Titanocene(IV) and vanadocene(IV) complexes of dicyanomethanidobenzoate

Article abstract of DOI:10.1016/j.jorganchem.2009.08.037

The new titanocene and vanadocene complexes of the non-linear pseudohalides Cp₂Ti(dcmb)₂, Cp₂VCl(dcmb), (η⁵-C₅H₄Me)₂VCl(dcmb) and Cp₂V(dcmb)₂ were prepared

Full text of DOI:10.1016/j.jorganchem.2009.08.037

Journal of Organometallic Chemistry 694 (2009) 4250–4255
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Journal of Organometallic Chemistry
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Titanocene(IV) and vanadocene(IV) complexes of dicyanomethanidobenzoate
a,
a
a
a
b
a
*
ˇ
ˇ ˇ
ˇ
ˇ
ˇ
Jan Honzícek , Jaromír Vinklárek , Milan Erben , Lukáš Strizík , Ivana Císarová , Zdenka Padelková
a Department of General and Inorganic Chemistry, Faculty of Chemical Technology, University of Pardubice, Studentská 573, 532 10 Pardubice, Czech Republic
b Department of Inorganic Chemistry, Faculty of Natural Science, Charles University in Prague, Hlavova 2030, 128 40 Praha 2, Czech Republic
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 14 July 2009
Received in revised form 25 August 2009
Accepted 26 August 2009
Available online 31 August 2009
The new titanocene and vanadocene complexes of the non-linear pseudohalides Cp2Ti(dcmb)2,
Cp2VCl(dcmb), (
5-C5H4Me)2VCl(dcmb) and Cp2V(dcmb)2 were prepared by reaction of titanocene
dichloride (Cp2TiCl2) and vanadocene dichlorides (Cp2VCl2, (
5-C5H4Me)2VCl2) with dicyanomethanido-
g
g
benzoic acid (dcmbH, PhC(OH)C(CN)2). These reactions have proven that the dcmb ligand could be coor-
dinated to the central metal by oxygen or nitrogen donor atoms. The bonding mode of the dcmb ligand
reflects properties of the central metal. The strongly oxophilic titanium(IV) shows the bonding through
oxygen atom while bonding through nitrogen atom was observed for less oxophilic vanadium(IV). The
bonding fashion of the dcmb ligands was determined by spectroscopic methods. X-ray diffraction anal-
ysis was used for the structure determination of the compounds dcmbHꢀH2O, Cp2Ti(dcmb)2ꢀCH2Cl2,
Keywords:
Bent metallocene
Titanocene
Vanadocene
Pseudohalide complexes
X-ray structure
(g
5-C5H4Me)2VCl(dcmb) and [Cp2V(OC(Ph)C(CN)C(OMe)NH)][dcmb].
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
2. Results and discussion
Bent metallocene complexes of the type [Cp2MCl2] (Cp = g5
-
2.1. Syntheses and characterization
C5H5; M = early transition metal) are currently under comprehen-
sive investigation due to their promising catalytic [1,2] and biolog-
ical activity [3,4]. Although metallocene complexes of linear
pseudohalide ligands [Cp2MX2] (X = NCO, NCS, NCSe, N3, CN) are
known for long time [5–7], their analogues containing non-linear
pseudohalides were described recently (X = dca, tcm, dcnm) [8–
10]. The similarity in coordination chemistry of titanocene dichlo-
ride (Cp2TiCl2; 1a) and vanadocene dichloride (Cp2VCl2; 2a) is well
known. The ligand-exchange reactions give pseudohalide com-
plexes with ligands bonded through the same donor atom. The
only difference was observed when the reactions are carried out
in an aqueous solution. In this case, several titanocene complexes
give dimers with two bis-cyclopentadienyl titanium(IV) units con-
nected via oxygen bridging [(Cp2TiX)2O] [9,11,12].
Dicyanomethanidobenzoic acid (dcmbH) was prepared accord-
ing to the procedure published elsewhere [13]. Its recrystallization
from wet MeCN gives dcmbHꢀH2O that was used for the reactions
with bent metallocenes. The X-ray diffraction analysis of
dcmbHꢀH2O has shown that the dcmb is protonated at oxygen
atom (see Fig. 1). The detail description of the molecular structure
is given in the separate section. The infrared and Raman spectra
show the bands of the C„N stretching at 2236 cmꢁ1
IR and Raman) 2229 cmꢁ1 s(C„N), IR) and 2228 cmꢁ1
Raman). The small vibrational coupling of the C„N stretching (IR:
= 7 cmꢁ1; Raman: = 8 cmꢁ1) is caused with nearly orthogonal
(m
a(C„N),
(m
(ms(C„N),
D
D
orientation of the CN groups.
