J(PC) ϭ 22.4 Hz, C], 130.2 (s,
2
C(CH3)2], 1.08 [d, J(PH) ϭ 6.3 Hz, 9 H, PCH3], 1.25 [tЈ, |2J(PH)
2
CH), 132.6[d, J(PC) ϭ 12.3 Hz, C], 141.2 (m, C) ppm. 31P NMR
ϩ
4J(PH)| ϭ 4.4 Hz, 18 H, PCH3], 2.52 (sept, 3J ϭ 6.8 Hz, 1 H,
2
(81 MHz, [D8]THF, 233 K): δ ϭ Ϫ4 [dd, J(PP) ϭ 94 and 44 Hz,
CH), 6.34 (d, 3J ϭ 7.2 Hz, 1 H, CH), 6.66 (t, 3J ϭ 7.2 Hz, 1 H,
CH), 6.72 (m, 1 H, CH), 7.24Ϫ7.26 (m, 6 H, CH), 7.75Ϫ7.82 (m,
4 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF, 296 K): δ ϭ 21.2
(s, CH3), 22.5Ϫ22.6 (m, PCH3), 27.9 (s, CH), 114.8 (s, CH), 126.5
[d, 2J(PC) ϭ 8.5 Hz, CH], 126.9 (s, CH), 131.7 [d, 3J(PC) ϭ
13.2 Hz, CH], 135.2 (s, CH), 135.4 [d, 1J(PC) ϭ 16.6 Hz, CH],
138.2 (m, C), 138.4 (s, CH), 140.4 (s, C), 171.2 (m, CoC) ppm. 31P
2 P, PCH3], 22 [dd, 2J(PP) ϭ 50 and 44 Hz, 1 P, PCH3], 58 [dt,
2J(PP) ϭ 94 and 50 Hz, 1 P, P Ph2] ppm. C28H43CoP4 (562.5):
calcd. C 59.79, H 7.71, P 22.03; found C 59.97, H 7.30, P 22.08.
[2-(Diphenylphosphanyl)benzyl-C2,P]tris(trimethylphosphane)cobalt
(7): Benzyldiphenylphosphane (679 mg, 2.45 mmol) in 50 mL of
THF was combined with [CoMe(PMe3)4] (930 mg, 2.45 mmol) in
50 mL of THF, at Ϫ70 °C. The color of the solution changed from
brown to deep-red. After the solution had warmed up, the mixture
was stirred at 20 °C for 4 h. The volatiles were then removed in
vacuo to give a light-red solid. This was dissolved in 50 mL of
diethyl ether and crystallized at 4 °C to give red cubes of 7, which
were suitable for X-ray diffraction. Yield 856 mg (62%); m.p.
2
NMR (81 MHz, [D8]THF, 233 K): δ ϭ Ϫ26 [dt, J(PP) ϭ 87 and
2
71 Hz, 1 P, PPh2], Ϫ4 [dd, J(PP) ϭ 87 and 47 Hz, 2 P, PCH3], 21
2
[dt, J(PP) ϭ 71 and 47 Hz, 1 P, PCH3] ppm. C30H47CoP4 (590.5):
calcd. C 61.02, H 8.02, P 20.98; found C 61.35, H 8.37, P 20.54.
[3-Cyano-2-(diphenylphosphanyl)phenyl-C1,P]tris(trimethylphos-
phane)cobalt (5): 2-(Diphenylphosphanyl)benzonitrile (486 mg,
1.69 mmol) in 50 mL of THF was combined with [CoMe(PMe3)4]
(640 mg, 1.69 mmol) in 50 mL of THF, at Ϫ70 °C. After the solu-
tion had warmed up, the dark-brown mixture was stirred at 20 °C
for 16 h. The volatiles were then removed in vacuo. The solid res-
idue was extracted with two 80-mL portions of pentane. At 4 °C,
black needles of 5 were obtained. Yield 408 mg (42%); m.p.
