Functionalized bis(1-methylimidazol-2-yl)methane and 1-(1-methylimidazol-2- yl)methyl-3,5-dimethylpyrazole and their reactions

Article abstract of DOI:10.1016/j.jorganchem.2014.01.021

Bis(1-methylimidazol-2-yl)methane and 1-(1-methylimidazol-2-yl)methyl-3,5- dimethylpyrazole [CH₂(min)(pz)] could be deprotonated with n-BuLi at the bridging carbon atom. The corresponding anions were inactive in the reaction with Ph₃SnCl but reacted with sulfur, followed by reaction with Ph₂SnCl₂ to give organotin derivatives Ph ₂ClSnSCH(min)₂ (1) and Ph₂ClSnSCH(min)(pz) (4) (min = 1-methylimidazol-2-yl and pz = 3,5-dimethylpyrazol-1-yl, respectively). The structure of 1 determined by X-ray structural analyses indicated that bis(1-methylimidazol-2-yl)methylthiolate acted as a bidentate monoanionic κ²-[N,S] chelating ligand. Reaction of 1 with W(CO) ₅THF yielded heterobimetallic complex Ph₂ClSnSCH(min) ₂W(CO)₅ (2), while similar reaction of 4 with W(CO) ₅THF resulted in the decomposition of 4 to give pyrazole derivative W(CO)₅(pzH). The structure of 2 has been confirmed by X-ray structural analyses, showing that 1 coordinated to the tungsten atom through the free nitrogen atom. Reaction of CH₂(min)(pz) with W(CO) ₅THF yielded bidentate chelating complex CH₂(min)(pz)W(CO) ₄, which when treated with n-BuLi, followed by reaction with Ph ₃SnCl, gave the final product CH₂(minSnPh ₃)(pz)W(CO)₄.

Full text of DOI:10.1016/j.jorganchem.2014.01.021

Journal of Organometallic Chemistry 757 (2014) 8e13
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Functionalized bis(1-methylimidazol-2-yl)methane and
1-(1-methylimidazol-2-yl)methyl-3,5-dimethylpyrazole and
their reactions
*
Hai-Jun Li, Xia-Li Liu, Ke Ding, Hai-Bin Song, Liang-Fu Tang
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Collaborative Innovation Center of Chemical Science and
Engineering (Tianjin), Tianjin 300071, People’s Republic of China
a r t i c l e i n f o
a b s t r a c t
Article history:
Bis(1-methylimidazol-2-yl)methane
and
1-(1-methylimidazol-2-yl)methyl-3,5-dimethylpyrazole
Received 20 November 2013
Received in revised form
9 January 2014
[CH2(min)(pz)] could be deprotonated with n-BuLi at the bridging carbon atom. The corresponding
anions were inactive in the reaction with Ph3SnCl but reacted with sulfur, followed by reaction with
Ph2SnCl2 to give organotin derivatives Ph2ClSnSCH(min)2 (1) and Ph2ClSnSCH(min)(pz) (4) (min ¼ 1-
methylimidazol-2-yl and pz ¼ 3,5-dimethylpyrazol-1-yl, respectively). The structure of 1 determined
by X-ray structural analyses indicated that bis(1-methylimidazol-2-yl)methylthiolate acted as a bidentate
Accepted 17 January 2014
Keywords:
monoanionic k
2-[N,S] chelating ligand. Reaction of 1 with W(CO)5THF yielded heterobimetallic complex
1-Methylimidazole
3,5-Dimethylpyrazole
Organotin
Carbonyl tungsten
Sulfur
Ph2ClSnSCH(min)2W(CO)5 (2), while similar reaction of 4 with W(CO)5THF resulted in the decomposition
of 4 to give pyrazole derivative W(CO)5(pzH). The structure of 2 has been confirmed by X-ray structural
analyses, showing that 1 coordinated to the tungsten atom through the free nitrogen atom. Reaction of
CH2(min)(pz) with W(CO)5THF yielded bidentate chelating complex CH2(min)(pz)W(CO)4, which when
treated with n-BuLi, followed by reaction with Ph3SnCl, gave the final product CH2(minSnPh3)(pz)
W(CO)4.
Ó 2014 Elsevier B.V. All rights reserved.