Aqueous solution of titanocene dichloride (1) reacts with
dcmbHꢀH2O giving Cp2Ti(dcmb)2 (3) as is shown in Scheme 2.
The exchange of both chlorine ligands was evidenced by spectro-
scopic measurement. The 1H NMR shows singlet at 6.72 (10H,
Cp) and multiplets at ꢂ7.45 (d, 4H, Ph), 7.40 (t, 2H, Ph) and
7.11 ppm (t, 4H, Ph). The intensity of the signals is in the line with
the proposed structure of compound 3. The dcmb ligands are
bonded through oxygen donor atoms as was proven by 13C NMR
spectra. The single band in the in the region of the cyano groups
at 193.6 ppm shows that all four cyano groups of the compound
3 are equivalent.
This work is focused on coordination ability of the dic-
yanomethanidobenzoate (dcmb, [PhC(O)C(CN)2]ꢁ). It is a pseudo-
halide analogue of benzoate containing dicyanomethanide groups
(@C(CN)2) instead of carbonyl oxygen (@O). The reactions with
titanocene dichloride (1: Cp2TiCl2) and vanadocene dichlorides
(2a: Cp2VCl2, 2b: (g
5-C5H4Me)2VCl2) show the bonding ability of
the dcmb ligand. It can be coordinated through oxygen or nitrogen
atom as was proposed based on the contribution structures de-
picted in Scheme 1.
Infrared and Raman spectra show characteristic bands of Cp2Ti
moiety such as C–H stretching (IR, Raman: ꢂ3100 cmꢁ1), Cp ring
* Corresponding author. Fax: +420 46603 7068.
E-mail address: jan.honzicek@upce.cz (J. Honzícek).
breathing (Raman: 1130 cmꢁ1), Cp ring tilting (Raman: 269 cmꢁ1
)
ˇ
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.08.037

ˇ
J. Honzícek et al. / Journal of Organometallic Chemistry 694 (2009) 4250–4255
4251
Scheme 1. Contributing structures of dcmb.
Fig. 2. ORTEP drawing of Cp2Ti(dcmb)2 present in the crystal structure of 3ꢀCH2Cl2
with atom numbering (ellipsoids: 30% probability). Selected bond lengths (Å) and
angles (°): Ti1–O1 1.969(2), Ti1–O2 1.947(2), Cg(C1–C5)–Ti1 2.0564(14), Cg(C6–
C10)–Ti1 2.0539(14), C11–O1 1.274(4), C21–O2 1.275(4), C13–N1 1.137(4), C14–N2
1.142(5), C11–C12 1.387(4), C12–C13 1.427(4), C12–C14 1.419(5), C23–N3
1.136(4), C24–N4 1.144(5), C21–C22 1.380(4), C22–C23 1.434(4), C22–C24
1.422(5), O1–Ti1–O2 95.79(9), Cg(C1-C5)–Ti1–Cg(C6–C10) 132.84(6), Ti1–O1–C11
156.89(19), Ti1–O2–C21 163.65(19), N1–C13–C12 177.6(4), N2–C14–C12 177.2(4),
O1–C11–C12 123.7(3), O1–C11–C15 116.6(3), C12–C11–C15 119.7(3), C11–C12–
C14 123.3(3), C11–C12–C13 121.5(3), C13–C12–C14 115.0(3), N3–C23–C22
177.8(4), N4–C24–C22 176.7(4), O2–C21–C22 122.4(2), O2–C21–C25 114.9(3),
C22–C21–C25 122.6(3), C21–C22–C24 124.4(3), C21–C22–C23 121.5(3), C23–C22–
C24 114.0(3).
Fig. 1. ORTEP drawing of dcmbHꢀH2O with atom numbering (ellipsoids: 30%
probability). Selected bond lengths (Å) and angles (°): C4–O1 1.309(2), C1–N1
1.142(3), C2–N2 1.147(3), C1–C3 1.424(3), C2–C3 1.421(3), C3–C4 1.380(3), C4–C5
1.469(3), N1–C1–C3 178.6(2), N2–C2–C3 178.6(2), C1–C3–C2 116.85(19), C1–C3–
C4 122.9(2), C2–C3–C4 120.17(19), O1–C4–C3 116.08(19), O1–C4–C5 120.46(18),
C3–C4–C5 123.37(19).
