New multidentate heteroscorpionate ligands: N-Phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and ethyl 2,2-bis(pyrazol-1-yl)dithioacetate as well as their derivatives

Article abstract of DOI:10.1016/j.jorganchem.2006.12.030

New multidentate heteroscorpionate ligands, N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,5-Me₂Pz)₂ (1), N-phenyl-2,2-bis(3,4,5-trimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,4,5-Me₃Pz)₂ (2)

Full text of DOI:10.1016/j.jorganchem.2006.12.030

Journal of Organometallic Chemistry 692 (2007) 1708–1715
www.elsevier.com/locate/jorganchem
New multidentate heteroscorpionate ligands:
N-Phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and ethyl
2,2-bis(pyrazol-1-yl)dithioacetate as well as their derivatives
a
a
b
a,
*
Run-Yu Tan , Juan Hong , Miao Du , Liang-Fu Tang
a
Department of Chemistry, State Key Laboratory of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, PR China
b
College of Chemistry and Life Science, Tianjin Normal University, Tianjin 300074, PR China
Received 7 November 2006; received in revised form 14 December 2006; accepted 22 December 2006
Available online 9 January 2007
Abstract
New multidentate heteroscorpionate ligands, N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,5-Me2Pz)2 (1),
N-phenyl-2,2-bis(3,4,5-trimethylpyrazol-1-yl)thioacetamide PhHNCSCH(3,4,5-Me3Pz)2 (2), and ethyl 2,2-bis(3,5-dimethylpyrazol-1-
yl)dithioacetate EtSCSCH(3,5-Me2Pz)2 (8), have been synthesized and their coordination chemistry studied. These heteroscorpionate
ligands can act as monodentate, bidentate, or tridentate ligands, depending on the coordinate properties of different metals. Reaction
of W(CO)6 with 1 or 2 under UV irradiation yields monosubstituted carbonyl tungsten complexes W(CO)5L (L = 1 or 2), in which
N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide acts as a monodentate ligand by the s-coordination to the tungsten atom. In addition, these
monosubstituted tungsten complexes have also been obtained by heating ligand 1 or 2 with W(CO)5THF in THF. While similar reaction
of Fe(CO)5 with 1, 2, or 8 under UV irradiation results in tricarbonyl iron complexes PhHNCSCH(3,5-Me2Pz)2Fe(CO)3 (5),
PhHNCSCH(3,4,5-Me3Pz)2Fe(CO)3 (6), and EtSCSCH(3,5-Me2Pz)2Fe(CO)3 (9), respectively, in which N-phenyl-2,2-bis(pyrazol-1-
yl)thioacetamide or ethyl 2,2-bis(pyrazol-1-yl)dithioacetate acts as a bidentate ligand through one pyrazolyl nitrogen atom and the
C@S p-bond in an g2-C,S fashion side-on bonded to the iron atom to adopt a neutral bidentate j2-(p,N) coordination mode. Treatment
of the lithium salt of 1 with Co(ClO4)2 Æ 6H2O gives complex [PhNCSCH(3,5-Me2Pz)2]2Co(ClO4) with the oxidation of cobalt(II) to
cobalt(III), in which N-phenyl-2,2-bis(3,5-dimethylpyrazol-1-yl)thioacetamide acts as a tridentate monoanionic j3-(N,N,S) chelating
ligand by two pyrazolyl nitrogen atoms and the sulfur atom of the enolized thiolate anion.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Bis(pyrazol-1-yl)methane; Heteroscorpionate ligand; Tungsten carbonyl; Iron carbonyl; Cobalt complex
1. Introduction
tion [3–8]. These intriguing heteroscorpionate ligands usu-
ally have asymmetric N2O, N2S, N3S, or N3O coordination
environments, which render them the potential to form
novel complexes with various main group and transition
metals. In addition, the modification of bis(pyrazol-1-
yl)methanes by organometallic groups has also successfully
broadened the scope of application of these novel ligands
[9–11].
Our recent investigations on bis(pyrazol-1-yl)methane
indicate that the modification of this ligand with organotin
groups on the methine carbon atom can provide unusual
reactivity [12,13]. For example, the reaction of triarylstan-
nyl-bis(pyrazol-1-yl)methane with W(CO)5THF results in
In recent years, poly(pyrazol-1-yl)alkane [1,2], especially
bis(pyrazol-1-yl)methane [3], has been performing as one of
the most popular nitrogen-containing donor ligands, and
its coordination chemistry towards main group and transi-
tion metals has been extensively studied. Recently, the
modification of bis(pyrazol-1-yl)methane by organic func-
tional groups on the bridging carbon atom to form novel
heteroscorpionate ligands has also drawn extensive atten-
*
Corresponding author. Fax: +86 22 23502458.
E-mail address: lftang@nankai.edu.cn (L.-F. Tang).
0022-328X/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.12.030

R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
1709
oxidative addition of the Sn–Csp3 bond to the tungsten(0)
atom to yield novel four-membered metallacyclic com-
plexes [12]. As part of our ongoing interest in functional-
ized bis(pyrazol-1-yl)methane ligands, we continue our
investigation of the modification of bis(pyrazol-1-yl)meth-
ane by introducing heteroatoms on the methine carbon to
form novel heteroscorpionate ligands. Herein we report
the modification of bis(pyrazol-1-yl)methane by phenyl iso-
thiocyanate and CS2 on the bridging carbon atom to yield
N-phenyl-2,2-bis(pyrazol-1-yl)thioacetamide and bis(pyra-
zol-1-yl)dithioacetate, which have the attractive character
of being able to act as a monodentate, bidentate, or triden-
tate ligand, depending on different metal atoms. Very
recently, the modification of bis(pyrazol-1-yl)methane by
enantiopure isocyanate and isothiocyanate fragments has
been reported [14,15].
chemistry owing to the existence of both sulfur and nitro-
gen atoms, which have different electron-donating ability.
