Dioxotungsten(VI) complexes with N2O tridentate ligands. Synthesis and structure of the chloro and alkyl derivatives

Article abstract of DOI:10.1021/om990464+

A new series of N₂O tridentate ligands HLⁿ (n = 2-5) have been prepared through N-methylation or N-benzylation of 2-N-(2-pyridylmethyl)aminophenpl (HL¹). Treatment of these ligands with WO₂Cl₂(DME) (DME = 1,2-dimethoxyethane) in the presence of triethylamine leads to the formation of cis-dioxotungsten(VI) complexes WO₂(Lⁿ)Cl (n = 1-5). Reaction of WO₂(L¹)Cl with Me₃SiCH₂MgCl gives the alkyl derivative WO₂(L¹)-(CH₂SiMe₃), which has been structurally characterized.

Full text of DOI:10.1021/om990464+

Organometallics 1999, 18, 5075-5079
5075
Dioxotu n gsten (VI) Com p lexes w ith N2O Tr id en ta te
Liga n d s. Syn th esis a n d Str u ctu r e of th e Ch lor o a n d
Alk yl Der iva tives
Yee-Lok Wong, J ian-Fang Ma, Feng Xue, Thomas C. W. Mak, and
Dennis K. P. Ng*
Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong,
People’s Republic of China
Received J une 14, 1999
A new series of N2O tridentate ligands HLn (n ) 2-5) have been prepared through
N-methylation or N-benzylation of 2-N-(2-pyridylmethyl)aminophenol (HL1). Treatment of
these ligands with WO2Cl2(DME) (DME ) 1,2-dimethoxyethane) in the presence of
triethylamine leads to the formation of cis-dioxotungsten(VI) complexes WO2(Ln)Cl (n ) 1-5).
Reaction of WO2(L1)Cl with Me3SiCH2MgCl gives the alkyl derivative WO2(L1)-
(CH2SiMe3), which has been structurally characterized.
In tr od u ction
To our knowledge, organometallic dioxotungsten com-
plexes with other ancillary ligands are extremely rare.7
We have recently reported several series of dioxotung-
sten(VI) complexes with N2O2 and N2S2 tetradentate
ligands, which are active toward oxygen atom transfer
reactions.8 We describe herein a new series of dioxo-
tungsten(VI) complexes containing N2O tridentate
ligands, which can be functionalized through N-alkyla-
tion. The molecular structure of an alkyl-dioxo complex,
namely WO2(L1)(CH2SiMe3), is also reported.
High-valent oxometalates have been widely used in
various homogeneous and heterogeneous catalytic reac-
tions such as oxidation, epoxidation, and ring-opening
polymerization.1 To reveal the nature of the catalytically
active sites and understand the chemical behavior of
the surface species, a substantial number of organome-
tallic oxo complexes have been synthesized and studied
as synthetic analogues.2 The use of alkoxy and phenoxy
groups and more recently the preorganized set of oxygen
donor atoms from calix[4]arenes as ancillary ligands to
mimic the oxo surfaces have also been described.3 High-
valent dioxotungsten complexes with hydrocarbon ligands
have been reported sporadically, most of which contain
cyclopentadienyl ligands of the types WO2(η-C5R5)Cl,
[WO2(η-C5R5)]2O, and WO2(η-C5R5)R′ (R ) H, Me; R′ )
alkyl, alkynyl).4 Bipyridine (bipy) and hydrotris(3,5-
dimethylpyrazolyl)borate [HB(Me2pz)3] have also been
employed as the supporting ligands to give the com-
plexes WO2(bipy)R2 (R ) alkyl, phenyl) and WO2[HB-
(Me2pz)3]R (R ) alkyl, phenyl, alkenyl), respectively.5,6
Resu lts a n d Discu ssion
Treatment of 2-N-(2-pyridylmethyl)aminophenol (HL1),
which could be prepared readily by reductive amination
from 2-aminophenol and 2-pyridinecarboxaldehyde,9
with n-BuLi and methyl iodide or various benzyl
bromides led to the formation of a new series of N2O
tridentate ligands HLn (n ) 2-5) (Scheme 1). The
substituents, having different steric and electronic
nature, were introduced to the nitrogen atom with a
view to studying their effects on complex formation and
properties of the resulting complexes. All the ligands
were characterized spectroscopically, while for HL3 the
molecular structure was also confirmed by single-crystal
X-ray analysis.10 The bond distances and angles of this
ligand are unexceptional, and the N2O binding sites
* To whom correspondence should be addressed. Fax: (852) 2603
5057. E-mail: dkpn@cuhk.edu.hk.
(1) (a) Sheldon, R. A.; Kochi, J . K. Metal-catalysed Oxidation of
Organic Compounds; Academic Press: New York, 1981. (b) Ivin, K.
J .; Mol, J . C. Olefin Metathesis and Metathesis Polymerization;
Academic Press: San Diego, 1997. (c) Piquemal, J .-Y.; Halut, S.;
Bre´geault, J .-M. Angew. Chem., Int. Ed. Engl. 1998, 37, 1146, and
references therein.
