Metalated 1,3-azaphospholes: 1H-1,3-benzazaphosphole and 1,3-benzazaphospholide tungsten(0) and tungsten(II) complexes

Article abstract of DOI:10.1002/1099-0682(200109)2001:10<2563::AID-EJIC2563>3.0.CO;2-2

2-tert-Butyl-1H-1,3-benzazaphosphole (1a) reacts with tBuLi without addition to the P=C bond to form a lithium benzazaphospholide that affords the η¹-(benzazaphospholide-P)tungsten(II) complex 2 upon reaction with [CpW(CO)₃Cl]. It is sensitive to alcoholysis and to air oxidation yielding 1a and the P-oxo-benzazaphospholide complex 3, respectively. The (1,3-benzazaphosphole)pentacarbonyltungsten complex 4, obtained from 1b and [W(CO)₅(THF)], reacts preferentially with tBuLi by lithiation of the NH function and is attacked by [CpW(CO)₃Cl] at phosphorus to give the mixed valence bimetallic tungsten(II)-tungsten(0) benzazaphospholide complex 5. A side product, (3-tert-butyl-2-methyl-1,3-benzazaphosphole)pentacarbonyltungsten (6), is attributed to side-reaction where tBuLi adds to the P=C bond in 4. The composition of the products was determined from X-ray structure analysis of 3 and spectroscopic data.

Full text of DOI:10.1002/1099-0682(200109)2001:10<2563::AID-EJIC2563>3.0.CO;2-2

FULL PAPER
Metalated 1,3-Azaphospholes: 1H-1,3-Benzazaphosphole and
1,3-Benzazaphospholide Tungsten(0) and Tungsten(II) Complexes
Joachim Heinicke,*[a] Anushka Surana,[a] Normen Peulecke,[a] Raj Kumar Bansal,[b]
Alexander Murso,[c] and Dietmar Stalke[c]
Keywords: Phosphorus heterocycles / Tungsten / Metalation
2-tert-Butyl-1H-1,3-benzazaphosphole (1a) reacts with tBuLi
with tBuLi by lithiation of the NH function and is attacked
without addition to the P=C bond to form a lithium benzaza- by [CpW(CO)3Cl] at phosphorus to give the mixed valence
phospholide that affords the η1-(benzazaphospholide-
P)tungsten(II) complex 2 upon reaction with [CpW(CO)3Cl].
It is sensitive to alcoholysis and to air oxidation yielding 1a
and the P-oxo-benzazaphospholide complex 3, respectively.
bimetallic tungsten(II)-tungsten(0) benzazaphospholide com-
plex 5. A side product, (3-tert-butyl-2-methyl-1,3-benzaza-
phosphole)pentacarbonyltungsten (6), is attributed to side-
reaction where tBuLi adds to the P=C bond in 4. The com-
The (1,3-benzazaphosphole)pentacarbonyltungsten complex position of the products was determined from X-ray structure
4, obtained from 1b and [W(CO)5(THF)], reacts preferentially
analysis of 3 and spectroscopic data.
Introduction
Results and Discussion
Synthesis
Phospholide[1Ϫ4] and pyrrolide[3Ϫ6] complexes have at-
tracted considerable interest in the past years, and some di-
and triazaphosphol(id)e complexes have also been re-
ported.[7] Azaphospholide complexes, analogues of pyrrol-
ide or of diphospholide complexes, as well as 1,3-benzaza-
phospholide complexes are, however, still unknown. The re-
cent discovery of a convenient synthetic access to 2-substi-
tuted 1H-1,3-benzazaphospholes[8] prompted us to fill this
gap partly and to explore the reactivity and use of these
very stable but under-investigated phosphaaromatic hetero-
cycles as ligands.[8Ϫ11] The only 1,3-benzazaphosphole
complex reported to date is pentacarbonyl-η1-(2-phenyl-
1,3-benzazaphosphole-P)chromium.[10] Lithiation of 2-
phenylbenzazaphosphole by Et2NLi has also been de-
scribed,[10] although the lithium benzazaphospholide was
not isolated and separated from the secondary amine, which
is preferentially attacked by electrophiles other than alkyl
halides. We report here on an alternative metalation proced-
ure avoiding this problem and the synthesis of the first 1,3-
benzazaphosphole and 1,3-benzazaphospholide tungsten
complexes.