Scheme 2. Preparation of compound 3.
[14,15]. The bands of the C„N stretching were observed in infrared
spectrum at 2214 cmꢁ1
(
m
a(C„N)) and 2202 cmꢁ1
(
m
s(C„N)) and
a(C„N)) and 2206 cmꢁ1
s(C„N)). This fact is further supported by small difference be-
tween (C„N) stretching bands (IR: Raman:
= 12 cmꢁ1
= 10 cmꢁ1). These
values are similar to those observed for
dcmbHꢀH2O.
in Raman spectrum at 2216 cmꢁ1
(m
Scheme 3. Preparation of compounds 4a and 4b.
(m
m
D
;
D
D
and exchange of the chlorine atoms with pseudohalides was
proved by infrared spectroscopy. Medium bands observed at
ꢂ3100 cmꢁ1
(mC–H) prove presence of the g
5-cyclopentadienyl
The structure of the compound 3, determined by X-ray diffrac-
tion analysis (see Fig. 2), proves the conclusions of the spectro-
scopic measurements. The detail description of the molecular
structure is given in the separate section.
rings. Bonding of the pseudohalide ligands is evident from strong
bands in the region 2210–2160 cmꢁ1
(mC„N). The coordination
of the dcmb through nitrogen atom is evident from medium to
strong bands of the C@O stretching (IR ꢂ1595 cmꢁ1). Significant
difference between energies of the C„N stretching modes was ob-
served in the infrared spectra of the compounds 4a and 4b (46 and
48 cmꢁ1 for 4a and 4b, respectively). The band at ꢂ2160 cmꢁ1 was
assigned to the coordinated cyano group whereas band at
ꢂ2210 cmꢁ1 to the uncoordinated group. The disubstituted com-
plex 5a shows bands of cyano groups at 2211, 2193 and
2167 cmꢁ1. Broad wavelength span of C„N stretching modes
observed for compound 4a, 4b and 5a indicate the presence of cy-
Synthesis of the vanadocene compounds Cp2VCl(dcmb) (4a),
(g
5-C5H4Me)2VCl(dcmb) (4b) and Cp2V(dcmb)2 (5a) is shown in
Schemes 3 and 4. Aqueous solutions of vanadocene dichlorides
(2a, 2b) react with dcmbH giving purple precipitates of
Cp2VCl(dcmb) (4a) and (g
5-C5H4Me)2VCl(dcmb) (4b), respectively.
Disubstituted analogue Cp2V(dcmb)2 (5a) was prepared in two-
phase system water/CH2Cl2.
Vanadocene complexes 4a, 4b and 5a were characterized by
spectroscopic methods. Presence of the bent metallocene moiety

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J. Honzícek et al. / Journal of Organometallic Chemistry 694 (2009) 4250–4255
4252
EPR spectra of complexes 4a, 4b and 5a, collected at room temper-
ature in anhydrous CH2Cl2, show the eight-line hyperfine coupling,
corresponding to the nuclear spin value of 51V (I = 7/2, 99.8%). The
|Aiso| and giso values of compounds 4a, 4b and 5a were found in
the range characteristic for the compounds containing [(Cp0)2V]2+
moiety, see Table 1.
The reactivity of Cp2V(dcmb)2 (5a) was further investigated. It
was found that coordinated cyano group of the compound 5a is
activated to the nucleophilic attack by methanol. Upon this reac-
tion, ketiminate complex [Cp2V(OC(Ph)C(CN)C(OMe)NH)][dcmb]
(6a) is formed, see Scheme 4. The EPR spectroscopic measurements
proved that this reaction does not produce any other paramagnetic
product. The compound 6a gives the eight-line spectrum with
|Aiso| = 67.2 ꢃ 10ꢁ4 cmꢁ1 and giso = 1.983 (see Table 1). The infrared
spectrum shows the bands of the cyano groups at 2207, 2201, 2178
and 2152 cmꢁ1. Strong band at 3222 cmꢁ1 was assigned to N–H
stretching mode of ketiminate moiety. The molecular structure of
the compound 6a was determined by X-ray diffraction analysis.
It is described in detail in the following section.
