Functionalized bis(pyrazol-1-yl)methanes by organotin halide on the methine carbon atom and their related reactions

Article abstract of DOI:10.1016/j.jorganchem.2008.01.041

The modification of bis(pyrazol-1-yl)methanes by organotin halide on the methine carbon atom has been successfully carried out, and their related reactions have also been studied. Bis(3,5-dimethylpyrazol-1-yl)(iododiphenylstannyl)methane [Ph₂ISnCH(3,5-Me₂Pz)₂] can be obtained by the selective cleavage of the Sn s(-) C_sp² bond in bis(3,5-dimethylpyrazol-1-yl)triphenylstannylmethane with I₂ in a 1:1 molar ratio, while {di(tert-butyl)chlorostannyl}bis(3,5-dimethylpyrazol-1-yl)methane [(t-Bu)₂ClSnCH(3,5-Me₂Pz)₂] and {di(tert-butyl)chlorostannyl}bis(3,4,5-trimethylpyrazol-1-yl)methane [(t-Bu)₂ClSnCH(3,4,5-Me₃Pz)₂] are easily prepared by the reaction of the bis(3,5-dimethylpyrazol-1-yl)methide or bis(3,4,5-trimethylpyrazol-1-yl)methide anion with di(tert-butyl)tin dichloride. The molecular structure of [(t-Bu)₂ClSnCH(3,5-Me₂Pz)₂] determined by X-ray structure analysis indicates that bis(3,5-dimethylpyrazol-1-yl)methide acts as a bidentate monoanionic κ²-[C,N] chelating ligand. Reaction of these bis(pyrazol-1-yl)methanes functionalized by organotin halide with W(CO)₅THF results in the oxidative addition of the relative electrophilic Sn-X (X = Cl or I) bond instead of the Sn s(-) C_sp³ bond to the tungsten(0) atom, yielding new metal-metal bonded complexes R₂SnCHPz₂W(CO)₃X (R = Ph or t-Bu, Pz represents substituted pyrazol-1-yl). Furthermore, treatment of the oxidative addition product (t-Bu)₂SnCH(3,5-Me₂Pz)₂W(CO)₃Cl with n-BuLi results in known complex CH₂(3,5-Me₂Pz)₂W(CO)₄ with the loss of the organotin fragment. In addition, reaction of Ph₂ISnCH(3,5-Me₂Pz)₂ with 2-PySNa (Py = pyridyl) leads to the replacement of iodide by 2-PyS^- anion to give Ph₂(2-PyS)SnCH(3,5-Me₂Pz)₂, which subsequently reacts with W(CO)₅THF to result in the decomposition of this ligand, also yielding the known bis(3,5-dimethylpyrazol-1-yl)methane derivative of CH₂(3,5-Me₂Pz)₂W(CO)₄.

Full text of DOI:10.1016/j.jorganchem.2008.01.041

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 1359–1366
www.elsevier.com/locate/jorganchem
Functionalized bis(pyrazol-1-yl)methanes by organotin halide
on the methine carbon atom and their related reactions
Zhen-Kang Wen, Yun-Fu Xie, Shu-Bin Zhao, Run-Yu Tan, Liang-Fu Tang *
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, People’s Republic of China
Received 14 November 2007; received in revised form 21 January 2008; accepted 24 January 2008
Available online 2 February 2008
Abstract
The modification of bis(pyrazol-1-yl)methanes by organotin halide on the methine carbon atom has been successfully carried out, and
their related reactions have also been studied. Bis(3,5-dimethylpyrazol-1-yl)(iododiphenylstannyl)methane [Ph2ISnCH(3,5-Me2Pz)2] can
be obtained by the selective cleavage of the Sn–Csp2 bond in bis(3,5-dimethylpyrazol-1-yl)triphenylstannylmethane with I2 in a 1:1 molar
ratio, while {di(tert-butyl)chlorostannyl}bis(3,5-dimethylpyrazol-1-yl)methane [(t-Bu)2ClSnCH(3,5-Me2Pz)2] and {di(tert-butyl)chloro-
stannyl}bis(3,4,5-trimethylpyrazol-1-yl)methane [(t-Bu)2ClSnCH(3,4,5-Me3Pz)2] are easily prepared by the reaction of the bis(3,5-dim-
ethylpyrazol-1-yl)methide or bis(3,4,5-trimethylpyrazol-1-yl)methide anion with di(tert-butyl)tin dichloride. The molecular structure
of [(t-Bu)2ClSnCH(3,5-Me2Pz)2] determined by X-ray structure analysis indicates that bis(3,5-dimethylpyrazol-1-yl)methide acts as a
bidentate monoanionic j2-[C,N] chelating ligand. Reaction of these bis(pyrazol-1-yl)methanes functionalized by organotin halide with
W(CO)5THF results in the oxidative addition of the relative electrophilic Sn–X (X = Cl or I) bond instead of the Sn–Csp3 bond to
the tungsten(0) atom, yielding new metal–metal bonded complexes R2SnCHPz2W(CO)3X (R = Ph or t-Bu, Pz represents substituted pyr-
azol-1-yl). Furthermore, treatment of the oxidative addition product (t-Bu)2SnCH(3,5-Me2Pz)2W(CO)3Cl with n-BuLi results in known
complex CH2(3,5-Me2Pz)2W(CO)4 with the loss of the organotin fragment. In addition, reaction of Ph2ISnCH(3,5-Me2Pz)2 with
2-PySNa (Py = pyridyl) leads to the replacement of iodide by 2-PySꢀ anion to give Ph2(2-PyS)SnCH(3,5-Me2Pz)2, which subsequently
reacts with W(CO)5THF to result in the decomposition of this ligand, also yielding the known bis(3,5-dimethylpyrazol-1-yl)methane
derivative of CH2(3,5-Me2Pz)2W(CO)4.
