Reaction of bis(pyrazol-1-yl)methanes modified by organotin groups on the methine carbon with W(CO)5THF to give novel heterodinuclear organometallic complexes

Article abstract of DOI:10.1021/om030221o

The reaction of bis(pyrazol-1-yl)methanes modified by organotin groups on the methine carbon with W(CO)₅THF to give novel heterodinuclear organometallic complexes was discussed. Their reactions with W(CO) ₅THF were investigated, indi

Full text of DOI:10.1021/om030221o

3290
Organometallics 2003, 22, 3290-3298
Rea ction of Bis(p yr a zol-1-yl)m eth a n es Mod ified by
Or ga n otin Gr ou p s on th e Meth in e Ca r bon w ith
W(CO)5THF to Give Novel Heter od in u clea r
Or ga n om eta llic Com p lexes
Liang-Fu Tang,* Shu-Bin Zhao, Wen-Li J ia, Zhi Yang, Da-Tong Song, and
J i-Tao Wang
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry,
Nankai University, Tianjin 300071, People’s Republic of China
Received March 21, 2003
A series of new bis(pyrazol-1-yl)methanes with organotin groups on the methine carbon
have been synthesized by the reaction of bis(pyrazol-1-yl)methyllithium with organotin halide.
Their reactions with W(CO)5THF have been investigated in detail, indicating that these
new ligands display versatile reactivities upon treatment with W(CO)5THF, depending on
the properties of the substituents on the tin atom. Treatment of triarylstannylbis(pyrazol-
1-yl)methanes, Ar3SnCHPz2 (Ar ) phenyl or p-tolyl; Pz ) substituted pyrazole), with
W(CO)5THF results in the oxidative addition of the tin-carbon(sp3) bond to the tungsten(0)
center to yield novel metal-metal bonded complexes CHPz2(CO)3W-SnAr3, in which four-
membered metallacycles are found and bis(pyrazol-1-yl)methide acts as a tridentate
monoanionic κ3-[N,C,N] chelating ligand. When there are alkyl substituents in the 4-position
of pyrazole rings, some decarbonylation intermediates Ar3SnCHPz2W(CO)4 can be isolated.
Sequentially heating these intermediates can also result in the oxidative addition of the
tin-carbon(sp3) bond to the tungsten(0) center, implying that the oxidative addition reaction
of the tin-carbon(sp3) bond may form these decarbonylation intermediates. While the
i
reactions of trialkylstannylbis(pyrazol-1-yl)methanes, R3SnCHPz2 (R ) Et or Pr), with
W(CO)5THF yield only the decarbonylation heterodinuclear complexes R3SnCHPz2W(CO)4,
in which bis(pyrazol-1-yl)methanes act as N,N-chelating bidentate ligands, no analogous
oxidative addition products are obtained. However, treatment of phenyldi(tert-butyl)-
stannylbis(pyrazol-1-yl)methanes, (tBu)2PhSnCHPz2 (Pz ) 3,5-dimethylpyrazole or 3,4,5-
trimethylpyrazole), with W(CO)5THF results in the oxidative addition of the tin-carbon(sp2)
bond instead of the tin-carbon(sp3) bond to the tungsten(0) center to yield metal-metal
bonded complexes (tBu)2SnCHPz2W(CO)3(Ph), in which a novel κ3-[N,Sn,N] coordination mode
as well as asymmetric semibridging carbonyl between the W-Sn bond is observed. In
addition, the reactions of trivinylstannylbis(pyrazol-1-yl)methanes, (CH2dCH)3SnCHPz2, with
W(CO)5THF result in a vinyl group bonded to the tungsten center in η2-fashion to give a
tridentate κ3-(π,N,N) coordination mode.
In tr od u ction
recent years. Their coordination behaviors can easily be
adjusted by changing the electronic and steric charac-
teristics of substituents on the pyrazole rings. Recent
Poly(pyrazol-1-yl)alkanes, especially bis(pyrazol-1-yl)-
methane, have been popular polydentate nitrogen donor
ligands since Trofimenko’s first report1 and especially
J ulia’s later modification.2 Their coordination chemistry
toward main group and transition metals has received
increasing attention;3-5 a number of main group6 and
transition metal7 complexes containing poly(pyrazol-1-
yl)alkanes have been synthesized and characterized in
(6) For some recent examples see: (a) Wang, Z. H.; Tang, L. F.; J ia,
W. L.; Wang, J . T.; Wang, H. G. Polyhedron 2002, 21, 873. (b) Pettinari,
C.; Pellei, M.; Cingolani, A.; Martini, D.; Drozdov, A.; Troyanov, S.;
Panzeri, W.; Mele, A. Inorg. Chem. 1999, 38, 5777. (c) Reger, D. L.;
Collins, J . E.; Mattews, M. A.; Rheingold, A. L.; Liable-Sands, L. M.;
Guzei, I. A. Inorg. Chem. 1997, 36, 6266. (d) Reger, D. L.; Collins, J .
E.; Lovland, R.; Adams, R. D. Inorg. Chem. 1996, 35, 1372. (e) Pettinari,
C.; Lorenzotti, A.; Sclavi, G.; Cingolani, A.; Rivarola, E.; Colapietro,
M.; Cassetta, A. J . Organomet. Chem. 1995, 496, 69.
(7) For some recent examples see: (a) Tang, L. F.; J ia, W. L.; Wang,
Z. H.; Wang, J . T.; Wang, H. G. J . Organomet. Chem. 2002, 649, 152.
(b) Reger, D. L.; Grattan, T. C.; Brown, K. J .; Little, C. A.; Lamba, J .
J . S.; Rheingold, A. L.; Sommer, R. D. J . Organomet. Chem. 2000, 607,
120. (c) Arroyo, N.; Go´mez-de la Torre, F.; J alo´n, F. A.; Manzano, B.
R.; Moreno-Lara, B.; Rodr´ıguez, A. M. J . Organomet. Chem. 2000, 603,
174. (d) Tsuji, S.; Swenson, D. C.; J ordan, R. F. Organometallics 1999,
18, 4758. (e) Reger, D. L.; Collins, J . E.; Rheingold, A. L.; Liable-Sands,
L. M.; Yap, G. P. A. Organometallics 1997, 16, 349. (f) Dhawan, I. K.;
Bruck, M. A.; Schilling, B.; Grittini, C.; Enemark, J . H. Inorg. Chem.
1995, 34, 3801.
* Corresponding author. E-mail: tanglf@eyou.com. Fax: 0086-22-
23502458.
(1) Trofimenko, S. J . Am. Chem. Soc. 1970, 92, 5118.
(2) J ulia, S.; del Mazo, J . M.; Avila, L.; Elguero, J . Org. Prep. Proc.
Int. 1984, 16, 299.
(3) Byers, P. K.; Canty, A. J .; Honeyman, R. T. Adv. Organomet.
Chem. 1992, 34, 1.
(4) Trofimenko, S. Prog. Inorg. Chem. 1986, 34, 115.
(5) Tang, L. F.; Wang, Z. H.; Wang, J . T. Youji Huaxue 1999, 19,
442.
10.1021/om030221o CCC: $25.00 © 2003 American Chemical Society
Publication on Web 07/03/2003

Reaction of Bis(pyrazol-1-yl)methanes
Organometallics, Vol. 22, No. 16, 2003 3291
investigations show that the bridging carbon atom can
also be modified by organic functional groups to form
novel heteroscorpionate ligands, which usually have
asymmetric N2O,8 N2S,9 N3S,10 or N3O11 coordination
environments. These ligands have been of considerable
interest owing to their important usage in biological
enzyme models. In addition, the replacement of the
bridging atom by the silicon atom to form poly(pyrazol-
1-yl)silanes has also been successful.12 However, the
modification of poly(pyrazol-1-yl)alkanes by organome-
tallic groups on the bridging carbon atom is rare.13 Our
recent investigation on poly(pyrazol-1-yl)methanes re-
veals that such modification may result in unusual
reactivity.14 Now we continue our investigation on the
modification of poly(pyrazol-1-yl)alkanes by introducing
organotin groups on the methine carbon and observing
their reactions with W(CO)5THF. These organometallic
ligands react with W(CO)5THF to give markedly differ-
ent heterodinuclear complexes, depending on the prop-
erties of substituents on the tin atom.
to the tungsten(0) center to yield novel four-membered
metallacyclic complexes 1a -5a , which were character-
ized by 1H NMR spectroscopy, IR spectra, and elemental
analyses, as well as X-ray structure analyses. The
oxidative addition of a Sn-C(sp2) bond to a tungsten-
(0) center to yield W-Sn bonded complexes with a κ3-
[C,N,N′] ligand is known,16 but there is no prior report
of tungsten complexes containing the sp3 hybridized
carbon in κ3-[N,C,N] ligands.17 The present results also
exhibit a novel coordination mode for poly(pyrazol-1-
yl)alkanes.
Complexes 1a -5a are air-stable in the solid state, and
even their solutions can be manipulated in air. They
are moderately soluble in chlorinated solvents, but
insoluble in alkanes and ether. The proton signals of
the CH group (4.32-4.63 ppm) are considerably shifted
to higher field, compared with those in 1-5, which
appear between 6.71 and 6.92 ppm. In addition, four
sets of proton signals of isopropyl methyl groups have
been observed in ligands 3 and 5 as well as complexes
3a and 5a , possibly as a result of these groups being
diastereotopic, which is due to the bulky isopropyl
groups in the pyrazole rings, which prevent their free
rotation. Three strong ν(CO) bands in the range 1970-
1830 cm-1 are observed in the IR spectra of 1a -5a ,
which is consistent with the tricarbonyltungsten species.