2.2. X-ray structures of dcmbHꢀH2O, 3ꢀCH2Cl2, 4b, and 6a
The molecular structures of dcmbHꢀH2O, 3ꢀCH2Cl2, 4b, and 6a
are depicted in Figs. 1–4, respectively. Their crystallographic data
are summarized in Table 2.
The X-ray structure of the dcmbHꢀH2O proves that the dcmb is
protonated at oxygen atom. The bond length C–O was found to be
considerably longer (1.309(2) Å), and the bond lengths C„N are
slightly shorter (1.142(3), 1.147(3) Å) than the appropriate bonds
in the anionic dcmb that was found in the crystal lattice of the
compound 6a (C@O = 1.243(2) Å, C„N = 1.156(2), 1.153(2) Å).
The hydrogen bonding interactions are depicted in Fig. 5. Two
hydrogen bonds were found between hydrogen atoms of water
and cyano groups of dcmb. Further hydrogen bond is between hy-
droxyl group of dcmbH and oxygen atom of water.
Fig. 3. ORTEP drawing of
(g
5-C5H4Me)2VCl(dcmb) (4b) with atom numbering
(ellipsoids: 30% probability). Selected bond lengths (Å) and angles (°): V1–N1
2.046(2), V1–Cl1 2.3680(9), Cg(C1–C5)–V1 1.9691(15), Cg(C7–C11)–V1 1.9709(14),
C16–O1 1.233(3), C13–N1 1.145(3), C15–N2 1.145(4), C13–C14 1.400(4), C14–C15
1.424(4), C14–C16 1.426(4), C17–C16 1.494(4), N1–V1–Cl1 84.57(7), Cg(C1–C5)–
V1–Cg(C7–C11) 135.03(7), V1–N1–C13 168.8(2), N1–C13–C14 177.7(3), N2–C15–
C14 178.9(3), C13–C14–C15 117.4(3), C13–C14–C16 122.7(3), C15–C14–C16
119.2(3), O1–C16–C14 122.3(3), O1–C16–C17 120.1(3), C14–C16–C17 117.6(2).
The complexes 3, 4b, and 6a show the typical bent metallocene
structure with two
g
5-bonded cyclopentadienyl (3, 6a) or methyl-
Table 1
cyclopentadienyl rings (4b). The two other positions around cen-
tral metal are occupied with two monodentate (3, 4b) or one
bidentate ligand (6a).
Hyperfine coupling constants and g-factors of the vanadocene complexes.
|Aiso| (10ꢁ4 cmꢁ1
)
giso
2a
2b
4a
4b
5a
6a
69.7
69.6
69.0
69.1
68.4
67.2
1.989
1.990
1.987
1.987
1.986
1.983
The dcmb ligands in the compound 3 are bonded through oxy-
gen atoms. The bond lengths Ti–O were found to be 1.947(2) and
1.969(2) Å. The bond angle is O–Ti–O 95.79(9)°. The distances Ti–
O are longer the angle O–Ti–O is larger than those in the benzoate
complex Cp2Ti(OOCPh)2 (Ti–O 1.922(7), 1.930(5) Å, O–Ti–
O = 91.4(3)° [16]. The bond lengths CN vary between 1.136(4)
and 1.144(5) Å. The bond lengths CO were found to be around
1.274(4) and 1.275(4) Å.
ano groups coordinated to the metal atom through the nitrogen
atom [9,10].
X-ray diffraction analysis of the compound 4b has proven the
proposed molecular structure with dcmb ligand bonded through
the nitrogen atom (see Fig. 3).
The compound 4b has one dcmb ligand bonded to the vana-
dium(IV). The distance V–N was found to be 2.046(2) Å. This value
is similar to pseudohalides bonded through sp-nitrogen atom (g5
-
C5H4Me)2V(NCO)2, Cp2V(NCS)2, Cp2V(dca)2, (g
5-C5H4Me)2V(dca)2,
Compounds 4a, 4b and 5a are paramagnetic making their char-
acterization by NMR spectroscopy quite difficult. However, the oxi-
dation state of vanadium(IV) is suitable to EPR spectroscopy. The
((V–N ꢂ2.03–2.05 Å) [8,10,17,18] and shorter than in Cp2V(N3)2
(ꢂ2.08 Å) that is pseudohalide bonded through sp2-nitrogen atom
[19]. Longer distance V–N was also reported for cationic com-
Scheme 4. Preparation of compounds 5a and 6a: (a) water, dcmbH in CH2Cl2, aqueous NaOH; (b) MeOH.