1
75Ϫ77 °C (dec.). H NMR (300 MHz, [D8]THF, 296 K): δ ϭ 0.97
[d, 2J(PH) ϭ 6.3 Hz, 9 H, PCH3], 1.16 [tЈ, |2J(PH) ϩ 4J(PH)| ϭ
2
4.6 Hz, 18 H, PCH3], 1.80 [d, J(PH) ϭ 8.2 Hz, 2 H, PCH2], 6.49
(m, 2 H, CH), 6.70 (m, 1 H, CH), 7.19Ϫ7.25 (m, 6 H, CH), 7.42
(m, 1 H, CH), 7.56Ϫ7.62 (m, 4 H, CH) ppm. 13C NMR (75.4 MHz,
1
[D8]THF, 296 K): δ ϭ 23.4 [d, J(PC) ϭ 20.8 Hz, PCH3], 23.9 [dd,
1J(PC) ϭ 12.6, 3J(PC) ϭ 6.4 Hz, PCH3], 50.4 [d, 1J(PC) ϭ 27.1,
3J(PC) ϭ 8.7 Hz, PCH2], 119.9 (s, CH), 121.6 (s, CH), 121.9 (s,
CH), 127.5 [d, 3J(PC) ϭ 8.0 Hz, CH], 127.6 (s, CH), 132.8 [d,
2J(PC) ϭ 11.6 Hz, CH], 141.6 (m, C), 143.6 (m, C), 144.6 (s, CH),
171.6 (m, CoC) ppm. 31P NMR (81 MHz, [D8]THF, 233 K): δ ϭ
1
114Ϫ116 °C (dec.). IR (Nujol): ν˜ ϭ 2209 cmϪ1 (CϵN). H NMR
2
(300 MHz, [D8]THF, 296 K): δ ϭ 1.11 [d, J(PH) ϭ 6.6 Hz, 9 H,
PCH3], 1.30 [tЈ, |2J(PH) ϩ 4J(PH)| ϭ 4.5 Hz, 18 H, PCH3], 6.66 (d,
3
3J ϭ 4.7 Hz, 1 H, CH), 6.68 (d, J ϭ 8.2 Hz, 1 H, CH), 7.01 (m, 1
H, CH), 7.24Ϫ7.30 (m, 6 H, CH), 7.80Ϫ7.86 (m, 4 H, CH) ppm.
13C NMR (75.4 MHz, [D8]THF, 296 K): δ ϭ 21.8 (m, PCH3), 22.3
(m, PCH3), 119.3 [m, C(CN)], 121.7, 125.5 (s, CH), 126.4 [d,
2
2
Ϫ4 [dd, J(PP) ϭ 104 and 54 Hz, 2 P, PCH3], 22 [dd, J(PP) ϭ 54
2
and 51 Hz, 1 P, PCH3], 63 [dt, J(PP) ϭ 104 and 51 Hz, 1 P, PPh2]
ppm. C28H43CoP4 (562.5): calcd. C 59.79, H 7.71, P 22.03; found
C 59.63, H 7.79, P 22.12.
2
2J(PC) ϭ 7.7 Hz, CH], 127.4 (s, CH), 132.4 [d, J(PC) ϭ 13.5 Hz,
CH], 134.2, 136.5 (s, CH), 138.8 (s, C), 139.6 (m, C), 169.9 (m,
CoC) ppm. 31P NMR (81 MHz, [D8]THF, 233 K): δ ϭ Ϫ26 [dt,
2J(PP) ϭ 89 and 73 Hz, 1 P, PPh2], Ϫ4 [dd, 2J(PP) ϭ 89 and 50 Hz,
2 P, PCH3], 21 [dt, 2J(PP) ϭ 73 and 50 Hz, 1 P, PCH3] ppm.
C28H41CoNP4 (574.5): calcd. C 58.54, H 7.19, N 2.44, P 21.57;
found C 58.41, H 7.48, N 2.41, P 21.51.