Ó 2008 Elsevier B.V. All rights reserved.
Keywords: Bis(pyrazol-1-yl)methane; Organotin halide; Tungsten carbonyl; Oxidative addition
1. Introduction
ing heteroscorpionate ligands usually have N2O [4], N2S
[5] or N2N0 [6] coordination environments, which render
them the potential to form novel complexes with various
main group and transition metals. In addition, the modifi-
cation of bis(pyrazol-1-yl)methane by organometallic
groups has also successfully broadened the scope of the
application of these novel ligands [7]. Our recent investiga-
tions on bis(pyrazol-1-yl)methane indicate that the modifi-
cation of this ligand with organotin groups on the methine
carbon atom can provide unusual reactivity [8]. For exam-
ple, the reaction of bis(pyrazol-1-yl)(triarylstannyl)meth-
ane with W(CO)5THF results in the oxidative addition of
the Sn–Csp3 bond to the tungsten(0) atom to give novel
four-membered metallacyclic complex, while the analogous
Poly(pyrazol-1-yl)alkanes, such as tris(pyrazol-1-
yl)methane [1] and bis(pyrazol-1-yl)methane [2], have been
performing as one of the most popular nitrogen-containing
donor ligands in recent years. Their coordination chemistry
towards main group and transition metals has been widely
exploited. Furthermore, the modification of poly(pyrazol-
1-yl)methanes by organic functional groups on the bridging
carbon atom to form novel heteroscorpionate ligands is
currently drawing extensive attention [1–3]. These intrigu-
*
Corresponding author. Fax: +86 22 23502458.
E-mail address: lftang@nankai.edu.cn (L.-F. Tang).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.01.041

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Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
reaction of bis(pyrazol-1-yl)(trialkylstannyl)methane with
W(CO)5THF does not take place [8b]. Furthermore, the
similar reaction of {di(tert-butyl)phenylstannyl}bis(pyra-
zol-1-yl)methane results in the oxidative addition of the
Sn–Csp2 bond to the tungsten(0) center [8b]. To gain further
understanding of the influence of the nature of substitu-
tions on the tin atom on the reaction, in this paper we have
synthesized bis(pyrazol-1-yl)methanes modified by organo-
tin halide on the methine carbon, and studied their related
reactivities.
2. Results and discussion
2.1. Modification of bis(pyrazol-1-yl)methanes with
organotin halide
Bis(3,5-dimethylpyrazol-1-yl)(iododiphenylstannyl)meth-
ane (1) is prepared by the selective cleavage of the Sn–Csp2
bond in bis(3,5-dimethylpyrazol-1-yl)triphenylstannylme-
thane with I2 in a 1:1 molar ratio at room temperature
in good yield (Scheme 1). Whereas {di(tert-butyl)chloro-
stannyl}bis(3,5-dimethylpyrazol-1-yl)methane (2) and {di-
(tert-butyl)chlorostannyl}bis(3,4,5-trimethylpyrazol-1-yl)
methane (3) can be easily obtained by the reaction of the
bis(3,5-dimethylpyrazol-1-yl)methide or bis(3,4,5-trimethyl-
pyrazol-1-yl)methide anion with di(tert-butyl)tin dichlo-
ride, attributed to the steric hindrance around the tin atom
preventing the replacement of another chloride.
Fig. 1. The molecular structure of 2. The thermal ellipsoids are drawn at
the 30% probability level. Selected bond distances (A) and angles (°):
˚
Sn(1)–C(6) 2.196(3), Sn(1)–C(16) 2.175(4), Sn(1)–Cl(1) 2.445(1), Sn(1)–
˚
N(1) 2.572(3), N(2)–C(6) 1.443(4), N(3)–C(6) 1.446(4) A; N(1)–Sn(1)–
Cl(1) 149.80(7), C(12)–Sn(1)–C(6) 111.7(1), C(6)–Sn(1)–N(1) 58.9(1),
N(2)–C(6)–N(3) 111.8(3), N(2)–C(6)–Sn(1) 99.7(1); N(1)–Sn(1)–C(6)–
N(2) 4.5(1), Sn(1)–N(1)–N(2)–C(6) 6.7(3)°.