2.2. Reaction of bis(pyrazol-1-yl)thioacetamide with
W(CO)6
Upon irradiation of the solution of ligand 1 or 2 and
W(CO)6 in THF at room temperature, or treatment of
ligand 1 or 2 with W(CO)5THF in refluxing THF, com-
plexes 3 and 4 are obtained (Scheme 1), which are charac-
terized by NMR, IR spectra, and elemental analyses. The
IR spectra of complexes 3 and 4 show a pattern of mCO
bands that is consistent with the W(CO)5 fragment, such
as a mCO band observed at ca. 2071 cmꢀ1, corresponding
to the A1eq mode for the pseudo C4v metal center in a metal
pentacarbonyl moiety [17–19]. The 13C NMR spectrum of
3 also supports the proposed structure, which clearly shows
two signals of the carbonyl carbon atoms with ca. a 1:4
intensity ratio.
2. Results and discussion
2.1. Synthesis of bis(pyrazol-1-yl)thioacetamide
The structure of complex 3 has also been confirmed by
crystal X-ray diffraction analysis, and presented in Fig. 1,
which clearly manifests that N-phenyl-2,2-bis(3,5-dim-
ethylpyrazol-1-yl)thioacetamide acts as a monodentate
ligand by the sulfur atom only, and the pyrazolyl nitrogen
atoms do not take part in the coordination to the metal.
The tungsten atom is six-coordinate with a slightly dis-
torted octahedral coordination geometry. The W–S
The modification of bis(pyrazol-1-yl)methane by phenyl
isothiocyanate on the methine carbon is easily carried out.
Treatment of the bis(pyrazol-1-yl)methide anion [16], pre-
pared in situ by the reaction of bis(pyrazol-1-yl)methane
with n-BuLi, with phenyl isothiocyanate, and subsequently
with water gives ligands 1 and 2 in reasonable yields, as
shown in Scheme 1, which have been characterized by
NMR. The proton signal of CH group in 1 (7.16 ppm)
and 2 (7.13 ppm), respectively, markedly shifts to lower
field than that of the methylene group in bis(3,5-dim-
ethylpyrazol-1-yl)methane (5.94 ppm), possibly due to the
deshielding effect by the C@S bond. In addition, the 13C
NMR signal of C@S occurs at 188.03 ppm for 1 and
189.63 ppm for 2, respectively. These two new multidetate
ligands are expected to exhibit intriguing coordination
˚
˚
(2.578(1) A) and C@S (1.675(3) A) distances are compara-
ble to those in other thiocarbonyl W(0) complexes (such as
˚
˚
2.5687(9) A for W–S and 1.708(4) A for C@S in W(CO)5-
(DTTT), DTTT = 3,5-dimethyl-tetrahydro-2H-1,3,5-thi-
adiazine-2-thione) [19]. An intramolecular hydrogen bonding
interaction has been observed between the N(5)–H group
and the N(2) atom. The hydrogen bond N(5)–Hꢁ ꢁ ꢁN(2) dis-
˚
tance is 2.765(4) A, and the angle of \N–Hꢁ ꢁ ꢁN is
143.30(5)ꢁ. It is noteworthy that one carbonyl C(3)O(3) is
Scheme 1. Syntheses of ligands 1 and 2 as well as their related reactions.

1710
R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
mides [25,26] have been reported in literatures, neutral thi-
oamides bonded to the iron(0) atom by the C@S p-bond in
an g2-C,S fashion are still rare [26]. Herein, complex 5 pro-
vides an interesting case. Such coordination mode is consis-
tent with the results of NMR spectra. For example, two
1
sets of H and 13C NMR signals corresponding to two
inequivalent pyrazolyl ligands have been observed in com-
plexes 5 and 6. In addition, the 13C NMR signals of the
thiocarbonyl groups in these two complexes are also mark-
edly shifted to higher field, compared with those in free
ligands and complexes 3 and 4.
The molecular structure of complex 5 has been con-
firmed by crystal X-ray diffraction analysis as shown in
Fig. 2. Selected bond distances and angles are listed in
Table 1. As seen in Fig. 2, N-phenyl-2,2-bis(3,5-dim-
ethylpyrazol-1-yl)thioacetamide acts as a neutral bidentate
j2-(p,N) ligand through only one pyrazolyl nitrogen atom
and the C@S p-bond, which is side-on bonded to the iron
atom in an g2-C,S fashion. The iron atom has a distorted
trigonal bipyramidal coordination geometry with one car-
bon atom and one nitrogen atom occupying the axial posi-
tions. The axial angle of \C(1)–Fe(1)–N(4) is 171.71(9)ꢁ.