The structure of 3a has also been confirmed by X-ray
crystallography as shown in Figure 1, which clearly
shows that the triphenylstannyl group has been trans-
ferred to the tungsten center and that new tungsten-
saturated carbon and tungsten-tin bonds have been
formed. Bis(3,5-diisopropylpyrazol-1-yl)methide acts as
a tridentate, monoanionic κ3-[N,C,N] chelating ligand,
resulting in the formation of two novel four-membered
metallaheterocycles. It is noteworthy that in the four-
membered metallaheterocycles the angles N-C-W are
very close to 90°. The geometry of the seven-coordinate
tungsten atom is best described as a capped octahedron
with the triphenylstannyl groups in the capping posi-
tion. The capped face is made up of C(2), C(3), and C(13)
atoms. The W-Sn distance is 2.7712(8) Å, which is
similar with that in CH(3,4,5-Me3Pz)2W(CO)3SnPh3
(2.7795(4) Å)14a and within the normal range for W-Sn
bonds.18 The isopropyl methyl groups are away from the
metal tungsten, which is analogous to the case in
hydrotris(3,5-diisopropylpyrazol-1-yl)borate complexes.19
Resu lts a n d Discu ssion
Mod ifica tion of Bis(p yr a zol-1-yl)m eth a n es w ith
Tr ia r ylsta n n yl Gr ou p s on th e Meth in e Ca r bon
a n d Th eir Rea ction s w ith W(CO)5THF . When bis-
(pyrazol-1-yl)methanes were treated with butyllithium
at -78 °C, their central carbon atom of the CH2 group
was deprotonated to give bis(pyrazol-1-yl)methyllithi-
um.14,15 The appropriate triaryltin chloride was then
added to yield products 1-5 (eq 1).
(12) (a) Pullen, E. E.; Rabinovich, D.; Incarvito, C. D.; Concolino, T.
E.; Rheingold, A. L. Inorg. Chem. 2000, 39, 1561. (b) Richburg, L. M.;
Farouq, J . A.; Incarvito, C. D.; Rheingold, A. L.; Rabinovich, D.
Polyhedron 2000, 19, 1815. (c) Stibrany, R. T.; Knapp, S.; Potenza, J .
A.; Schugar, H. J . Inorg. Chem. 1999, 38, 132.
(13) (a) Antin˜olo, A.; Carrillo-Hermosilla, F.; D´ıez-Barra, E.; Ferna´n-
dez-Baeza, J .; Ferna´ndez-Lo´pez, M.; Lara-Sa´nchez, A.; Moreno, A.;
Otero, A.; Rodriguez, A. M.; Tejeda, J . J . Chem. Soc., Dalton Trans.
1998, 3737. (b) Katritzky, A. R.; Abdel-Rahman, A. E.; Leahy, D. E.;
Schwarz, O. A. Tetrahedron 1983, 39, 4133.
(14) (a) Tang, L. F.; J ia, W. L.; Song, D. T.; Wang, Z. H.; Chai, J . F.;
Wang, J . T. Organometallics 2002, 21, 445. (b) Tang, L. F.; J ia, W. L.;
Zhao, X. M.; Yang, P.; Wang, J . T. J . Organomet. Chem. 2002, 658,
198.
(15) Otero, A.; Ferna´ndez-Baeza, J .; Tejeda, J .; Antin˜olo, A.; Carrillo-
Hermosilla, F.; D´ıez-Barra, E.; Lara-Sa´nchez, A.; Ferna´ndez-Lo´pez,
M.; Lanfranchi, M.; Pellinghelli, M. A. J . Chem. Soc., Dalton Trans.
1999, 3537.
Treatment of 1-5 with W(CO)5THF in refluxing THF
resulted in the oxidative addition of the Sn-C(sp3) bond
(8) (a) Otero, A.; Ferna´ndez-Baeza, J .; Antin˜olo, A.; Carrillo-Her-
mosilla, F.; Tejeda, J .; D´ıez-Barra, E.; Lara-Sanchez, A.; Sanchez-
Barba, L.; Lo´pez-Solera, I.; Ribeiro, M. R.; Campos, J . M. Organome-
tallics 2001, 20, 2428. (b) Beck, A.; Weibert, B.; Burzlaff, N. Eur. J .
Inorg. Chem. 2001, 521. (c) Otero, A.; Ferna´ndez-Baeza, J .; Tejeda, J .;
Antin˜olo, A.; Carrillo-Hermosilla, F.; D´ıez-Barra, E.; Lara-Sa´nchez, A.;
Ferna´ndez-Lo´pez, M. J . Chem. Soc., Dalton Trans. 2000, 2367. (d)
Hammes, B. S.; Carrano, C. J . Inorg. Chem. 1999, 38, 3562.
(9) (a) Hammes, B. S.; Carrano, C. J . Inorg. Chem. 2001, 40, 919.
(b) Hammes, B. S.; Carrano, C. J . J . Chem. Soc., Chem. Commun. 2000,
1635. (c) Astley, T.; Hitchman, M. A.; Skelton, B. W.; White, A. H. Aust.
J . Chem. 1997, 50, 145. (d) Alsfasser, R.; Vahrenkamp, H. Inorg. Chim.
Acta 1993, 209, 19.
(16) Buffin, B. P.; Poss, M. J .; Arif, A. M.; Richmond, T. G. Inorg.
Chem. 1993, 32, 3805.
(10) Kla¨ui, W.; Berghahn, M.; Rheinwald, G.; Lang, H. Angew.
Chem., Int. Ed. 2000, 39, 2464.
(11) Mu¨ller, M.; Lork, E.; Mews, R. Angew. Chem., Int. Ed. 2001,
40, 1247.
(17) (a) van Koten, G. Pure Appl. Chem. 1989, 61, 1681. (b) Rietveld,
M. H. P.; Grove, D. M.; van Koten, G. New J . Chem. 1997, 21, 751.
(18) Holt, M. S.; Wilson, W. L.; Nelson, J . H. Chem. Rev. 1989, 89,
11.

3292 Organometallics, Vol. 22, No. 16, 2003
Tang et al.
F igu r e 1. Molecular structure of 3a . Thermal ellipsoids
are drawn at the 30% probability level. Selected bond
distances (Å) and angles (deg): W(1)-N(1) ) 2.222(5),
W(1)-N(3) ) 2.212(5), W(1)-C(13) ) 2.343(6), W(1)-Sn-
(1) ) 2.7712(8), N(2)-C(13) ) 1.463(7); N(3)-W(1)-N(1)
) 81.81(19), C(13)-W(1)-Sn(1) ) 76.98(15), N(1)-W(1)-
C(13) ) 60.41(19), C(3)-W(1)-N(1) ) 170.8(2), N(4)-
C(13)-N(2) ) 109.5(5), C(4)-C(7)-C(9) ) 111.2(7), N(2)-
C(13)-W(1) ) 91.4(3), N(4)-C(13)-W(1) ) 91.2(3).
IR and 1H NMR spectroscopic data of 6a -10a are
similar to those of 1a -5a , indicating that they should
have analogous structures. For example, in the 1H NMR
spectra of 6a -10a , the proton signal of the CH group
appears at ca. 4.32 ppm, and for 1a -5a it appears
between 4.32 and 4.63 ppm. However, the proton signal
of the CH group in 6b -10b is significantly different
from that in 1a -10a , which appears in the range 6.57-
6.70 ppm, but is similar to that of the corresponding
free ligands (6.50-6.70 ppm). The IR spectra of 6b-
10b are also different from those of 1a -10a . Four bands
in the carbonyl stretching region are observed in 6b-
10b, and these values of ν(CO) can also be compared
with those reported for (N-N)M(CO)4 complexes (N-N
represents substituted bis(pyrazol-1-yl)methane),14b,20
indicating a typical cis-tetracarbonyl arrangement.
The molecular structure of 6b has been confirmed by
X-ray diffraction analyses as shown in Figure 2. As seen
in Figure 2, the tungsten atom is six-coordinate with a
quasi-octahedral coordination geometry; ligand 6 acts
as a chelating bidentate ligand in the complex, and the
tri(p-tolyl)stannyl group on the methine carbon lies in
the axial position so as to reduce steric repulsion with
the methyl groups in the 5-position of the pyrazole rings.
The metallacyclic ring W-N-N-C-N-N adopts a boat
conformation. The average W-N distance is 2.2715 Å,
which is slightly longer than that in 3a (2.217 Å), but
comparable to those found for Ph3GeCH(3,5-Me2Pz)2W-
(CO)4 (2.25 Å) and Me3SiCH(3,5-Me2Pz)2W(CO)4 (2.269
Å).14b In addition, the angels N(1)-W(1)-N(3) (80.8(2)°),
C(1)-W(1)-C(4) (161.6(3)°), and N(2)-C(15)-N(4) (111.0-
(5)°) are also similar to the corresponding angles in Ph3-
GeCH(3,5-Me2Pz)2W(CO)4 (80.2(4)°, 160.4(3)°, and 111.1-
(8)°, respectively) and Me3SiCH(3,5-Me2Pz)2W(CO)4
(80.55(15)°, 162.4(2)°, and 111.6(4)°, respectively). Two
cis-carbonyl groups are markedly distorted, with angles
W(1)-C(1)-O(1) of 165.9(6)° and W(1)-C(4)-O(4) of
171.1(9)°, possibly owing to the steric repulsion between
the ligand with two cis-carbonyls. It is worth noting that
some angles around the Sn(1) and C(15) atoms (such
as the angles C(23)-Sn(1)-C(15) of 98.0(3)° and N(2)-
C(15)-Sn(1) of 120.0(4)°) significantly deviate from the
tetrahedral geometry of the sp3 hybridized Sn(1) and
It has been found that the coordination behavior of
poly(pyrazol-1-yl)alkanes can easily be adjusted by
changing the electronic and steric characteristics of
substituents in the 3-, 4-, and 5-positions of the pyrazole
rings. Bulky substituents in the 3- and 5-positions of
pyrazole rings prevent the accessibility of the metals
to the coordinated nitrogen atoms owing to their strong
steric repulsion. Equation 1 shows that stable oxidative
addition products 3a and 5a can be formed even with
bulky isopropyl groups in the 3- and 5-positions of the
pyrazole rings. To investigate the influence of substit-
uents in the 4-position of the pyrazole rings on the
oxidative addition reaction, ligands 6-10 were synthe-
sized. Treatment of these ligands with W(CO)5THF
under the same experiment conditions as the above
reactions of ligands 1-5 with W(CO)5THF yielded the
analogous oxidative addition products 6a -10a , ac-
companied by the decarbonylation complexes 6b-10b
at the same time (eq 2). It seems that the alkyl
substituents in the 4-position of the pyrazole rings can
stabilize the decarbonylation intermediates 7b-10b via
their electron-donating properties to increase the overall
electron density of the ligands. Sequentially heating
complexes 6b-10b resulted in the oxidative addition
of the Sn-C(sp3) bond to the tungsten(0) center to form
complexes 6a -10a . In addition, when heating ligands
6-10 and W(CO)5THF at reflux in THF for a long time
or the reactions of these ligands with W(CO)6 in dioxane
at reflux yielded only complexes 6a -10a ; complexes
6b-10b could not be obtained. The above results show
that the oxidative addition reaction of the Sn-C(sp3)
bond to the tungsten(0) center may form the decarbo-
nylation intermediates 6b-10b.