1. Introduction
formation of unexpected (3,5-dimethylpyrazol-1-yl)dithioformate
derivatives [8]. These results inspire us to explore the related
The coordination behavior of bis(pyrazol-1-yl)methanes to-
wards main group and transition metals has been extensively
investigated in recent years [1], suggesting an encouraging
advantage that their electronic and steric effects can be readily
adjusted by changing the substituents on the pyrazolyl rings. The
deprotonation of their methylene bridge to give bis(pyrazol-1-yl)
methide anions has been reported [2,3] and the resulting anions
can react with various electrophiles to yield versatile hetero-
scorpionate ligands [4e6], which widely broadens the application
areas of bis(pyrazol-1-yl)methanes. Our recent investigations
demonstrated that bis(pyrazol-1-yl)methanes functionalized
with organic functional groups on the methine carbon atom dis-
played unusual reactivity [7e10]. For instance, the reaction of
2-hydroxyphenyl functionalized bis(pyrazol-1-yl)methanes with
W(CO)5THF resulted in the cleavage of a Csp3eN bond to form novel
pyrazole derivatives [7]. Another intriguing example is the reaction
reactivity of other ligands with similar structural features. As the
isoelectronic and isosteric ligand of pyrazole, imidazole has been
widely used in the coordination chemistry and bioinorganic
chemistry [11,12] and the replacement of pyrazole by 1-
methylimidazole to form bis(1-methylimidazol-2-yl)methane has
been described in the literature [13]. This ligand acted as a good
donor to various main group and transition metals because of the
strong donating ability of imidazole [14e28]. The coordination
behavior of bis(1-methylimidazol-2-yl)methane is very similar to
that of bis(pyrazol-1-yl)methanes, such as acting as a chelating
bidentate ligand upon coordinating to metals. The lithiation of
bis(1-methylimidazol-2-yl)methane at the methylene group could
be successfully carried out, and the corresponding anion could
readily react with various electrophiles to form new polydentate
ligands [13,29e36]. As an extension of our investigations on
functionalized bis(pyrazol-1-yl)methanes, herein we report the
modification of bis(1-methylimidazol-2-yl)methane and 1-(1-
methylimidazol-2-yl)methyl-3,5-dimethylpyrazole at the methy-
lene group as well as their related reactions. These functionalized
ligands showed markedly different reaction patterns, compared to
the analogs of bis(pyrazol-1-yl)methanes.
of bis(3,5-dimethylpyrazol-1-yl)methylthiolate with Fe3(CO)12
,
followed by the treatment with RX, which gave rise to the
* Corresponding author. Fax: þ86 22 23502458.
E-mail address: lftang@nankai.edu.cn (L.-F. Tang).
0022-328X/$ e see front matter Ó 2014 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2014.01.021

H.-J. Li et al. / Journal of Organometallic Chemistry 757 (2014) 8e13
9
2. Results and discussion
2.1. Functionalized bis(1-methylimidazol-2-yl)methane and its
reactions
Being different from bis(3,5-dimethylpyrazol-1-yl)methide
anion [37], we herein found that bis(1-methylimidazol-2-yl)
methide anion, prepared in situ by the lithiation of bis(1-
methylimidazol-2-yl)methane at the methylene group using n-
BuLi at low temperature, did not react with Ph3SnCl. The expected
derivative Ph3SnCH(min)2 (min ¼ 1-methylimidazol-2-yl) could
not be obtained (Scheme 1), with almost full recovering of starting
materials after workup. The reason is not completely clear at pre-
sent, which may be relative to the isomerism of carbanions origi-
nated from diheteroarylmethanes [38], leading to the replacement
of pyrazole by 1-methylimidazole increasing the acidity of methy-
lene protons, therefore decreasing the nucleophilicity of the cor-
responding anion towards Ph3SnCl. However, bis(1-methyl
imidazol-2-yl)methylthiolate anion could be obtained by the re-
action of lithiated bis(1-methylimidazol-2-yl)methane with sulfur,
which was stable at room temperature, and readily reacted with
Ph2SnCl2 to give complex 1. This complex has been characterized by
elemental analyses, as well as NMR spectra. The characteristic
proton signal of CH group appeared at 6.16 ppm, markedly shifted
to lower field than that of the methylene group in bis(1-
methylimidazol-2-yl)methane (4.24 ppm) [13], mainly owing to
the deshielding effect by the electronegative sulfur atom. It should
be noted that although complex 1 possessed two different imida-
zolyl rings in solid (Fig. 1), only one set of 1H NMR signals for the
bis(1-methylimidazol-2-yl)methide group were observed in solu-
tion, which should be the result of the fast exchange in the coor-
dination behavior of two imidazole ligands on the NMR time scale.
Similar phenomenon has also been observed for organotin de-
rivatives of bis(pyrazol-1-yl)methylthiolate [39]. In addition, the
119Sn NMR signal of complex 1 appeared at ꢀ230.4 ppm, similar to
those of other five-coordinated organotin derivatives [39e41].