Whilst 1H-1,3-benzazaphospholes and nBuLi produce
mixtures of addition and metalation products, a selective
monolithiation of the NH function is achieved by treatment
of 1a with one equivalent of tBuLi in ether or THF at low
temperature. Like ambident anions formed by the
metalation of pyridylphosphanes,[12] the resulting lithium
1,3-benzazaphospholide Li-1a can be used directly for the
synthesis of complexes as exemplified by the reaction with
[CpW(CO)3Cl] (Scheme 1). Li-1a reacts selectively at phos-
phorus to give the dark red-brown benzazaphospholide
tungsten complex 2. It is slightly soluble in hexane and
readily soluble in more polar solvents like toluene or ethers.
Like related Cp(CO)3W-phospholide[13Ϫ15] or Cp(CO)3W-
phosphide[16] complexes, 2 is a very reactive compound. Al-
though less sensitive towards hydrolysis than the extremely
reactive N-silyl- or P-stannyl-benzazaphospholes,[17] the
PϪW bond of 2 is cleaved readily by OH/OD reagents, as
shown by the addition of CD3OD to yield 1b. The latter is
also formed on heating 2 to 80 °C in toluene for one day,
whereas related but more stable Cp(CO)3W complexes with
non-anellated phospholide ligands form tungsten-bridged
complexes.[15] Compound 2 is also sensitive to air oxidation.
Crystallization of a sample oxidized in THF gave single
crystals of the toluene monosolvate of the P-oxo-benzaza-
phospholide tungsten complex 3, from toluene/hexane,
which allowed an X-ray crystal structure analysis (Fig-
ure 1).
[a]
Institut für Chemie und Biochemie, Ernst-Moritz-Arndt-
Universität Greifswald,
Soldmannstraße 16, 17487 Greifswald, Germany,
Fax: (internat.) ϩ49-3834/86-4319
E-mail: heinicke@uni-greifswald.de
The (1,3-benzazaphosphole)pentacarbonyltungsten com-
plex 4, obtained from 1b and [W(CO)5(THF)], can be
lithiated in an analogous manner with tert-butyllithium and
trapped with [CpW(CO)3Cl]. The formation of the mixed
valence bimetallic complex 5, with zero- and two-valent
[b]
Department of Chemistry, University of Rajasthan,
Jaipur 302 004, India,
[c]
Institut für Anorganische Chemie, Universität Würzburg,
Am Hubland, 97074 Würzburg, Germany,
Fax: (internat.) ϩ49-931/888-4619
E-mail: dstalke@chemie.uni-wuerzburg.de
Eur. J. Inorg. Chem. 2001, 2563Ϫ2567
WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ1948/01/1010Ϫ2563 $ 17.50ϩ.50/0
2563

J. Heinicke, A. Surana, N. Peulecke, R. K. Bansal, A. Murso, D. Stalke
FULL PAPER
shift in the formal 6π- or 10π-heterocyclic phosphido com-
plexes with the same MLn fragment reflects a larger in-
crease in the electron density at phosphorus and may be
attributed to a reduced ability of the π-electrons at phos-
phorus to take part in cyclodelocalization; it may also be
supported by a more effective back donation compared to
that in Ph2PϪW(CO)3Cp or in the W0(CO)5-benzazaphos-
phole complex 4. The 13C nuclei of the five-membered ring
and of C-5 to C-7 are markedly deshielded by the com-
plexation, ∆δ(2؊1a) ഠ 20 (C-2), 12 (C-3a, C-7, C-7a) and
7 (C-5, C-6), whilst the one-bond PϪC couplings show dif-
1
ferent trends, JPϪC2 increases from 57 Hz in 1a to 61.8 Hz
in 2, and 1JPϪC3a decreases from 41 to 14 Hz. The chemical
shift values are significantly closer to those of 3H-1,3-
benzazaphospholes[17,19,20] than to those of 1 although the
one-bond coupling constants of 2 are significantly larger
than in the 3H-isomers. These findings imply that the na-
ture of 2 is in-between that of the aromatic 1H- and the
non-aromatic 3H-3-alkyl-1,3-benzazaphospholes,[21Ϫ23] al-
though probably closer to the latter. For the related phos-
pholide CpW(CO)3 complexes a similar situation was de-
duced from the X-ray crystal structure analysis.[15] The
compounds were classified from the structural standpoint
as halfway between phospholes with pyramidal P and local-
ized π-bonds and phospholes with planar P and delocalized
π-bonds.