[2-(Diphenylphosphanyl)-3-isopropylphenyl-C1,P](ethene)bis(tri-
methylphosphane)cobalt (8): A sample of 4 (610 mg, 1.03 mmol)
was heated in vacuo at 100 °C for 3 h. It was then dissolved in
70 mL of diethyl ether at 20 °C, and was stirred under 1 bar of
ethene for 3 h. The volatiles were removed in vacuo and the solid
residue was extracted with two 50-mL portions of pentane. Crystal-
lization at 4 °C afforded orange crystals of 8, together with the
[2-(Diphenylphosphanyl)tolyl-C,P]tris(trimethylphosphane)cobalt
(6). Method a): 2-(Diphenylphosphanyl)toluene (616 mg,
2.23 mmol) and CoCl(PMe3)3 (720 mg, 2.23 mmol) in 40 mL of dark crystals of 4. After mechanical separation the yield was
THF were combined at Ϫ70 °C with 1.6  MeLi in diethyl ether 185 mg (33%); m.p. 105Ϫ107 °C (dec.). 1H NMR (300 MHz,
2
(1.4 mL, 2.23 mmol), whilst stirring. The dark-green mixture
turned red-brown. After the solution had warmed up, and after
stirring at 20 °C for 30 min, the volatiles were removed in vacuo
and the solid residue was extracted with two 80-mL portions of
diethyl ether. Removal of the solvent afforded a dark-brown solid
of 6. Raw yield 928 mg (74%). Method b): 2-(Diphenylphosphanyl)-
[D8]THF, 296 K): δ ϭ 0.85 [d, J(PH) ϭ 5.8 Hz, 9 H, PCH3], 0.97
(d, 3J ϭ 6.9 Hz, 6 H, CCH3), 1.01 [d, 2J(PH) ϭ 5.9 Hz, 9 H, PCH3],
1.51 (m, 1 H, ϭCH2), 1.88 (m, 2 H, ϭCH2), 2.35 (m, 1 H, ϭCH2),
3
4
2.46 (sept, J ϭ 6.9 Hz, 1 H, CHCH3), 6.42 (t, J ϭ 2.4 Hz, CH),
6.45 (t, 4J ϭ 2.2 Hz, CH), 6.72 (dt, 3J ϭ 7.5, 4J ϭ 1.8 Hz, 1 H,
CH), 7.26Ϫ7.28 (m, 3 H, CH), 7.38 Ϫ7.41 (m, 3 H, CH), 7.64Ϫ7.70
toluene (489 mg, 1.77 mmol) in 50 mL of THF was combined with (m, 2 H, CH), 7.94Ϫ8.00 (m, 2 H, CH) ppm. 13C NMR (75.4 MHz,
1
[CoMe(PMe3)4] (670 mg, 1.77 mmol) in 50 mL of THF, at Ϫ70 °C.
As the solution warmed up, the mixture turned red-brown and was
[D8]THF, 296 K): δ ϭ 16.4 [d, J(PC) ϭ 22.7 Hz, PCH3], 18.9 [d,
1J(PC) ϭ 18.4 Hz, PCH3], 20.9 (s, CHCH3), 28.5 [d, 3J(PC) ϭ
Eur. J. Inorg. Chem. 2003, 853Ϫ862
859

H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt
FULL PAPER
4.5 Hz, CHCH3], 31.4 [d, 2J(PC) ϭ 16.1 Hz, ϭCH2], 37.1 [d, red solution formed. The volatiles were removed in vacuo and the
3
2J(PC) ϭ 15.5 Hz, ϭCH2], 116.2 [d, J(PC) ϭ 6.1 Hz, CH], 126.6 solid residue was extracted with two 50-mL portions of pentane.
[d, 3J(PC) ϭ 8.2 Hz, CH], 127.4 [d, 2J(PC) ϭ 12.6 Hz, C], 128.9 (s,
Crystallization at 4 °C afforded dark red plates of 11. Yield 475 mg
1
CH), 131.4 [d, 2J(PC) ϭ 11.1 Hz, CH], 132. 1 [d, 2J(PC) ϭ (85%); m.p. 152Ϫ153 °C. IR (Nujol): ν˜ ϭ 1913 cmϪ1 (CϵO). H
1
3
112.3 Hz, CH], 136.1 [d, J(PC) ϭ 15.9 Hz, C], 138.2 (s, C), 141.7 NMR (300 MHz, [D8]THF, 296 K): δ ϭ 0.52 (t, J ϭ 7.5 Hz, 3 H,
(s, C) ppm. 31P NMR (81 MHz, [D8]THF, 193 K): δ ϭ Ϫ21 [dd,
CH3), 1.09 [tЈ, |2J(PH) ϩ J(PH)| ϭ 7.2 Hz, 18 H, PCH3], 2.43 (q,
4
2
2J(PP) ϭ 49 and 56 Hz, 1 P, PPh2], 9 [dd, J(PP) ϭ 49 and 33 Hz, 3J ϭ 7.5 Hz, 2 H, CH2), 7.26Ϫ7.40 (m, 9 H, CH), 7.54Ϫ7.61 (m,
1 P, PCH3], 17 [dd, 2J(PP) ϭ 33 and 56 Hz, 1 P, PCH3] ppm.
C29H42CoP3 (542.5): calcd. C 64.21, H 7.80, P 17.13; found C
63.85, H 7.90, P 17.15.