The molecular structure of 1 has been further confirmed by X-
ray structural analyses, which consisted of two crystallographically
independent molecules with similar structural parameters. One of
them is presented in Fig. 1. As shown in the figure, bis(1-
methylimidazol-2-yl)methylthiolate coordinates to the tin atom
by only one nitrogen atom and the sulfur atom, acting as a biden-
Fig. 1. The molecular structure of 1. The thermal ellipsoids are drawn at the 30%
probability level. The uncoordinated solvent was omitted for clarity. Selected bond
ꢁ
ꢀ
distances (A) and angles ( ): Sn(1)eN(3) 2.248(5), Sn(1)eS(1) 2.419(2), Sn(1)eCl(1)
ꢀ
2.501(2), C(1)eS(1) 1.839(6) A; N(3)eSn(1)eCl(1) 167.0(1), C(16)eSn(1)eC(10)
121.1(2), C(10)eSn(1)eN(3) 90.9(2), C(10)eSn(1)eN(3) 90.9(2), C(10)eSn(1)eS(1)
123.1(2), N(3)eSn(1)eS(1) 80.7(1), S(1)eSn(1)eCl(1) 86.48(5), C(1)eS(1)eSn(1)
102.5(2), C(6)eC(1)eS(1) 112.4(4)ꢁ.
organotin derivative Ph2ClSnSeCH(pz)2 with a similar funda-
ꢀ
mental skeleton (2.373(4) A, pz ¼ 3,5-dimethylpyrazol-1-yl) [39],
possibly owing to the stronger donor ability of the imidazolyl ni-
trogen, compared to the corresponding pyrazolyl nitrogen atom
[28,32].
Compound 1 is anticipated to act as a good donor for transition
metals owing to the high affinity of sulfur for many metals as well
as the strong donating ability of the free imidazolyl nitrogen atom.
At the same time, 1 is expected to be able to provide multiple co-
ordination sites since the oxidative addition of the Snehalogen [42]
and SneS [43] bonds to low-oxidative transition metals is known.
However, upon treatment of 1 with W(CO)5THF at 45 ꢁC, only
complex 2 was obtained. When the reaction was carried out at a
higher temperature, no isolable product was obtained. Complex 2
has been characterized by IR and NMR spectra. Its IR spectrum
showed a pattern of nCO bands for the W(CO)5 fragment. A nCO band
was observed at 2069.6 cmꢀ1, which was assigned to the A1eq mode
for the pseudo C4v metal center in a metal pentacarbonyl moiety
[44]. Its NMR spectra also support the proposed structure. For
example, two sets of 1H and 13C signals corresponding to the imi-
dazolyl moieties were observed in its 1H and 13C NMR spectra,
suggesting their location in different coordination environments.
Furthermore, two signals of the carbonyl carbon atoms with ca. a
1:4 intensity ratio were observed in its 13C NMR spectrum. The
119Sn NMR signal occurred at ꢀ234.0 ppm, very similar to that of 1,
consistent with the fact of the reaction center away from the tin
atom.
tate monoanionic k
2-[N,S] chelating ligand. The tin atom adopts a
five-coordinate distorted trigonal bipyramidal geometry with the
N(3) and Cl(1) atoms occupying the axial positions. The SneN bond
ꢀ
distance is 2.248(5) A, shorter than that in five-coordinate
The molecular structure of 2 was confirmed by X-ray structural
analyses, and is presented in Fig. 2, which manifests that 1 co-
ordinates to the tungsten atom through the free nitrogen atom
only. The fundamental framework of 1 is kept in 2. The SneN and
SneS bond distances are not significantly changed in these two
complexes. But the axial angle NeSneCl of 162.0(2)ꢁ in 2 is smaller
than the corresponding angle (167.0(1)ꢁ) in 1, implying possibly the
bigger steric repulsion in 2. The tungsten atom adopts a six-
coordinate distorted octahedral geometry. The WeN bond
Scheme 1. The modification of bis(1-methylimidazol-2-yl)methane.

10
H.-J. Li et al. / Journal of Organometallic Chemistry 757 (2014) 8e13
Fig. 3. The molecular structure of 3.HCl. The thermal ellipsoids are drawn at the 30%
ꢁ
ꢀ
probability level. Selected bond distances (A) and angles ( ): N(4)eH(4) 0.917(9),
H(4).Cl(1)i 2.098(10), N(4)eH(4).Cl(1)i 3.013(1) A; N(4)eH(4).Cl(1)i 175.8(19),
ꢀ
Fig. 2. The molecular structure of 2. The thermal ellipsoids are drawn at the 30%
N(2)eC(6)eC(8) 111.5(1)o. Symmetry operation: i ¼ ꢀx þ 1, ꢀy, ꢀz þ 1.