Ligands 1–3 have been characterized by elemental anal-
yses and NMR spectra, and the structure of 2 is further
confirmed by X-ray structural analysis. The molecular
structure of 2 is presented in Fig. 1, which shows that the
bis(3,5-dimethylpyrazol-1-yl)methide anion is a bidentate
j2-[C,N] chelating ligand, which coordinates to the tin
atom by only one nitrogen atom and the carbon atom to
form a new four-membered heterometallacycle. The tin
atom adopts a five-coordinate markedly distorted trigonal
bipyramidal geometry with the N(1) and Cl(1) atoms
occupying the axial positions, and the axial angle of
N(1)–Sn(1)–Cl(1) is 149.80(7)°. The Sn–N bond distance
˚
is 2.572(3) A, slightly longer than those in other triorgano-
tin complexes with a bidentate j2-[C,N] chelating ligand
˚
˚
(such as 2.4899(14) A in LSnMe2F [9], 2.519 A in
LSnPh2Cl [10], L = 2-(N,N-dimethylaminomethyl)phenyl),
but markedly shorter than those in bulky di(tert-butyl)tin
˚
chloride derivatives (such as 2.904(14) A in LSn(t-Bu)2Cl
[11]). It is also worthy of note that although two different
pyrazole rings exist in solid, only one set of NMR signals
for the bis(pyrazol-1-yl)methide group is observed in solu-
tion, possibly as the result of the fast exchange in the coor-
dination behavior of two pyrazole ligands on the NMR
time scale. This type of fast exchange has already been
extensively observed for other poly(pyrazol-1-yl)methane
complexes [4c,5d,12].
2.2. Reaction of ligands 1–3 with W(CO)5THF
The oxidative addition of the tin(IV)–halogen bond to
low-valent group 6 metals to give heterobimetallic M–Sn
complexes has been well-established [13]. Furthermore,
the reactivity of the tin(IV)–halogen bond in RnSnX4ꢀn
(R = alkyl or aryl, n = 0–3) markedly decreases with the
increasing of the number of the organic substituents, which
leads to the increasing of the electron density on the tin
atom [14]. Thus, the oxidative addition reaction of the
Sn–X bond in triorganotin halide is rare. Combined
with our previous works [8], ligands 1–3 possibly have
Scheme 1. Modification of bis(pyrazol-1-yl)methane by organotin halide.

Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
1361
two different reactivity patterns with W(CO)5THF, namely
the oxidative addition of the Sn–X (X = Cl or I) bond or
the Sn–Csp3 bond to the tungsten(0) atom. To confirm the
reaction modes, ligands 1–3 are treated with W(CO)5THF
under the similar experimental conditions as the reaction of
bis(3,5-dimethylpyrazol-1-yl)(triarylstannyl)methane with
W(CO)5(THF) [8b], and only the oxidative addition of
the Sn–X bond is observed instead of the Sn–Csp3 bond
to the tungsten(0) atom to yield complexes 4–6 (Scheme
2), possibly owing to the higher electrophilic nature of
the Sn–X bond compared to the Sn–Csp3 bond. Further-
more, this reaction is markedly different from the reaction
of Ph2ClSnSCH(3,5-Me2Pz)2 with W(CO)5THF [5d]. The
latter yields pyrazole derivative of (3,5-Me2PzH)W(CO)5
with the decomposition of the ligand and no oxidative
addition product of the Sn–Cl or Sn–S bond to the tung-
sten atom is obtained.
Complexes 4–6 have been characterized by IR and
NMR spectra as well as elemental analyses, and the struc-
tures of complexes 4 and 5 are further confirmed by X-ray
structural analyses. Their IR spectra show one significant
low-frequency absorption band of m (CO) at 1787 cmꢀ1
for 4, 1773 cmꢀ1 for 5 and 1774 cmꢀ1 for 6, implying that
the semibridging carbonyl probably exists, consistent with
the results of their X-ray structural analyses. The 13C signal
of the CH group in complexes slightly shifts to the higher
field than that in the corresponding ligands. In addition,
the 119Sn NMR signals of complexes also markedly down-
field shift than those in the corresponding ligands, indicat-
ing that the chemical environment around the tin atom is
significantly changed. These NMR spectral data support
the conclusion that the oxidative addition of the Sn–X
bond has taken place.
