Facile construction of the guanidine substituent or guanidinate anionic ligand through addition of the adjacent amino group to carbodiimide

Article abstract of DOI:10.1039/b813711k

The reaction of N,N′-dicyclohexylcarbodiimide (DCCI) with [Cp ₂Yb(o-H₂NC₆H₄S)]₂ (Cp = C₅H₅) (1) forms the monomer product Cp ₂Yb[SC₆H₄N=C(NHCy)₂] (2), indicating that the adjacent NH₂ group can add to the C=N double bonds of carbodiimide to construct a neutral guanidine group. When DCCI reacts with [Cp₂Y(o-H₂NC₆H₄S)] ₂·2THF (4), a dimer product [CpY(μ-η²: η¹-SC₆H₄N=C(NHCy)NCy)(THF)]₂ (5) was isolated, through the amino group addition and cyclopentadienyl elimination. Interestingly, on treatment of 4 with one or two equivalent of ⁱPrN=C=NⁱPr at the same conditions gave an amino group partial addition product CpY(THF)[μ-η²:η¹- SC₆H₄N=C(NHⁱPr)NⁱPr)](μ- η²:η¹-SC₆H₄NH ₂)YCp₂·THF (6), where only one NH₂ group can add to the C=N double bonds of carbodiimide molecule, another one is remained. However, when we extended this reaction to the gadolinium complex, a novel co-crystalline compound {Cp₂Gd[SC₆H ₄N=C(NHCy)₂]}·{CpGd(THF)[μ-η²: η¹-SC₆H₄N=C(NHCy)NCy)][μ- η²:η¹-SC₆H₄NH ₂]GdCp₂·THF} (8) was obtained from the reaction of [Cp₂Gd(o-H₂NC₆H₄S)]₂ (7) with DCCI. In order to investigate the sequence of addition and the elimination of the cyclopentadienyl group, a deprotonation reaction of the addition product has also been studied. Reaction of CpYb[SC₆H₄NC(NH ⁱPr)₂]₂(THF) (9), formed by reaction of Cp ₃Yb with two equivalent of o-aminothiophenol, and subsequently with 2 equiv. of ⁱPrN=C=NⁱPr, with one equiv. of Cp ₃Yb gave a cyclopentadienyl elimination product [CpYb(μ- η²:η¹-SC₆H₄N=C(NH ⁱPr)NⁱPr)(THF)]₂ (3). This result reveals that addition of the NH₂ group to carbodiimide is prior to the elimination of cyclopentadienyl group. All of new compounds have been characterized by elemental analysis and spectroscopic properties. The solid-state structures of complexes 2, and 5-9 were determined by single-crystal X-ray diffraction.

Full text of DOI:10.1039/b813711k

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Facile construction of the guanidine substituent or guanidinate anionic ligand
through addition of the adjacent amino group to carbodiimide†
Jie Zhang,* Liping Ma, Yanan Han, Fuyan Han Zhengxing Zhang, Ruifang Cai, Zhenxia Chen and
Xigeng Zhou*
Received 7th August 2008, Accepted 15th December 2008
First published as an Advance Article on the web 4th February 2009
DOI: 10.1039/b813711k
The reaction of N,N¢-dicyclohexylcarbodiimide (DCCI) with [Cp2Yb(o-H2NC6H4S)]2 (Cp = C5H5) (1)
=
forms the monomer product Cp2Yb[SC6H4N C(NHCy)2] (2), indicating that the adjacent NH2 group
=
can add to the C N double bonds of carbodiimide to construct a neutral guanidine group. When DCCI
2
1
=
reacts with [Cp2Y(o-H2NC6H4S)]2·2THF (4), a dimer product [CpY(m-h :h -SC6H4N C(NHCy)NCy)-
(THF)]2 (5) was isolated, through the amino group addition and cyclopentadienyl elimination.