probability level. The uncoordinated solvent was omitted for clarity. Selected
ꢁ
ꢀ
bond distances (A) and angles ( ): W(1)eN(1) 2.292(6), Sn(1)eN(4) 2.269(6), Sn(1)e
ꢀ
S(1) 2.442(2), Sn(1)eCl(1) 2.507(2), C(10)eS(1) 1.861(7) A; W(1)eC(1)eO(1)
175.1(7), W(1)eC(2)eO(2) 175.9(8), W(1)eC(3)eO(3) 178.3(6), W(1)eC(4)eO(4)
177.1(7), W(1)eC(5)eO(5) 173.6(6), C(1)eW(1)eC(4) 175.1(3), C(2)eW(1)eC(5)
172.5(3), C(3)eW(1)eN(1) 174.1(3), C(15)eSn(1)eS(1) 126.1(2), N(4)eSn(1)eS(1)
79.4(2), N(4)eSn(1)eCl(1) 162.0(2), S(1)eSn(1)eCl(1) 83.56(7), C(10)eS(1)eSn(1)
103.6(2), C(9)eC(10)eC(11) 112.9(6), C(11)eC(10)eS(1) 111.8(4)ꢁ.
led to the decomposition of this compound to give known complex
5. This result is markedly different from that of the reaction of 1
with W(CO)5THF, but is similar with that of the reaction of orga-
notin derivative of bis(pyrazol-1-yl)methylthiolate [39].
Compound 3 is foreseen to act as an unsymmetric N,N0-biden-
tate chelating ligand for transition metals and the reaction of 3 with
W(CO)5THF affording complex 6 in good yield provides such a case.
It is well established that the acidity of the methylene protons is
enhanced upon coordination of the methylene-bridged bidentate
ligand to low-valent metal center [45,46], while the deprotonation
ꢀ
distance is 2.292(6) A, comparable to those reported in other
pentacarbonyl tungsten complexes with imidazolyl ligands, such as
2.265(3) A in CH2]C(min)2W(CO)5 [15]. It is worthy of note that
five angles WeCeO, especially the angle W(1)eC(5)eO(5) of
173.6(6)ꢁ, and the angle C(2)eW(1)eC(5) of 172.5(3)ꢁ deviate from
linearity, showing the steric congestion in this complex.
ꢀ
in the
a position of the coordinated imidazolyl ring has also been
reported [26,47]. Thus complex 6 was expected to have comparable
reactive features. However, we found that treatment of 6 with n-
BuLi and followed reaction with Ph3SnCl gave heterobimetalic
complex 7 in 9% yield. Complexes 6 and 7 have been characterized
by IR and NMR spectra and shared some similar spectroscopic
features. For example, four carbonyl stretching bands, as expected
for cis-tetracarbonyl complexes, were observed in their IR spectra,
and three corresponding carbonyl carbon signals with ca. an in-
tensity ratio of 1:1:2 were observed in their 13C NMR spectra.
The molecular structure of 7 determined by X-ray structural
analyses is presented in Fig. 4, which clearly shows that one SnPh3
group joins the 5-position of an imidazolyl ring. The tin atom
adopts a four-coordinate tetrahedral geometry. But the angles
C(12)eSn(1)eC(15) of 104.6(1)ꢁ and C(12)eSn(1)eC(21) of
113.1(1)ꢁ markedly deviate from the tetrahedral geometry of the sp3
hybridized tin atom, reflecting the presence of the steric repulsion
between the SnPh3 group with the imidazolyl moiety. The tungsten
atom has a six-coordinate quasi-octahedral coordination environ-
2.2. Synthesis and reactivity of 1-(1-methylimidazol-2-yl)methyl-
3,5-dimethylpyrazole
1-(1-Methylimidazol-2-yl)methyl-3,5-dimethylpyrazole (3) was
obtained by the reaction of 2-chloromethyl-1-methylimidazole with
3,5-dimethylpyrazole in an alkaline condition (Scheme 2), while its
hydrochloride (3.HCl) was obtained (Fig. 3) upon an insufficient
amount of base in this reaction. In this salt, the proton binds to the
more strongly basic imidazolyl nitrogen atom. The reaction of the
lithiated 3 with sulfur, followed by reaction with Ph2SnCl2 afforded
compound 4, proving a successful deprotonation of 3 at the
methylene group with n-BuLi. However, the corresponding anion
did not react with Ph3SnCl, like bis(1-methylimidazol-2-yl)methide
anion.
Compound 4 has been characterized by NMR spectra. The pro-
ton signal of the CH group appeared at 6.73 ppm. Its 119Sn NMR
signal emerged at ꢀ229.4 ppm, consistent with five-coordinated
organotin complexes [39e41]. Treatment of 4 with W(CO)5THF
ꢀ
ment. The WeNimidazolyl bond distance is 2.232(3) A, slightly
shorter than that in 2, possibly owing to the chelation effect of the
ꢀ
ligand in 7. The WeNpyrazolyl bond distance is 2.261(3) A, compa-
rable to the corresponding values found in other tungsten com-
ꢀ
plexes with pyrazolyl ligands (such as average 2.271 A in (2-
ꢀ
MeOC6H4)CH(pz)2W(CO)4 [7] and 2.278
A
in (2-ClC6H4)
CH(pz)2W(CO)4 [9]). Two cis-carbonyl groups are distorted with the
angles W(1)eC(1)eO(1) of 174.4(4)ꢁ and W(1)eC(4)eO(4) of
173.3(4)ꢁ. The angle C(1)eW(1)eC(4) of 169.8(2)ꢁ also deviates
from linearity.