Scheme 1
Figure 1. Solid state structure of 3 (anisotropic displacement para-
In the oxidation product 3 the framework of 2 is pre-
served (Figure 1) but the transition to four-coordinate
phosphorus consolidates a non-aromatic, 3H-indole-like π-
system. The lack of cyclodelocalization becomes evident by
comparison of selected bond lengths and angles of the five-
membered ring in 3 and the corresponding parameters of
its phosphaaromatic precursor 1a[17] (Table 1). Within the
PϪCϪN fragment the PϪC bond is considerably widened
and becomes longer than the PϪC(aryl) bond, whilst the
CϪN bond is shortened. The smaller N1ϪC7 bond and the
approximation of the C1ϪC2ϪN angle in 3 to an ideal sp2
geometry at the expense of the C2ϪC1ϪP angle reflects the
strengthening of a coplanar N-phenyl-azomethine π-system.
In the acyclic metallaphosphane oxide [oTol2P(O)Ϫ
W(CO)3Cp],[16b] the P1ϪW1 distances of the two independ-
ent molecules in the unit cell are slightly longer [2.571(8),
meters drawn at 50% probability level, hydrogen atoms and toluene
˚
omitted for clarity); selected bond lengths [A] and angles[°]:
W1ϪP1 2.5591(7), WϪC(O) 1.989(3) Ϫ 2.005(3), WϪC(Cp)
2.314(3) Ϫ 2.361(3), P1ϪO1 1.507(2); W1ϪP1ϪO1 116.91(8),
O1ϪP1ϪC1 114.18(12), O1ϪP1ϪC7 113.32(12), W1ϪP1ϪC1
107.79(9), W1ϪP1ϪC7 113.12(8), P1ϪW1ϪC17 78.03(8),
P1ϪW1ϪC18 73.43(8), C17ϪW1ϪC19 76.77(12), C19ϪW1ϪC18
77.28(12); for ring parameters see Table 1
tungsten bound at the phosphorus atom, shows that the
blockage of the phosphorus lone electron pair does not
favor an attack at nitrogen, but that the lithiated pentacar-
bonyl tungsten complex Li·4 also prefers substitution at the
softer nucleophilic site. The lithiation itself proceeds less se-
lectively, as seen from the occurrence of 6. It is assumed
that 6 is formed by the addition of tBuLi to the PϭC
double bond of 4 followed by reaction with [CpW(CO)3Cl]
and elimination of [CpW(CO)3H]. In the crude product the
ratio 5:6 was found to be ca. 2:1.
˚
2.589(9) A] than in 3, although shorter than the sum of the
[24]
˚
covalent radii (2.65 A),
and the PϪO bonds (double
˚
bond character) are slightly shorter [1.46(2), 1.49(2) A]. The
Structure
WϪPϪO angle is larger in 3 due to the small CϪPϪC
The H, 13C and 31P NMR chemical shifts and coupling angle within the five-membered ring.