Complexes 6a -10a and 6b-10b have also been
1
characterized by elemental analysis, IR, H NMR spec-
troscopies, and for 6b X-ray diffraction analyses. The
(20) Tang, L. F.; Wang, Z. H.; Xu, Y. M.; Wang, J . T.; Wang, H. G.;
Yao, X. K. Polyhedron 1999, 18, 2383.
(19) Trofimenko, S. Chem. Rev. 1993, 93, 943.

Reaction of Bis(pyrazol-1-yl)methanes
Organometallics, Vol. 22, No. 16, 2003 3293
(eq 3), which were characterized by elemental analysis
and IR and 1H NMR spectroscopies. Their IR and 1H
NMR spectroscopic data are similar to those of 6b-10b,
indicating that they have analogous structures. The
analogous oxidative addition products were not ob-
tained. Furthermore, the oxidative addition reaction of
the Sn-C bond to the tungsten(0) center did not take
place, even with raising the reaction temperature or
prolongating the reaction time. The steric effects of
substituents attached to the tin atom may not be mainly
responsible for the oxidative addition reaction of the
Sn-C bond to the tungsten(0) center owing to the larger
F igu r e 2. Molecular structure of 6b. Thermal ellipsoids
are drawn at the 30% probability level. Selected bond
distances (Å) and angles (deg): W(1)-N(1) ) 2.259(6),
W(1)-N(3) ) 2.284(6), Sn(1)-C(15) ) 2.221(7), N(2)-C(15)
) 1.447(8), N(4)-C(15) ) 1.455(8), Sn(1)-C(16) ) 2.133-
(6); N(1)-W(1)-N(3) ) 80.8(2), C(1)-W(1)-C(4) ) 161.6-
(3), N(2)-C(15)-N(4) ) 111.0(5), W(1)-C(1)-O(1) ) 165.9-
(6), W(1)-C(4)-O(4) ) 171.1(9), C(16)-Sn(1)-C(30) )
119.5(3), C(23)-Sn(1)-C(15) ) 98.0(3), N(2)-C(15)-Sn-
(1) ) 120.0(4).
i
steric hindrance of the Pr3Sn group in 16 than that of
the Ph3Sn group in 1.21 It seems that the electronic
effects of substituents attached to the tin atom play a
key role. Compared to the electron-donating alkyl
groups, the aryl groups have strong electron-withdraw-
ing ability, which may decrease the electron density
around the tin atom in the Ar3Sn groups, resulting in
the higher oxidative addition reactivity of the Ar3Sn-
C(sp3) bond than that of the R3Sn-C(sp3) to the tungsten-
(0) center.
C(15) atoms, possibly owing to the repulsion among the
p-tolyl groups and between the tri(p-tolyl)stannyl group
and the CH(3,5-Me2Pz)2W(CO)4 unit.
To verify if the aryl group is necessary for the
oxidative addition reaction, ligands 17 and 18 have been
synthesized (eq 4). It is interesting that treatment of
It is also noteworthy that despite the similar struc-
tural features between 6b, Ph3GeCH(3,5-Me2Pz)2W-
(CO)4, and Me3SiCH(3,5-Me2Pz)2W(CO)4,14b and even
larger steric effects of the Ph3Ge group,21 the analogous
oxidative addition reaction of the Ge-C or Si-C bond
in Ph3GeCH(3,5-Me2Pz)2W(CO)4 and Me3SiCH(3,5-Me2-
Pz)2W(CO)4 to the tungsten(0) center did not take place,
which may be related to the lower reactivity of the
Ge-C and Si-C bonds22 as well as the lower stability
of the W-Ge and W-Si bonds, compared with the Sn-C
and W-Sn bonds, respectively.23
Mod ifica tion of Bis(p yr a zol-1-yl)m eth a n es w ith
Tr ia lk ylsta n n yl Gr ou p s on th e Meth in e Ca r bon
a n d Th eir Rea ction s w ith W(CO)5THF . Ligands 11-
16 were readily obtained using trialkyltin chloride
instead of triaryltin chloride as described in eq 1.
Treatment of these ligands with W(CO)5THF under
experimental conditions similar to those described in
eq 1 yielded only heterobimetallic complexes 11a -16a
ligands 17 and 18 results in the oxidative addition
reaction of the Sn-C(sp2) bond instead of the Sn-C(sp3)
bond to the tungsten(0) center to yield novel complexes
17a and 18a in good yield. Unlike the results reported,16
the phenyl groups in 17 and 18 have no chelate-assisted
effects during the oxidative addition reaction of the Sn-
C(sp2) bond to the tungsten(0) center. It is likely that
bulky substituents on the tin atom decrease the reactiv-
ity of the Sn-C(sp3) bond,24 strengthening the reactivity
of the Sn-C(sp2) bond in 17 and 18.
(21) White, D. P.; Anthony, J . C.; Oyefeso, A. O. J . Org. Chem. 1999,
64, 7707.
(22) MacDiarmid, A. G. Organometallic Compounds of the Group
IV Elements; Dekker: New York, 1968.
(23) Wilkinson, G.; Stone, F. G. A.; Abel, E. W. Comprehensive
Organometallic Chemistry, Vol. 6; Pergamon: Oxford, 1982; p 1062.
(24) Wilkinson, G.; Stone, F. G. A.; Abel, E. W. Comprehensive
Organometallic Chemistry, Vol. 2; Pergamon: Oxford, 1982; p 537.

3294 Organometallics, Vol. 22, No. 16, 2003
Tang et al.
ties and structural features. The above results also show
that bis(pyrazol-1-yl)methanes modified by organotin
groups containing unsaturated aryl groups on the
methine carbon display unusual reactivities. To detect
if bis(pyrazol-1-yl)methanes modified by unsaturated
vinyltin groups on the methine carbon have analogous
reactivity, ligands 19 and 20 have been prepared (eq
5). Treatment of 19 and 20 with W(CO)5THF in reflux-
F igu r e 3. Molecular structure of 17a . Thermal ellipsoids
are drawn at the 30% probability level. Selected bond
distances (Å) and angles (deg): W(1)-C(1) ) 1.947(10),
W(1)-C(2) ) 1.971(10), W(1)-C(15) ) 2.247(9), C(1)-O(1)
) 1.185(11), C(2)-O(2) ) 1.135(10), W(1)-N(1) ) 2.262-
(6), W(1)-N(3) ) 2.254(7), N(2)-C(9) ) 1.453(10), N(4)-
C(9) ) 1.428(10), W(1)-Sn(1) ) 2.8778(12), Sn(1)-C(9) )
2.237(9), Sn(1)‚‚‚C(1) ) 2.541(11); C(15)-W(1)-Sn(1) )
154.0(2), W(1)-C(1)-O(1) ) 167.8(8), W(1)-C(2)-O(2) )
177.3(9), W(1)-C(3)-O(3) ) 176.9(9), N(3)-W(1)-N(1) )
81.5(2), N(4)-C(9)-N(2) ) 109.2(7), C(9)-Sn(1)-W(1) )
78.2(2).
ing THF yielded heterobimetallic complexes 19a and
20a , which were confirmed by IR and H NMR spectra,
1
as well as X-ray diffraction analyses of 19a . The
analogous oxidative addition reaction of the Sn-C(sp3)
or Sn-C(sp2) bond did not take place. The proton signals
of a vinyl group in 19a and 20a are considerably shifted
to higher field compared with those of the other two
vinyl groups and those in free ligands 19 and 20,
indicating that this vinyl group may be bonded to the
metal.26 In addition, two sets of proton signals of
uncoordinated vinyl groups and bis(pyrazol-1-yl)methane
ligands have been observed in complexes 19a and 20a ,
possibly owing to the steric repulsion of substituents as
well as the rigidity caused by the coordination of an
olefinic double bond to the tungsten center, inhibiting
their free rotation in solution, or as a result of these
groups being diastereotopic.