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J. Honzícek et al. / Journal of Organometallic Chemistry 694 (2009) 4250–4255
4253
Fig. 5. Hydrogen bonds in dcmbHꢀH2O. Selected bond lengths (Å) and angles (°):
O1ꢀ ꢀ ꢀO2 2.549(2), O2ꢀ ꢀ ꢀN2c 2.861(3), O2ꢀ ꢀ ꢀN1d 2.856(3). Operators for generating
equivalent atoms: for c: ꢁx + 2, y ꢁ 1/2, ꢁz + 3/2; for d: x + 1, y, z + 1.
Fig. 4. ORTEP drawing of Cp2V(OC(Ph)C(CN)C(OMe)NH)][dcmb] (6a) with atom
numbering (ellipsoids: 30% probability). Selected bond lengths (Å) and angles (°):
V1–O1 1.9895(11), V1–N1 2.0775(14), Cg(C1-C5)–V1 1.9702(9), Cg(C6–C10)–V1
1.9654(10), C14–O1 1.2848(18), C12–N1 1.290(2), C21–N2 1.147(2), C12–O2
1.3427(19), C22–O2 1.451(2), C24–O3 1.243(2), C31–N3 1.156(2), C32–N4
1.153(2), O1–V1–N1 83.92(5), Cg(C1–C5)–V1–Cg(C6–C10) 134.10(4), V1–O1–C14
131.57(11), V1–N1–C12 129.13(12), C12–O2–C22 118.07(13), N2–C21–C13
177.8(2), N3–C31–C23 178.4(2), N4–C32–C23 179.6(2).
[Cp2V(acac)][OTf] (V–O ꢂ2.00 Å; V–O–C ꢂ129.7°) [21]. The dis-
tance V–N is significantly shorter than in compounds with neutral
ligands bonded through sp2-nitrogen atom [Cp2V(bpy)][OTf]2,
[Cp2V(phen)][OTf]2 (ꢂ2.13–2.14 Å) and similar with those or with
those with anionic univalent ligand bonded through sp2-nitrogen
atom Cp2V(N3)2 (ꢂ2.08 Å) [19].
pounds with neutral ligands bonded through sp-nitrogen atom
[Cp2V(NCMe)Cl][FeCl4] (2.087(2) Å) [20]. The bond length of the
coordinated CN group (1.145(3) Å) was found to be the same as
the uncoordinated one (1.145(4) Å). The bond length CO is signifi-
cantly shorter (1.233(3) Å) than in the titanium compound
1.275(4) Å. It is similar to the anionic dcmb (1.243(2) Å).
Compound 6 contains vanadocene(IV) ketiminate cation, while
the dcmb counter anion is out of the primary coordination sphere
of the vanadium. The bond length V–O (1.9895(11) Å) and bond
angle V–O–C (131.57(11)°) are similar to those in complex
3. Conclusions
The coordination chemistry of the dcmb ligand was investi-
gated using reactions of dcmbH with titanocene dichloride (1)
and vanadocene dichlorides (2a and 2b). These reactions give
two types of the complexes. The reaction with titanocene dichlo-
ride (1) forms Cp2Ti(dcmb)2 (3) that have both dcmb ligands
bonded through the oxygen atoms. Bonding of the dcmb ligands
Table 2
Crystallographic data for dcmbHꢀH2O, 3ꢀCH2Cl2, 4b and 6a.