1
patterns, the observance of molecular ions in the mass spec-
The known compound η1-(2-phenyl-1,3-benzazaphos-
trum and satisfactory elemental analysis give evidence for phole-P)pentacarbonylchromium exhibits a very low posit-
the structures of 2, 4 and 5. Like related Cp(CO)3W-phos- ive complexation shift (∆δ ϭ 4.4) and classifies 1H-1,3-
1
pholide complexes,[15] compound 2 (δ ϭ Ϫ102.4, JPϪW
ϭ
benzazaphospholes as weak donors.[10] The tungsten penta-
50.1 Hz) reveals a strong up-field coordination shift carbonyl complex 4 even displays a negative coordination
∆δ(2؊Li·1a) ϭ Ϫ159 and a very small one-bond PϪW shift (∆δ ϭ Ϫ35.0). The upfield shift of the tungsten relative
coupling constant. The acyclic [Cp(CO)3WϪPPh2] (δ ϭ to the related chromium complex reflects the typical core-
1
Ϫ63.3, JPϪW ϭ 52 Hz)[16] exhibits a similar low PϪW effect in transition metal phosphane complexes[25] and is
coupling constant, but a much smaller upfield coordination also observed for related (phosphaindolizine)metallapenta-
shift relative to the corresponding alkali metal phosphides carbonyls (M ϭ Cr, Mo, W).[26] The one bond 31PϪ183W
(Ph2PLi: δ ϭ Ϫ21.4[18]). The larger upfield coordination coupling constant is much larger than in 2, 5 and 6 and
2564
Eur. J. Inorg. Chem. 2001, 2563Ϫ2567

1H-1,3-Benzazaphosphole and 1,3-Benzazaphospholide Tungsten(0) and Tungsten(II) Complexes
FULL PAPER
The P-tetracoordinated di-tungsten complex 5 and the side
product 6, a 3-alkyl-benzazaphosphole W(CO)5 complex,
reveal 13C NMR spectroscopic data which likewise are in
accordance with a non-aromatic nature. Compound 2 is a
borderline case: its carbon chemical shifts resemble those
of 3H-1,3-benzazaphospholes whilst the magnitude of the
1JPϪC2 coupling constant is significantly larger. Only the
electronic structure of the neutral benzazaphosphole
W(CO)5 complex 4 is similar to that in the phosphaarom-
atic heterocycles 1.
Table 1. Comparison of selected structure data of 3 and corres-
ponding data of 1a[17]
˚
Bond length [A], angle [°]
3
1a
P1ϪC1
P1ϪC7
N1ϪC7
N1ϪC2
C1ϪC2
C7ϪC8
P1ϪC7ϪN1
C1ϪP1ϪC7
C2ϪN1ϪC7
C1ϪC2ϪN1
C2ϪC1ϪP1
1.817(3)
1.882(3)
1.290(3)
1.430(3)
1.404(4)
1.522(4)
113.43(19)
87.88(12)
112.6(2)
117.1(2)
108.27(19)
1.793(3)
1.712(4)
1.374(4)
1.380(4)
1.389(4)
1.514(4)
112.3(2)
90.1(2)
115.1(3)
111.9(3)
110.7(2)
Experimental Section
General: All manipulations were carried out under an atmosphere
of dry argon using standard Schlenk and cannula techniques. Ether,
THF and hydrocarbons were refluxed over sodium/benzophenone
and distilled prior to use. C6D6 and [D8]THF were dried with so-
dium or LiAlH4 and recondensed. NMR spectra were recorded on
a multinuclear FT NMR spectrometer Bruker Model ARX300 at
similar to that in pentacarbonyltungsten complexes of less-
basic triorganophosphanes.[25] The effect of the com-
plexation on the 1H-1,3-benzazaphosphole π-system is ra-
ther small and limited mainly to the carbon atoms adjacent
to phosphorus. C-2 and C-3a of 4 are shifted by ∆δ ഠ 7 in
the 13C NMR spectrum and display much lower PϪC coup-
ling constants. For C-4 and the methyl carbon in the β-
position to the phosphorus this trend is much smaller, and
the other nuclei show no marked influence. In the tungsten
complexes 5 and 6, however, the cyclodelocalization seems
to be lost. Both, the tungsten(II)- and the 3-tert-butyl-sub-
stituted 1,3-benzazaphosphole tungsten pentacarbonyl spe-
cies, exhibit the signals of the 13C nuclei C-5 to C-7a at
significantly lower field than in 1 or 4, in regions typical
for 3-alkyl-1,3-benzazaphospholes.[17,19,20] The phosphido-
character of the benzazaphospholide ligand is markedly re-
duced by complexation with W(CO)5 as indicated by the
less-negative phosphorus resonance of 5 relative to 2 (∆δ ϭ
1
300.1 (1H), 75.5 (13C), and 121.5 (31P) MHz. The H, 13C and 31P
chemical shifts are δ values relative to Me4Si or H3PO4 (85%);
coupling constants are quoted in Hz. IR spectra were measured on
a PerkinϪElmer Model system 2000 and mass spectra on a single-
focussing mass spectrometer AMD40 (Intectra). Melting points
were determined in sealed capillaries under argon and are uncorrec-
ted. Elemental analyses were carried out using an elemental ana-
lyzer LECO Model CHNS-932 with standard combustion condi-
tions (carbon combustion sometimes incomplete) and handling of
the samples in air.