Although a number of group 6 metal carbonyl com-
plexes containing an alkene unit as part of a polydentate
ligand have been reported, most of them involve P-
donors as the other chelate-assisted groups.27 Complexes
with chelating alkene ligands and N-donors as the other
ligating groups are rare. Some group 6 metal carbonyl
complexes containing intramolecular η2-bound arene as
well as N-donor chelate ligands are known, but the η2-
arene bonding interaction is relatively weak in these
complexes.28,29
Both complexes 17a and 18a have been characterized
by 1H NMR and IR spectra. They have very similar
spectroscopic data. The molecular structure of 17a has
also been confirmed by X-ray diffraction analyses as
shown in Figure 3. As seen in Figure 3, the phenyl group
has been transferred to the tungsten center, resulting
in a novel κ3-(N,Sn,N) coordination mode, and the
phenyl group is trans to the organotin group with the
angle C(15)-W(1)-Sn(1) of 154.0(2)°. The tungsten
atom is seven-coordinate, close to the distorted capped-
octahedral geometry, with the Sn(1) atom in the unique
capping position and the capped face made up of N(1),
N(3), and C(1) atoms. The W-Sn distance is 2.8778-
(12) Å, which is longer than that in 3a (2.7712(8) Å). It
is interesting to note that an asymmetric semibridging
carbonyl is observed between the W-Sn bond, while
such a semibridging carbonyl between the transition
metal and main group metal bond is rare.25 The angle
W(1)-C(1)-O(1) of 167.8(8)° is significantly smaller
than the angles W(1)-C(2)-O(2) of 177.3(9)° and W(1)-
C(3)-O(3) of 176.9(9)° possibly owing to the existence
of the semibridging carbonyl. The asymmetric param-
eter R for C(1)O(1) is 0.31, which falls within the range
of R values for semibridging carbonyls.25 In addition,
the existence of the semibridging carbonyl is also in good
agreement with the fact that the IR spectra of 17a and
18a show a low-frequency absorption band at 1783.9
cm-1 for 17a and 1781.6 cm-1 for 18a , respectively.
It is known that organotin compounds containing
unsaturated organic groups often show special reactivi-
To confirm the metal-olefin coordination mode, the
structure of complex 19a was determined by X-ray
(26) Bennett, M. A. Chem. Rev. 1962, 62, 611.
(27) Wilkinson, G.; Stone, F. G. A.; Abel, E. W. Comprehensive
Organometallic Chemistry, Vol. 3; Pergamon: Oxford, 1982; p 1324.
(28) (a) Shiu, K. B.; Chou, C. C.; Wang, S. L.; Wei, S. C. Organo-
metallics 1990, 9, 286. (b) Shiu, K. B.; Yeh, L. Y.; Peng, S. M.; Cheng,
M. C. J . Organomet. Chem. 1993, 460, 203.
(29) (a) Cobbledick, R. E.; Dowdell, L. R. J .; Einstein, F. W. B.;
Hoyano, J . K.; Peterson, L. K. Can. J . Chem. 1979, 57, 2285. (b) Davis,
H. B.; Hoyano, J . K.; Leung, P. Y.; Peterson, L. K.; Wolstenholme, B.
Can. J . Chem. 1980, 58, 151.
(25) Curtis, M. D.; Han, K. R.; Butler, W. M. Inorg. Chem. 1980,
19, 2096.

Reaction of Bis(pyrazol-1-yl)methanes
Organometallics, Vol. 22, No. 16, 2003 3295
to give novel four-membered metallacyclic complexes,
while the analogous reactions of trialkylbis(pyrazol-1-
yl)methanes with W(CO)5THF do not take place. How-
ever, the reactions of phenyldi(tert-butyl)stannylbis-
(pyrazol-1-yl)methanes with W(CO)5THF result in the
oxidative addition reaction of the Sn-C(sp2) bond
instead of the Sn-C(sp3) bond to the tungsten(0) center.
In addition, the reactions of trivinylstannylbis(pyrazol-
1-yl)methanes with W(CO)5THF result in a vinyl group
bonded to the tungsten center in η2-fashion to give a
κ3-(π,N,N) coordination mode.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All reactions were carried out
under an atmosphere of argon. Solvents were dried and
distilled prior to use according to standard procedures. 1H
NMR spectra were recorded on a Mercury 300 spectrometer
using CDCl3 as solvent unless otherwise noted. IR spectra were
recorded as KBr pellets on a Nicolet FT-IR 170SX spectrom-
eter. Elemental analyses were carried out on a Perkin-Elmer
240C analyzer. The preparation and spectroscopic data of 7
and 7a , as well as 8 and 8a , have been reported in a previous
paper.14a iPr3SnCl,30 tBu2PhSnCl,31 (CH2dCH)3SnCl,32 bis(3,5-
dimethylpyrazol-1-yl)methane,6a and bis(3,4,5-trimethylpyra-
zol-1-yl)methane6a were prepared according to the literature
methods.
F igu r e 4. Molecular structure of 19a . Thermal ellipsoids
are drawn at the 30% probability level. Selected bond
distances (Å) and angles (deg): W(1)-N(1) ) 2.288(9),
W(1)-N(3) ) 2.295(9), W(1)-C(15) ) 2.385(10), W(1)-
C(16) ) 2.361(12), C(15)-C(16) ) 1.392(18), C(19)-C(20)
) 1.362(10), N(2)-C(9) ) 1.451(13), Sn(1)-C(9) ) 2.192-
(11), Sn(1)-C(17) ) 2.119(16), Sn(1)-C(15) ) 2.070(12);
C(19)-Sn(1)-C(9) ) 101.9(5), C(17)-Sn(1)-C(19) ) 118.8-
(7), N(4)-C(9)-N(2) ) 112.5(9), N(2)-C(9)-Sn(1) ) 112.0-
(7), C(15)-Sn(1)-C(9) ) 104.2(4), C(16)-C(15)-Sn(1) )
124.4(11), C(18)-C(17)-Sn(1) ) 125.7(14), N(1)-W(1)-
N(3) ) 82.6(3).
P r ep a r a tion of Bis(3,5-d iisop r op ylp yr a zol-1-yl)m eth -
a n e, Bis(3,5-d ieth ylp yr a zol-1-yl)m eth a n e, a n d Bis(3,5-
d im eth yl-4-eth ylp yr a zol-1-yl)m eth a n e. These ligands were
prepared similarly using the appropriate pyrazole with CH2-
Br2 as described for bis(pyrazol-1-yl)methane.33 Data for bis-
(3,5-diisopropylpyrazol-1-yl)methane: yield 61%, mp 47-49 °C.
1H NMR: δ 1.00, 1.18 (d, d, 12H, 12H, CH(CH3)2), 2.88, 3.40
(m, m, 2H, 2H, CH(CH3)2), 5.79 (s, 2H, H4 of pyrazole ring),
6.17 (s, 2H, CH2). Data for bis(3,5-diethylpyrazol-1-yl)-
crystallography, which shows that there are two crys-
tallographically independent molecules in the unit cell
with very similar crystallographic data. For simplicity
only one of them is given in Figure 4. As shown in
Figure 4, a vinyl group is bound to the tungsten in η2-
fashion, resulting in a κ3-(π,N,N) coordination mode. The
significantly short W-C(sp2) bond distances of 2.385-
(10) Å for W(1)-C(15) and 2.361(12) Å for W(1)-C(16),
compared to those in PhP(3,5-Me2Pz)2W(CO)3 (2.58(2)
and 2.82(3) Å),29a but relatively close to the value of
2.247(9) Å for the W-C(sp2) σ bond in 17a , indicate the
strong metal-π bonding interactions in 19a , which is
in good agreement with the markedly upfield shift of a
1
methane: yield 71%, mp 34-36 °C. H NMR: δ 1.18, 1.21 (t,
t, 6H, 6H, CH2CH3), 2.59, 2.83 (q, q, 4H, 4H, CH2CH3), 5.85
(s, 2H, H4 of pyrazole ring), 6.11 (s, 2H, CH2). Data for bis-
(3,5-dimethyl-4-ethylpyrazol-1-yl)methane: yield 75%, mp 99-
1
101 °C. H NMR: δ 1.02 (t, 6H, CH2CH3), 2.15, 2.34 (s, s, 6H,
6H, CH3), 2.29 (q, 4H, CH2CH3), 6.05 (s, 2H, CH2).
P r ep a r a tion of P h 3Sn CH(3,5-Me2P z)2 (1). To a solution
of bis(3,5-dimethylpyrazol-1-yl)methane (0.408 g, 2 mmol) in
THF (40 mL) under Ar was added a hexane solution of nBuLi
(2 M, 1.0 mL) at -78 °C, and the mixture was stirred for 1 h
at that temperature. To the mixture was added a solution of
triphenyltin chloride (0.77 g, 2 mmol) in THF (10 mL). The
reaction mixture was stirred at -78 °C for 1 h, allowed to
slowly reach room temperature, and stirred overnight. The
solvent was removed under reduced pressure, and the residual
solid was recrystallized from hexane to yield 0.46 g (42%) of 1
1
vinyl group in the H NMR spectrum. It is noteworthy
that some angles around the Sn(1) atom (such as the
angles C(19)-Sn(1)-C(9) of 101.9(5)° and C(17)-Sn(1)-
C(19) of 118.8(7)°) significantly deviate from the tetra-
hedral geometry of the sp3 hybridized Sn(1) atom,
possibly owing to the repulsion among the vinyl groups
as well as between the vinyl groups with the pyrazole
ligands.
1
as white crystals, mp 126-128 °C. H NMR: δ 1.93, 2.20 (s,
s, 6H, 6H, CH3), 5.77 (s, 2H, H4 of pyrazole ring), 6.72 (s, 1H,
CH), 7.48-7.60 (m, 15H, C6H5). Anal. Found: C, 62.93; H, 5.42;
N, 10.11. Calcd for C29H30N4Sn: C, 62.96; H, 5.47; N, 10.13.
P r ep a r a tion of P h 3Sn CH(3,5-Et2P z)2 (2). This ligand was
obtained similarly using bis(3,5-diethylpyrazol-1-yl)methane
(0.52 g, 2 mmol) instead of bis(3,5-dimethylpyrazol-1-yl)-
methane as described above for 1. Yield: 0.49 g (40%), mp 64-
66 °C. 1H NMR: δ 0.88, 1.11 (t, t, 6H, 6H, CH2CH3), 2.29, 2.57
(q, q, 4H, 4H, CH2CH3), 5.81 (s, 2H, H4 of pyrazole ring), 6.71
(s, 1H, CH), 7.29-7.54 (m, 15H, C6H5). Anal. Found: C, 65.31;
H, 5.96; N, 9.56. Calcd for C33H38N4Sn: C, 65.04; H, 6.28; N,
9.19.