In summary, the lithiation of bis(1-methylimidazol-2-yl)
methane and 1-(1-methylimidazol-2-yl)methyl-3,5-dimethylpyra
zole at bridging carbon atom is readily carried out. The reactivity
of the corresponding anions with Ph3SnCl is different from that of
bis(pyrazolyl-1-yl)methide anion. No reaction occurred upon
treatment of the former with Ph3SnCl. In addition, the structurally
similar
organotin
derivatives
Ph2ClSnSCH(min)2
and
Ph2ClSnSCH(min)(pz) showed markedly different reaction patterns
with W(CO)5THF. The former reaction yielded heterobimetallic
complex Ph2ClSnSCH(min)2W(CO)5, while the latter reaction
Scheme 2. Synthesis and reactivity of 1-(1-methylimidazol-2-yl)methyl-3,5-
dimethylpyrazole.

H.-J. Li et al. / Journal of Organometallic Chemistry 757 (2014) 8e13
11
the mixture was stirred for 1 h at that temperature. Then sulfur
(32 mg, 1 mmol) was added to the mixture. The reaction mixture
was stirred at ꢀ78 ꢁC for 1 h, allowed to slowly reach room tem-
perature, and stirred continuously for 2 h. Ph2SnCl2 (0.34 g,1 mmol)
was added to the above solution, and the reaction mixture was
stirred overnight. The solvent was removed under a reduced
pressure, and the residue was recrystallized from CH2Cl2/hexane to
give white solids of 1. Yield: 0.32 g (62%). 1H NMR (DMSO-d6):
d 3.54
(s, 6H, CH3), 6.16 (s, 1H, CH), 6.85 (s, br, 2H, protons of imidazole),
7.26e7.51 (m, 8H), 7.61e7.81 (m, 4H) (protons of C6H5 and imid-
azole) ppm. 119Sn NMR (DMSO-d6):
d
ꢀ230.4 ppm. Anal. Calc. for
C21H21ClN4SSn.0.5CH2Cl2: C, 46.27; H, 3.97; N, 10.04. Found: C,
46.25; H, 4.20; N, 10.06%.
3.3. Reaction of 1 with W(CO)5THF
Compound 1 (0.10 g, 0.2 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 (70 mg, 0.2 mmol) in THF (15 ml) for 8 h. The reaction
mixture was stirred and heated at 45 ꢁC for 4 h. The solvent was
removed under a reduced pressure, and the residue was purified by
column chromatography on silica using ethyl acetate as the eluent.
The eluate was concentrated to dryness, and the residue was
recrystallized from CH2Cl2/hexane to give yellow crystals of 2.
Fig. 4. The molecular structure of 7. The thermal ellipsoids are drawn at the 30%
ꢁ
ꢀ
probability level. Selected bond distances (A) and angles ( ): W(1)eN(1) 2.261(3),
ꢀ
W(1)eN(4) 2.232(3), Sn(1)eC(12) 2.131(4), Sn(1)eC(15) 2.114(3) A; W(1)eC(1)eO(1)
174.4(4), W(1)eC(2)eO(2) 177.1(4), W(1)eC(3)eO(3) 179.7(4), W(1)eC(4)eO(4)
173.3(4), C(1)eW(1)eC(4) 169.8(2), C(3)eW(1)eN(4) 96.4(2), C(2)eW(1)eN(4)
176.7(2), C(3)eW(1)eN(1) 174.7(2), N(1)eW(1)eN(4) 78.9(1), C(15)eSn(1)eC(21)
112.5(1), C(12)eSn(1)eC(15) 104.6(1), C(12)eSn(1)eC(21) 113.1(1), N(2)eC(10)eC(11)
111.1(3)ꢁ.
Yield: 43 mg (26%). 1H NMR (DMSO-d6):
d 2.83 (s, 3H, CH3), 3.17 (s,
3H, CH3), 6.22 (s, 1H, CH), 7.29 (d, J ¼ 1.2 Hz, 1H), 7.38 (J ¼ 1.2 Hz,
1H), 7.39 (J ¼ 1.3 Hz, 1H), 7.57 (d, J ¼ 1.3 Hz, 1H) (protons of imid-
azole), 7.42e7.50 (m, 6H), 7.69e7.91 (m, 4H) (C6H5) ppm. 13C NMR
resulted in the decomposition of the ligand, similar to the reaction of
Ph2ClSnSCH(pz)2 [39]. These results suggest that the replacement of
pyrazole in bis(3,5-dimethylpyrazolyl-1-yl)methane by imidazole to
form bis(1-methylimidazol-2-yl)methane or 1-(1-methylimidazol-
2-yl)methyl-3,5-dimethylpyrazole will obviously change the prop-
erty of the methylene bridge in these ligands as well as the reactivity
of the corresponding ligands.