Materials: Compounds 1a and 1b were synthesized as reported re-
cently;[8] [W(CO)5(THF)] and [CpW(CO)3Cl] were obtained by
known procedures.[27] Other materials were used as purchased un-
less stated otherwise.
η5-(2-tert-Butyl-1,3-benzazaphosphol-3-yl-P)(η5-cyclopentadienyl)-
tricarbonyltungsten (2): A solution of 1a (290.6 mg, 1.52 mmol) in
ether was cooled to Ϫ78 °C and lithiated with an equimolar
amount of tBuLi dissolved in pentane (31P NMR in [D8]THF: δ ϭ
1
II
26.4) and the increased JPϪW coupling constant, whereas
0
1JPϪW is smaller than in 4 and 6 due to the higher donor
strength of the benzazaphospholide relative to the 1H- and
3H-1,3-benzazaphospholes.
56.6). After 30 min.
a solution of [CpW(CO)3Cl] (560 mg,
1.52 mmol) in ether was added (Ϫ78 °C) affording a red brown
mixture. This was allowed to warm to room temperature and
stirred for one day. The precipitate was then removed, and the solv-
ent was evaporated in vacuo. The residue was crystallized from hot
toluene affording 614 mg (77%) of red solid 2, slightly contamin-
Conclusion
1
ated by 1a. It is insoluble in hexane, m.p. 80Ϫ83 °C. Ϫ H NMR
The aim of this work was to investigate the metalation of
1H-1,3-benzazaphospholes and to present novel 1,3-benza-
zaphospholide complexes as PϪC homologues of indolides.
It was shown that 1H-1,3-benzazaphospholes and tungsten
pentacarbonyl complexes, represented by 1a and 4, may be
lithiated by tBuLi selectively or preferentially at the NH
function. The resulting ambident 1,3-benzazaphospholide
anions react with the [CpW(CO)3Cl] exclusively at the
softer nucleophilic site and furnish the η1-P-coordinated
tungsten(II) complex 2 and the mixed valence bimetallic
tungsten(II)-tungsten(0) species 5. The benzazaphospholide
complexes are sensitive to hydrolysis and oxidation. A crys-
tal structure analysis of the benzazaphospholide oxide com-
plex 3 (toluene monosolvate) gave evidence of the molecular
composition and, by comparing the bond lengths with
4
([D8]THF): δ ϭ 1.41 (d, JPϪH ϭ 0.6, 9 H, CMe3), 5.34 (s, 5 H,
3
4
4
Cp), 7.08 (‘‘t’’dd, J ϭ 7.5, JPϪH ϭ 3.3, J ϭ 1.2, 1 H, H-5), 7.22
(m, 3J ϭ 7.4, 7.7, 4J ഠ JPϪH ഠ 1, 1 H, H-6), 7.75 (br. d, 3J ϭ
5
7.7 Hz, 1 H) and 7.78 (d, 3J ϭ 8.1, 1 H) (H-4 and H-7). Ϫ 13C{1H}
NMR ([D8]THF): δ ϭ 32.2 (d, 3J ϭ 5.6, CMe3), 40.7 (d, 2J ϭ 20.3,
3
CMe3), 94.3 (Cp), 123.8 (d, J ϭ 6, C-5), 124.7 (C-7), 126.3 (C-6),
2
1
2
127.1 (d, J ϭ 20, C-4), 150.3 (d, J ϭ 14, C-3a), 155.5 (d, J ϭ 9,
C-7a), 209.3 (d, 1J ϭ 62, C-2), 214.9, 218.3, 233.4 (3 CO). Ϫ
31P{1H} NMR ([D8]THF): δ ϭ Ϫ102.4 (1JPϪW ϭ 50.1). Ϫ EI-MS
(70 eV): m/z (%) ϭ 523 (23) [Mϩ 184W)], 480 (27), 455 (44), 196
(
(72), 184 (93), 28 (100). Ϫ C19H18NO3PW (523.17): calcd. C 43.62,
H 3.47, N 2.68; found C 40.52, H 3.50, N 2.47.