Con clu sion s
The modification of bis(pyrazol-1-yl)methane by the
substitution of organotin groups on the methine carbon
atom is readily carried out. These new ligands display
versatile reactivities upon treatment with W(CO)5THF,
depending on the properties of the substituents on the
tin atom. The reactions of triarylstannylbis(pyrazol-1-
yl)methanes with W(CO)5THF result in the oxidative
addition of the Sn-C(sp3) bond to the tungsten(0) center
(30) Prince, R. H. J . Chem. Soc. 1959, 1783.
(31) Kandil, S. A.; Allred, A. L. J . Chem. Soc. (A) 1970, 2987.
(32) Seyferth, D.; Stone, F. G. A. J . Am. Chem. Soc. 1957, 79, 515.
(33) Tang, L. F.; Wang, Z. H.; Xu, Y. M.; Wang, J . T.; Wang, H. G.;
Yao, X. K. Polyhedron 1998, 17, 3765.

3296 Organometallics, Vol. 22, No. 16, 2003
Tang et al.
P r ep a r a tion of P h 3Sn CH(3,5-iP r 2P z)2 (3). This ligand
was obtained as an oil, similarly using bis(3,5-diisopropylpyra-
zol-1-yl)methane (0.63 g, 2 mmol) instead of bis(3,5-dimeth-
ylpyrazol-1-yl)methane as described above for 1. Yield: 0.57
dimethyl-4-ethylpyrazol-1-yl)methane (0.52 g, 2 mmol) with
triethyltin chloride (0.48 g, 2 mmol) as described above for 1.
A viscous oil was obtained after the hexane solvent was
removed. Yield: 0.34 g (37%). 1H NMR: δ 0.96 (t, 9H,
SnCH2CH3), 1.13 (t, 6H, 4-CH2CH3 on pyrazole ring), 1.31 (q,
6H, SnCH2CH3), 1.92, 2.13 (s, s, 6H, 6H, 3 or 5-CH3), 2.32 (q,
4H, 4-CH2CH3 on pyrazole ring), 6.21 (s, 1H, CH).
P r ep a r a tion of Et3Sn CH(3,5-Et2P z)2 (14). This ligand
was obtained similarly by the reaction of bis(3,5-diethylpyra-
zol-1-yl)methane (0.52 g, 2 mmol) with triethyltin chloride
(0.48 g, 2 mmol) as described above for 1. A viscous oil was
obtained after the hexane solvent was removed. Yield: 0.37 g
(40%). 1H NMR: δ 0.92 (t, 9H, SnCH2CH3), 1.02 (q, 6H, SnCH2-
CH3), 1.17, 1.23 (t, t, 6H, 6H, 3 or 5-CH2CH3), 2.41, 2.59 (q, q,
4H, 4H, 3 or 5-CH2CH3), 5.85 (s, 2H, H4 of pyrazole ring), 6.29
(s, 1H, CH).
1
g (43%). H NMR: δ 0.64, 0.76, 1.17, 1.20 (d, d, d, d, 6H, 6H,
6H, 6H, CH(CH3)2), 2.91-3.02 (m, 4H, CH(CH3)2), 5.82 (s, 2H,
H4 of pyrazole ring), 6.92 (s, 1H, CH), 7.30, 7.52 (m, m, 9H,
6H, C6H5).
P r ep a r a tion of (p-CH3P h )3Sn CH(3,5-Et2P z)2 (4). This
ligand was obtained similarly by the reaction of bis(3,5-
diethylpyrazol-1-yl)methane (0.52 g, 2 mmol) with tri(p-
methylphenyl)tin chloride (0.855 g, 2 mmol) as described above
for 1. Yield: 0.48 g (37%), mp 81-83 °C. 1H NMR: δ 0.88,
1.18 (t, t, 6H, 6H, CH2CH3), 2.21, 2.56 (q, q, 4H, 4H, CH2CH3),
2.31 (s, 9H, C6H4CH3), 5.80 (s, 2H, H4 of pyrazole ring), 6.71
(s, 1H, CH), 7.17, 7.41 (d, d, 6H, 6H, C6H4). Anal. Found: C,
66.15; H, 6.89; N, 8.73. Calcd for C36H44N4Sn: C, 66.37; H,
6.81; N, 8.60.
P r ep a r a tion of (p-CH3P h )3Sn CH(3,5-iP r 2P z)2 (5). This
ligand was obtained similarly by the reaction of bis(3,5-
diisopropylpyrazol-1-yl)methane (0.63 g, 2 mmol) with tri(p-
methylphenyl)tin chloride (0.855 g, 2 mmol) as described above
for 1. Yield: 0.45 g (32%), mp 75-77 °C. 1H NMR: δ 0.60,
0.74, 1.20, 1.26 (d, d, d, d, 6H, 6H, 6H, 6H, CH(CH3)2), 2.34 (s,
9H, C6H4CH3), 2.93-3.01 (m, 4H, CH(CH3)2), 5.80 (s, 2H, H4
of pyrazole ring), 6.91 (s, 1H, CH), 7.18, 7.46 (d, d, 6H, 6H,
C6H4). Anal. Found: C, 67.57; H, 7.58; N, 7.65. Calcd for
P r ep a r a tion of Et3Sn CH(3,5-iP r 2P z)2 (15). This ligand
was obtained similarly by the reaction of bis(3,5-diisopropy-
lpyrazol-1-yl)methane (0.63 g, 2 mmol) with triethyltin chloride
(0.48 g, 2 mmol) as described above for 1. A viscous oil was
obtained after the hexane solvent was removed. Yield: 0.4 g
1
(38%). H NMR: δ 0.79, 0.86, 1.22 (d, d, d, 6H, 6H, 12H, CH-
(CH3)2), 0.95 (t, 9H, SnCH2CH3), 1.10 (q, 6H, SnCH2CH3), 2.88,
3.10 (m, m, 2H, 2H, CH(CH3)2), 5.80 (s, 2H, H4 of pyrazole
ring), 6.44 (s, 1H, CH).
i
P r ep a r a tion of P r 3Sn CH(3,5-Me2P z)2 (16). This ligand
was obtained similarly by the reaction of bis(3,5-dimethylpyra-
zol-1-yl)methane (0.408 g, 2 mmol) with triisopropyltin chloride
(0.57 g, 2 mmol) as described above for 1. A viscous oil was
obtained after the hexane solvent was removed. Yield: 0.39 g
(43%). 1H NMR: δ 1.24 (d, 18H, CH(CH3)2), 1.47 (m, 3H,
CH(CH3)2), 2.08, 2.16 (s, s, 6H, 6H, 3 or 5-CH3), 5.76 (s, 2H,
H4 of pyrazole ring), 6.24 (s, 1H, CH).
P r epar ation of tBu 2P h Sn CH(3,5-Me2P z)2 (17). This ligand
was obtained similarly by the reaction of bis(3,5-dimethylpyra-
zol-1-yl)methane (0.408 g, 2 mmol) with phenyldi(tert-butyl)-
tin chloride (0.69 g, 2 mmol) as described above for 1. Yield:
0.46 g (45%), mp 70-72 °C. 1H NMR: δ 1.24 (s, 18H, C(CH3)3),
1.99, 2.16 (s, s, 6H, 6H, 3 or 5-CH3), 5.72 (s, 2H, H4 of pyrazole
ring), 6.30 (s, 1H, CH), 7.23, 7.36 (m, m, 3H, 2H, C6H5). Anal.
Found: C, 58.61; H, 7.82; N, 10.57. Calcd for C25H38N4Sn: C,
58.50; H, 7.46; N, 10.91.
P r ep a r a tion of tBu 2P h Sn CH(3,4,5-Me3P z)2 (18). This
ligand was obtained similarly by the reaction of bis(3,4,5-
trimethylpyrazol-1-yl)methane (0.46 g, 2 mmol) with phenyldi-
(tert-butyl)tin chloride (0.69 g, 2 mmol) as described above for
1. A viscous oil was obtained after the hexane solvent was
removed. Yield: 0.41 g (38%). 1H NMR: δ 1.25 (s, 18H,
C(CH3)3), 1.81, 1.92, 2.12 (s, s, s, 6H, 6H, 6H, 3, 4, or 5-CH3),
6.36 (s, 1H, CH), 7.23, 7.34 (m, m, 3H, 2H, C6H5).
C
40H52N4Sn: C, 67.89; H, 7.41; N, 7.92.
P r ep a r a tion of (p-CH3P h )3Sn CH(3,5-Me2P z)2 (6). This
ligand was obtained similarly using tri(p-methylphenyl)tin
chloride (0.855 g, 2 mmol) instead of triphenyltin chloride as
described above for 1. Yield: 0.55 g (46%), mp 122-124 °C.
1H NMR: δ 1.64, 2.16 (s, s, 6H, 6H, CH3), 2.30 (s, 9H,
C6H4CH3), 5.71 (s, 2H, H4 of pyrazole ring), 6.64 (s, 1H, CH),
7.12, 7.42 (d, d, 6H, 6H, C6H4). Anal. Found: C, 64.54; H, 6.05;
N, 9.46. Calcd for C32H36N4Sn: C, 64.56; H, 6.09; N, 9.41.
P r ep a r a tion of P h 3Sn CH(3,5-Me2-4-EtP z)2 (9). This
ligand was obtained similarly using bis(3,5-dimethyl-4-eth-
ylpyrazol-1-yl)methane (0.52 g, 2 mmol) instead of bis(3,5-
dimethylpyrazol-1-yl)methane as described above for 1.