4 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF, 296 K): δ ϭ 17.2
(s, PCH3), 18.2 (m, PCH3), 19.9 (s, CH3), 26.7 (s, CH2), 47.5 (s,
CH), 55.9 (s, CH2), 117.6 [d, 1J(PC) ϭ 21.2 Hz, CH], 126.9 (s, CH),
2
3
128.6 [d, J(PC) ϭ 9.0 Hz, CH], 129.3 [d, J(PC) ϭ 3.1 Hz, CH],
128.8 (s, CH), 130.1 [d, 1J(PC) ϭ 15.1 Hz, CH], 130.4 (s, CH),
137.8 (s, C), 138.2 (s, C), 145.5 (s, C), 157.7 (s, C) ppm. 31P NMR
(81 MHz, [D8]THF, 193 K): δ ϭ 9 [d, 2J(PP) ϭ 81 Hz, 2 P, PCH3],
84 [t, 2J(PP) ϭ 81 Hz, 1 P, PPh2] ppm. C28H36CoO2P3 (556.4):
calcd. C 60.44, H 6.52, P 16.70; found C 60.40, H 6.72, P 16.53.
[2-(Diphenylphosphanyl)tolyl-C,P](ethene)bis(trimethylphos-
phane)cobalt (9): A sample of 6 (820 mg, 1.45 mmol) in 50 mL of
diethyl ether was stirred under 1 bar of ethene for 1 h. A light-red
solution formed. The volatiles were removed in vacuo and the solid
residue was extracted with three 50-mL portions of pentane. Crys-
tallization at 4 °C afforded orange needles of 9. Yield 584 mg
(78%); m.p. 87Ϫ89 °C (dec.). 1H NMR (300 MHz, [D8]THF,
296 K): δ ϭ 0.71 [d, 2J(PH) ϭ 6.1 Hz, 9 H, PCH3], 1.21 [d,
2J(PH) ϭ 5.4 Hz, 9 H, PCH3], 1.65 (m, 2 H, ϭCH2), 1.97 (m, 2
H, ϭCH2), 6.82 (m, 1 H, CH), 6.90 (m, 2 H, CH), 7.14 (t, 3J ϭ
6.5 Hz, 1 H, CH), 7.32Ϫ7.36 (m, 6 H, CH), 7.45 (m, 2 H, CH),
8.02Ϫ8.04 (m, 2 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF,
296 K): δ ϭ 16.9 [d, 1J(PC) ϭ 18.4 Hz, PCH3], 19.7[d, 1J(PC) ϭ
16.6 Hz, PCH3], 31.7 (m, CoCH2), 38.7 [d, 2J(PC) ϭ 16.5 Hz, ϭ
CH2], 39.8 [d, 2J(PC) ϭ 20.5 Hz, ϭCH2], 121.9 [d, 4J(PC) ϭ
(Carbonyl)[2-(diphenylphosphanyl)-3-isopropylbenzoyl-C,P]bis(tri-
methylphosphane)cobalt (12): A sample of 4 (750 mg, 1.27 mmol)
in 50 mL of THF was stirred under 1 bar of CO for 3 h. A light-
red solution formed. The volatiles were removed in vacuo and the
solid residue was extracted with two 50-mL portions of pentane.
Crystallization at 4 °C afforded dark-red crystals of 12. Yield
572 mg (79%); m.p. 161Ϫ162 °C. IR (Nujol): ν˜ ϭ 1906 cmϪ1
1
3
(CϵO). H NMR (300 MHz, [D8]THF, 296 K): δ ϭ 0.65 [d, J ϭ
6.7 Hz, 6 H, C(CH3)2], 1.05 [tЈ, |2J(PH) ϩ 4J(PH)| ϭ 7.3 Hz, 18 H,
PCH3], 3.04 (sept, 3J ϭ 6.7 Hz, 1 H, CH), 7.30Ϫ7.39 (m, 9 H, CH),
7.58Ϫ7.65 (m, 4 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF,
296 K): δ ϭ 21.7 (s, CH3), 18.2 [dt, 1J(PC) ϭ 12.6, 3J(PC) ϭ 4.2 Hz,
PCH3], 30.9 (s, CH), 117.6 (s, CH), 117.9 (s, CH), 126.9 [d,
2J(PC) ϭ 8.9 Hz, CH], 127.2 (s, CH), 130.2 (s, CH), 130.5 [d,
3J(PC) ϭ 12.2 Hz, CH], 137.6 (s, C), 137.9 (s, C), 138.3 (m, C),
150.3 (s, C) ppm. 31P NMR (81 MHz, [D8]THF, 233 K): δ ϭ 8 [d,
2J(PP) ϭ 79 Hz, 2 P, PCH3], 85 [t, 2J(PP) ϭ 79 Hz, 1 P, PPh2] ppm.