(DMSO-d6):
d 33.2, 33.3 (CH3), 36.2 (CH), 123.7, 125.5, 127.7, 128.7,
129.9, 134.3, 135.3, 142.5, 145.8, 146.6 (carbons of C6H5 and imid-
azole), 197.8 (4 C), 201.8 (CO) ppm. 119Sn NMR (DMSO-d6):
d
ꢀ234.0 ppm. IR: nCO ¼ 2069.6 (m), 1977.0 (s), 1940.4 (vs), 1913.4
(vs), 1861.3 (vs) cmꢀ1. Anal. Calc. for C26H21ClN4O5SSnW: C, 37.20;
H, 2.52; N, 6.67. Found: C, 37.46; H, 2.32; N, 6.37%.
3. Experimental
3.4. Synthesis of CH2(mim)(pz) (3)
Solvents were dried by standard methods and distilled prior to
use. All reactions were carried out under an argon atmosphere.
NMR spectra were recorded on a Bruker 400 spectrometer, and the
chemical shifts were reported in ppm with respect to the reference
(internal SiMe4 for 1H and 13C NMR spectra, external SnMe4 for
119Sn NMR). IR spectroscopic data were obtained from a Nicolet 380
spectrometer as KBr pellets. Element analyses were carried out on
an Elementar Vairo EL analyzer. Bis(1-methylimidazol-2-yl)
methane (CH2(mim)2) [13] and 2-chloromethyl-1-methylimidazole
[48] were prepared according to the published methods.
NaH (0.60 g, 25 mmol) was added to the solution of 3,5-
dimethylpyrazole (1.92 g, 20 mmol) in THF (40 ml). After the
reaction mixture was stirred at room temperature for 1 h,
2-chloromethyl-1-methylimidazole (2.6 g, 20 mmol) was added.
The mixture was stirred and heated at reflux for 6 h. The solvent
was removed under a reduced pressure, and the residue was
recrystallized from hexane to give white solids of 3. Yield: 3.32 g
(87%). 1H NMR (CDCl3):
d 2.19 (s, 3H, CH3), 2.25 (s, 3H, CH3), 3.68
(s, 3H, NCH3), 5.30 (s, 2H, CH2), 5.78 (s, 1H, H4 of pyrazole), 6.81
(d, J ¼ 0.9 Hz, 1H), 6.95 (d, J ¼ 0.9 Hz, 1H) (protons of imidazole)
ppm. 13C NMR (CDCl3):
d 11.1, 13.4 (CH3), 33.2 (NCH3), 46.2 (CH),
105.8 (C4 of pyrazole), 122.1, 127.6, 140.0, 142.8, 147.4 (carbons of
imidazole and pyrazole) ppm. Anal. Calc. for C10H14N4: C, 63.13; H,
7.42; N, 29.45. Found: C, 62.74; H, 7.28; N, 28.96%.
3.1. Attempted synthesis of Ph3SnCH(mim)2
To a solution of CH2(mim)2 (0.18 g, 1 mmol) in THF (40 ml) was
added a hexane solution of n-BuLi (1.6 M, 0.63 ml) at ꢀ78 ꢁC, and
the mixture was stirred for 1 h at that temperature. To the mixture
was added a solution of Ph3SnCl (0.39 g,1 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 CH2Cl2/hexane to give a white solid, which was
confirmed by NMR as the mixture of CH2(mim)2 and Ph3SnCl. No
expected Ph3SnCH(mim)2 was obtained.
The hydrochloride of 3 (3.HCl) precipitated from the reaction
mixture upon an insufficient amount of base. The solid was filtered
and dried under vacuum.1H NMR (CDCl3):
d 2.15 (s, 3H, CH3), 2.46 (s,
3H, CH3), 4.00 (s, 3H, NCH3), 5.73 (s, 2H, CH2), 5.81 (s, 1H, H4 of
pyrazole), 7.11 (d, J ¼ 0.8 Hz, 1H), 7.33 (d, J ¼ 0.8 Hz, 1H) (protons of
imidazole) ppm. 13C NMR (CDCl3):
d 11.5, 13.4 (CH3), 35.5 (NCH3),
41.7 (CH), 106.4 (C4 of pyrazole), 119.4, 123.4, 140.9, 141.6, 149.0
(carbons of imidazole and pyrazole) ppm. Anal. Calc. for C10H15ClN4:
C, 52.98; H, 6.67; N, 24.71. Found: C, 53.14; H, 6.36; N, 25.06%.