Fig. 1. The molecular structure of complex 3. The thermal ellipsoids are
˚
drawn at the 30% probability level. Selected bond distances (A) and angles
(ꢁ): W(1)–S(1) 2.578(1), W(1)–C(2) 2.028(4), W(1)–C(5) 1.968(4), S(1)–
C(12) 1.675(3), O(1)–C(1) 1.139(5), O(5)–C(5) 1.153(4), N(1)–C(13)
1.463(3), N(3)–C(13) 1.450(4), N(5)–C(12) 1.317(3), N(5)–C(11) 1.427(3),
N(5)ꢁ ꢁ ꢁN(2) 2.765(4); C(5)–W(1)–C(2) 88.9(1), C(1)–W(1)–C(3) 174.5(1),
C(2)–W(1)–C(4) 177.3(1), C(5)–W(1)–S(1) 169.0(1), C(2)–W(1)–S(1)
101.2(1), C(12)–S(1)–W(1) 119.4(1), O(3)–C(3)–W(1) 173.3(3), O(1)–C(1)–
W(1) 175.5(3), O(4)–C(4)–W(1) 179.1(3), N(5)–C(12)–C(13) 114.5(2), N(5)–
C(12)–S(1) 124.0(2), C(13)–C(12)–S(1) 121.5(2), N(3)–C(13)–N(1) 111.4(2),
N(3)–C(13)–C(12) 110.2(2), N(5)–Hꢁ ꢁ ꢁN(2) 143.30(5).
˚
˚
The Fe–S (2.275(6) A) and Fe–C(10) (2.015(2) A) distances
are comparable to those in p bonded thio ester derivatives
˚
of iron(0) carbonyl complexes (such as 2.2810(9) A for Fe–
˚
S and 1.987(3) A for Fe–C in [HC(S)OEt]2Fe2(CO)6) [27].
˚
˚
The C@S (1.757(2) A) and C(S)–N (1.428(3) A) bond dis-
˚
tances are longer than those in 3 (1.675(3) A for C@S
and 1.317(3) A for C(S)–N, respectively), indicating that
˚
the p coordination to the iron atom weakens the double
bond character of the C@S.
significantly distorted with the angle of \W(1)–C(3)–O(3)
of 173.3(3)ꢁ, indicating the presence of the steric repulsion
between the ligand and carbonyl.
2.4. Synthesis of cobalt complex
2.3. Reaction of bis(pyrazol-1-yl)thioacetamide with
Fe(CO)5
The reaction of PhNCS(Li)CH(3,5-Me2Pz)2 with Co-
(ClO4)2 Æ 6H2O in CH3OH solution yields Co(III) complex
7. Its IR spectrum displays the characteristic strong and
Upon irradiation of ligands 1 and 2 with Fe(CO)5 under
the similar experimental conditions to those for 1 and 2
with W(CO)6, novel complexes 5 and 6 are yielded, which
are air-stable in the solid state and even their solution
can be manipulated in air without notable decomposition.
Their proton signals of the CH groups (6.44 ppm in 5 and
6.43 ppm in 6, respectively) are considerably shifted to
higher field than those (7.13–7.16 ppm) in free ligands 1
and 2 as well as complexes 3 and 4. Furthermore, their pro-
ton signals of the NH groups (5.15 ppm in 5 and 5.05 ppm
in 6, respectively) are also markedly upfield shifted, com-
pared with those in free ligands 1 and 2 (12.47 ppm), pos-
sibly due to the disappearance of the hydrogen bonds in
complexes.
It is known that thioamide has variable coordination
modes depending on different metals. For example, it can
act as a monodentate ligand by the sulfur atom [19–21],
as in complex 3, as well as a chelating bidentate ligand
by both sulfur and nitrogen atoms [22]. Although iron(0)
carbonyl complexes of thiocarbamoyls [23,24] or thioa-
Fig. 2. The molecular structure of complex 5. The thermal ellipsoids are
drawn at the 30% probability level.

R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
1711
Table 1
Selected bond distances (A) and angles (ꢁ) for complexes 5 and 9
˚
Complex 5
Complex 9
Fe(1)–C(1)
Fe(1)–C(2)
Fe(1)–C(3)
Fe(1)–C(10)
Fe(1)–N(4)
Fe(1)–S(1)
N(5)–C(10)
N(5)–C(9)
N(3)–C(16)
N(1)–C(16)
C(10)–S(1)
1.775(3)
1.800(3)
1.825(3)
2.015(2)
1.997(1)
2.2775(6)
1.428(3)
1.394(3)
1.447(3)
1.453(3)
1.757(2)
Fe(1)–C(1)
Fe(1)–C(2)
Fe(1)–C(3)
Fe(1)–C(7)
Fe(1)–N(1)
Fe(1)–S(1)
N(2)–C(8)
N(3)–C(8)
C(7)–C(8)
C(7)–S(1)
C(7)–S(2)
1.807(4)
1.824(4)
1.763(4)
2.042(3)
1.988(2)
2.2806(9)
1.446(4)