i
i
= =
Interestingly, on treatment of 4 with one or two equivalent of PrN C N Pr at the same conditions gave
an amino group partial addition product CpY(THF)[m-h :h -SC6H4N C-(NH Pr)N Pr)](m-h :h -
2
1
i
i
2
1
=
=
SC6H4NH2)YCp2·THF (6), where only one NH2 group can add to the C N double bonds of
carbodiimide molecule, another one is remained. However, when we extended this reaction to the
=
gadolinium complex, a novel co-crystalline compound {Cp2Gd[SC6H4N C(NHCy)2]}·
2
1
2
1
=
{CpGd(THF)[m-h :h -SC6H4N C(NHCy)NCy)][m-h :h -SC6H4NH2]GdCp2·THF} (8) was obtained
from the reaction of [Cp2Gd(o-H2NC6H4S)]2 (7) with DCCI. In order to investigate the sequence of
addition and the elimination of the cyclopentadienyl group, a deprotonation reaction of the addition
product has also been studied. Reaction of CpYb[SC6H4NC(NHiPr)2]2(THF) (9), formed by reaction
of Cp3Yb with two equivalent of o-aminothiophenol, and subsequently with 2 equiv. of PrN C N Pr,
with one equiv. of Cp3Yb gave a cyclopentadienyl elimination product [CpYb(m-h :h -
SC6H4N C(NH Pr)N Pr)(THF)]2 (3). This result reveals that addition of the NH2 group to
carbodiimide is prior to the elimination of cyclopentadienyl group. All of new compounds have been
characterized by elemental analysis and spectroscopic properties. The solid-state structures of
complexes 2, and 5–9 were determined by single-crystal X-ray diffraction.
i
i
= =
2
1
i
i
=
Our recent interest is in the investigation of the ligand-
Introduction
based substituent effects on activity of organolanthanides toward
unsaturated organic small molecules. We found the adjacent amino
group of the o-aminothiophenolate ligand readily adds into the
The search for new ligands to support metal complexes receives
a continual interest in inorganic chemistry and organometallic
chemistry.1 Some efforts focus on the amidinate and guanidi-
nate ligand systems. The amidinates are known to be versatile
ligands in organometallic chemistry.2 The relative guanidinate
anion can impart a similar coordination environment while
offering increased stability due to the possibility of the additional
zwitterionic resonance structure. Moreover, guanidinate ligands
provide tunability in terms of steric and electronic properties by
variation of the organic substituents on the nitrogen atoms.3 These
organometallic guanidinates were usually prepared by metathesis
and insertion.4–7 However, there are some disadvantages about the
two synthetic protocols: it is very difficult to completely remove
the salt MCl (alkali metal chlorides) in most cases; another is
the low reactivity of the metal–ligand bonds toward carbodiimide
molecules. In fact, a more alluring strategy for preparation of these
organometallic guanidinates is through the addition of amino
group to carbodiimide.8–11
=
C N bond of carbodiimide or isocyanate to construct a novel
guanidinate or thiazolate skeleton.9,10 In order to extend the scope
of these additions and obtain more information about their mech-
anisms, the reactions of organolanthanide o-aminothiophenolate
i
i
=
complexes with DCCI and PrN CN Pr have been investigated.
Herein, we would like to report these results. Three aspects are
mainly included in this contribution: (i) the steric hindrance
= =
effects of the substituted group R of RN C NR (R = cyclohexyl,
isopropyl); (ii) the radii effects of the rare earth metal ions and
(iii) the reaction sequence of the amino group addition and
cyclopentadienyl elimination.