3.2. Synthesis of ClPh2SnSCH(mim)2 (1)
3.5. Synthesis of ClPh2SnSCH(mim)(pz) (4)
To a solution of CH2(mim)2 (0.18 g, 1 mmol) in THF (40 ml) was
This compound was obtained similarly using 3 instead of
CH2(mim)2 as described above for 1. CH2Cl2 was used as the
added a hexane solution of n-BuLi (1.6 M, 0.63 ml) at ꢀ78 ꢁC, and

12
H.-J. Li et al. / Journal of Organometallic Chemistry 757 (2014) 8e13
Table 1
Crystal data and refinement parameters for complexes 1, 2, 3.HCl and 7.
Compound
1.THF
2.0.36CH2Cl2
3.HCl
7
Formula
Formula weight
Crystal size (mm)
C25H29ClN4OSSn
587.72
C26.36H21.72Cl1.72N4O5SSnW
870.42
C10H15ClN4
226.71
C32H28N4O4SnW
835.12
0.24 ꢂ 0.20 ꢂ 0.16
0.20 ꢂ 0.12 ꢂ 0.10
0.20 ꢂ 0.18 ꢂ 0.14
0.20 ꢂ 0.16 ꢂ 0.12
T (K)
113(2)
113(2)
113(2)
113(2)
ꢀ
l
(MoK
a
) (A)
0.71073
Monoclinic
Cc
13.898(3)
16.917(3)
24.324(4)
102.137(2)
5591.3(17)
8
1.396
2384
1.107
1.71e27.87
26968
0.71073
Monoclinic
P21/c
8.0178(13)
29.918(3)
12.5860(16)
93.688(4)
3012.9(7)
4
1.919
1669
4.908
1.76e27.83
22217
0.71073
Monoclinic
P21/c
8.476(3)
10.995(4)
12.264(4)
103.971(5)
1109.1(7)
4
1.385
480
0.318
2.48e27.88
10607
0.71073
Orthorhombic
P212121
13.294(3)
15.069(3)
15.472(3)
90
3099.6(11)
4
1.790
1616
4.556
2.02e25.02
31625
5445 (0.0453)
5263
Crystal system
Space group
ꢀ
a (A)
ꢀ
b (A)
ꢀ
c (A)
b
(ꢁ)
3
ꢀ
V (A)
Z
Dc (g cmꢀ3
F(000)
)
m
(mmꢀ1
Range (ꢁ)
)
q
No. of measured reflections
No. of unique reflections (Rint
No. of observed reflections with (I > 2
No. of parameters
GOF
)
11521 (0.0431)
10878
644
7052 (0.0346)
6738
398
2646 (0.0384)
2023
143
s(I))
382
0.991
1.108
1.236
1.029
Residuals R1, wR2
0.0424, 0.1184
0.0498, 0.1025
0.0303, 0.0838
0.0182, 0.0383
recrystallization solvent. Yield: 60%. 1H NMR (CDCl3):
d
2.07 (s, 3H,
on silica using ethyl acetate/hexane (1/1 v/v) as the eluent. The
eluate was concentrated to dryness, and the residue was recrys-
tallized from CH2Cl2/hexane to give yellow crystals of 7. Yield:
CH3), 2.28 (s, 3H, CH3), 3.33 (s, 3H, NCH3), 5.83 (s, 1H, H4 of pyr-
azole), 6.73 (s, 1H, CH), 6.82 (d, J ¼ 0.8 Hz, 1H), 6.99 (d, J ¼ 0.8 Hz,
1H) (protons of imidazole), 7.35e7.50 (m, 6H), 7.73e7.93 (m, 4H)
60 mg (9%). 1H NMR (DMSO-d6):
d 2.37 (s, 3H, CH3), 2.39 (s, 3H,
(C6H5) ppm. 119Sn NMR (CDCl3):
d
ꢀ229.4 ppm. Anal. Calc. for
CH3), 3.68 (s, 3H, NCH3), 5.30 (s, 2H, CH2), 6.16 (s, 1H, H4 of pyr-
azole), 7.03 (s, 1H, proton of imidazole), 7.48e7.49 (m, 9H), 7.62e
C
22H23ClN4SSn: C, 49.89; H, 4.38; N, 10.58. Found: C, 49.63; H, 3.98;
N, 10.96%.
7.64 (m, 6H) (C6H5) ppm. 13C NMR (DMSO-d6):
d 11.4, 16.2 (CH3),
35.8 (NCH3), 43.2 (CH2), 106.8 (C4 of pyrazole), 129.1, 129.8, 130.7,
135.8, 136.7, 140.9, 142.8, 146.8, 151.9 (C6H5, carbons of imidazole as
well as C3 and C5 of pyrazole), 203.2 (2 C), 212.6, 213.3 (CO) ppm.