1.455(3)
1.533(4)
1.740(3)
1.805(3)
Fe(2)–C(4)
Fe(2)–C(5)
Fe(2)–C(6)
Fe(2)–C(19)
Fe(2)–N(5)
Fe(2)–S(3)
N(6)–C(20)
N(7)–C(20)
C(19)–C(20)
C(19)–S(3)
C(19)–S(4)
1.804(4)
1.830(4)
1.758(4)
2.032(3)
1.988(2)
2.2855(9)
1.447(3)
1.445(3)
1.533(4)
1.754(3)
1.786(3)
C(1)–Fe(1)–C(3)
C(2)–Fe(1)–C(3)
C(1)–Fe(1)–N(4)
C(2)–Fe(1)–N(4)
C(1)–Fe(1)–C(10)
C(3)–Fe(1)–C(10)
N(4)–Fe(1)–C(10)
C(2)–Fe(1)–S(1)
C(3)–Fe(1)–S(1)
C(10)–Fe(1)–S(1)
C(10)–S(1)–Fe(1)
O(4)–C(1)–Fe(1)
O(5)–C(2)–Fe(1)
O(6)–C(3)–Fe(1)
N(3)–C(16)–N(1)
N(3)–C(16)–C(10)
N(5)–C(10)–C(16)
N(5)–C(10)–S(1)
N(5)–C(10)–Fe(1)
C(16)–C(10)–Fe(1)
S(1)–C(10)–Fe(1)
89.9(1)
100.0(1)
171.71(9)
88.91(9)
90.1(1)
C(1)–Fe(1)–C(3)
C(2)–Fe(1)–C(3)
C(3)–Fe(1)–N(1)
C(1)–Fe(1)–N(1)
C(3)–Fe(1)–C(7)
C(2)–Fe(1)–C(7)
N(1)–Fe(1)–C(7)
C(1)–Fe(1)–S(1)
C(2)–Fe(1)–S(1)
C(7)–Fe(1)–S(1)
C(7)–S(1)–Fe(1)
O(1)–C(1)–Fe(1)
O(2)–C(2)–Fe(1)
O(3)–C(3)–Fe(1)
N(2)–C(8)–N(3)
C(8)–C(7)–S(1)
S(1)–C(7)–S(2)
C(8)–C(7)–S(2)
S(2)–C(7)–Fe(1)
C(8)–C(7)–Fe(1)
S(1)–C(7)–Fe(1)
89.7(1)
90.2(1)
173.3(1)
91.0(1)
91.5(1)
152.3(1)
81.9(1)
152.0(1)
105.5(1)
47.07(8)
59.24(9)
174.3(3)
175.5(3)
178.9(4)
109.3(2)
114.2(2)
122.4(1)
111.3(1)
119.4(1)
110.8(1)
73.7(1)
C(4)–Fe(2)–C(6)
C(5)–Fe(2)–C(6)
C(6)–Fe(2)–N(5)
C(4)–Fe(2)–N(5)
C(6)–Fe(2)–C(19)
C(5)–Fe(2)–C(19)
N(5)–Fe(2)–C(19)
C(4)–Fe(2)–S(3)
C(5)–Fe(2)–S(3)
C(19)–Fe(2)–S(3)
C(19)–S(3)–Fe(2)
O(4)–C(4)–Fe(2)
O(5)–C(5)–Fe(2)
O(6)–C(6)–Fe(2)
N(7)–C(20)–N(6)
C(20)–C(19)–S(3)
S(3)–C(19)–S(4)
C(20)–C(19)–S(4)
S(4)–C(19)–Fe(2)
C(20)–C(19)–Fe(2)
S(3)–C(19)–Fe(2)
91.3(2)
87.3(1)
174.5(1)
91.4(1)
92.7(1)
155.5(1)
81.9(1)
152.0(1)
108.1(1)
47.49(8)
58.66(9)
175.9(3)
173.2(3)
177.4(4)
109.2(2)
114.5(2)
119.3(1)
113.5(2)
118.7(1)
111.7(1)
73.9(1)
153.75(9)
81.70(8)
153.96(8)
105.99(7)
47.83(6)
58.22(7)
179.1(2)
175.9(2)
174.9(2)
110.3(1)
107.98(1)
113.8(1)
119.4(1)
117.7(1)
112.5(1)
73.95(8)
broad band at 3423.1 cmꢀ1 of O–H stretching vibration,
originating from the water in the lattice. The strong peak
at 1562.1 cmꢀ1 is attributed to the C@N stretching vibra-
tion. In addition, the strong peak near 1090 cmꢀ1 indicates
the presence of typical non-coordinate perchlorate ion [28].
The molecular structure of complex 7 has been confirmed
by crystal X-ray diffraction analysis, and the structure of
its cation is presented in Fig. 3. In this complex, the cobalt
atom is octahedrally coordinated by four pyrazolyl nitro-
gen atoms and two sulfur atoms, and N-phenyl-2,2-
bis(3,5-dimethylpyrazol-1-yl)thioacetamide acts as a tri-
dentate monoanionic j3-(N,N,S) chelating ligand. Two sul-
fur atoms lie in a cis-position with the bite angle of \S–Co–
2.5. Synthesis of ethyl 2,2-bis(3,5-dimethylpyrazol-1-yl)-
dithioacetate and its reaction with Fe(CO)5
Ethyl 2,2-bis(3,5-dimethylpyrazol-1-yl)dithioacetate (8)
can be easily obtained by the reaction of 2,2-bis(3,5-dim-
ethylpyrazol-1-yl)dithioacetate anion [34] with ethyl iodide
(Scheme 2). Treatment of this ligand with Fe(CO)5 under
UV irradiation gives complex 9, which has been character-
ized by NMR. The proton signal of CH group in 9
(6.22 ppm) is considerably shifted to higher field than that
in free ligand 8 (7.07 ppm), but similar with those in com-
plexes 5 (6.44 ppm) and 6 (6.43 ppm), respectively. In addi-
tion, two sets of 1H and 13C NMR signals corresponding to
two inequivalent pyrazolyl ligands have been observed in
complex 9. These results are consistent with the j2-(p,N)
coordination mode of ligand 8 in this complex.