η5-(2-tert-Butyl-3-oxo-1,3-benzazaphosphol-3-yl-P)(η5-cyclo-
pentadienyl)tricarbonyltungsten Toluene Monosolvate (3): A small
amount of 2 dissolved in THF was oxidized by allowing slow dif-
those of 1a, of a non-aromatic, 3H-indole-like π-system. fusion of air into the Schlenk tube. Since addition of hexane failed
Eur. J. Inorg. Chem. 2001, 2563Ϫ2567 2565

J. Heinicke, A. Surana, N. Peulecke, R. K. Bansal, A. Murso, D. Stalke
FULL PAPER
1
to give a precipitate the solvent was removed in vacuum and re-
placed by toluene. On addition of hexane small, pale-yellow single
crystals of the toluene monosolvate 3 deposited at ϩ4 °C within 3
days (yield not determined). The crystal and molecular structure
was determined by X-ray diffraction (Table 1, Figure 1). Ϫ 1H
NMR (C6D6): δ ϭ 1.71 (s, 9 H, CMe3), 2.11 (s, 3 H, toluene), 4.60
76.1 (sat, JPϪW ϭ 180.8, 90.8). Ϫ EI-MS (70 eV, 240 °C): m/z ϭ
804 (34), [Mϩ Ϫ 1 (184W)], 776 (20), 749 (12) [Mϩ Ϫ 2CO], 721
(32) [Mϩ Ϫ 3CO], 683 (54) [Mϩ Ϫ 2CO-Cp], 665 (100) [Mϩ
Ϫ
5CO], 645 (41), 625 (62), 604 (48), 396 (61), 341 (62), 309 (50), 149
(65). Ϫ C21H12NO8PW2 (804.77): calcd. C 31.34, H 1.50, N 1.74;
found C 29.00, H 1.76, N 1.64.
(s, 5 H, Cp), 6.93 (ddd, J ϭ 7.1, JPϪH ϭ 3.6, J ϭ 1.3, 1 H, 4- or 6 (hexane): 1H NMR ([D8]THF): δ ϭ 1.19 (d, 3J ϭ 16.1, 9 H,
3
4
7-H), 6.97Ϫ7.13 (m, toluene), 7.05 and 7.40 (both ‘‘t’’m, 3J ഠ 6, 7, CMe3), 2.63 (d, J ϭ 6.8 Hz, 3 H, Me), 7.41Ϫ7.45 (m, 1 H, H5),
3
3
4
5
5- and 6-H, partially superimposed by C6D6 side band), 7.65 (ddd,
7.54 (‘‘tt’’, J ഠ 7.4, 7.8, J ഠ JPϪH ഠ 1.2, 1 H, H-6), 7.70Ϫ7.75
ca. 3J ϭ 7.2, J ϭ 2, 1, 1 H, 7- or 4-H). Ϫ 31P{1H} NMR ([D8]THF): (m, 2 H, H-4, H-7). Ϫ 13C{1H} NMR ([D8]THF): δ ϭ 21.7 (d,
δ ϭ 61.3 (1JPϪW ϭ 135).