C29H38CoO2P3 (570.5): calcd. C 61.06, H 6.71, P 16.29; found C
61.05, H 6.86, P 16.21.
2
3
4.9 Hz, CH], 124.9 [d, J(PC) ϭ 11.0 Hz, CH], 127.3 [d, J(PC) ϭ
3
3
8.4 Hz, CH], 127.5 [d, J(PC) ϭ 8.3 Hz, CH], 127.6 [d, J(PC) ϭ
1
2
7.2 Hz, CH], 128.2 [d, J(PC) ϭ 22.0 Hz, CH], 133.2 [d, J(PC) ϭ
10.5 Hz, CH], 134. 1 [d, 2J(PC) ϭ 11.6 Hz, CH], 141.1 [d, 1J(PC) ϭ
20.9 Hz, C], 162.1 (s, C).) ppm. 31P NMR (81 MHz, [D8]THF,
233 K): δ ϭ 11 [dd, 2J(PP) ϭ 40 and 25 Hz, 1 P, PCH3], 18 [dd,
2J(PP) ϭ 25 and 38 Hz, 1 P, PCH3], 66 [dd, 2J(PP) ϭ 40 and 38 Hz,
1 P, PPh2] ppm. C27H38CoP3 (514.5): calcd. C 63.04, H 7.45, P
18.06; found C 63.12, H 7.07, P 18.72.
(Carbonyl)[2-(diphenylphosphanyl)tolyl-C,P]bis(trimethylphos-
phane)cobalt (10): A sample of 6 (590 mg, 1.05 mmol) in 30 mL of
THF was stirred under 1 bar of CO for 30 min. A light-red solution
formed. The volatiles were removed in vacuo and the solid residue
was extracted with 50 mL of pentane. Crystallization at 4 °C af-
forded red crystals of 10, which were suitable for X-ray diffraction.
Yield 410 mg (76%); m.p. 132Ϫ135 °C (dec.). IR (Nujol): ν˜ ϭ 1894
cmϪ1 (CϵOax), 1850 cmϪ1 (CϵOeq). 1H NMR (300 MHz,
[D8]THF, 296 K): CϵOax isomer (88%): δ ϭ 1.00 [tЈ, |2J(PH) ϩ
4J(PH)| ϭ 6.2 Hz, 18 H, PCH3], 2.09 (m, 2 H, CoCH2), 6.84 (t,
mer-cis-[2-(Diphenylphosphanyl)tolyl-C,P](iodo)(methyl)bis(trimeth-
ylphosphane)cobalt (13): A sample of 6 (810 mg, 1.44 mmol) in
50 mL of diethyl ether at Ϫ70 °C was combined with a slight excess
of iodomethane (552 mg, 3.89 mmol). The mixture was allowed to
warm to 20 °C, after which it turned brown and deposited an off-
white solid of tetramethylphosphonium iodide (IR). After 4 h, the
solid was removed by filtering. Crystallization at 4 °C afforded or-
ange crystals of 13·0.5OEt2, which were suitable for X-ray diffrac-
tion. Yield 440 mg (46%); m.p. 82Ϫ84 °C (dec.). 1H NMR
(300 MHz, [D8]THF, 296 K): δ ϭ 0.53 (m, 3 H, CoCH3), 0.95 [s
(br), 18 H, PCH3], 1.12 (m, 2 H, CoCH2), 6.56 (m, 1 H, CH), 7.05
(m, 2 H, CH), 7.31Ϫ7.74 (m, 11 H, CH) ppm. 31P NMR (81 MHz,
[D8]THF, 213 K): δ ϭ Ϫ11 (m, 1 P, PCH3), Ϫ1 (m, 1 P, PCH3), 10
(m, 1 P, PPh2) ppm. C28H42CoIO0.5P3 (665.4): calcd. C 50.54, H
6.36, P 13.96; found C 50.40, H 6.64, P 14.21.