The structure of complex 9 has also been confirmed by
crystal X-ray diffraction analysis, which consists of two
crystallography independent molecules. The two mole-
cules are essentially the same, only slightly different in
bond distances and angles. One of them is presented in
Fig. 4, and selected bond distances and angles are listed
in Table 1. Similar with N-phenyl-2,2-bis(3,5-dim-
ethylpyrazol-1-yl)thioacetamide ligand in complex 7, ethyl
˚
S (89.2(1)ꢁ). The average Co–S (2.262 (1) A) and Co–N
˚
(1.970(4) A) distances are comparable to those in related
octahedral cobalt(III) complexes [29–32]. The N(5)–C(7)
˚
˚
(1.287(6) A) and N(10)–C(25) (1.263(6) A) distances are
˚
considerably shorter than the N(5)–C(6) (1.433(7) A) and
˚
N(10)–C(24) (1.423(7)A) distances, but similar to the
C@N distance of the –C(Sꢀ)@N– fragment in complexes
˚
[Cp(CH3)C@N–N@C(S)C4H3O]W(CO)3SnCl2 (1.298(6) A)
and
[Cp(CH3)C@N–N@C(S)C4H3S]Mo(CO)3SnCl2
˚
(1.286(8) A) [33], indicating the C@N double bond charac-
ter of these two bonds.

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R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
Fig. 4. The molecular structure of complex 9. The thermal ellipsoids are
drawn at the 30% probability level.
Fig. 3. Crystal structure of the complex cation of 7. The thermal ellipsoids
are drawn at the 30% probability level. The anion and uncoordinated
˚
water molecule have been omitted for clarity. Selected bond distances (A)
and angles (ꢁ): Co(1)–N(1) 1.952(4), Co(1)–N(4) 1.976(4), Co(1)–N(6)
2.002(4), Co(1)–N(9) 1.951(4), Co(1)–S(1) 2.259(1), Co(1)–S(2) 2.264(1),
S(1)–C(7) 1.712(5), N(2)–C(8) 1.430(6), N(3)–C(8) 1.437(6), N(5)–C(6)
1.433(7), N(5)–C(7) 1.287(6), N(7)–C(26) 1.448(6), N(8)–C(26) 1.428(6),
N(10)–C(24) 1.423(7), N(10)–C(25) 1.263(6); N(1)–Co(1)–N(9) 179.7(1),
N(1)–Co(1)–N(4) 87.9(1), N(4)–Co(1)–N(6) 91.7(1), N(1)–Co(1)–S(1)
89.2(1), N(1)–Co(1)–S(2) 91.4(1), N(4)–Co(1)–S(2) 173.8(1), S(1)–Co(1)–
S(2) 79.59(5), C(7)–S(1)–Co(1) 104.1(1), N(2)–C(8)–N(3) 111.4(4), N(8)–
C(26)–N(7) 111.0(4), C(25)–N(10)–C(24) 119.9(4), C(7)–N(5)–C(6)
120.5(4), N(10)–C(25)–S(2) 129.9(4), C(26)–C(25)–S(2) 116.0(3), N(5)–
C(7)–C(8) 113.9(4), N(5)–C(7)–S(1) 130.1(4).
(171.71(9)ꢁ) in complex 7. In addition, the C@S (C(7)–
˚
S(1) 1.740(3) A) is comparable to that in complex 7
˚
(1.757(2) A), but still slightly longer than that in complex
˚
3 (1.675(3) A). Other structural parameters, such as the
˚
˚
Fe–S distances (2.2806(9) A in complex 9 and 2.275(6) A
in complex 7) and Fe–C distances (Fe(1)–C(7)
˚
˚
2.042(3) A in complex 9) and Fe–C(10) (2.015(2) A in
complex7), are very similar in complexes 9 and 7.
In summary, new heteroscorpionate ligands, N-phenyl-
2,2-bis(pyrazol-1-yl)thioacetamides and ethyl 2,2-bis(pyra-
zol-1-yl)dithioacetate, have been successfully prepared. N-
phenyl-2,2-bis(pyrazol-1-yl)thioacetamides can coordinate
in three different ways, as monodentate ligand by the sulfur
atom to carbonyl tungsten complexes, as neutral j2-(p,N)
bidentate ligand by one pyrazolyl nitrogen atom and the
C@S p-bond to carbonyl iron complexes, and as tridentate
monoanionic j3-(N,N,S) chelating ligand by two pyrazolyl
nitrogen atoms and the sulfur atom to cobalt(III) com-
plexes. Ethyl 2,2-bis(pyrazol-1-yl)dithioacetate also acts
as a neutral j2-(p,N) bidentate ligand when reacts with car-
bonyl iron.
3. Experimental
Solvents were dried by standard methods and distilled
prior to use. All reactions were carried out under an argon
atmosphere using standard Schlenk and Cannula tech-
niques. NMR spectra (1H and 13C) were recorded on a
Bruker AV300 spectrometer, and the chemical shifts were
reported in ppm with respect to reference standards (inter-
nal SiMe4 for 1H NMR and 13C NMR spectra) using
CDCl3 as solvent unless otherwise noted. IR spectral data
were obtained from a Bruker Equinox55 spectrometer in
KBr pellets or Nujol mulls. Elemental analyses were car-
ried out on an Elementar Vairo EL analyzer. Melting
Scheme 2. Synthesis of ligand 8 and its reaction with Fe(CO)5.
2,2-bis(3,5-dimethylpyrazol-1-yl)dithioacetate also acts as
a neutral bidentate j2-(p,N) ligand through only one pyr-
azolyl nitrogen atom and the C@S p-bond, which is side-
on bonded to the iron atom in an g2-C,S fashion. The
axial angle of \C(3)–Fe(1)–N(1) (173.3(1)ꢁ) is slightly big-
ger than the corresponding angle of \C(1)–Fe(1)–N(4)

R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
1713
points were reported with a X-4 digital melting-point appa-
ratus and were uncorrected.
using CH2Cl2/hexane (v/v = 1:1) as eluent. The red or yel-
low eluent was concentrated to dryness under vacuum, and
the residual was recrystallized from CH2Cl2/hexane to give
complexes 3–6.