Fig. 2. The molecular structure of 4. The thermal ellipsoids are drawn at
the 30% probability level. Selected bond distances (A) and angles (°):
˚
W(1)–Sn(1) 2.839(1), W(1)–I(1) 2.8576(8), Sn(1)–C(14) 2.221(7),
Sn(1)ꢁ ꢁ ꢁC(1) 2.538(7), W(1)–C(1) 1.944(8), W(1)–C(2) 1.971(8), W(1)–
N(1) 2.274(6), W(1)–N(4) 2.276(5), C(1)–O(1) 1.170(8), C(2)–O(2)
˚
1.142(8) A; N(1)–W(1)–N(4) 83.6(2), C(1)–W(1)–Sn(1) 60.7(2), C(3)–
W(1)–Sn(1) 121.4(2), C(1)–W(1)–I(1) 147.7(2), Sn(1)–W(1)–I(1)
151.52(2), C(14)–Sn(1)–W(1) 79.3(1), N(2)–C(14)–N(3) 111.5(6), O(1)–
C(1)–W(1) 170.9(7), O(2)–C(2)–W(1) 176.5(7)°.
bridging carbonyl between the W–Sn bond is observed in
these complexes. Their structural parameters are also very
analogous (Table 1), such as similar Snꢁ ꢁ ꢁC distance. Com-
plex 5 has a slightly longer W–Sn distance than complex 4,
and longer values than the reported cyclopentadienyl het-
erobimetallic derivatives with the W–Sn bond (such as
The crystal structures of 4 and 5 are presented in Figs. 2
and 3, respectively. Their molecular fundamental
frameworks are similar, and analogous to those in
Ph2SnCH(3,5-Me2Pz)2(CO)3WCl [15] and (t-Bu)2SnCH(3,5-
Me2Pz)2W(CO)3(Ph) [8b]. For example, a novel j3-[N,Sn,
N] coordination mode as well as an unsymmetrically semi-
˚
2.7681(8) A in Cp2HWSnCl(t-Bu)2) [16].
2.3. Reaction of complex 5 with n-BuLi
The alkylation reaction of organometal halide with
alkyllithium has been widely used to synthesize alkyl metal
complexes with catalytic activities. Herein, treatment of 5
with n-BuLi leads to the known complex CH2(3,5-
Me2Pz)2W(CO)4 [17] with the loss of the organotin frag-
ment. Although the mechanism is unclear at present, the
formation of this complex should be partially attributed
to the reductivity of n-BuLi as well as the strong Lewis
acidity of the tungsten atom in complex 5, led by the large
electronegative chlorine. In addition, one carbonyl group
in this complex should origin from absorbing the CO
sourced from the decomposition of some of complex 5.
2.4. Reaction of ligand 1 with 2-PySNa (Py = pyridyl)
To investigate the reactivity of the Sn–X bond with
other nucleophiles and obtain polyfunctional bis(pyrazol-
Scheme 2. Reaction of functionalized bis(pyrazol-1-yl)methane with
W(CO)5THF.

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Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
Scheme 3. Synthesis and reaction of Ph2(2-PyS)SnCH(3,5-Me2Pz)2.
position of this ligand, and no product of oxidative addi-
tion to the tungsten atom is observed.
In summary, bis(pyrazol-1-yl)methanes functionalized
by organotin halide on the methine carbon atom can easily
be obtained. Treatment of these ligands with W(CO)5THF
results in the oxidative addition of the Sn–X (X = Cl or I)
bond with relative high electrophilic nature to the tung-
sten(0) atom, instead of the Sn–Csp2 or Sn–Csp3 bond. Com-
bined with our previous works [8], the suggestion is made
that the electronic effect of the substituents on the tin atom
plays the major role in the oxidative addition reactions of
functionalized bis(pyrazol-1-yl)methanes with W(CO)5-
THF. For example, the relative electronegative substituents
on the tin atom such as halogen or aryl groups are favor of
the oxidative addition reactions. Furthermore, the ligands
are inclined to decomposition in the reactions of bis(pyra-
zol-1-yl)methanes modified by organotin groups with het-
eroatom on the bridge with W(CO)5THF [5d]. In
addition, preliminary investigations show that treatment
of the oxidative addition product with n-BuLi leads to
the loss of the organotin fragment.
Fig. 3. The molecular structure of 5. The thermal ellipsoids are drawn at
the 30% probability level. Selected bond distances (A) and angles (°):
W(1)–Sn(1) 2.8865(5), W(1)–Cl(1) 2.514(1), W(1)–N(2) 2.268(4), W(1)–
˚
N(4) 2.269(4), W(1)–C(1) 1.941(6), Sn(1)–C(4) 2.204(5), Sn(1)ꢁ ꢁ ꢁC(1)
˚
2.484(6), C(1)–O(1) 1.175(7), N(3)–C(4) 1.455(5), N(1)–C(4) 1.445(5) A;
N(2)–W(1)–N(4) 80.5(1), C(3)–W(1)–N(4) 168.9(2), Cl(1)–W(1)–Sn(1)
152.84(3), C(4)–Sn(1)–W(1) 78.6(1), C(4)–Sn(1)–C(1) 120.0(1), O(1)–
C(1)–W(1) 171.1(5), N(1)–C(4)–N(3) 109.5(3), C(17)–C(15)–C(18)
113.5(7)°.