(2) Bottomley, F.; Sutin, L. Adv. Organomet. Chem. 1988, 28, 339.
(3) (a) Giannini, L.; Dovesi, S.; Solari, E.; Floriani, C.; Chiesi-Villa,
A.; Rizzoli, C. Angew. Chem., Int. Ed. Engl. 1999, 38, 807, and
references therein. (b) Giannini, L.; Guillemot, G.; Solari, E.; Floriani,
C.; Re, N.; Chiesi-Villa, A.; Rizzoli, C. J . Am. Chem. Soc. 1999, 121,
2797, and references therein.
(4) (a) Legzdins, P.; Rettig, S. J .; Sa´nchez, L. Organometallics 1985,
4, 1470. (b) Faller, J . W.; Ma, Y. J . Organomet. Chem. 1988, 340, 59.
(c) Faller, J . W.; Ma, Y. Organometallics 1988, 7, 559. (d) Legzdins,
P.; Phillips, E. C.; Sa´nchez, L. Organometallics 1989, 8, 940. (e) Shiu,
C.-W.; Su, C.-J .; Pin, C.-W.; Chi, Y.; Peng, S.-M.; Lee, G.-H. J .
Organomet. Chem. 1997, 545-546, 151.
(5) (a) Zhang, C.; Schlemper, E. O.; Schrauzer, G. N. Organometallics
1990, 9, 1016. (b) Zhang, C.; Zhang, X.; Liu, N. H.; Schrauzer, G. N.;
Schlemper, E. O. Organometallics 1990, 9, 1307.
(6) (a) Eagle, A. A.; Tiekink, E. R. T.; Young, C. G. J . Chem. Soc.,
Chem. Commun. 1991, 1746. (b) Eagle, A. A.; Young, C. G.; Tiekink,
E. R. T. Organometallics 1992, 11, 2934. (c) Sundermeyer, J .; Putterlik,
J .; Pritzkow, H. Chem. Ber. 1993, 126, 289. (d) Adam, W.; Putterlik,
J .; Schuhmann, R. M.; Sundermeyer, J . Organometallics 1996, 15,
4586.
(7) (a) Santini-Scampucci, C.; Riess, J . G. J . Organomet. Chem. 1974,
73, C13. (b) Santini-Scampucci, C.; Riess, J . G. J . Chem. Soc., Dalton
Trans. 1976, 195.
(8) (a) Wong, Y.-L.; Yan, Y.; Chan, E. S. H.; Yang, Q.; Mak, T. C.
W.; Ng, D. K. P. J . Chem. Soc., Dalton Trans. 1998, 3057. (b) Wong,
Y.-L.; Ma, J .-F.; Law, W.-F.; Yan, Y.; Wong, W.-T.; Zhang, Z.-Y.; Mak,
T. C. W.; Ng, D. K. P. Eur. J . Inorg. Chem. 1999, 313.
(9) Pitt, C. G.; Bao, Y.; Thompson, J .; Wani, M. C.; Rosenkrantz,
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10.1021/om990464+ CCC: $18.00 © 1999 American Chemical Society
Publication on Web 11/02/1999

5076 Organometallics, Vol. 18, No. 24, 1999
Wong et al.
Sch em e 1
F igu r e 1. Molecular structure of WO2(L1)(CH2SiMe3).
Selected bond lengths (Å) and angles (deg) are as follows:
W(1)-O(1) ) 1.986(4), W(1)-O(2) ) 1.709(4), W(1)-O(3)
) 1.711(4), W(1)-N(1) ) 2.333(4), W(1)-N(2) ) 2.369(4),
W(1)-C(13) ) 2.149(6); O(1)-W(1)-O(2) ) 97.66(18),
O(1)-W(1)-O(3) ) 100.89(17), O(2)-W(1)-O(3) ) 106.96-
(19), O(1)-W(1)-N(1) ) 78.87(15), O(2)-W(1)-N(1) )
89.11(16), O(3)-W(1)-N(1) ) 163.73(18), O(1)-W(1)-N(2)
) 74.27(16), O(2)-W(1)-N(2) ) 157.53(16), O(3)-W(1)-
N(2) ) 95.25(17), N(1)-W(1)-N(2) ) 68.89(12), O(1)-
W(1)-C(13) ) 154.13(19), O(2)-W(1)-C(13) ) 98.6(2),
O(3)-W(1)-C(13) ) 93.5(2), N(1)-W(1)-C(13) ) 81.38(18),
N(2)-W(1)-C(13) ) 83.12(19), W(1)-C(13)-Si(1) ) 116.8-
(3).
adopt a favorable conformation to coordinate to a metal
center in a facial manner. These tridentate ligands were
found to be rather unstable, and the pale yellow solid
darkened gradually upon exposure to air over a few
days. The ligands should therefore be freshly prepared
for complex formation.