3.1. Preparation of PhHNCSCH(3,5-Me2Pz)2 (1)
To a solution of bis(3,5-dimethylpyrazol-1-yl)methane
(0.408 g, 2 mmol) in THF (30 ml) was added a hexane solu-
tion of n-BuLi (2 M, 1.0 ml) at ꢀ70 ꢁC, and the mixture
was stirred for 1 h at that temperature. To the mixture
was added phenyl isothiocyanate (0.24 ml, 2 mmol). The
reaction mixture was stirred at ꢀ70 ꢁC for 1 h, and allowed
to slowly reach room temperature and stirred overnight.
The solvent was removed under a reduced pressure, and
the residual solid was washed with hexane and dried in
vacuo to yield PhNCS(Li)CH(3,5-Me2Pz)2 as a slightly yel-
low solid. After water (1 ml) was added to this solid,
CH2Cl2 (20 ml) was used to extract this solid. The extracted
solution was passed through a short silica column to give a
yellow solution. After the solvent was removed,
PhHNCSCH(3,5-Me2Pz)2 (1) (0.44 g) was obtained as a
yellow solid. Yield: 65%, mp 102–104 ꢁC. 1H NMR: d
12.47 (br, s, 1H, NH), 7.87, 7.42, 7.28 (d, t, t, 2H, 2H,
1H, C6H5), 7.16 (s, 1H, CH), 5.91 (s, 2H, H4 of pyrazole
ring), 2.45, 2.27 (s, s, 6H, 6H, CH3). 1H NMR
(CDCl3 + D2O): d 7.88, 7.41, 7.27 (d, t, t, 2H, 2H, 1H,
C6H5), 7.17 (s, 1H, CH), 5.88 (s, 2H, H4 of pyrazole ring),
2.43, 2.25 (s, s, 6H, 6H, CH3). 13C NMR: d 188.03 (C@S),
148.86, 139.68 (3- or 5-position carbon of pyrazole ring),
137.46, 127.82, 125.94, 121.88 (C6H5), 106.08 (4-position
carbon of pyrazole ring), 74.00 (CH), 12.84, 10.40 (3- or
5-CH3). Anal. Calc. for C18H21N5S: C, 63.69; H, 6.24; N,
20.63. Found: C, 63.35; H, 6.21; N, 20.18%.
3.3.1. PhHNCSCH(3,5-Me2Pz)2W(CO)5 (3)
This complex was obtained by the reaction of W(CO)6
with ligand 1 as a orange-red crystal. Yield: 82%. In addi-
tion, this complex has also been obtained by the reaction
of ligand 1 with W(CO)5 THF in THF under reflux for
1
1 h. H NMR: d 12.01 (br, s, 1H, NH), 7.65, 7.48, 7.35 (d,
t, m, 2H, 2H, 2H, C6H5 and CH), 5.95 (s, 2H, H4 of pyrazole
ring), 2.32, 2.21 (s, s, 6H, 6H, CH3). 13C NMR: d 206.62,
197.12 (CO), 188.99 (C@S), 150.73, 141.05 (3- or 5-position
carbon of pyrazole ring), 137.13, 129.43, 128.40, 123.65
(C6H5), 108.10 (4-position carbon of pyrazole ring), 74.59
(CH), 13.74, 11.04 (3- or 5-CH3). IR (KBr, cmꢀ1):
m
NH = 3198.2 (w); mCO = 2071.6 (m), 1981.4 (m), 1950.3
(vs), 1924.7 (vs), 1884.6 (vs). (Nujol, cmꢀ1): mNH = 3185
(w); mCO = 2071.6 (m), 1982.1 (m), 1951.0 (vs), 1912.1 (vs),
1883.2 (vs). Anal. Calc. for C23H21N5O5SW: C, 41.64; H,
3.19; N, 10.56. Found: C, 41.58; H, 3.05; N, 10.66%.
3.3.2. PhHNCSCH(3,4,5-Me3Pz)2W(CO)5 (4)
This complex was obtained by the reaction of W(CO)6
1
with ligand 2 as a red crystal. Yield: 80%. H NMR: d
12.04 (br, s, 1H, NH), 7.65, 7.49–7.33 (d, m, 2H, 4H,
C6H5 and CH), 2.24, 2.15, 1.90 (s, s, s, 6H, 6H, 6H,
CH3). 13C NMR: d 197.18 (CO), 189.09 (C@S), 149.89,
140.05 (3- or 5-position carbon of pyrazole ring), 137.29,
129.36, 128.83, 123.65 (C6H5), 114.45 (4-position carbon
of pyrazole ring), 74.80 (CH), 12.28, 9.65, 8.01 (3-, 4-, or
5-CH3). IR (Nujol, cmꢀ1): mNH = 3185 (w); mCO = 2071.4
(m), 1984.9 (m), 1948.6 (vs), 1913.3 (vs), 1877.8 (vs). Anal.
Calc. for C25H25N5O5SW: C, 43.43; H, 3.64; N, 10.13.
Found: C, 43.05; H, 3.70; N, 10.16%.