1-yl)methane ligands, the reaction of ligand 1 with 2-
PySNa (Py = pyridyl) has been carried out, which yields
ligand 7 in good yield (Scheme 3). This ligand has also been
characterized by NMR spectra and X-ray single crystal dif-
fraction. Its 119Sn NMR signal in CDCl3 occurs at
ꢀ156.6 ppm, markedly shifts to the lower field than that
in 1 (ꢀ193 ppm). The crystal structure of 7, presented in
Fig. 4, shows that the tin atom is four-coordinate with a
distorted tetrahedral geometry. The pyridyl and pyrazolyl
nitrogen atoms as well as sulfur atom do not coordinate
to the tin atom. This ligand is expected to act as an unsym-
metric multidentate N,N,S or N,N,N0 ligand for other
metal atoms. In addition, the oxidative addition of the
Sn–S bond to low-oxidative transition-metal complexes is
also observed [18]. However, upon treatment of 7 with
W(CO)5(THF) under similar experimental conditions as
the reaction of 1 with W(CO)5(THF), only known complex
CH2(3,5-Me2Pz)2W(CO)4 [17] is isolated with the decom-
3. Experimental
All reactions were carried out under an atmosphere of
argon. Solvents were dried and distilled prior to use
according to standard procedures. NMR spectra were
recorded on a Bruker AV300 or Mercury 300BB spectrom-
eter using CDCl3 as solvent unless otherwise noted, and the
chemical shifts were reported in ppm with respect to the
reference (internal SiMe4 for 1H NMR and 13C NMR spec-
Table 1
Comparison of some key bond distances (A) and angles (°) in semibridging carbonyl complexes
˚
Complex
W–Sn
Snꢁ ꢁ ꢁC
Sn–Csp3
N–W–N
W–C–O
W–Sn–Csp3
Ref.
Ph2SnCHPz2W(CO)3I (4)
(t-Bu)2SnCHPz2W(CO)3Cl (5)
Ph2SnCHPz2W(CO)3Cl
2.839(1)
2.538(7)
2.484(6)
2.527(4)
2.541(11)
2.221(7)
2.204(5)
2.204(4)
2.237(9)
83.6(2)
80.5(1)
82.5(1)
81.5(2)
170.9(7)
171.1(5)
170.9(4)
167.8(8)
79.3(1)
78.6(1)
79.2(1)
78.2(2)
This work
This work
[15]
2.8865(5)
2.8547(9)
2.8778(12)
(t-Bu)2SnCHPz2W(CO)3Ph
[8b]

Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
1363
solution of n-BuLi (2.5 M, 0.80 ml) at ꢀ70 °C, and the mix-
ture was stirred for 1 h at that temperature. To this mixture
was added a solution of di(tert-butyl)tin chloride (0.76 g,
2.5 mmol) in THF (10 ml). The reaction mixture was stir-
red at ꢀ70 °C for 1.5 h, and allowed to slowly approach
room temperature and stirred overnight. The solvent was
removed under a reduced pressure, and the residual solid
was recrystallized from hot hexane to yield 0.60 g (64%)
1
of 2 as white crystals, mp 140–142 °C. H NMR: d 1.29
(s, 18H, (CH3)3C), 2.09, 2.10 (s, s, 6H, 6H, CH3), 5.75 (s,
2H, H4 of pyrazole ring), 6.06 (s, 1H, CH). 13C NMR: d
11.0, 13.5 (3 or 5-CH3), 30.4 ((CH3)3C), 38.2 ((CH3)3C),
72.8 (CH), 107.0 (4-position carbon of pyrazole ring),
139.9, 147.3 (3 or 5-position carbon of pyrazole ring).
119Sn NMR: d ꢀ69.9. Anal. Calc. for C19H33ClN4Sn: C,
48.38; H, 7.05; N, 11.88. Found: C, 48.26; H, 7.35; N,
11.65%.
3.3. Synthesis of (t-Bu)2ClSnCH(3,4,5-Me3Pz)2 (3)
Fig. 4. The molecular structure of 7. The thermal ellipsoids are drawn at
˚
This ligand was obtained similarly using bis(3,4,5-trim-
ethylpyrazol-1-yl)methane (0.47 g, 2.0 mmol) instead of
bis(3,5-dimethylpyrazol-1-yl)methane as described above
for 2. Yield: 0.49 g (49%), white crystals, mp 141–143 °C.
1H NMR: d 1.28 (s, 18H, (CH3)3C), 1.80, 2.00, 2.03 (s, s,
s, 6H, 6H, 6H, CH3), 6.08 (s, 1H, CH). 13C NMR: d 7.2,
8.5, 10.9 (3, 4 or 5-CH3), 29.4 ((CH3)3C), 36.9 ((CH3)3C),
72.3 (CH), 112.1 (4-position carbon of pyrazole ring),
135.1, 145.0 (3 or 5-position carbon of pyrazole ring).