2J ϭ 15, Me), 124.7 (d, 2J ϭ 4, C-7), 127.8 (d, 3J ϭ 8.4, C-5), 130.2
(d, 2J ϭ 13.3, C-4), 132.5 (br., C-6), 133.5 (d, 1J ϭ 48.2, C-3a),
156.8 (d, 2J ϭ 16, C-7a), 181.3 (br., uncertain due to low intensity,
η1-(2-Methyl-1H-1,3-benzazaphosphole-P)pentacarbonyltungsten
(4): A solution of [W(CO)5(THF)], prepared by irradiation of
[W(CO)6] (2.324 g, 6.60 mmol) in THF (300 mL; 145 mL of CO
evolved), was added to a solution of 1b (0.984 g, 6.60 mmol) in
THF (5 mL). After one day at room temperature the solvent and
volatile tungsten complexes were removed in vacuo and the residue
fractionally extracted with hexane yielding in the later fractions
1.272 g (41%) of orange 4, m.p. 122Ϫ124 °C. Ϫ 1H NMR (CDCl3):
C-2). Ϫ 31P{1H} NMR ([D8]THF): δ ϭ 50.8 (sat, JPϪW ϭ 216.4).
1
Crystal Data and Structure Determination for 3: The data set was
collected at low temperature using an oil-coated shock-cooled crys-
tal[28] on a Bruker APEX-CCD diffractometer equipped with Mo-
Kα (λ ϭ 71.073 pm) radiation and a low temperature device at
173(2) K. The structure was solved by Patterson methods
(SHELXS-NT 97)[29] and refined by full-matrix least-squares
methods against F2 (SHELXL-NT 97).[30] R values defined as R1 ϭ
3
δ ϭ 2.73 (d, JPϪH ϭ 17.8, 3 H, Me), 7.23 (‘‘t’’dd, 3J ഠ 7.6, 8,
5
4JPϪH ϭ 3.8, 4J ϭ 0.9, 1 H, H-5), 7.36 (‘‘tt’’, 3J ഠ 7.6, JPϪH
ഠ
Σ||Fo| Ϫ |Fc||/Σ|Fo|,
wR2 ϭ [Σw(F2o Ϫ F2c)2/Σw(F2o)2]0.5
P ϭ 1/3[max(F2o,0) ϩ 2F2c]. SADABS
,
w ϭ
4J ഠ 1.2, 1 H, H-6), 7.52 (d, J ϭ 8.6, 1 H, H-7), 7.87 (‘‘t’’, J ഠ
3
3
[σ2(F2o) ϩ (g1P)2 ϩ g2P]Ϫ1
,
3JPϪH ഠ 7.8, 1 H, H-4), 9.60 (br, 1 H, NH). Ϫ H NMR (C6D6):
1
3
3
2.0 was employed as the program for empirical absorption correc-
δ ϭ 2.04 (d, JPϪH ϭ 18, 3 H, Me), 6.98 (br. d, J ϭ 8.3, 1 H, H-
tion.[31]
7), 7.06 (dddd, 3J ϭ 7.0, 8.0, JPϪH ϭ 2.8, 4J ϭ 1.0, 1 H, H-5),
4
3
5
4
3: C26H26NO4PW, M ϭ 631.30, monoclinic, space group P21/n, a ϭ
11.3819(3), b ϭ 10.4653(3), c ϭ 21.1456(6) A, β ϭ 104.5600(10)°,
7.20 (‘‘tt’’, J ϭ 8.3, 7.0, JPϪH ഠ J ഠ 1.3, 1 H, H-6), 7.98 (‘‘t’’
br., 3J ഠ 3JPϪH ഠ 7, 8, 1 H, H-4). Ϫ 13C{1H} NMR (CDCl3): δ ϭ
15.8 (d, 2J ϭ 15.0, Me), 114.3 (d, 3J ϭ 3.2, C-7), 121.4 (d, 3J ϭ
14.0, C-5), 125.8 (d, 4J ϭ 3.5, C-6), 126.5 (d, 2J ϭ 13.5, C-4), 136.3
(d, 1J ϭ 21.9, C-3a), 141.9 (s, C-7a), 167.6 (d, 1J ϭ 30.8, C-2),
˚
V ϭ 2.43787(12) nm3, Z ϭ 4, ρcal. ϭ 1.720 Mg/m3, µ ϭ 4.836
mmϪ1, F(000) ϭ 1240. 41621 reflections measured, 6055 unique,
R(int) ϭ 0.0383, wR2(all data) ϭ 0.0545, R1[I Ͼ 2σ(I)] ϭ 0.0230,
g1 ϭ 0.0301, g2 ϭ 0.8837 for 5742 data, 228 restraints and 363
parameters. In addition to the tungsten complex the unit cell con-
tains a non-coordinating disordered toluene molecule. The occu-
pancy factors of the solvent molecule refined to 0.788 and 0.272.