1
Yield: 0.55 g (45%), mp 99-101 °C. H NMR: δ 0.97 (t, 6H,
CH2CH3), 1.86, 2.15 (s, s, 6H, 6H, 3 or 5-CH3), 2.26 (q, 4H,
CH2CH3), 6.65 (s, 1H, CH), 7.31, 7.55 (m, m, 9H, 6H, C6H5).
Anal. Found: C, 65.28; H, 6.35; N, 9.46. Calcd for C33H38N4-
Sn: C, 65.04; H, 6.29; N, 9.19.
P r ep a r a tion of (p-CH3P h )3Sn CH(3,5-Me2-4-EtP z)2 (10).
This ligand was obtained similarly by the reaction of bis(3,5-
dimethyl-4-ethylpyrazol-1-yl)methane (0.52 g, 2 mmol) with
tri(p-methylphenyl)tin chloride (0.855 g, 2 mmol) as described
above for 1. Yield: 0.55 g (42%), mp 81-83 °C. 1H NMR: δ
0.89 (t, 6H, CH2CH3), 1.81, 2.14 (s, s, 6H, 6H, 3 or 5-CH3),
2.22 (q, 4H CH2CH3), 2.31 (s, 9H, C6H4CH3), 6.64 (s, 1H, CH),
7.25, 7.52 (d, d, 6H, 6H, C6H4). Anal. Found: C, 66.61; H, 6.82;
N, 8.85. Calcd for C36H44N4Sn: C, 66.37; H, 6.81; N, 8.60.
P r ep a r a tion of Et3Sn CH(3,5-Me2P z)2 (11). This ligand
was obtained similarly using triethyltin chloride (0.48 g, 2
mmol) instead of triphenyltin chloride as described above for
1. After the hexane solvent was removed under reduced
P r ep a r a tion of (CH2dCH)3Sn CH(3,5-Me2P z)2 (19). This
ligand was obtained similarly using trivinyltin chloride (0.47
g, 2 mmol) instead of triphenyltin chloride as described above
for 1. A viscous oil was obtained after the hexane solvent was
removed. Yield: 0.28 g (35%). 1H NMR: δ 1.98, 2.17 (s, s, 6H,
6H, 3 or 5-CH3), 5.81 (s, 2H, H4 of pyrazole ring), 6.32 (s, 1H,
CH), 5.75, 5.78, 6.16, 6.20, 6.42-6.54 (d, d, d, d, m, CHdCH2).
P r ep a r a tion of (CH2dCH)3Sn CH(3,4,5-Me3P z)2 (20).
This ligand was obtained similarly by the reaction of trivinyltin
chloride (0.47 g, 2 mmol) with bis(3,4,5-trimethylpyrazol-1-
yl)methane (0.46 g, 2 mmol) as described above for 1. A viscous
oil was obtained after the hexane solvent was removed. Yield:
1
pressure, a viscous oil was obtained. Yield: 0.38 g (47%). H
NMR: δ 0.97 (t, 9H, CH2CH3), 1.12 (q, 6H, CH2CH3), 1.98,
2.13 (s, s, 6H, 6H, 3 or 5-CH3), 5.73 (s, 2H, H4 of pyrazole ring),
6.18 (s, 1H, CH).
1
P r ep a r a tion of Et3Sn CH(3,4,5-Me3P z)2 (12). This ligand
was obtained similarly by the reaction of bis(3,4,5-trimeth-
ylpyrazol-1-yl)methane (0.46 g, 2 mmol) with triethyltin
chloride (0.48 g, 2 mmol) as described above for 1. A viscous
oil was obtained after the hexane solvent was removed. Yield:
0.28 g (32%). H NMR: δ 1.82, 1.89, 2.11 (s, s, s, 6H, 6H, 6H,
3, 4, or 5-CH3), 6.34 (s, 1H, CH), 5.68, 5.75, 6.14, 6.18, 6.42-
6.53 (d, d, d, d, m, CHdCH2).
Rea ction s of 1-5 w ith W(CO)5THF to Give CH(3,5-
Me2P z)2W(CO)3Sn P h 3 (1a ), CH(3,5-Et2P z)2W(CO)3Sn P h 3
(2a ), CH(3,5-iP r 2P z)2W(CO)3Sn P h 3 (3a ), CH(3,5-Et2P z)2W-
(CO)3Sn (p-MeP h )3 (4a ), a n d CH(3,5-iP r 2P z)2W(CO)3Sn (p-
MeP h )3 (5a ). Since all reactions were run similarly, a general
procedure was described. Ligand (0.3 mmol) was added to a
solution of W(CO)5THF in THF, prepared in situ by the
1
0.35 g (40%). H NMR: δ 0.91 (t, 9H, CH2CH3), 1.11 (q, 6H,
CH2CH3), 1.80, 1.90, 2.07 (s, s, s, 6H, 6H, 6H, 3, 4 or 5-CH3),
6.18 (s, 1H, CH).
P r ep a r a tion of Et3Sn CH(3,5-Me2-4-EtP z)2 (13). This
ligand was obtained similarly by the reaction of bis(3,5-

Reaction of Bis(pyrazol-1-yl)methanes
Organometallics, Vol. 22, No. 16, 2003 3297
irradiation of a solution of W(CO)6 (0.3 mmol) in THF (20 mL)
for 8 h, and the mixture was stirred and heated at reflux for
2 h. After the reaction was completed, the solvent was removed
under reduced pressure, and the residual solid was purified
by column chromatography on alumina using CH2Cl2/hexane
(1:2 v/v) as eluent. The eluate was concentrated to dryness
again, and the residual solid was recrystallized from CH2Cl2/
hexane to give orange-red crystals.
Sp ectr oscop ic Da ta for 1a . Yield: 36%. 1H NMR: δ 1.80,
2.32 (s, s, 6H, 6H, 3 or 5-CH3), 4.32 (s, 1H, CH), 5.59 (s, 2H,
H4 of pyrazole ring), 7.23-7.34 (m, 15H, C6H5). IR (cm-1):
1970.5 vs, 1879.4 s, 1849.6 vs [ν (CO)]. Anal. Found: C, 47.06;
H, 3.59; N, 6.59. Calcd for C32H30N4O3SnW: C, 46.81; H, 3.68;
N, 6.82.
CH), 7.14, 7.33 (m, m, 6H, 9H, C6H5). IR (cm-1): 1995.6 vs,
1878.9 sh, 1850.8 vs, 1835.2 vs [ν (CO)]. Anal. Found: C, 47.86;
H, 3.87; N, 6.61. Calcd for C35H34N4O4SnW: C, 47.92; H, 3.91;
N, 6.39.
Sp ectr oscop ic Da ta for 8b. Yield: 13%. 1H NMR: δ 1.93,
1.96, 2.51 (s, s, s, 6H, 6H, 6H, 3, 4, or 5-CH3), 2.31 (s, 9H,
C6H4CH3), 6.66 (s, 1H, CH), 7.08, 7.13 (d, d, 6H, 6H, C6H4). IR
(cm-1): 1994.6 s, 1859.4 (br) vs, 1834.6 s [ν (CO)]. Anal.
Found: C, 49.51; H, 4.21; N, 5.98. Calcd for C38H40N4O4SnW:
C, 49.65; H, 4.39; N, 6.09.
Sp ectr oscop ic Da ta for 9a a n d 9b. 9a : Yield: 34%. 1H
NMR: δ 0.98 (t, 6H, CH2CH3), 1.78, 2.29 (s, s, 6H, 6H, 3 or
5-CH3), 2.34 (q, 4H, CH2CH3), 4.31 (s, 1H, CH), 7.22, 7.39 (m,
m, 9H, 6H, C6H5). IR (cm-1): 1968.3 vs, 1875.7 s, 1842.3 vs [ν
(CO)]. Anal. Found: C, 48.22; H, 3.97; N, 6.28. Calcd for
Sp ectr oscop ic Da ta for 2a . Yield: 34%. 1H NMR: δ 1.07,
1.32 (t, t, 6H, 6H, CH2CH3), 2.15, 2.73 (q, q, 4H, 4H, CH2CH3),
4.41 (s, 1H, CH), 5.67 (s, 2H, H4 of pyrazole ring), 7.21, 7.41
(m, m, 9H, 6H, C6H5). IR (cm-1): 1967.0 vs, 1875.3 vs, 1850.8
vs [ν (CO)]. Anal. Found: C, 49.61; H, 4.18; N, 6.69. Calcd for
C
36H38N4O3SnW‚0.25CH2Cl2: C, 48.46; H, 4.29; N, 6.24. 9b:
Yield: 10%. 1H NMR: δ 1.08 (t, 6H, CH2CH3), 1.98, 2.42 (s, s,
6H, 6H, 3 or 5-CH3), 2.39 (q, 4H, CH2CH3), 6.69 (s, 1H, CH),
7.12, 7.36 (m, m, 6H, 9H, C6H5). IR (cm-1): 1997.3 s, 1883.4 s,
1868 s, 1844.8 sh, 1832.3 vs [ν (CO)]. Anal. Found: C, 48.86;
H, 4.52; N, 6.38. Calcd for C37H38N4O4SnW: C, 49.09; H, 4.23;
N, 6.19.
C
36H38N4O3SnW: C, 49.29; H, 4.37; N, 6.39.
Sp ectr oscop ic Da ta for 3a . Yield: 41%. 1H NMR: δ 0.87,
1.10, 1.31, 1.38 (d, d, d, d, 6H, 6H, 6H, 6H, CH(CH3)2), 2.54-
2.63, 3.06-3.16 (m, m, 2H, 2H, CH(CH3)2), 4.63 (s, 1H, CH),
5.63 (s, 2H, H4 of pyrazole ring), 7.22, 7.45 (m, m, 9H, 6H,
C6H5). IR (cm-1): 1971.4 vs, 1879.4 vs, 1862.9 vs, 1831.9 sh [ν
(CO)]. Anal. Found: C, 50.75; H, 5.08; N, 6.29. Calcd for
Sp ectr oscop ic Da ta for 10a a n d 10b. 10a : Yield: 32%.