3.2. Preparation of PhHNCSCH(3,4,5-Me3Pz)2 (2)
This ligand was obtained as a yellow solid in a similar
method using bis(3,4,5-trimethylpyrazol-1-yl)methane
instead of bis(3,5-dimethylpyrazol-1-yl)methane as
described above for 1. Yield: 60%, mp 140–142 ꢁC. 1H
NMR: d 12.47 (br, s, 1H, NH), 7.84, 7.40, 7.26 (d, t, t,
2H, 2H, 1H, C6H5), 7.13 (s, 1H, CH), 2.34, 2.18, 1.88 (s,
s, s, 6H, 6H, 6H, CH3). 13C NMR: d 189.63 (C@S),
149.06, 138.63 (3- or 5-position carbon of pyrazole ring),
137.12, 128.83, 126.88, 122.93 (C6H5), 113.25 (4-position
carbon of pyrazole ring), 76.80 (CH), 12.30, 9.95, 8.09 (3-
, 4-, or 5-CH3). Anal. Calc. for C20H25N5S: C, 65.36; H,
6.86; N, 19.06. Found: C, 65.67; H, 6.51; N, 19.53%.
3.3.3. PhHNCSCH(3,5-Me2Pz)2Fe(CO)3 (5)
This complex was obtained by the reaction of Fe(CO)5
with ligand 1 as a yellow crystal. Yield: 70%. H NMR: d
1
7.16, 6.96, 6.74 (t, d, t, 2H, 2H, 1H, C6H5), 6.44 (s, 1H,
CH), 5.74, 5.64 (s, s, 1H, 1H, H4 of pyrazole ring), 5.15 (s,
1H, NH, which disappeared when D2O was added), 2.38,
2.19, 1.97, 1.60 (s, s, s, s, 3H, 3H, 3H, 3H, CH3). 13C
NMR: d 209.15, 208.74, 206.49 (CO), 151.40, 149.89,
142.67, 141.12 (3- or 5-position carbon of pyrazole ring),
148.31, 129.11, 118.84, 114.84 (C6H5), 108.89, 105.21 (4-
position carbon of pyrazole ring), 90.14 (C@S), 73.29
(CH), 15.70, 13.80, 11.73, 9.82 (3- or 5-CH3). IR (KBr,
cmꢀ1): mCO = 2064.8 (vs), 2010.8 (s), 2003.4 (s), 1993.0 (vs),
1976.1 (vs). Anal. Calc. for C21H21FeN5O3S: C, 52.62; H,
4.42; N, 14.61. Found: C, 52.39; H, 4.86; N, 15.06%.
3.3. Reaction of 1 and 2 with W(CO)6 and Fe(CO)5
Since all reactions were run similarly, a general proce-
dure was described. The solution of W(CO)6 or Fe(CO)5
(0.3 mmol) and ligand 1 or 2 (0.3 mmol) dissolved in
THF (30 ml) was irradiated with a 300 W high-pressure
mercury lamp for 10 h at room temperature. After the reac-
tion completed, the solvent was removed in vacuo, and the
residual was purified by column chromatography on silica
3.3.4. PhHNCSCH(3,4,5-Me3Pz)2Fe(CO)3 (6)
This complex was obtained by the reaction of Fe(CO)5
with ligand 2 as a yellow crystal. Yield: 68%. H NMR: d
1
7.17, 6.94, 6.73 (t, d, t, 2H, 2H, 1H, C6H5), 6.43 (s, 1H,

1714
R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
CH), 5.05 (s, 1H, NH), 2.32, 2.16, 1.91, 1.77, 1.75, 1.50 (s,
s, s, s, s, s, 3H, 3H, 3H, 3H, 3H, 3H, CH3). 13C NMR: d
209.06, 208.71, 206.47 (CO), 150.01, 148.80, 139.61,
137.71 (3- or 5-position carbon of pyrazole ring), 148.34,
129.34, 119.07, 114.69 (C6H5), 112.93, 111.30 (4-position
carbon of pyrazole ring), 90.25 (C@S), 73.66 (CH), 13.79,
12.13, 10.08, 8.37, 8.33, 7.80 (3-, 4-, or 5-CH3). IR (KBr,
cmꢀ1): mCO = 2064.6 (vs), 2010.9 (s), 2003.2 (s), 1993.2
(vs), 1976.2 (vs). Anal. Calc. for C23H25FeN5O3S: C,
54.44; H, 4.97; N, 13.80. Found: C, 54.16; H, 4.96; N,
13.37%.
was added carbon disulfide (0.12 ml, 2 mmol). The reaction
mixture was stirred at ꢀ70 ꢁC for 1 h, and allowed to
slowly reach room temperature and stirred continuously
for 2 h. Then, ethyl iodide (0.16 ml, 2 mmol) was added
and the mixture was stirred for 8 h at room temperature.
The solvent was removed under a reduced pressure, and
the residual solid was dissolved in CH2Cl2 (10 ml). The
solution was passed through a short silica column to give
a red solution. After the solvent was removed again, the
residual solid was washed with hexane to give 0.26 g of 8
1
as orange-yellow crystals. Yield: 40%, mp 103–105 ꢁC. H
NMR: d 7.07 (s, 1H, CH), 5.82 (s, 2H, H4 of pyrazole ring),
3.17 (q, 2H, CH3CH2), 2.22, 2.18 (s, s, 6H, 6H, CH3), 1.26
(t, 3H, CH3CH2). 13C NMR: d 226.14 (C@S), 149.18,
141.82 (3- or 5-position carbon of pyrazole ring), 107.38
(4-position carbon of pyrazole ring), 81.90 (CH), 31.70
(CH3CH2), 13.90 (CH3CH2), 12.09, 11.86 (3- or 5-CH3).
Anal. Calc. for C14H20N4S2: C, 54.51; H, 6.54; N, 18.16.
Found: C, 54.26; H, 6.72; N, 18.05%.