The toluene molecule was assigned ideal positions and refined us-
ing ADP restraints. All non-hydrogen atoms were refined aniso-
tropically. The hydrogen atoms of the cyclopentadienyl ligand were
taken from the difference Fourier map and refined freely, all other
hydrogen atoms were geometrically idealized and refined using a
riding model. Selected bond lengths and angles of 3 can be found
in Table 1.
2
1
2
194.6 (d sat, J ϭ 8.5, JCϪWϭ 124, 4 CO), 199.8 (d, J ϭ 29.1, 1
CO). Ϫ 31P{1H} NMR (CDCl3): δ ϭ 36.7 (sat, 1JPϪW ϭ 242.6). Ϫ
˜
IR (Nujol): ν ϭ 3405 m (NH), 2071 m, 1981 vs, 1946 vs, 1880 s
(CO) cmϪ1. Ϫ EI-MS (70 eV): m/z (%; data for 184W) ϭ 473 (80)
[Mϩ], 445 (4), 417 (64) [Mϩ Ϫ 2CO], 389 (68) [Mϩ Ϫ 3CO], 361
(41) [Mϩ Ϫ 4CO], 333 (62) [Mϩ Ϫ 5CO], 149 (100) [1bϩ], 148 (98).
Ϫ C13H8NO5PW (473.02): calcd. C 33.01, H 1.70, N 2.96; found
C 33.20, H 2.11, N 2.60.
η1-{2-Methyl-3-[(η5-cyclopentadienyl)tricarbonyltungsten]-1,3-
benzazaphosphole-P}pentacarbonyltungsten (5) and η1-(3-tert-Butyl-
2-methyl-1,3-benzazaphosphole-P)pentacarbonyltungsten
(6):
Crystallographic data for the structure of 3 has been deposited with
the Cambridge Crystallographic Data Centre as supplementary
publication no. CCDC-161162. Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [Fax: (internat.) ϩ44-1223/336-033, E-mail:
deposit@ccdc.cam.ac.uk].
[CpW(CO)3Cl] (277 mg, 0.754 mmol) was added at Ϫ70 °C to a
solution prepared from 4 (358 mg, 0.757 mmol) in ether (10 mL)
and tBuLi in pentane (0.45 mL, 0.754 mmol) as described above.
The mixture was allowed to stir at room temperature for 3 days.
Then it was filtered and washed with ether. Removal of the solvent
in vacuo afforded a mixture of 5 and 6 in a molar ratio of ca. 2:1
1
(based on H integral ratio of the CH3 signals) along with a small
amount of unchanged 4. Fractional crystallization with hexane and
then with toluene gave 300 mg (49%) of 5 (from toluene) and 80 mg
(20%) of 6 (from hexane) as red solids. Compound 6 was impure
and identified by it’s characteristic NMR spectroscopic data.
Acknowledgments
This work was generously supported by the Deutsche Forschungs-
gemeinschaft and the Fonds der Chemischen Industrie. We thank
B. Witt and Dr. M. K. Kindermann for NMR studies.
1
3
5: H NMR ([D8]THF): δ ϭ 2.72 (d, J ϭ 7.4, 3 H, Me), 5.20 (d,
3
J ϭ 2.0, 5 H, Cp), 7.27Ϫ7.35 (m, 1 H H-5), 7.37 (‘‘t’’, J ഠ 7.3, 1
3
3
3
H, H-6), 7.78 (d, J ϭ 7.6, 1 H, H-7), 7.85 (dd, J ϭ 6.7, JPϪH
ϭ
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2
1
2
C-2), 198.6 (d, sat, J ϭ 5.4, JCϪW ϭ 126, 4 CO), 200.6 (d, J ϭ
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