1H NMR: δ 1.03 (t, 6H, CH2CH3), 1.74 (s, 6H, 3 or 5-CH3),
2.25-2.28 (m, 19H, 3 or 5-CH3, CH2CH3 and C6H4CH3), 4.34
(s, 1H, CH), 7.03, 7.24 (d, d, 6H, 6H, C6H4). IR (cm-1): 1972.4
s, 1929.3 m, 1882.6 s, 1858.7 s [ν (CO)]. Anal. Found: C, 50.68;
H, 4.54; N, 6.47. Calcd for C39H44N4O3SnW: C, 50.95; H, 4.82;
C
40H46N4O3SnW: C, 51.47; H, 4.97; N, 6.01.
Sp ectr oscop ic Da ta for 4a . Yield: 28%. 1H NMR: δ 0.87,
1
1.20 (t, t, 6H, 6H, CH2CH3), 2.15, 2.70 (q, q, 4H, 4H, CH2CH3),
4.39 (s, 1H, CH), 5.65 (s, 2H, H4 of pyrazole ring), 7.06, 7.30
(d, d, 6H, 6H, C6H4). IR (cm-1): 1968.1 s, 1878.1 s, 1856.1 vs
[ν (CO)]. Anal. Found: C, 50.68; H, 4.94; N, 6.15. Calcd for
N, 6.09. 10b: Yield: 10%. H NMR: δ 1.08 (t, 6H, CH2CH3),
1.99, 2.33 (s, s, 6H, 6H, 3 or 5-CH3), 2.41 (q, 4H, CH2CH3),
2.55 (s, 9H, C6H4CH3), 6.66 (s, 1H, CH), 6.99, 7.13 (d, d, 6H,
6H, C6H4). IR (cm-1): 1999.5 s, 1882.0 sh, 1868.1 s, 1851.5 vs,
1831.8 vs, [ν (CO)]. Anal. Found: C, 50.85; H, 4.92; N, 6.26.
Calcd for C40H44N4O4SnW: C, 50.71; H, 4.68; N, 5.91.
C
39H44N4O3SnW: C, 50.95; H, 4.82; N, 6.09.
Sp ectr oscop ic Da ta for 5a . Yield: 35%. 1H NMR: δ 0.87,
1.08, 1.25, 1.35, (d, d, d, d, 6H, 6H, 6H, 6H, CH(CH3)2), 2.28
(s, 9H, C6H4CH3), 2.60, 3.10 (m, m, 2H, 2H, CH(CH3)2), 4.59
(s, 1H, CH), 5.62 (s, 2H, H4 of pyrazole ring), 7.03, 7.32 (d, d,
6H, 6H, C6H4). IR (cm-1): 1964.7 vs, 1875.4 s, 1854.4 vs, 1824.1
sh [ν (CO)]. Anal. Found: C, 52.83; H, 5.31; N, 5.74. Calcd for
The reaction of ligands 6-10 with W(CO)6 in dioxane at
reflux for 12 h directly yielded complexes 6a -10a , and
complexes 6b-10b could not be obtained.
Hea tin g Com p lexes 9b a n d 10b a t 60 °C in CDCl3. First,
1
the H NMR spectra of 9b and 10b (15 mg) in CDCl3 (0.6 mL)
C
43H52N4O3SnW: C, 52.94; H, 5.37; N, 5.74.
were recorded; then, the solution was heated at 60 °C for 30
Rea ction s of 6-10 w ith W(CO)5THF to Give CH(3,5-
1
min. After cooling to room temperature, the H NMR spectra
Me2P z)2W(CO)3Sn (p -MeP h )3 (6a ), (p -MeP h )3Sn CH (3,5-
Me2P z)2W(CO)4 (6b), CH(3,4,5-Me3P z)2W(CO)3Sn P h 3 (7a ),
P h 3Sn CH(3,4,5-Me3P z)2W(CO)4 (7b), CH(3,4,5-Me3P z)2W-
(CO)3Sn (p-MeP h )3 (8a ), (p-MeP h )3Sn CH(3,4,5-Me3P z)2W-
(CO)4 (8b), CH(3,5-Me2-4-EtP z)2W(CO)3Sn P h 3 (9a ), P h 3Sn -
CH (3,5-Me2-4-E t P z)2W(CO)4 (9b ), CH (3,5-Me2-4-E t P z)2-
W(CO)3Sn (p-MeP h )3 (10a ), a n d (p-MeP h )3Sn CH(3,5-Me2-
4-EtP z)2W(CO)4 (10b). The reactions were carried out simi-
larly as described above for the reactions of 1-5 with
W(CO)5THF. After the reaction was complete, the solvent was
removed under reduced pressure. The residual solid was
purified by column chromatography on alumina using CH2-
Cl2/hexane (1:2 v/v) as eluent to yield two products. The first
orange-red band was confirmed as compounds 6a -10a , re-
spectively, and the second green-yellow band was confirmed
as compounds 6b-10b, respectively, by their spectroscopic
data as well as X-ray crystal diffraction.
were recorded again. The results showed that the signal of
protons at 6.69 ppm for 9b and 6.66 ppm for 10b disappeared,
and a new proton signal at 4.31 ppm for 9b and 4.34 ppm for
10b was observed, respectively.
Rea ction s of 11-16 w ith W(CO)5THF to Give Et3Sn CH-
(3,5-Me2P z)2W(CO)4 (11a ), Et3Sn CH(3,4,5-Me3P z)2W(CO)4
(12a ), Et3Sn CH(3,5-Me2-4-EtP z)2W(CO)4 (13a ), Et3Sn CH-
(3,5-E t2P z)2W(CO)4 (14a ), E t 3Sn CH (3,5-iP r 2P z)2W(CO)4
(15a ), a n d iP r 3Sn CH(3,5-Me2P z)2W(CO)4 (16a ). The same
procedure was followed as described above for the reactions
of 1-5 with W(CO)5THF. Only complexes 11a -16a were
obtained as green-yellow solids; no analogous oxidative addi-
tion products of 1a were obtained.
Sp ectr oscop ic Da ta for 11a . Yield: 48%. 1H NMR: δ 1.03
(t, 9H, CH2CH3), 1.21 (q, 6H, CH2CH3), 2.32, 2.50 (s, s, 6H,
6H, 3 or 5-CH3), 5.95 (s, 2H, H4 of pyrazole ring), 6.25 (s, 1H,
CH). IR (cm-1): 1999.6 s, 1879.0 vs, 1860.4 vs, 1822.5 vs [ν
(CO)]. Anal. Found: C, 35.64; H, 4.35; N, 7.72. Calcd for
Sp ectr oscop ic Da ta for 6a a n d 6b. 6a : Yield: 30%. 1H
NMR: δ 1.81, 2.28 (s, s, 6H, 6H, 3 or 5-CH3), 2.31 (s, 9H,
C6H4CH3), 4.32 (s, 1H, CH), 5.60 (s, 2H, H4 of pyrazole ring),
7.01, 7.27 (d, d, 6H, 6H, C6H4). IR (cm-1): 1937.9 vs, 1875.9 s,
1855.5 vs [ν (CO)]. Anal. Found: C, 48.67; H, 4.07; N, 6.43.
Calcd for C35H36N4O3SnW: C, 48.70; H, 4.20; N, 6.49. 6b:
C
21H30N4O4SnW: C, 35.78; H, 4.29; N, 7.95.
Sp ectr oscop ic Da ta for 12a . Yield: 52%. 1H NMR: δ 1.02
(t, 9H, CH2CH3), 1.18 (q, 6H, CH2CH3), 1.91, 2.25, 2.45 (s, s,
s, 6H, 6H, 6H, 3, 4, or 5-CH3), 6.33 (s, 1H, CH). IR (cm-1):
1991.9 s, 1925.9 w, 1864.9 vs, 1832.4 vs [ν (CO)]. Anal.
Found: C, 37.48; H, 4.56; N, 7.77. Calcd for C23H34N4O4SnW:
C, 37.68; H, 4.67; N, 7.64.
1
Yield: 8%. H NMR: δ 2.03, 2.55 (s, s, 6H, 6H, 3 or 5-CH3),
2.31 (s, 9H, C6H4CH3), 6.01 (s, 2H, H4 of pyrazole ring), 6.57
(s, 1H, CH), 7.01, 7.09 (d, d, 6H, 6H, C6H4). IR (cm-1): 2005.7
m, 1888.4 s, 1850.0 vs, 1822.9 vs [ν (CO)]. Anal. Found: C,
48.73; H, 4.25; N, 6.18. Calcd for C36H36N4O4SnW: C, 48.52;
H, 4.07; N, 6.29.
Sp ectr oscop ic Da ta for 13a . Yield: 42%. 1H NMR:
δ
0.98-1.12 (m, 21H, SnCH2CH3 and 4-CH2CH3 of pyrazole
ring), 2.28, 2.50 (s, s, 6H, 6H, 3 or 5-CH3), 2.41 (q, 4H, 4-CH2-
CH3 of pyrazole ring), 6.34 (s, 1H, CH). IR (cm-1): 1997.3 s,
1878.8 s, 1862.6 s, 1822.7 s [ν (CO)]. Anal. Found: C, 39.68;
1
Sp ectr oscop ic Da ta for 7b. Yield: 9%. H NMR: δ 1.94,
1.96, 2.51 (s, s, s, 6H, 6H, 6H, 3, 4, or 5-CH3), 6.70 (s, 1H,

3298 Organometallics, Vol. 22, No. 16, 2003
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p ou n d s 3a , 6b, 17a , a n d 19a
Tang et al.