3
3J ϭ 7.3 Hz, 1 H, CH), 7.02 (m, 2 H, CH), 7.18 (d, J ϭ 6.9 Hz, 1
H, CH), 7.26Ϫ7.31 (m, 6 H, CH), 7.43Ϫ7.47 (m, 4 H, CH); CϵOeq
isomer (12%): δ ϭ 0.86 [d, 2J(PH) ϭ 7.3 Hz, 18 H, PCH3], 1.29 [d,
2J(PH) ϭ 7.5 Hz, 18 H, PCH3], 2.35 (m, 2 H, CoCH2), 6.95Ϫ7.62
(m, 14 H, CH) ppm. 13C NMR (75.4 MHz, [D8]THF, 296 K):
CϵOax isomer (88%): δ ϭ 20.1 (s, PCH3), 24.0 (m, CoCH2), 124.1
[d, 3J(PC) ϭ 4.6 Hz, CH], 127.4 (s, CH), 127.4 [d, 1J(PC) ϭ
16.4 Hz, CH], 128.5 [d, 2J(PC) ϭ 8.3 Hz, CH], 128.8 (s, CH), 129.9
(s, CH), 133.1 [d, 2J(PC) ϭ 12.3 Hz, CH], 140.1 (s, C) ppm. 31P
NMR (81 MHz, [D8]THF, 233 K): COax isomer (88%): δ ϭ 6 [d,
2J(PP) ϭ 98 Hz, 2 P, PCH3], 73 [t, 2J(PP) ϭ 98 Hz, 1 P, PPh2];
COeq isomer (12%): δ ϭ Ϫ1 [dd, 2J(PP) ϭ 82 and 38 Hz, 1 P,
PCH3], 25 [dd, 2J(PP) ϭ 38 and 51 Hz, 1 P, PCH3], 67 [dd, 2J(PP) ϭ
82 and 51 Hz, PPh2] ppm. C26H34CoOP3 (514.4): calcd. C 60.71,
H 6.66, P 18.06; found C 60.94, H 7.45, P 17.62.
[2-(Diphenylphosphanyl)tolyl-C,P](iodo)bis(trimethylphosphane)-
cobalt (14): A sample of 6 (760 mg, 1.35 mmol) in 60 mL of THF
was combined with iodomethane (192 mg, 1.35 mmol). After 4 h,
a slight precipitate of tetramethylphosphonium iodide formed,
which was filtered off. The filtrate was concentrated to dryness.
Extraction with three 80-mL portions of diethyl ether and cooling
to 4 °C afforded black crystals of 14. Yield 780 mg (94%); m.p.
157Ϫ159 °C (dec.). Magnetic moment: µeff ϭ 1.93 µB. C25H34CoIP3
(613.3): calcd. C 48.96, H 5.59, P 15.15; found C 48.62, H 5.88,
P 15.25.
(Carbonyl)[2-(diphenylphosphanyl)-3-ethylbenzoyl-C,P]bis(trimeth-
ylphosphane)cobalt (11): A sample of 3 (580 mg, 1.01 mmol) in mer-trans-[2-(Diphenylphosphanyl)-3-ethylphenyl-C1,P](iodo)-
50 mL of THF was stirred under 1 bar of CO for 30 min. A light-
860
(methyl)bis(trimethylphosphane)cobalt (15): A sample of 3 (870 mg,
Eur. J. Inorg. Chem. 2003, 853Ϫ862

Cyclometalation of Diphenyl(2-substituted phenyl)phosphans
FULL PAPER
Table 1. Crystal data for compounds 3, 6, 7, and 13
3
6
7
13
Empirical formula
Formula mass
Crystal size [mm]
Crystal system
Space group
C29H45CoP4
576.5
0.38 ϫ 0.25 ϫ 0.16
orthorhombic
Pbca
9.060(1)
18.069(2)
38.641(6)
90
C28H43CoP4
562.4
0.38 ϫ 0.25 ϫ 0.12
orthorhombic
Pbca
9.8127(16)
18.7719(19)
32.408(7)
90
C28H43CoP4
562.4
0.50 ϫ 0.40 ϫ 0.22
monoclinic
P21/n
15.231(2)
24.516(4)
16.201(3)
90
101.38(1)
90
C26H37CoIOP3 0.5 Et2O
665.4