Reaction of these ligands with WO2Cl2(DME), which
is a versatile precursor to other high-valent dioxotung-
sten(VI) complexes,8 in the presence of triethylamine
gave the corresponding dioxo complexes WO2(Ln)Cl (n
) 1-5) (Scheme 1). Due to the poor solubility of WO2-
(L1)Cl in common organic solvents, this compound could
only be purified by washing with various solvents, and
no characterizing data could be obtained. By contrast,
all the other dioxo complexes, in particular WO2(Ln)Cl
(n ) 3-5), have sufficient solubility to be purified and
characterized with a range of spectroscopic methods.
Very convincing evidence for complex formation comes
from the appearance of two doublets at δ 4.56-5.32 for
the two methylene protons adjacent to the pyridine ring
in the 1H NMR spectra of these compounds, showing
that the two protons become diastereotopic upon com-
plexation. For the N-benzyl analogues WO2(Ln)Cl (n )
3-5), the two methylene protons in the benzyl groups
are also diastereotopic, giving another two doublets in
the spectra. It is worth noting that the solvent CDCl3
used should be relatively dry. Some unidentified signals
appeared in the 1H NMR spectra for wet solutions of
these compounds, indicating that although these chloro-
dioxo complexes are air stable, they are slightly sensi-
tive to moisture and decompose readily in the presence
of water.
The protonated molecular ion (MH+) was identified in
all cases with a predicted accurate mass and isotopic
distribution pattern.
Treatment of WO2(L1)Cl with an excess of the Grig-
nard reagent Me3SiCH2MgCl resulted in ligand substi-
tution reaction and the formation of WO2(L1)(CH2SiMe3)
in 30% yield (Scheme 1). This high-valent alkyl tungsten
complex is stable to air and moisture. It has limited
solubility in hydrocarbons, ethers, and chlorinated
solvents, but can be dissolved in dipolar aprotic solvents
such as N,N-dimethylformamide (DMF) and dimethyl
1
sulfoxide (DMSO). The H NMR spectrum of WO2(L1)-
(CH2SiMe3) in DMSO-d6 showed, apart from the signals
due to L1 and the trimethylsilyl group, two upfield
doublets at δ 1.19 and -0.13 with a geminal coupling
constant of 12.4 Hz, which could be ascribed to the two
diastereotopic methylene protons next to tungsten. No
satellite resonances due to 183W and 29Si nuclei were
observed probably due to the low intensity. The 13C
NMR spectrum recorded in DMSO-d6 was also in accord
with C1 symmetry except that the carbon signal for the
WCH2 moiety was not seen. It is likely that the signal
was obscured by the strong solvent septet.12
The structure of WO2(L1)(CH2SiMe3) was established
by single-crystal X-ray analysis. Figure 1 gives a
perspective view of the structure together with selected
bond distances and angles. The compound exhibits a
distorted octahedral geometry with a facially coordi-
nated tridentate ligand L1 and cis-dioxo ligands that are
trans to the two nitrogen atoms of the ligand. The Wd
The IR spectra of all these dioxo compounds showed
two strong bands within 913-918 and 946-961 cm-1
attributed to the asymmetric and symmetric WdO
stretches, respectively, in a cis-dioxo moiety.11 The
compounds WO2(Ln)Cl (n ) 2-5) were also character-
ized with liquid secondary ion (LSI) mass spectrometry.
(10) Crystallographic data for HL3: C19H18N2O, fw 290.4, monoclinic
space group P21/c (no. 14), with a ) 14.624(3) Å, b ) 11.306(2) Å, c )
9.878(2) Å, â ) 101.12(3)°, V ) 1602.6(5) Å3, and Dcalcd ) 1.203 g cm-3
for Z ) 4. The structure was solved by direct methods and refined by
a full-matrix least-squares procedure using 3675 data to a conventional
R value of 0.0571 (Rw ) 0.1490).
(11) (a) Oku, H.; Ueyama, N.; Nakamura, A. Inorg. Chem. 1995,
34, 3667. (b) Eagle, A. A.; Tiekink, E. R. T.; Young, C. G. Inorg. Chem.
1997, 36, 6315.
(12) The 13C{1H} NMR spectra of WO2(η-C5R5)(CH2SiMe3) and WO-
(η2-O2)(η-C5R5)(CH2SiMe3) (R ) H, Me) in C6D6 showed this carbon
1
signal at δ 19.2-33.1 with J CW ) 92.7-135.0 Hz (see ref 4d).