Results and discussion
Reactions of lanthanocene derivatives containing the
o-aminothiophenolate ligand with carbodiimides
Department of Chemistry, Fudan University, Shanghai, 200433, People’s
Republic of China. E-mail: zhangjie@fudan.edu.cn, xgzhou@fudan.edu.cn
† CCDC reference numbers 676384 (2), 676383 (5), 609335 (6), 676386
(7), 676382 (8) and 676385 (9). For crystallographic data in CIF or other
electronic format see DOI: 10.1039/b813711k
We first investigated the reaction of [Cp2Yb(o-H2NC6H4S)]2
(1)10a with N,N¢-dicyclohexylcarbodiimide (DCCI). The addition
of two molar equiv. of DCCI to a THF solution of 1 at
ambient temperature results in a N–H bond addition product
3298 | Dalton Trans., 2009, 3298–3305
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=
Cp2Yb[SC6H4N C(NHCy)2] (2), as shown in Scheme 1. X-Ray
double bonds of carbodiimide molecules. An increase of the
reaction temperature cannot obtain the amino group completed
addition product, similar to 5. Reaction of complex 4 with two
diffraction analysis indicates that the neutral guanidine substituent
is coordinated to the central metal with h -bonding mode,
no elimination of cyclopentadienyl group takes place, which is
1
i
i
= =
equivalent of PrN C N Pr under the reflux temperature for 24 h
significantly different from the observation in the reaction of
= =
1 with N,N¢-diisopropylcarbodiimide ( PrN C N Pr) ([CpYb(m-
also give 6, the residue NH2 group cannot further add into the
i
i
=
C N bonds of the other carbodiimide molecules.
2
1
i
i
10a
=
h :h -SC6H4N C(NH Pr)N Pr)(THF)]2 (3)). The reactive dis-
crimination in the two reactions maybe attribute to the difference
of the nucleophilic ability of the formed neutral guanidine group
due to the effect of steric hindrances in the R groups (R =
cyclohexyl, isopropyl). Furthermore, both of two hydrogen atoms
of the ortho-position amino group shift on the nitrogen atoms of
carbodiimide moiety in this reaction.
When we extend this addition to other lanthanides with larger
ionic radii, their reactions seem to be more complicated. For
example, the reaction of DCCI with [Cp2Gd(o-H2NC6H4S)]2 (7)
in a 1 : 1 ratio gave an interesting co-crystalline compound {Cp2-
3
1
=
=
Gd[SC6H4N C(NHCy)2 ]}·{CpGd(THF)[m-h :h -SC6H4N C-
2
1
(NHCy)NCy)][m-h :h -SC6H4NH2]GdCp2·THF} (8), which is in
fact an equimolar mixture of two complexes: one is Cp2Gd-
=
To further investigate the scope of the addition, we also synthe-
sized the complex [Cp2Y(o-H2NC6H4S)]2·2THF (4) by the reaction
of Cp3Y with o-aminothiophenol in THF at room temperature,
[SC6H4N C(NHCy)2] (8a), which is a NH2 addition product
and similar to 2, another is a NH2 partial addition and Cp-
abstraction product {CpGd(THF)[m-h :h -SC6H4N C(NHCy)-
3
1
=
i
i
2
1
= =
and examined its reactivity toward DCCI and PrN C N Pr.
Treatment of two equiv. of DCCI with 4 in THF at ambient
temperature gave a centrosymmetric dimer product [CpY(m-
NCy)][m-h :h -SC6H4NH2]GdCp2·THF}(8b), and similar to 6, as
shown in Scheme 3. We try to isolate a single component through
increase of the quantities of carbodiimide or 7, but not obtain the
success. The formation of the co-crystalline compound 8 should
be the balance of two components of 8a and 8b in the crystallizing
process. The results indicate that the NH2 group addition and/or
cyclopentadienyl elimination are strongly effected by the factors
of the rare earth metal ion character and the steric hindrance of
the R group of carbodiimide.
2
1
=
h :h -SC6H4N C(NHCy)NCy)(THF)]2 (5) (Scheme 2). Herein,
accompanied with the amino group addition to carbodiimide,
the elimination of the cyclopentadienyl group takes place. This is
different from the observation in the reaction of 1 and DCCI, but
i
i
= =
similar to that of reaction of 1 with PrN C N Pr. Interestingly,
4 reacts with two equiv. of N,N¢-diisopropylcarbodiimide, only
2
1
the amino group partial addition product CpY(THF)[m-h :h -
In order to study the sequence of the NH2 addition and Cp
elimination, an extension experiment has also been designed.