119Sn NMR: d ꢀ72.8. Anal. Calc. for C21H37ClN4Sn: C,
50.47; H, 7.46; N, 11.21. Found: C, 50.25; H, 7.26; N,
11.01%.
the 30% probability level. Selected bond distances (A) and angles (°):
Sn(1)–C(1) 2.215(5), Sn(1)–S(1) 2.481(1), Sn(1)–C(12) 2.149(5), Sn(1)–
C(18) 2.162(5), S(1)–C(24) 1.766(5), N(1)–C(1) 1.430(6), N(3)–C(1)
1.458(6) A; C(12)–Sn(1)–C(18) 105.5(1), C(12)–Sn(1)–C(1) 122.5(1),
˚
C(24)–S(1)–Sn(1) 96.1(1), N(1)–C(1)–N(3) 113.7(4)°.
tra, external SnMe4 for 119Sn NMR). IR spectra were
recorded as KBr pellets on a Bruker Equinox55 spectrom-
eter. Element analyses were carried out on an Elementar
Vairo EL analyzer. Ph3SnCH(3,5-Me2Pz)2 [8b] and
(t-Bu)2SnCl2 [19] were prepared according to the literature
methods. Melting points were measured with an X-4 digital
micro melting-point apparatus and were uncorrected.
3.4. Reaction of ligands 1–3 with W(CO)5THF
3.1. Synthesis of Ph2ISnCH(3,5-Me2Pz)2 (1)
Ligand (0.3 mmol) was added to a solution of
W(CO)5THF in THF, prepared in situ by the 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
5 h. Then, the solvent was removed under a reduced pres-
sure, and the residual solid was purified by column chro-
matography on silica using CH2Cl2/hexane (3/1 v/v) as
eluent. The eluate was concentrated to dryness again, and
the residual solid was recrystallized from CH2Cl2/hexane
to give green-yellow crystals.
A solution of I2 (0.51 g, 2.0 mmol) in CHCl3 (40 ml) was
dropwise added to a stirred solution of Ph3SnCH(3,5-
Me2Pz)2 (1.11 g, 2.00 mmol) in CHCl3 (30 ml) at 10 °C.
After addition completed, the reaction mixture was contin-
uously stirred for 1 h at room temperature. The solvent was
removed under a reduced pressure, and the residual solid
was recrystallized from hot hexane to yield 0.91 g (75%)
1
of 1 as white crystals, mp 164–166 °C. H NMR: d 2.09,
2.11 (s, s, 6H, 6H, CH3), 5.80 (s, 2H, H4 of pyrazole ring),
6.34 (s, 1H, CH), 7.26–7.34, 7.78–7.82 (m, m, 6H, 4H,
C6H5). 13C NMR: d 11.2, 13.4 (3 or 5-CH3), 75.4 (CH),
107.6 (4-position carbon of pyrazole ring), 128.4, 129.4,
136.3, 140.6 (C6H5), 139.9, 145.0 (3 or 5-position carbon
of pyrazole ring). 119Sn NMR: d ꢀ193.0. Anal. Calc. for
C23H25IN4Sn: C, 45.81; H, 4.18; N, 9.29. Found: C,
45.78; H, 4.32; N, 9.56%.
3.4.1. Ph2SnCH(3,5-Me2Pz)2W(CO)3I (4)
This complex was obtained by the reaction of ligand 1
with W(CO)5THF. The reaction mixture was stirred and
heated at reflux for 3 h. Yield: 45%. 1H NMR: d 2.31,
2.69 (s, s, 6H, 6H, CH3), 5.91 (s, 2H, H4 of pyrazole ring),
6.27 (s, 1H, CH), 7.04–7.06, 7.25–7.30 (m, m, 4H, 6H,
C6H5). 119Sn NMR (DMSO-d6): d ꢀ207.3. IR (cmꢀ1):
3.2. Synthesis of (t-Bu)2ClSnCH(3,5-Me2Pz)2 (2)
m
CO = 1985 (vs), 1892 (vs), 1787 (s). Anal. Calc. for
C26H25IN4O3SnW: C, 35.85; H, 2.89; N, 6.43. Found: C,
35.75; H, 2.78; N, 6.59%.