Dioxotungsten(VI) Complexes with N2O Ligands
Organometallics, Vol. 18, No. 24, 1999 5077
Gen er a l P r oced u r e for th e P r ep a r a tion of HLn (n )
2-5). To a light brown solution of HL1 (0.20 g, 1.0 mmol) in
THF (10 mL) was added n-BuLi (1.6 M solution in hexanes,
1.3 mL, 2.1 mmol) dropwise at 0 °C. The mixture was stirred
at this temperature for 1 h, then allowed to warm to room
temperature. Iodomethane or differently substituted benzyl
bromides (1.0 mmol) were added slowly, and stirring was
continued for 12 h (only 6 h was required for the reaction with
iodomethane). The volatiles were removed under reduced
pressure, and water (20 mL) was added. The mixture was
extracted with CH2Cl2 (3 × 50 mL), and the combined extracts
were dried with anhydrous magnesium sulfate before being
O bond distances [1.709(4)-1.711(4) Å] are virtually
identical to the mean value of 1.709 Å determined for a
number of dioxotungsten complexes.13 The W-O single
bond distance [1.986(4) Å] is in the range typical of
W(VI) alkoxides.14 The W-C bond [2.149(6) Å] is also
comparable to those found in other alkyl-oxo tungsten
complexes.4a,c,5a,6a,b,15 The W-N bonds are relatively long
(>2.33 Å) because of the strong trans influence of the
oxo ligands.11b,16 The angle subtended by the dioxo
ligands [106.96(19)°] is typical of related dioxotungsten
complexes.4a,e,5,6b,11b,17
Attempts to prepare other alkyl-dioxo complexes by
treating WO2(Ln)Cl (n ) 1-3) with RMgX (R ) Me, Et,
Ph, CH2Ph, CH2SiMe3) were not successful (except for
n ) 1, R ) CH2SiMe3, as shown in Scheme 1). For the
reactions involving WO2(Ln)Cl (n ) 2, 3), free ligands
HLn (n ) 2, 3) were regenerated after the workup
procedure, showing that the compounds underwent
decomplexation rather than ligand substitution reac-
tions. The reasons for the difference in reactivity remain
elusive at this stage. To examine the reactivity of the
chloro functionality in these complexes toward other
anions, the compounds WO2(Ln)Cl (n ) 1, 3) were also
treated with NaOR (R ) Me, Et, Ph) in tetrahydrofuran
(THF), and thiophenol in the presence of triethylamine
in CH2Cl2. Surprisingly, only the starting complexes
were recovered with no indication of the formation of
substituted products even after prolonged heating. This
is in contrast with the chemistry of WO2[HB(Me2pz)3]-
Cl, which can be converted to various alkyl, -OR, -SR,
and -SeR derivatives through displacement of the
chloro ligand.6a,b,11b
concentrated with
a rotary evaporator. The residue was
chromatographed on a silica gel column using ethyl acetate/
hexanes (1:3 for n ) 2-4; 1:2 for n ) 5) as eluent. HL5 was
isolated as a pale yellow oily solid, while the other ligands were
further purified by recrystallization from CH2Cl2/hexanes (1:
1), yielding pale yellow crystals.
2-N-Meth yl-N-(2-pyr idylm eth yl)am in oph en ol (HL2): 0.18
g (83%), mp 88-91 °C. H NMR: δ 8.66 (d, J ) 4.5 Hz, 1 H,
ArH), 7.70 (dt, J ) 1.6, 7.6 Hz, 1 H, ArH), 7.21-7.29 (m, 2 H,
ArH), 7.10 (d, J ) 7.8 Hz, 1 H, ArH), 6.95-7.02 (m, 2 H, ArH),
6.79-6.85 (m, 1 H, ArH), 4.02 (s, 2 H, CH2), 2.73 (s, 3 H, CH3).
13C{1H} NMR: δ 158.5, 151.8, 149.0, 140.5, 137.2, 124.4, 122.8,
122.6, 119.8, 119.1, 116.0, 62.3, 39.8. HRMS (LSI): m/z
215.1180 (calcd for C13H15N2O (MH+) 215.1184). Anal. Calcd
for C13H14N2O: C, 72.87; H, 6.59; N, 13.07. Found: C, 72.78;
H, 6.61; N, 12.96.
1
2-N-Ben zyl-N-(2-pyr idylm eth yl)am in oph en ol (HL3): 0.17
g (60%), mp 97-99 °C. H NMR: δ 8.60 (d, J ) 4.8 Hz, 1 H,
1
ArH), 7.49 (dt, J ) 1.7, 7.7 Hz, 1 H, ArH), 7.06-7.17 (m, 7 H,
ArH), 6.93-6.98 (m, 2 H, ArH), 6.87 (d, J ) 7.7 Hz, 1 H, ArH),
6.73-6.79 (m, 1 H, ArH), 4.28 (s, 2 H, CH2), 4.15 (s, 2 H, CH2).
13C{1H} NMR: δ 158.9, 152.8, 148.3, 139.1, 138.0, 136.9, 128.7,
127.9, 126.9, 125.0, 122.6, 122.3, 121.9, 118.9, 116.3, 60.8, 57.6.
MS (EI): m/z 290 (M+). Anal. Calcd for C19H18N2O: C, 78.59;
H, 6.25; N, 9.65. Found: C, 78.49; H, 6.28; N, 9.57.
Exp er im en ta l Section
Gen er a l In for m a tion . All reactions were carried out using
standard Schlenk-line techniques under an atmosphere of
nitrogen; workups were performed in air. Dichloromethane
was predried over 4 Å molecular sieves and distilled from
calcium hydride. THF was distilled from sodium benzophenone
ketyl. All other reagents and solvents were of reagent grade
and used as received. The ligand HL1 and the tungsten
complex WO2Cl2(DME) were prepared according to literature
procedures with minor modification.9,18 All 1H and 13C NMR
spectra were recorded on a Bruker DPX 300 spectrometer (1H,
300; 13C, 75.4 MHz) in CDCl3 solutions unless otherwise stated.