Compound
dcmbHꢀH2O
3ꢀCH2Cl2
4b
6a
Formula
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C10H8N2O2
Monoclinic
P21/c
7.2938(9)
14.4572(9)
9.7381(16)
–
115.559(10)
–
4
C31H22Cl2N4O2Ti
Monoclinic
P21/c
20.2962(13)
9.4628(8)
14.6041(9)
–
93.387(9)
–
4
C22H19ClN2OV
Monoclinic
P21/c
10.2582(8)
16.1031(7)
12.3337(9)
–
112.851(6)
–
4
C31H24N4O3V
Triclinic
ꢀ
P1
9.5171(3)
11.3965(3)
12.2166(3)
84.4690(15)
81.1871(14)
79.8848(16)
2
a
(°)
b (°)
c
Z
l
(°)
(mmꢁ1
)
0.097
1.349
0.533
1.426
0.685
1.464
0.427
1.424
Dx (g cm ꢁ3
)
Crystal size (mm)
Crystal color
Crystal shape
0.80 ꢃ 0.55 ꢃ 0.10
Colourless
Plate
0.68 ꢃ 0.17 ꢃ 0.10
0.20 ꢃ 0.20 ꢃ 0.13
0.25 ꢃ 0.20 ꢃ 0.18
Yellow
Green
Green
Block
Block
Plate
h range (°)
h k l range
No. of reflections measured
No. of unique reflections; Rint
2.71–27.49
ꢁ8/9, ꢁ18/18, ꢁ12/12
9936
2092, 0.123
1569
127
1.084
0.0604, 0.0860
0.439, ꢁ0.539
2.01–27.50
ꢁ26/26, ꢁ12/11, ꢁ18/16
24,803
6363, 0.206
4770
362
1.116
0.0655, 0.0948
0.820, ꢁ0.652
3.32–27.50
ꢁ12/13, ꢁ20/19, ꢁ16/14
17,288
4298, 0.083
2942
244
1.095
0.0528, 0.0978
0.331, ꢁ0.444
1.7– 27.5
ꢁ12/12, ꢁ14/14, ꢁ15/15
11,133
5909, 0.035
4772
352
1.008
0.0380, 0.1013
0.267, ꢁ0.386
a
No. of observed reflections (I > 2
No. of parameters
Sb all data
r(I))
Rc, wRc
D
q
, max., min. (e Åꢁ3
)
P
P
jF2o ꢁ F2o;meanj= F2o.
a
Rint
¼
P
2
1=2
S ¼ ½ ðwðF2o ꢁ Fc2Þ Þ=ðNdiffrs ꢁ NparamsÞꢄ
for all data.
b
c
P
P
2
2
1=2
R(F) =
R
||Fo| ꢁ Fc||/
R
|Fo| for observed data, wRðF2Þ ¼ ½ ðwðFo2 ꢁ F2c Þ Þ=ð wðFo2Þ Þꢄ
for all data.

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J. Honzícek et al. / Journal of Organometallic Chemistry 694 (2009) 4250–4255
4254
through the nitrogen atoms was observed in the case of the vana-
docene compounds Cp2VCl(dcmb) (4a), (
5-C5H4Me)2VCl(dcmb)
710m, 696m, 627m, 557m. Raman (quartz capillary, cmꢁ1):
3134(1), 3122(1), 3115(1), 3102(1), 3069(2), 2216(10), 2206(9),
1600(6), 1500(3), 1477(2), 1438(3), 1419(6), 1364(2), 1220(2),
1177(2), 1162(1), 1130(7), 1064(1), 1033(1), 842(2), 788(1),
722(2), 688(1), 616(1), 563(1), 447(1), 414(2), 378(4), 348(1),
299(3), 269(9), 223(1), 206(4). The single crystals of 3ꢀCH2Cl2 suit-
able for X-ray structure analysis were prepared by careful overlay-
ering of the CH2Cl2 solution with hexane at 6 °C.
g
(4b) and Cp2V(dcmb)2 (5a). The bonding mode of the dcmb ligand
reflects properties of the central metal. The more oxophilic tita-
nium(IV) is bonding the dcmb ligand through oxygen atom while
bonding through nitrogen atom was observed for less oxophilic
vanadium(IV). Both types of the bonding were evidenced by spec-
troscopic measurements. The structures of the compounds 3 and
4b were determined by X-ray diffraction analysis.
4.4. Synthesis of complex Cp2VCl(dcmb) (4a)
4. Experimental
0.14 g (1.18 mmol) of dcmbHꢀH2O was added to the aqueous
solution of Cp2VCl2 (2a) (0.14 g; 0.56 mmol) in water (10 ml).
The suspension was stirred for 1 h at room temperature. The pre-
cipitate of the product was filtered out using glass frit and dried
under vacuum. The crude product was recrystallized from
CH2Cl2/hexane giving purple powder of the compound 4a. Yield:
0.15 g (0.39 mmol, 70%). Anal. Calcd for C20H15ClN2OV: C, 62.27;
H, 3.92; N, 7.26. Found: C, 62.41; H, 3.74; N, 7.49%. EPR (CH2Cl2
solution): |Aiso| = 69.0 ꢃ 10ꢁ4 cmꢁ1, giso = 1.987. IR (Nujol mull,
cmꢁ1): 3095m, 2210s, 2164s, 1728m, 1593m, 1564m, 1261m,
1155m, 1093m, 1074m, 1026m, 840m, 803m.