3.4. Preparation of [PhNCSCH(3,5-Me2Pz)2]2-
Co(ClO4) Æ H2O (7 Æ H2O)
A methanol (5 ml) solution of PhNCS(Li)CH(3,5-
Me2Pz)2 (345 mg, 1 mmol) was slowly placed over the same
solution (5 ml) of Co(ClO4)2 Æ 6H2O (183.5 mg, 0.5 mmol)
in air. After several days, brown crystals were formed,
which were filtered off and dried in vacuo to give 0.13 g
(30%) of complex 7 Æ H2O. IR (KBr, cmꢀ1): mOH = 3423.1
3.6. Reaction of ligand 8 with Fe(CO)5
(br, s); mC@N = 1562.1 (vs), mClO ¼ 1090:5 (vs). Anal. Calc
4
for C36H40ClCoN10O4S2 Æ H2O: C, 50.65; H, 4.69; N,
This reaction was carried out similarly as described
above for the reaction of ligand 1 or 2 with Fe(CO)5. After
the reaction completed, the solvent was removed in vacuo,
and the residual was purified by column chromatography
on silica using CH2Cl2/hexane (v/v = 1:1) as eluent. The
red eluent was concentrated to dryness under vacuum,
and the residual was recrystallized from CH2Cl2/hexane
to give EtSCSCH(3,5-Me2Pz)2Fe(CO)3 (9) as a red crystal.
Yield: 65%. 1H NMR: 6.22 (s, 1H, CH), 5.84, 5.72 (s, s, 1H,
16.42. Found: C, 50.30; H, 4.99; N, 16.38%.
3.5. Preparation of CH3CH2SCSCH(3,5-Me2Pz)2 (8)
To a solution of bis(3,5-dimethylpyrazol-1-yl)methane
(0.408 g, 2 mmol) in THF (30 ml) was added a hexane solu-
tion of n-BuLi (2 M, 1.0 ml) at ꢀ70 ꢁC, and the mixture
was stirred for 1 h at that temperature. To the mixture
Table 2
Crystallographic data and refinement parameters for complexes 3, 5, 7, and 9
Complex
3
5
7 Æ H2O
9
Formula
C
663.36
0.28 · 0.22 · 0.20
Monoclinic
P21/c
23H21N5O5SW
C21H21FeN5O3S
479.34
0.28 · 0.24 · 0.22
Monoclinic
P21/c
C36H42ClCoN10O5S2
853.30
0.22 · 0.18 · 0.16
Orthorhombic
P212121
C34H40Fe2N8O6S4
896.68
0.22 · 0.18 · 0.16
Triclinic
Formula weight
Crystal size (mm)
Crystal system
Space group
ꢀ
P1
Cell parameters
˚
a (A)
18.339(13)
10.936(8)
13.592(9)
90
108.521(8)
90
13.504(1)
14.773(1)
12.286(1)
90
110.637(1)
90
14.085(5)
16.327(6)
17.722(7)
90
90
90
11.871(1)
11.886(1)
14.950(2)
96.487(2)
91.105(2)
91.230(2)
2094.9(6)
2
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A)
2585(3)
4
2293.7(4)
4
4075(3)
4
Z
T (K)
293(2)
1.705
4.40–50.06
1296
0.71073
4.592
293(2)
1.388
4.24–50.06
992
0.71073
0.780
293(2)
1.391
3.4–50.06
1776
0.71073
0.643
293(2)
1.421
4.16–50.06
928
0.71073
0.943
Dcalc (g cmꢀ3
2h Range (ꢁ)
F(000)
)
˚
k (MoKa) (A)
l (mmꢀ1
)
Number of reflections measured
Number of reflections observed [Rint
Number of parameters
13500
4548 [0.0256]
321
12266
4055 [0.0186]
284
22180
7193 [0.0485]
511
11482
7305 [0.0186]
496
]
Goodness-of-fit
1.015
1.046
1.048
1.040
Residuals R, Rw [I > 2r(I)]
0.020, 0.048
0.032, 0.083
0.047, 0.120
0.0389, 0.0981

R.-Y. Tan et al. / Journal of Organometallic Chemistry 692 (2007) 1708–1715
1715
1H, H4 of pyrazole ring), 2.56 (m, 5H, CH3 and CH2CH3),
References
2.36, 2.10, 1.90 (s, s, s, 3H, 3H, 3H, CH3), 1.08 (t, 3H,
CH2CH3). 13C NMR: d 208.93, 208.63, 206.68 (CO),
151.24, 148.70, 142.55, 140.05 (3- or 5-position carbon of
pyrazole ring), 108.84, 105.62 (4-position carbon of pyra-
zole ring), 82.85 (CH), 32.34 (CH3CH2), 15.74 (CH3CH2),
14.21, 13.72, 11.71, 11.54 (3- or 5-CH3). The carbon of
thiocarbonyl group was not observed possibly owing to
low solubility and low sensitivity of carbonyl carbon. IR
(KBr, cmꢀ1): mCO = 2069.0 (vs), 2003.7 (vs), 1990.4 (vs).
Anal. Calc. for C17H20FeN4O3S2: C, 45.54; H, 4.50; N,
12.50. Found: C, 45.51; H, 4.62; N, 12.76%.
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CH(3,5-Me2Pz)2 in CH3OH over the solution of
Co(ClO4)2 Æ 6H2O in the same solvent. Complex 7 had
water of crystallization, which was disordered. The site
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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). R.
Y. Tan thanks the 100 projects of Nankai University for
Undergraduates.
Appendix A. Supplementary material
CCDC 619075, 619076, 619077 and 626511 contain the
supplementary crystallographic data for 3, 5, 7 and 9.
These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the
Cambridge Crystallographic Data Centre, 12 Union Road,
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