As shown in Scheme 4, the amino group bis-addition product
i
i
2
1
=
SC6H4N C(NH Pr)N Pr)](m-h :h -SC6H4NH2)YCp2·THF (6) can
=
be isolated, of which only one amino group add into the C N
Scheme 1
Scheme 2
Scheme 3
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◦
˚
Table 1 Selected bond lengths (A) and angles ( ) for 2
˚
Bond lengths/A
Yb(1)–N(1)
Yb(1)–C(3)
Yb(1)–C(8)
Yb(1)–C(2)
Yb(1)–C(7)
Yb(1)–C(1)
Yb(1)–C(9)
Yb(1)–C(6¢)
2.307(6)
2.577(9)
2.581(17)
2.582(9)
2.584(16)
2.603(9)
2.603(16)
2.607(15)
Yb(1)–C(10)
Yb(1)–C(4)
Yb(1)–C(5)
Yb(1)–S(1)
S(1)–C(11)
N(1)–C(17)
N(2)–C(17)
N(3)–C(17)
2.619(14)
2.621(9)
2.622(10)
2.645(2)
1.770(8)
1.318(9)
1.351(10)
1.354(10)
Scheme 4
CpYb[SC6H4NC(NHiPr)2]2(THF) (9), prepared by reaction of
Cp3Yb with two equivalent of o-aminothiophenol, and subse-
Bond angles/◦
i
i
= =
quently with two equiv. of PrN C N Pr, readily reacts with one
2
1
equiv. of Cp3Yb to give a Cp elimination product [CpYb(m-h :h -
N(1)–Yb(1)–S(1)
C(17)–N(1)–Yb(1)
N(1)–C(17)–N(2)
75.66(16)
128.7(5)
123.3(7)
N(1)–C(17)–N(3)
N(2)–C(17)–N(3)
120.1(7)
116.6(7)
i
i
=
SC6H4N C(NH Pr)N Pr)(THF)]2 (3). This product was previously
i
i
10a
= =
obtained by reaction of PrN C N Pr with 1.
This result
indicates that the new formed guanidine groups can further
provide one proton to eliminate the cyclopentadienyl group of
analysis results reveal 2 is a solvent-free monomer with ytterbium
=
Cp3Yb. In other words, the N–H bond addition to the C N bond
5
atom bonded to two h -cyclopentadienyl rings and one chelating
of carbodiimide molecules should be prior to the elimination of
cyclopentadienyl group in our observations.
-
3+
=
ligand [SC6H4N C(NHCy)2] . The coordination number of Yb
is eight. The neutral guanidine moiety is only coordinated to the
center metal by one nitrogen atom, and is significantly different
from the observations in others guanidinate compounds, in which
the guanidinate anionic ligand is usually coordinated to the metal
by two nitrogen atoms.3,7 Two N–H bonds of the amino group
All of the new complexes are air- and moisture-sensitive. They
are high or moderately soluble in THF and slightly soluble
in n-hexane, and were characterized by elemental analysis and
spectroscopy properties, which were in good agreement with the
proposed structures. The mass spectra display that all of them
are characterized by the molecule ion peaks. In the IR spectra,
=
additions to the two C N double bonds of the carbodiimide
the characterized absorption at ca. 2100 cm-1 for the vas(N C N)
molecule has been confirmed from their structure parameters. The
bond angles around C17 are consistent with sp2 hybridization,
and the three C–N distances of the guanidine moiety are partial
= =
stretch of free carbodiimides is absent, but the new strong band at
ca. 1530 cm-1 attributable to the guanidinate anionic and/or at ca.