Chemical shifts were relative to internal SiMe4 (δ ) 0). IR
spectra were taken on a Nicolet Magna 550 FT-IR spectrom-
eter as KBr pellets. Electron impact (EI) mass spectra were
obtained on a Hewlett-Packard 5989B mass spectrometer. LSI
mass spectra were measured on a Bruker APEX 47e Fourier
transform ion cyclotron resonance (FT-ICR) mass spectrometer
with 3-nitrobenzyl alcohol as matrix. Elemental analyses were
performed by the Medac Ltd., Brunel Science Centre, and the
Shanghai Institute of Organic Chemistry, Chinese Academy
of Sciences.
2-N-(4-ter t-Bu tylben zyl)-N-(2-pyr idylm eth yl)am in oph e-
1
n ol (HL4): 0.24 g (70%), mp 103-105 °C. H NMR: δ 8.54 (d,
J ) 4.8 Hz, 1 H, ArH), 7.34 (dt, J ) 1.8, 7.7 Hz, 1 H, ArH),
7.15 (d, J ) 7.8 Hz, 1 H, ArH), 7.02-7.07 (m, 5 H, ArH), 6.96-
6.98 (m, 2 H, ArH), 6.74-6.80 (m, 1 H, ArH), 6.70 (d, J ) 7.5
Hz, 1 H, ArH), 4.25 (s, 2 H, CH2), 4.07 (s, 2 H, CH2), 1.21 (s,
t
9 H, Bu). 13C{1H} NMR: δ 159.1, 152.6, 149.6, 148.1, 139.7,
136.5, 134.9, 128.4, 124.7 (two overlapping signals), 122.4,
121.9, 121.5, 118.8, 116.3, 60.8, 57.4, 34.2, 31.2. HRMS (LSI):
m/z 347.2116 (calcd for C23H27N2O (MH+) 347.2123). Anal.
Calcd for C23H26N2O: C, 79.73; H, 7.56; N, 8.09. Found: C,
79.53; H, 7.75; N, 7.78.
2-N-(3,5-Di-ter t-bu tylben zyl)-N-(2-p yr id ylm eth yl)a m i-
n op h en ol (HL5): 0.35 g (86%). 1H NMR: δ 8.54 (d, J ) 4.5
Hz, 1 H, ArH), 7.39 (dt, J ) 1.7, 7.7 Hz, 1 H, ArH), 7.17 (d, J
) 8.0, 1 H, ArH), 7.12 (t, J ) 1.8 Hz, 1 H, ArH), 7.07 (dd, J )
5.0, 6.8 Hz, 1 H, ArH), 6.95-7.02 (m, 4 H, ArH), 6.74-6.82
(m, 2 H, ArH), 4.28 (s, 2 H, CH2), 4.13 (s, 2 H, CH2), 1.21 (s,
t
18 H, Bu). 13C{1H} NMR: δ 159.2, 152.7, 150.2, 148.0, 139.8,
137.0, 136.6, 124.9, 123.3, 122.5, 122.1, 121.8, 121.0, 118.9,
116.3, 60.8, 58.8, 34.6, 31.4. HRMS (LSI): m/z 403.2791 (calcd
for C27H35N2O (MH+) 403.2749). Satisfactory analytical data
for this compound could not be obtained.
Gen er a l P r oced u r e for th e P r ep a r a tion of WO2(Ln )Cl
(n ) 1-5). A solution of WO2Cl2(DME) in THF was added
dropwise to a solution of HLn (n ) 1-5, 1 equiv) in THF with
vigorous stirring. The pale yellow mixture turned to dark
purple immediately. The mixture was stirred at room tem-
perature for 15 min, then triethylamine (1 equiv) was added,
and the mixture was kept stirring overnight. Due to the poor
solubility of WO2(L1)Cl, this compound was collected by
filtration, washed with EtOH, THF, and diethyl ether, and
(13) Mayer, J . M. Inorg. Chem. 1988, 27, 3899.
(14) (a) Chisholm, M. H.; Hoffman, D. M.; Huffman, J . C. Inorg.
Chem. 1983, 22, 2903. (b) Chisholm, M. H.; Folting, K.; Heppert,
J . A.; Hoffman, D. M.; Huffman, J . C. J . Am. Chem. Soc. 1985, 107,
1234.
(15) Legzdins, P.; Phillips, E. C.; Rettig, S. J .; Sa´nchez, L.; Trotter,
J .; Yee, V. C. Organometallics 1988, 7, 1877.
(16) Eagle, A. A.; George, G. N.; Tiekink, E. R. T.; Young, C. G. Inorg.
Chem. 1997, 36, 472.
(17) (a) Dreisch, K.; Andersson, C.; Sta˚lhandske, C. Polyhedron
1992, 11, 2143. (b) Sergienko, V. S.; Abramenko, V. A.; Ilyukhin, A. B.