To a solution of bis(3,5-dimethylpyrazol-1-yl)methane
(0.41 g, 2.0 mmol) in THF (40 ml) was added a hexane

1364
Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
3.4.2. (t-Bu)2SnCH(3,5-Me2Pz)2W(CO)3Cl (5)
This complex was obtained by the reaction of ligand 2
with W(CO)5THF. Yield: 45%. H NMR: d 1.09 (s, 18H,
3.5. Reaction of complex 5 with n-BuLi
1
To a solution of 5 (85.0 mg, 0.115 mmol) in THF (10 ml)
was added a hexane solution of n-BuLi (2.5 M, 0.050 ml) at
ꢀ50 °C. The mixture was stirred for 0.5 h at that tempera-
ture, and allowed to slowly reach room temperature and
stirred for 2 h. After the solvent was removed under a
reduced pressure, the residual solid was purified by column
chromatography on silica using CH2Cl2 as eluent. The elu-
ate was concentrated to dryness again, and the residual
solid was recrystallized from CH2Cl2/hexane to give
green-yellow crystals, which was identified as complex
(CH3)3C), 2.43, 2.70 (s, s, 6H, 6H, CH3), 6.00 (s, 2H, H4
of pyrazole ring), 6.08 (s, 1H, CH). 13C NMR: d 12.9,
16.8 (3 or 5-CH3), 31.6 ((CH3)3C), 36.9 ((CH3)3C), 61.6
(CH), 109.3 (4-position carbon of pyrazole ring), 139.0,
156.0 (3 or 5-position carbon of pyrazole ring), 214.3
(CO). Only one signal of carbonyl carbon was observed
possibly due to the low signal intensity and the limited sol-
ubility of 5. 119Sn NMR: d ꢀ72.6. IR (KBr, cmꢀ1):
m
m
CO = 1974 (vs), 1891 (vs), 1773 (s); (CH2Cl2, cmꢀ1):
CO = 1989 (vs), 1898 (vs), 1786 (s). Anal. Calc. for
1
CH2(3,5-Me2Pz)2W(CO)4 according to its H NMR and
1
C22H33ClN4O3SnW: C, 35.73; H, 4.50; N, 7.58. Found:
C, 35.56; H, 4.29; N, 7.69%.
IR spectra. Yield: 12%. H NMR: d 2.42, 2.48 (s, s, 6H,
6H, CH3), 6.01 (m, 3H, H4 of pyrazole ring and one of
hydrogen of CH2), 6.39 (d, J = 14.7 Hz, 1H, one of hydro-
gen of CH2). IR (cmꢀ1): mCO = 2002 (s), 1876 (vs), 1852
(vs), 1829 (vs).
3.4.3. (t-Bu)2SnCH(3,4,5-Me3Pz)2W(CO)3Cl (6)
This complex was obtained by the reaction of ligand 3
1
with W(CO)5THF. Yield: 40%. H NMR: d 1.08 (s, 18H,
(CH3)3C), 1.92, 2.31, 2.58 (s, s, s, 6H, 6H, 6H, CH3),
6.15 (s, 1H, CH). 13C NMR: d 8.5, 10.7, 14.0 (3, 4 or 5-
CH3), 31.4 ((CH3)3C), 36.2 ((CH3)3C), 61.6 (CH), 115.1
(4-position carbon of pyrazole ring), 135.8, 153.9 (3 or 5-
position carbon of pyrazole ring), 214.6 (CO). Only one
signal of carbonyl carbon was observed possibly due to
the low signal intensity and the limited solubility of 6.
119Sn NMR: d ꢀ65.5. IR (KBr, cmꢀ1): mCO = 1983 (vs),
1894 (vs), 1868 (sh), 1774 (s); (CH2Cl2, cmꢀ1):
3.6. Reaction of 1 with 2-PySNa (Py = pyridyl)
NaH (8.0 mg, 0.33 mmol) was added to a solution of 2-
pyridinethiol (37 mg, 0.33 mmol) in benzene (10 ml) at
room temperature. The reaction mixture was stirred for
2 h, and then a solution of 1 (0.20 g, 0.33 mmol) in benzene
(10 ml) was added to the above solution. The reaction mix-
ture was stirred overnight at room temperature, and fil-
tered off. The solvent was removed under a reduced
pressure, and the residual solid was recrystallized from
hot hexane to give 0.11 g (57%) of 7 as pale yellow crystals,
mp 146–148 °C. 1H NMR: d 1.81, 2.07 (s, s, 6 H, 6H, CH3),
m
CO = 1987 (vs), 1895 (vs), 1782 (s). Anal. Calc. for
C24H37ClN4O3SnW: C, 37.55; H, 4.86; N, 7.30. Found:
C, 37.61; H, 4.78; N, 7.39%.