4.1. Methods and materials
All reactions and manipulations were performed under an inert
atmosphere of argon using standard Schlenk techniques. Water
was distilled and saturated with argon. Other solvents were dried
by standard methods and saturated with argon. The starting mate-
rials Cp2TiCl2 (1) [22], Cp2VCl2 (2a) [22], (g
5-C5H4Me)2VCl2 (2b)
[23] and dcmbH [13] were prepared according to published meth-
ods. IR spectra were recorded in 4000–350 cmꢁ1 region on a Per-
kin–Elmer 684 spectrometer in KBr pellets. Raman spectra were
run on a Bruker IFS 55 equipped with FRA 106 extension at 50–
3500 cmꢁ1 in quartz capillaries. The EPR spectra were recorded
on an ERS 221 (ZWG Berlin) spectrometer at X-band in flat cuvettes
at ambient temperature.
4.5. Synthesis of complex (g
5-C5H4Me)2VCl(dcmb) (4b)
0.14 g (1.18 mmol) of dcmbHꢀH2O was added to the aqueous
solution of (
5-C5H4Me)2VCl2 (2b) (0.16 g; 0.57 mmol in 10 ml of
g
water). The suspension was stirred for 1 h at room temperature.
The precipitate of the product was filtered on the frit and dried un-
der vacuum. The crude product was recrystallized from CH2Cl2/
hexane giving purple powder of the compound 4b. Yield: 0.17 g
(0.41 mmol, 72%). Anal. Calcd for C22H19ClN2OV: C, 63.86; H,
4.63; N, 6.77. Found: C, 63.59; H, 4.57; N, 6.51%. EPR (CH2Cl2 solu-
tion): |Aiso| = 69.1 ꢃ 10ꢁ4 cmꢁ1, giso = 1.987. IR (Nujol mull, cmꢁ1):
3084m, 2208s, 2160s, 1593s, 1564s, 1326s, 1167m, 1074m,
1028m, 908m, 854s, 791m, 704s, 552m. The single crystals suitable
for X-ray structure analysis were prepared by careful overlayering
of the CH2Cl2 solution with hexane at 6 °C.
4.2. Synthesis of dcmbHꢀH2O
DcmbH (2 g, 12 mmol) was dissolved in wet MeCN. The solvent
was allowed to evaporate over time to give large crystals of
dcmbHꢀH2O. Yield: 2.1 g (11 mmol, 95%). Anal. Calcd for
C10H8N2O2: C, 63.82; H, 4.28; N, 14.89. Found: C, 63.93; H, 4.18;
N, 14.95%. 1H NMR(CD3CN, 360 MHz): 8.78 (s-br, 1H, OH), 7.73–
7.65 (m, 3H, C6H5), 7.57 (t, J = 7.6 Hz, 2H, C6H5). 13C NMR(CD3CN,
91 MHz): 184.2 (2C, CN), 134.3 (1C, C6H5), 131.6 (1Cipso, C6H5),
129.8 (2C, C6H5), 129.2 (2C, C6H5), 115.3 (1C, C@C), 113.5 (1C,
C@C). IR (KBr pellet, cmꢁ1): 3408s-br, 3073w, 2236s, 2229s,
1602s, 1593s, 1564s, 1557s, 1554s, 1448s, 1387s, 1356m, 1318m,
1263w, 1226m, 1173m, 1100m, 1029m, 905m, 779s, 709s, 695s,
591m, 559m, 440w, 494w, 388m. Raman (quartz capillary,
cmꢁ1): 3079(1), 3070(<1), 2236(7), 2228(8), 1602(10), 1564(2.5),
1498(<1), 1448(<1), 1387(5), 1228(1), 1162(1), 1030(1), 1003(4),
981(<1), 910(<1), 850(<1), 781(1), 712(<1), 696(<1), 686(1),
618(<1), 590(<1), 558(<1), 495(<1), 467(<1), 438(<1), 410(<1),
339(<1), 242(<1), 212(<1), 193(1), 169(3), 120(4). Single crystals
suitable for X-ray diffraction analysis were obtained upon slow
evaporation of the MeCN solution.