Russ. J . Inorg. Chem. 1995, 40, 1740. (c) Herrmann, W. A.; Fridgen,
J .; Lobmaier, G. M.; Spiegler, M. New J . Chem. 1999, 5.
(18) Dreisch, K.; Andersson, C.; Sta˚lhandske, C. Polyhedron 1991,
10, 2417.

5078 Organometallics, Vol. 18, No. 24, 1999
Wong et al.
Ta ble 1. Cr ysta llogr a p h ic Da ta for
WO2(L1)(CH2SiMe3)
then dried in vacuo. For the other dioxo complexes, the
resulting mixture was loaded onto a short bed of silica gel
column, which was eluted with ethyl acetate. The dark purple
band was collected and concentrated to give a pale purple solid.
For WO2(L2)Cl, the solid was washed extensively with ethyl
acetate and diethyl ether to give a pale gray solid, which was
then dried in vacuo. For WO2(Ln)Cl (n ) 3-5), the solid was
further purified by column chromatography using CHCl3 as
eluent. The first band was collected and concentrated to give
a white solid.
formula
fw
C16H22N2O3SiW
502.3
cryst size (mm3)
cryst syst
space group
a (Å)
0.02 × 0.12 × 0.20
monoclinic
P21/ c (No. 14)
11.800(1)
21.896(3)
7.768(2)
98.78(1)
1983.5(6)
4
b (Å)
c (Å)
â (deg)
WO2(L2)Cl. According to the general procedure, WO2Cl2-
(DME) (2.22 g, 5.9 mmol) was treated with HL2 (1.27 g, 5.9
mmol) and triethylamine (0.83 mL, 5.9 mmol) in THF (50 mL)
V (Å3)
Z
F(000)
976
1.682
5.897
1
to give WO2(L2)Cl (1.51 g, 55%). H NMR: δ 9.39 (d, J ) 5.3
Dcalcd (g cm-3
)
Hz, 1 H, ArH), 7.87 (dt, J ) 1.6, 7.7 Hz, 1 H, ArH), 7.51 (t, J
) 6.5 Hz, 1 H, ArH), 7.39 (d, J ) 8.2 Hz, 1 H, ArH), 7.27 (d,
J ) 7.6 Hz, 1 H, ArH), 7.12 (dt, J ) 1.4, 7.8 Hz, 1 H, ArH),
6.92 (dt, J ) 1.3, 7.8 Hz, 1 H, ArH), 6.69 (dd, J ) 1.3, 8.2 Hz,
1 H, ArH), 4.89 (d, J ) 14.7 Hz, 1 H, CH2), 4.65 (d, J ) 14.7
Hz, 1 H, CH2), 3.62 (s, 3 H, CH3). 13C{1H} NMR: δ 157.9, 154.3,
151.2, 140.4, 138.8, 129.9, 125.2, 123.1, 121.9, 121.7, 119.7,
67.8, 50.4. IR: v(WO2) ) 961s, 913s cm-1. HRMS (LSI): m/z
465.0165 (calcd for C13H14ClN2O3W (MH+) based on 35Cl and
184W 465.0182). Anal. Calcd for C13H13ClN2O3W: C, 33.61; H,
2.82; N, 6.03. Found: C, 33.74; H, 2.88; N, 5.98.
µ (mm-1
)
total no. of reflns
no. of indep reflns
no. of params, p
Ra
6671
3856 (Rint ) 0.0429)
236
0.0419
b
Rw
0.0911
1.097
+0.89 and -1.17
S(GOF)c
largest diff peak and hole (e Å-3
)
a
b
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) {[∑w(Fo2 - Fc2)2]/[∑w(Fo2)2]}1/2
.
)
c S ) {[∑w(Fo2 - Fc2)2]/ (n - p)}1/2; weighting scheme, w ) [σ2(Fo
2
2
+ (aP)2 + bP]-1, where P ) (Fo + 2Fc2)/3.
WO2(L3)Cl. According to the general procedure, WO2Cl2-
(DME) (2.11 g, 5.6 mmol) was treated with HL3 (1.61 g, 5.6
mmol) and triethylamine (0.78 mL, 5.6 mmol) in THF (50 mL)
to give WO2(L3)Cl (1.38 g, 46%). 1H NMR: δ 9.38 (dd, J ) 0.9,
5.4 Hz, 1 H, ArH), 7.83 (dt, J ) 1.7, 7.7 Hz, 1 H, ArH), 7.37-
7.51 (m, 6 H, ArH), 7.21 (d, J ) 7.3 Hz, 1 H, ArH), 7.05 (dt, J
) 1.4, 7.7 Hz, 1 H, ArH), 6.71 (dd, J ) 1.3, 8.3 Hz, 1 H, ArH),
6.57 (dt, J ) 1.4, 7.7 Hz, 1 H, ArH), 6.36 (dd, J ) 1.4, 8.2 Hz,
1 H, ArH), 5.32 (d, J ) 14.1 Hz, 1 H, CH2), 5.22 (d, J ) 14.4
Hz, 1 H, CH2), 4.99 (d, J ) 14.1 Hz, CH2), 4.63 (d, J ) 14.4
Hz, 1 H, CH2). 13C{1H} NMR: δ 158.8, 155.3, 151.3, 140.5,
136.0, 133.0, 132.5, 129.9, 129.4, 128.6, 125.9, 125.0, 123.4,
120.3, 119.6, 65.8, 63.6. IR: v(WO2) ) 946s, 915s cm-1. HRMS
(LSI): m/z 541.0542 (calcd for C19H18ClN2O3W (MH+) based
on 35Cl and 184W 541.0495). Anal. Calcd for C19H17ClN2O3W:
C, 42.21; H, 3.17; N, 5.18. Found: C, 42.45; H, 3.21; N, 5.01.