3.6. Reaction of 4 with W(CO)5THF
119Sn NMR (DMSO-d6):
d
ꢀ60.1 ppm. IR: nCO ¼ 2004.4 (s), 1870.2
This reaction was carried out similarly using 4 instead of 1 as
described above for the reaction of 1. The reaction time was 12 h.
(vs),1846.0 (vs),1803.6 (vs) cmꢀ1. Anal. Calc. for C32H28N4O4SnW: C,
46.02; H, 3.38; N, 6.71. Found: C, 45.93; H, 3.40; N, 6.69%.
Complex 5 was obtained in 31% yield. 1H NMR (CDCl3):
d 2.31 (s, 6H,
CH3), 5.93 (s, 1H, H4 of pyrazole), 9.32 (s, br, 1H, NH). IR:
nNH ¼ 3385.1 (m), nCO ¼ 2075.4 (w), 1926.9 (s), 1851.7 (m), 1832.4
3.9. Crystal structure determinations
(m) cmꢀ1
.
Crystals of 1 suitable for X-ray analyses were obtained by slow
diffusion of hexane into its THF solutions at 4 ꢁC. While crystals of 2,
3.HCl and 7 suitable for X-ray analyses were obtained by slow
diffusion of hexane into their CH2Cl2 solutions at 4 ꢁC. Crystals of 1
contained one THF molecule. Crystals of 2 contained 0.36 CH2Cl2
molecules. One phenyl group (C(21)eC(26)) in this complex was
found to be disordered. Satisfactory results were obtained when
C(21)eC(26) were given occupancy factors of 0.64 and C(21)0e
C(26)0 were given occupancy factors of 0.36, respectively. In addi-
tion, the solvent was absence when C(21)eC(26) were given oc-
cupancy factors of 0.64. All intensity data were collected on a
Rigaku Saturn CCD detector. Semi-empirical absorption corrections
were applied using the Crystalclear program [49]. The structures
were solved by direct methods and difference Fourier map using
SHELXS of the SHELXTL package and refined with SHELXL [50] by
full-matrix least-squares on F2. All non-hydrogen atoms were
refined anisotropically. A summary of the fundamental crystal data
for 1, 2, 3.HCl and 7 is listed in Table 1.
3.7. Reaction of 3 with W(CO)5THF
This reaction was carried out similarly using 3 instead of 1 as
described above for the reaction of 1. The reaction mixture was
stirred and heated at reflux for 8 h to give complex 6. Yield: 75%. 1H
NMR (CDCl3):
d 2.40 (s, 3H, CH3), 2.49 (s, 3H, CH3), 3.80 (s, 3H,
NCH3), 5.22 (s, 2H, CH2), 5.98 (s, 1H, H4 of pyrazole), 6.86 (s, br, 1H),
7.29 (s, br, 1H) (protons of imidazole) ppm. 13C NMR (CDCl3):
d 11.8,
16.8 (CH3), 33.7 (NCH3), 42.3 (CH2), 107.2 (C4 of pyrazole), 121.8,
133.1, 140.0, 141.7, 153.9 (carbons of imidazole and pyrazole), 203.0
(2 C), 212.9, 213.4 (CO) ppm. IR: nCO ¼ 2005.1 (s), 1870.2 (vs), 1846.0
(vs), 1803.6 (vs) cmꢀ1. Anal. Calc. for C14H14N4O4W: C, 34.59; H,
2.90; N, 11.53. Found: C, 34.95; H, 2.89; N, 11.50%.
3.8. Synthesis of CH2(mim-SnPh3)(pz)W(CO)4 (7)
To a solution of 6 (0.39 g, 0.8 mmol) in THF (50 ml) was added a
hexane solution of n-BuLi (1.6 M, 0.63 ml) at ꢀ78 ꢁC, and the
mixture was stirred for 1 h at that temperature. The solution of
Ph3SnCl (0.30 g, 0.8 mmol) in THF (5 ml) was added dropwise to the
above mixture. The reaction mixture was continuously stirred
at ꢀ78 ꢁC for 0.5 h, allowed to slowly reach room temperature, and
stirred overnight. The solvent was removed under a reduced
pressure, and the residue was purified by column chromatography
Acknowledgments
This work is supported by the National Natural Science Foun-
dation of China (No. 20972075). The authors also thank the re-
viewers for their valuable comments and suggestions.

H.-J. Li et al. / Journal of Organometallic Chemistry 757 (2014) 8e13
13
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CCDC 968931, 968932, 968933 and 968934 contain the sup-
plementary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
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