0.44 ϫ 0.20 ϫ 0.19
triclinic
¯
P1
˚
a [A]
10.492(2)
14.450(2)
20.882(3)
87.92(1)
75.56(1)
87.99(1)
3062.8(8)
4
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
90
90
90
90
3
˚
V [A ]
6325.7(14)
8
1.211
5969.6(17)
8
1.252
5930.6(17)
8
1.260
Z
Dcalcd. [g/cm3]
1.443
1.741
µ(Mo-Kα) [mmϪ1
]
0.760
0.804
0.809
Temperature [K]
Data coll. range [°]
h
k
l
No. reflect. measured
No. unique data
Parameters
GoF on F2
R1 [I Ն 2σ(I)]
wR2 (all data)
293(2)
293(2)
293(2)
293(2)
4.2 Յ 2Θ Յ 54
Ϫ1 Յ h Յ 11
Ϫ23 Յ k Յ 1
Ϫ1 Յ l Յ 49
8431
6891 [Rint ϭ 0.0587]
318
1.017
0.0573
0.1754
4.5 Յ 2Θ Յ 55
0 Յ h Յ 12
Ϫ1 Յ k Յ 24
Ϫ42 Յ l Յ 1
7506
6859 [Rint ϭ 0.0667]
307
0.937
0.0586
0.1735
5.1 Յ 2Θ Յ 54
Ϫ1 Յ h Յ 19
Ϫ31 Յ k Յ 1
Ϫ20 Յ l Յ 20
15074
12931 [Rint ϭ 0.0441]
569
1.003
0.0555
0.1307
4.8 Յ 2Θ Յ 55
Ϫ1 Յ h Յ 13
Ϫ18 Յ k Յ 18
Ϫ26 Յ l Յ 27
16375
14074[Rint ϭ 0.030]
605
0.978
0.0459
0.1182
1.51 mmol) in 50 mL of diethyl ether at Ϫ70 °C was combined with
iodomethane (514 mg, 3.62 mmol). The mixture was allowed to
warm to 20 °C, after which it turned red and deposited solid tetra-
methylphosphonium iodide. After 3 h, the solid was removed by
filtering. From the filtrate, dark-red crystals of 15 were obtained at
Ϫ27 °C. Yield 504 mg (52%); m.p. 115Ϫ116 °C. 1H NMR
Acknowledgments
Financial support for this work by Fonds der Chemischen Industrie
is gratefully acknowledged.
3
(300 MHz, [D8]THF, 296 K): δ ϭ 0.52 (t, J ϭ 7.5 Hz, 3 H, CH3),
[1] [1a]
R. W. Hilts, R. A. Franchuk, M. Cowie, Organometallics
0.54 (m, 3 H, CoCH3), 1.03 [s (br), 18 H, PCH3], 2.43 (q, 3J ϭ
7.5 Hz, 2 H, CH2), 5.81Ϫ7.77 (m, 13 H, CH) ppm. 31P NMR
(81 MHz, [D8]THF, 213 K): δ ϭ Ϫ32 [t, 2J(PP) ϭ 23 Hz, 1 P, PPh2],
10 [d, 2J(PP) ϭ 23 Hz, 2 P, PCH3] ppm. C27H39CoIP3 (642.4):
calcd. C 50.48, H 6.12, P 14.47; found C 50.24, H 5.72, P 14.54.
[1b]
1991, 10, 1297Ϫ1304.
C. Tejel, M. A. Ciriano, L. A. Oro,
M. Bordonaba, C. Graiff, A. Tiripicchio, A. Burini, Organo-
metallics 2000, 19, 3115Ϫ3119.
[2] [2a]
R. F. Jordan, A. S. Guram, Organometallics 1990, 9,
[2b]
2116Ϫ2123.
G. G. Hlatky, H. W. Turner, R. R. Eckman, J.
Am. Chem. Soc. 1989, 11, 2728Ϫ2729.
H.-F. Klein, S. Schneider, M. He, U. Flörke, H.-J. Haupt, Eur.
J. Inorg. Chem. 2000, 2295Ϫ2301.
H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt, Eur. J. Inorg.
Chem. 2003, 240Ϫ248.
[3]
[4]
[5]
Crystal Structure Analyses: Crystal data are presented in Table 1.