Table 2
Crystallographic data and refinement parameters for compounds 2, 4, 5 and 7
Compound
2
4
5
7
Formula
C
471.63
0.30 ꢂ 0.26 ꢂ 0.18
Monoclinic
P21/c
19H33ClN4Sn
C26H25IN4O3SnW
870.94
0.20 ꢂ 0.16 ꢂ 0.12
Monoclinic
P21/n
C22H33ClN4O3SnW
739.51
0.22 ꢂ 0.20 ꢂ 0.14
Monoclinic
P21/n
C28H29N5SSn
586.31
Formula weight
Crystal size (mm)
Crystal system
Space group
0.24 ꢂ 0.20 ꢂ 0.14
Triclinic
ꢀ
P1
Cell parameters
˚
a (A)
10.476(1)
24.089(4)
10.405(1)
90
116.130(2)
90
10.319(3)
16.716(5)
16.115(5)
90
90.633(5)
90
9.787(1)
17.206(1)
16.281(1)
90
102.272(2)
90
8.543(3)
12.136(4)
13.568(4)
85.751(6)
83.467(6)
81.616(6)
1380.3(8)
2
˚
b (A)
˚
c (A)
a (°)
b (°)
c (°)
3
˚
V (A )
2357.4(6)
4
2779.6(14)
4
2679.1(5)
4
Z
T (K)
294(2)
1.329
3.38–52.76
968
293(2)
2.081
3.52–52.94
1640
294(2)
1.833
3.48–52.74
1432
293(2)
1.411
3.02–52.96
596
1.026
Dcalc (g cmꢀ3
2h Range (°)
F(000)
)
l (mmꢀ1
)
1.206
6.178
5.351
Number of reflections measured
13148
15898
14918
8027
Number of reflections observed [Rint
Number of reflections observed with (I P 2r(I))
Number of parameters
]
4805 [0.0341]
3416
236
5705 [0.0541]
3981
329
5453 [0.0434]
4096
299
5635 [0.0379]
3986
320
Residuals R, Rw (I P 2r(I))
Goodness-of-fit
0.032, 0.068
0.988
0.036, 0.051
1.033
0.030, 0.059
1.033
0.046, 0.086
1.022

Z.-K. Wen et al. / Journal of Organometallic Chemistry 693 (2008) 1359–1366
1365
5.68 (s, 2H, H4 of pyrazole ring), 6.73 (s, 1H, CH), 6.66 (m,
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1H, C5H4N), 7.17–7.30, 7.71–7.84 (m, m, 7H, 6H, C6H5
and C5H4N). 13C NMR: d 10.7, 13.4 (3 or 5-CH3), 74.5
(CH), 107.1 (4-position carbon of pyrazole ring), 118.1,
124.4, 128.0, 128.5, 135.8, 136.3, 136.6, 139.3, 143.5,
147.1, 147.7 (C6H5, C5H4N and 3 or 5-position carbon of
pyrazole ring). 119Sn NMR: d ꢀ156.6. Anal. Calc. for
C28H29N5SSn: C, 57.36; H, 4.99; N, 11.94. Found: C,
57.64; H, 5.35; N, 11.78%.
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(g) G.A. Santillan, C.J. Carrano, Inorg. Chem. 46 (2007) 1751;
This reaction was carried out similarly using 7 instead of 1
as described above for 4. After the reaction completed, the
reaction mixture was isolated by column chromatography
on silica using CH2Cl2 as eluent. The eluate was concen-
trated to dryness again, and the residual solid was recrystal-
lized from CH2Cl2/hexane to give green-yellow crystals,
which was identified as complex CH2(3,5-Me2Pz)2W(CO)4
according to its 1H NMR and IR spectra. Yield: 10%.
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(h) A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
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3.8. X-ray crystallography
Colorless crystals of 2 as well as pale yellow crystals of 7
suitable for X-ray analysis were obtained by slow cooling
their hot hexane solutions. While green-yellow crystals of
4 and 5 suitable for X-ray analysis were grown by slow dif-
fusion of hexane into their CH2Cl2 solutions at ꢀ10 °C. All
intensity data were collected with a Bruker SMART CCD
diffractometer, using graphite monochromated Mo Ka
(d) J.T. Hoffman, Ba.L. Tran, C.J. Carrano, Dalton Trans. (2006)
3822;
(e) F. Mohr, E. Cerrada, M. Laguna, Dalton Trans. (2006) 5567;
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(h) E.T. Papish, M.T. Taylor, F.E. Jernigan III, M.J. Rodig, R.R.
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(i) S. Milione, V. Bertolasi, T. Cuenca, A. Grassi, Organometallics 24
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(j) M. Porchia, G. Papini, C. Santini, G.G. Lobbia, M. Pellei, F.
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radiation (k = 0.71073 A). The structures were resolved
by the direct method and refined by full-matrix least-
squares on F2. All non-hydrogen atoms were refined aniso-
tropically. A summary of the fundamental crystal data for
these complexes is listed in Table 2.
(l) I. Hegelmann, N. Burzlaff, Eur. J. Inorg. Chem. (2003) 409;
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(m) A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
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Acknowledgements
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3304;
This work is supported by the National Natural Science
Foundation of China (Nos. 20672059 and 20421202) and
the Ministry of Education of China (NCET-04-0227).
´
(b) A. Otero, J. Fernandez-Baeza, A. Antinolo, F. Carrillo-Hermo-
silla, J. Tejeda, A. Lara-Sanchez, L. Sanchez-Barba, M. Fernandez-
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Lopez, A.M. Rodrıguez, I. Lopez-Solera, Inorg. Chem. 41 (2002)
Appendix A. Supplementary material
5193;
´
(c) A. Otero, J. Fernandez-Baeza, A. Antinolo, J. Tejeda, A. Lara-
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´
´
´
´
Sanchez, L. Sanchez-Barba, M. Sanchez-Molina, S. Franco, I.
CCDC 666272, 666273, 666274 and 666275 contain the
supplementary crystallographic data for 2, 4, 5 and 7.
These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.a-
c.uk/data_request/cif. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.jorganchem.2008.01.041.
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