WO2(L4)Cl. This compound was prepared from WO2Cl2-
(DME) (1.66 g, 4.4 mmol), HL4 (1.52 g, 4.4 mmol), and
triethylamine (0.62 mL, 4.4 mmol) in THF (50 mL) by using
158.8, 155.4, 151.3, 151.0, 140.4, 135.9, 131.9, 129.8, 127.0,
126.3, 125.0, 123.4, 122.8, 120.0, 119.3, 66.6, 63.6, 34.8, 31.4.
IR: v(WO2) ) 957s, 917s cm-1. HRMS (LSI): m/z 653.1747
(calcd for C27H34ClN2O3W (MH+) based on 35Cl and 184W
653.1747). Anal. Calcd for C27H33ClN2O3W: C, 49.67; H, 5.09;
N, 4.29. Found: C, 49.86; H, 5.05; N, 4.37.
WO2(L1)(CH2SiMe3). To an ice-cooled suspension of WO2-
(L1)Cl (0.45 g, 1.0 mmol) in THF (30 mL) was added a solution
of Me3SiCH2MgCl (3.0 mmol) in diethyl ether (20 mL) over a
period of 30 min. The mixture was then allowed to warm to
room temperature and stirred overnight. The volatiles were
then removed under reduced pressure, and water (20 mL)
was added. The mixture was extracted with CH2Cl2 (3 × 50
mL), and the combined extracts were dried over anhydrous
magnesium sulfate, then concentrated to ca. 5 mL to afford a
pale brown solid, which was filtered off and washed thoroughly
with chloroform and diethyl ether. The product was further
purified by recrystallization using DMF/hexanes to yield
pale yellow crystals (0.15 g, 30%). 1H NMR (DMSO-d6): δ
9.08 (d, J ) 5.2 Hz, 1 H, ArH), 8.03 (d, J ) 4.4 Hz, 1 H, ArH),
7.98 (dt, J ) 1.4, 7.7 Hz, 1 H, ArH), 7.58 (t, J ) 6.4 Hz, 1 H,
ArH), 7.50 (d, J ) 7.8 Hz, 1 H, ArH), 7.29 (d, J ) 7.1 Hz, 1 H,
ArH), 6.99 (t, J ) 7.7 Hz, 1 H, ArH), 6.73 (t, J ) 7.2 Hz, 1 H,
ArH), 6.53 (d, J ) 8.0 Hz, 1 H, ArH), 4.67 (dd, J ) 4.7, 16.6
Hz, 1 H, ArCH2), 4.56 (d, J ) 16.6 Hz, 1 H, ArCH2), 1.19 (d, J
) 12.4 Hz, 1 H, WCH2), 0.03 (s, 9 H, CH3), -0.13 (d, J ) 12.4
Hz, 1 H, WCH2). 13C{1H} NMR (DMSO-d6): δ 161.1, 157.1,
149.9, 140.1, 136.2, 128.9, 126.1, 124.9, 124.4, 119.4, 117.9,
58.6, 1.8. IR: v(WO2) ) 951s, 906s cm-1. MS (LSI): a cluster
peaking at m/z 503.10 (MH+). Anal. Calcd for C16H22N2O3-
SiW: C, 38.26; H, 4.41; N, 5.58. Found: C, 38.11; H, 4.25; N,
5.39.
1
the general procedure (1.99 g, 76%). H NMR: δ 9.36 (d, J )
5.3 Hz, 1 H, ArH), 7.83 (dt, J ) 1.4, 7.7 Hz, 1 H, ArH), 7.43-
7.48 (m, 3 H, ArH), 7.31 (d, J ) 8.2 Hz, 2 H, ArH), 7.23 (d, J
) 7.7 Hz, 1 H, ArH), 7.05 (dt, J ) 1.2, 7.8 Hz, 1 H, ArH), 6.69
(dd, J ) 1.1, 8.2 Hz, 1 H, ArH), 6.59 (dt, J ) 1.1, 7.7 Hz, 1 H,
ArH), 6.42 (dd, J ) 1.2, 8.2 Hz, 1 H, ArH), 5.29 (d, J ) 14.1
Hz, 1 H, CH2), 5.20 (d, J ) 14.5 Hz, 1 H, CH2), 4.93 (d, J )
14.1 Hz, 1 H, CH2), 4.64 (d, J ) 14.5 Hz, 1 H, CH2), 1.39 (s, 9
t
H, Bu). 13C{1H} NMR: δ 158.7, 155.4, 152.5, 151.2, 140.5,
136.3, 132.2, 129.9, 129.8, 126.0, 125.5, 125.0, 123.4, 120.3,
119.4, 65.4, 63.6, 34.7, 31.3. IR: v(WO2) ) 961s, 918s cm-1
.