Data collection: 3: A crystal was sealed under argon in a glass
capillary and mounted on a Bruker AXS P4 diffractometer. Intens-
ities were collected (ω-scans) using graphite-monochromated Mo-
Kα radiation; Lp correction and absorption correction based on ψ-
scans were applied. The structure was solved by direct and conven-
tional Fourier methods. All non-hydrogen atoms were treated an-
isotropically, hydrogen atoms were treated with a riding model in
idealized positions. 6: Crystal mounting, data collection, structure
solution, and refinement as for 3. 7: Crystal mounting, data collec-
tion, structure solution, and refinement as for 3. Two independent
molecules per asymmetric unit. 13·0.5OEt2: Crystal mounting, data
collection, structure solution, and refinement as for 3. Two inde-
pendent molecules per asymmetric unit. CCDC-184438 (3),
-184439 (6), -184440 (7), and -184441 (13) contain the supplement-
ary crystallographic data for this paper. These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; Fax: (internat.) ϩ 44-1223/336-
033; E-mail: deposit@ccdc.cam.ac.uk].
P. W. N. M. van Leeuwen, P. C. J. Kamer, J. N. H. Reek, P.
Dierkes, Chem. Rev. 2000, 100, 2741Ϫ2769.
[6] [6a]
M. A. Bennett, S. K. Bhargava, M. Ke, A. C. Willis, J.
[6b]
Chem. Soc., Dalton Trans. 2000, 3537Ϫ3545.
K. von De-
[6c]
uten, L. Dahlenburg, Cryst. Struct. Commun. 1980, 9, 421.
G. del Piero, G. Perego, A. Zazzetta, M. Cesari, Cryst. Struct.
Commun. 1974, 3, 7235.
[7]
[8]
[7a] A. J. Cheney, B. L Shaw, J. Chem. Soc., Dalton Trans. 1972,
[7b]
754Ϫ763.
A. J. Cheney, B. L Shaw, J. Chem. Soc., Dalton
Trans. 1972, 860Ϫ865.
A. G. Orpen, L. Brammer, F. H. Allen, O. Kennard, D. G.
Watson, R. Taylor, J. Chem. Soc., Dalton Trans. 1989, S1ϪS83.
[9] [9a]
H.-F. Klein, E. Auer, T. Jung, C. Röhr, Organometallics
[9b]
1995, 14, 2725Ϫ2732.
Bakhmutov, A. I. Yanovsky, Yu. T. Stuchkov, M. E. Vol’pin, J.
Organomet. Chem. 1987, 330, 161Ϫ178.
Mulichak, R. W. Jones, J. W. Bacon, V. B. Pett, D. Zacharias,
I. Ya. Levitin, M. V. Tsikalova, V. I.
[9c]
P. L. Choo, A. M.
Inorg. Chim. Acta 1990, 171, 183Ϫ192.
Eur. J. Inorg. Chem. 2003, 853Ϫ862
861

H.-F. Klein, R. Beck, U. Flörke, H.-J. Haupt
FULL PAPER
[10]
[18]
[19]
[20]
[21]
H.-F. Klein, U. Lemke, M. Lemke, A. Brand, Organometallics
G. P. Schiemenz, A. Kaack, Liebigs Ann. Chem. Soc. 1973,
1998, 17, 4196Ϫ4201.
1480Ϫ1493.
[11]
H.-F. Klein, H. H. Karsch, Chem. Ber. 1975, 108, 944Ϫ954.
M. Hingst, M. Tepper, O. Stelzer, Eur. J. Inorg. Chem. 1998,
[12]
H.-F. Klein, H. H. Karsch, Chem. Ber. 1976, 109, 1453Ϫ1464.
V. Galamb, G. Palyi, R. Boese, R. Schmid, Organometallics
73Ϫ82.
[13]
S. O. Grim, A. W. Yankowsky, Phosphorus Sulfur 1977, 3,
1987, 6, 861Ϫ867.
H.-F. Klein, X. Li, U. Flörke, H.-J. Haupt, Z. Naturforsch.,
191Ϫ195.
[14]
V. D. Bianco, S. Doronzo, Inorg. Synth. 1976, 16, 155Ϫ161.
Teil B 2000, 55, 707Ϫ717.
Received July 15, 2002
[I02386]
[15]
M. Bressan, P. Rigo, Inorg. Chem. 1975, 14, 38Ϫ42.
[16]
L. Horner, G. Simons, Phosphorus Sulfur 1983, 15, 165Ϫ176.
T. B. Rauchfuss, F. T. Patino, D. M. Roundhill, Inorg. Chem.
[17]
1975, 14, 652Ϫ656.
862
Eur. J. Inorg. Chem. 2003, 853Ϫ862