4.6. Synthesis of complex Cp2V(dcmb)2 (5a)
0.15 g (0.6 mmol) of Cp2VCl2 (2a) was dissolved in water
(10 ml) and vigorously stirred with the solution of 0.14 g
(1.2 mmol) of dcmbHꢀH2O in CH2Cl2 (20 ml) was added. Two milli-
liters of carbonate free NaOH solution (0.6 mol lꢁ1) was added
dropwise to this mixture. Upon the addition, the blue-green water
layer turns color to colorless, whereas the organic layer turns to
purple. The organic layer was separated and dried over MgSO4.
The volatiles were evaporated under vacuum yielding red powder
of compound 5a. Yield: 0.24 g (0.46 mmol, 78%). Anal. Calcd for
C30H20N4O2V: C, 69.37; H, 3.88; N, 10.79. Found: C, 69.12; H,
4.3. Synthesis of complex Cp2Ti(dcmb)2 (3)
3.60; N, 10.98%. EPR (CH2Cl2 solution): |Aiso| = 68.4 ꢃ 10ꢁ4 cmꢁ1
,
0.14 g (1.18 mmol) of dcmbHꢀH2O was added to the aqueous
solution of Cp2TiCl2 (1) (0.14 g; 0.56 mmol) in water (10 ml). The
suspension was stirred for 1 h at room temperature. The precipi-
tate of the product was filtered out using glass frit and dried under
vacuum. The crude product was recrystallized from CHCl3/hexane
giving orange powder of the compound 3. Yield: 0.17 g (0.33 mmol,
59%). Anal. Calcd for C30H20N4O2Ti: C, 69.78; H, 3.90; N, 10.85.
Found: C, 69.56; H, 3.72; N, 10.91%. 1H NMR(CD2Cl2, 360 MHz):
7.46 (d, J = 7.3 Hz, 4H, C6H5), 7.40 (t, J = 7.5 Hz, 2H, C6H5), 7.11 (t,
J = 7.8 Hz, 4H, C6H5), 6.72 (s, 10H, C5H5). 13C NMR(CD2Cl2,
91 MHz): 193.6 (4C, CN), 134.6 (2Cipso, C6H5), 132.7 (2C, C6H5),
128.8 (4C, C6H5), 128.4 (4C, C6H5), 121.1 (10C, C5H5), 117.0 (1C,
C@C), 116.4 (1C, C@C). IR (KBr pellet, cmꢁ1): 3121m, 2214s,
2202m, 1470vs, 1437s, 1398s, 1219m, 1014m, 837m, 781s,
giso = 1.986. IR (KBr pellet, cmꢁ1): 3112m, 2963m, 2211s, 2193s,
2167s, 1597s, 1567s, 1446m, 1328s, 1262m, 1095s, 1024s, 930m,
848m, 802s, 703s, 552m, 394m.
4.7. Synthesis of [Cp2V(OC(Ph)C(CN)C(OMe)NH)][dcmb] (6a)
The compound 5a (0.10 g; 0.19 mmol) was dissolved in dry
methanol and heated for 5 min under reflux. The volatiles were
evaporated in vacuo yielding brown powder of compound 6a.
Yield: 0.09 g (0.18 mmol, 94%). Anal. Calcd for C31H24N4O3V: C,
67.51; H, 4.39; N, 10.16. Found: C, 67.73; H, 4.52; N, 9.84%. EPR
(methanol solution): |Aiso| = 67.2 ꢃ 10ꢁ4 cmꢁ1, giso = 1.983. IR (KBr
pellet, cmꢁ1): 3222s, 3110m, 2207s, 2201s, 2178sh, 2152sh,
1614vs, 1468s, 1436m, 1373s, 1261m, 1229m, 1218m, 1143m,

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J. Honzícek et al. / Journal of Organometallic Chemistry 694 (2009) 4250–4255
4255
1070m, 1004m, 909w, 845m, 791m, 746w, 720w, 701w, 667w,
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Appendix A. Supplementary data
CCDC 738949, 738948, 738947 and 738950 contain the supple-
mentary crystallographic data for this paper. These data can be ob-
tained free of charge from The Cambridge Crystallographic Data
Centre via http://www.ccdc.cam.ac.uk/data_request/cif. Supple-
mentary data associated with this article can be found, in the on-
line version, at doi:10.1016/j.jorganchem.2009.08.037.
[27] G.M. Sheldrick, SHELXL97, University of Göttingen, Germany, 1997.