HRMS (LSI): m/z 597.1154 (calcd for C23H26ClN2O3W (MH+)
based on 35Cl and 184W 597.1121). Anal. Calcd for C23H25
-
ClN2O3W: C, 46.29; H, 4.22; N, 4.69. Found: C, 46.53; H, 4.19;
N, 4.68.
X-r ay Cr ystallogr aph ic An alysis of WO2(L1)(CH2SiMe3).
Crystal data and data processing parameters are given in
Table 1. Data collection was performed at 294 K on a MSC/
Rigaku RAXIS IIc imaging-plate system using Mo KR radia-
tion (λ ) 0.71073 Å) from a Rigaku RU-200 rotating-anode
WO2(L5)Cl. This compound was prepared from WO2Cl2-
(DME) (2.00 g, 5.3 mmol), HL5 (2.15 g, 5.3 mmol), and
triethylamine (0.74 mL, 5.3 mmol) in THF (50 mL) by using
1
the general procedure (2.01 g, 58%). H NMR: δ 9.38 (d, J )
generator operating at 50 kV and 90 mA (2θmin ) 3°, 2θmax
)
4.8 Hz, 1 H, ArH), 7.82 (dt, J ) 1.5, 7.7 Hz, 1 H, ArH), 7.52 (t,
J ) 1.8 Hz, 1 H, ArH), 7.46 (t, J ) 6.5 Hz, 1 H, ArH), 7.20 (d,
J ) 7.8 Hz, 1 H, ArH), 7.15 (d, J ) 1.8 Hz, 2 H, ArH), 7.04 (dt,
J ) 1.5, 7.7 Hz, 1 H, ArH), 6.70 (dd, J ) 1.5, 8.3 Hz, 1 H,
ArH), 6.52 (dt, J ) 1.2, 7.7 Hz, 1 H, ArH), 6.27 (dd, J ) 1.2,
8.3 Hz, 1 H, ArH), 5.27 (d, J ) 13.8 Hz, 1 H, CH2), 5.19 (d, J
) 14.4 Hz, 1 H, CH2), 4.99 (d, J ) 13.8 Hz, 1 H, CH2), 4.56 (d,
55°, 30 6° oscillation frames in the range of 0-180°, exposure
10 min per frame).19 A self-consistent semiempirical absorption
(19) (a) Tanner, J .; Krause, K. Rigaku J . 1994, 11, 4. (b) Tanner,
J .; Krause, K. Rigaku J . 1990, 7, 28. (c) Krause, K. L.; Phillips, G. N.,
J r. J . Appl. Crystallogr. 1992, 25, 146. (d) Sato, M.; Yamamoto, M.;
Imada, K.; Katsube, Y.; Tanaka, N.; Higashi, T. J . Appl. Crystallogr.
1992, 25, 348.
t
J ) 14.4 Hz, 1 H, CH2), 1.35 (s, 18 H, Bu). 13C{1H} NMR: δ

Dioxotungsten(VI) Complexes with N2O Ligands
Organometallics, Vol. 18, No. 24, 1999 5079
correction based on Fourier coefficient fitting of symmetry-
equivalent reflections was applied by using the ABSCOR
program.20 The structure was solved by direct methods, which
yielded the positions of all non-hydrogen atoms, which were
refined anisotropically. The methyl groups were disordered
with a site occupancy 0.5. Hydrogen atoms were placed in their
idealized positions (C-H 0.96 Å) with fixed isotropic thermal
parameters and allowed to ride on their parent carbon or
nitrogen atoms. All the H atoms were held stationary and
included in structure factor calculations in the final stage of
full-matrix least-squares refinement. All computations were
performed with a PC-486 computer using the SHELX-97
program package.21 Further details are included in the Sup-
porting Information.
Ack n ow led gm en t. This work was supported by the
Research Grants Council of the Hong Kong Special
Administrative Region, China (Earmarked Grant: CUHK
464/95P).
Su p p or tin g In for m a tion Ava ila ble: Listings of non-
hydrogen coordinates, bond distances and angles, anisotropic
thermal parameters, and hydrogen coordinates and isotropic
thermal parameters for HL3 and WO2(L1)(CH2SiMe3). This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM990464+
(20) Higashi, T. ABSCOR-An Empirical Absorption Correction
Based on Fourier Coefficient Fitting; Rigaku Corporation: Tokyo, 1995.
(21) Sheldrick, G. M. SHELX-97: Package for Crystal Structure
Solution and Refinement; University of Gottingen: Germany, 1997.