3a
6b‚H2O
17a ‚2CH2Cl2
19a
formula
fw
C
40H46N4O3SnW
C36H38N4O5SnW
909.24
C30H42Cl4N4O3SnW
951.02
C20H24N4O3SnW
670.97
933.35
cryst size, mm
cryst syst
space group
cell params
a (Å)
0.22× 0.20 × 0.16
monoclinic
P21/c
0.30× 0.25 × 0.05
monoclinic
P21/n
0.25× 0.20 × 0.20
0.16× 0.10 × 0.06
monoclinic
P21/c
monoclinic
P21/c
11.050(3)
21.455(6)
17.805(5)
107.101(5)
4035(2)
4
11.467(3)
22.037(6)
15.422(4)
100.008(5)
3837.6(17)
4
14.224(7)
15.507(8)
17.597(9)
106.315(8)
3725(3)
4
9.463(3)
14.280(5)
34.137(9)
94.382(7)
4600(2)
8
b (Å)
c (Å)
â (deg)
V, Å3
Z
T (K)
293
293
293
293
calcd density (Mg m-3
F(000)
)
1.536
1.574
1.696
1.938
1848
1784
1864
2560
µ, mm-1
no. of reflns collcd
3.507
3.689
4.077
6.110
18 932
8253
15 735
6723
15 634
7455
26 238
9460
no. of reflns obsd with (I g 2σ(I))
no. of params
443
432
416
514
R, Rw (I g 2σ(I))
0.0497, 0.0634
0.950
0.0413, 0.0810
0.918
0.0484, 0.0892
1.030
0.0638, 0.0895
1.021
goodness-of-fit on F2
H, 5.31; N, 7.54. Calcd for C25H38N4O4SnW: C, 39.45; H, 5.03;
N, 7.36.
Sp ectr oscop ic Da ta for 19a . Yield: 35%. 1H NMR: δ 2.30,
2.38, 2.42, 2.61 (s, s, s, s, 3H, 3H, 3H, 3H, 3 or 5-CH3), 2.49,
3.40, 4.70 (dd, d, d, 1H, 1H, 1H, η2-CHdCH2), 5.20, 5.38, 6.10-
6.26 (dd, dd, m, 1H, 1H, 4H, CHdCH2), 5.84, 6.03-6.08 (s, m,
1H, 2H, H4 of pyrazole ring and CH). IR (cm-1): 1930.6 vs,
1846.9 m, 1830.7 s, 1824.0 s, 1780.2 vs [ν (CO)]. Anal. Found:
C, 35.43; H, 3.43; N, 8.14. Calcd for C20H24N4O3SnW: C, 35.80;
H, 3.61; N, 8.35.
Sp ectr oscop ic Da ta for 20a . Yield: 30%. 1H NMR: δ 1.85,
1.95, (s, s, 3H, 3H, 4-CH3), 2.22, 2.30, 2.37, 2.56 (s, s, s, s, 3H,
3H, 3H, 3H, 3 or 5-CH3), 2.49, 3.41, 4.72 (dd, d, d, 1H, 1H,
1H, η2-CHdCH2), 5.21, 5.40, 5.94-6.01, 6.08-6.24 (dd, dd, m,
m, 1H, 1H, 2H, 2H, CHdCH2), 6.05 (s, 1H, CH). IR (cm-1):
1931.6 s, 1848.5 sh, 1832.7 s, 1789.2 s [ν (CO)]. Anal. Found:
C, 36.65; H, 4.24; N, 7.93. Calcd for C22H28N4O3SnW‚0.5CH2-
Cl2: C, 36.44; H, 3.94; N, 7.56.
Sp ectr oscop ic Da ta for 14a . Yield: 36%. 1H NMR:
δ
0.99-1.13 (m, 15H, SnCH2CH3), 1.27, 1.33 (t, t, 6H, 6H, 3 or
5-CH2CH3), 2.59-2.86 (m, 8H, 3 or 5-CH2CH3), 6.03 (s, 2H,
H4 of pyrazole ring), 6.31 (s, 1H, CH). IR (cm-1): 1998.4 s,
1877.8 vs, 1846.9 vs, 1820.5 vs [ν (CO)]. Anal. Found: C, 39.78;
H, 5.34; N, 7.63. Calcd for C25H38N4O4SnW: C, 39.45; H, 5.03;
N, 7.36.
Sp ectr oscop ic Da ta for 15a . Yield: 41%. 1H NMR: δ 0.81,
0.89, 1.24 (d, d, d, 6H, 6H, 12H, 6H, CH(CH3)2), 1.01 (t, 9H,
SnCH2CH3), 1.12 (q, 6H, SnCH2CH3), 2.88, 3.10 (m, m, 2H,
2H, CH(CH3)2), 5.81 (s, 2H, H4 of pyrazole ring), 6.44 (s, 1H,
CH). IR (cm-1): 2002.0 s, 1924.0 m, 1858.9 vs, 1830.7 vs [ν
(CO)]. Anal. Found: C, 42.30; H, 5.77; N, 7.23. Calcd for
C
29H46N4O4SnW: C, 42.62; H, 5.67; N, 6.85.
Sp ectr oscop ic Da ta for 16a . Yield: 44%. 1H NMR: δ 1.16
X-r a y Cr ysta llogr a p h ic Deter m in a tion of 3a , 6b, 17a ,
a n d 19a . Orange-red crystals of 3a and 19a as well as green-
yellow crystals of 6b suitable for X-ray analyses were grown
by slow diffusion of hexane into the CH2Cl2 solution of 3a , 19a ,
and 6b at -10 °C. Green-yellow crystals of 17a suitable for
X-ray analyses were obtained by slowly evaporating the CH2-
Cl2/hexane solution of 17a at 4 °C. The crystals of complex
17a quickly eliminated the partly incorporated solvents when
taken out of the solvent phase, so the single crystal of complex
17a was sealed in a capillary tube. In 17a the methyl carbon
atoms of a tert-butyl group (C(26), C(27), and C(28)) were found
to be disordered. Satisfactory results were obtained when
C(26), C(27), and C(28) were given occupancy factors of 0.58
and C(26)′, C(27)′, and C(28)′ were given occupancy factors of
0.42. All intensity data were collected with a Bruker SMART
CCD diffractometer, using graphite-monochromated Mo KR
radiation (λ ) 0.71073 Å). The structures were resolved by
the direct method and refined by full-matrix least-squares on
F2. All non-hydrogen atoms were refined anisotropically. A
summary of the fundamental crystal data for complexes 3a ,
6b, 17a , and 19a is listed in Table 1.
(d, 18H, SnCH(CH3)2), 1.89 (m, 3H, SnCH(CH3)2), 2.38, 2.53
(s, s, 6H, 6H, 3 or 5-CH3), 5.96 (s, 2H, H4 of pyrazole ring),
6.36 (s, 1H, CH). IR (cm-1): 1997.8 s, 1882.3 s, 1854.6 s, 1823.6
s [ν (CO)]. Anal. Found: C, 38.35; H, 4.56; N, 7.83. Calcd for
C
24H36N4O4SnW: C, 38.58; H, 4.86; N, 7.50.
Rea ction s of 11 a n d 12 w ith W(CO)6. These reactions
were carried out in dioxane at reflux for 12 h to give
compounds 11a and 12a .
Rea ction s of 17 a n d 18 w ith W(CO)5THF to Give
tBu 2Sn CH(3,5-Me2P z)2W(CO)3P h (17a ) a n d tBu 2Sn CH-
(3,4,5-Me3P z)2W(CO)3P h (18a ). The same procedure was
followed as described above for the reactions of 1-5 with
W(CO)5THF, but the reaction time was 4 h. After recrystallized
from CH2Cl2/hexane, compounds 17a and 18a were obtained
as green-yellow crystals.
Sp ectr oscop ic Da ta for 17a . Yield: 53%. 1H NMR: δ 1.10
(s, 18H, C(CH3)3), 1.82, 2.46 (s, s, 6H, 6H, 3 or 5-CH3), 5.86 (s,
2H, H4 of pyrazole ring), 6.19 (s, 1H, CH), 6.85, 7.23 (m, m,
3H, 2H, C6H5). IR (cm-1): 1966.6 vs, 1878.1 vs, 1783.9 s [ν
(CO)]. Anal. Found: C, 42.83; H, 4.66; N, 6.84. Calcd for
C
28H38N4O3SnW: C, 43.05; H, 4.90; N, 7.17.
Sp ectr oscop ic Da ta for 18a . Yield: 48%. 1H NMR: δ 1.19
Ack n ow led gm en t. This work is supported by the
National Natural Science Foundation of China (No.
20172029) and State Key Laboratory of Elemento-
Organic Chemistry of Nankai University.
(s, 18H, C(CH3)3), 1.76, 1.85, 2.39 (s, s, s, 6H, 6H, 6H, 3, 4, or
5-CH3), 6.23 (s, 1H, CH), 6.86, 7.22 (m, m, 3H, 2H, C6H5). IR
(cm-1): 1959.1 s, 1861.1 s, 1781.6 s [ν (CO)]. Anal. Found: C,
44.23; H, 5.34; N, 7.04. Calcd for C30H42N4O3SnW: C, 44.52;
H, 5.23; N, 6.92.
Rea ction s of 19 a n d 20 w ith W(CO)5THF to Give (CH2d
CH)3Sn CH(3,5-Me2P z)2W(CO)3 (19a) an d (CH2dCH)3Sn CH-
(3,4,5-Me3P z)2W(CO)3 (20a ). The same procedure was fol-
lowed as described above for the reactions of 1-5 with
W(CO)5THF, but the reaction time was 12 h. After recrystal-
lization from CH2Cl2/hexane, compounds 19a and 20a were
obtained as orange-red crystals.
Su p p or tin g In for m a tion Ava ila ble: Table of crystal-
lographic data, atom coordinates, thermal parameters, and
bond distances and angles for 3a , 6b, 17a , and 19a . This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM030221O