1570 cm-1 attributable to the neutral guanidine group is present.10a
Their structures of 2, and 5–9 have also been identified by X-ray
single-crystal diffraction analysis.
˚
˚
averaged (C17–N1 1.318(9) A, C17–N2 1.351(10) A, and C17–N3
˚
1.354(10) A). The distance of C17–N1 is slightly longer than the
12
˚
=
C N double distance (1.28 A), the distances of C17–N2 and
C17–N3 are significantly shorter than the C(sp2)–N(sp3) single
bond distances (1.416 A), indicating that the p-electrons of
the C N double bond in the present structure are delocalized
13
˚
Crystal structures
=
over the N3C core. Consistent with this observation, the dis-
The molecular structure of 2 is shown in Fig. 1. Selected bond
lengths and angles of 2 are listed in Table 1. The X-ray crystal
˚
tance of Yb1–N1 is 2.307(6) A, significantly shorter than the
corresponding distance in the original compound [Cp2Yb(m-
1
2
9
˚
h :h -H2NC6H4S)]2·2THF (1) (Yb1–N1 2.459(2) A), indicating
a contribution from the increase of the nucleophilicity of the
guanidine moiety.
The crystal structure of complex 5 (Fig. 2 and Table 2) show
that the adjacent amino group in 5 has combined with N,N¢-
diisopropylcarbodiimide, forming a novel guanidinate dianionic
2-
=
ligand [SC6H4N C(NHCy)NCy] , which connected the central
2
1
metal with the m-h :h -bonding mode. One hydrogen atom of
the adjacent amino group shifts to the uncoordinated nitrogen
atom. The guanidinate ligand also exhibits delocalized bonding
throughout the N3C guanidinate core. The planarity of YN2C
ring and nearly equivalent C12–N1 and C12–N2 (1.337(4) and
˚
˚
1.320(4) A, respectively), Y1–N1 and Y1–N2 (2.320(3) A and
˚
2.382(3) A, respectively) bond lengths suggest the existence of
a resonance stabilization in the YbN2C ring and no hydrogen
atom at coordinated nitrogen atom. The distance between the
˚
central carbon and uncoordinated nitrogen (C12–N3 1.378(4) A)
is significantly shorter than the expected for C(sp2)–N(sp3) single
bonds (C–Nav , 1.416),13 and indicate a stronger p–p conjugation
between the lone-pair electron on non-coordinated nitrogen and
the N–C–N unit.
=
Fig. 1 Thermal ellipsoid plot of Cp2Yb[SC6H4N(H)C(NHCy) NCy], 2,
with ellipsoids at the 30% probability level. Hydrogen atoms omitted for
clarity.
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◦
◦
˚
˚
Table 3 Selected bond lengths (A) and angles ( ) for 6
Table 2 Selected bond lengths (A) and angles ( ) for 5
˚
˚
Bond lengths/A
Bond lengths/A
Y(1)–N(1)
Y(1)–N(2)
Y(1)–O(1)
Y(1)–C(3)
Y(1)–C(4)
Y(1)–C(2)
Y(1)–C(5)
2.320(3)
2.382(3)
2.435(3)
2.652(4)
2.672(4)
2.680(4)
2.685(4)
Y(1)–C(1)
Y(1)–S(1)
Y(1)–C(12)
S(1)–Y(1A)
N(1)–C(12)
N(2)–C(12)
N(3)–C(12)
2.699(4)
2.7899(11)
2.806(4)
2.8376(13)
1.337(4)
1.320(4)
1.378(4)
Y(1)–N(2)
Y(1)–N(4)
Y(1)–O(1)
Y(1)–C(2)
Y(1)–C(1)
Y(1)–C(4)
Y(1)–C(5)
Y(1)–C(3)
Y(1)–S(2)
Y(1)–C(18)
Y(1)–S(1)
Y(2)–N(1)
Y(2)–C(28)
Y(2)–C(27)
Y(2)–C(32)
2.296(4)
2.389(4)
2.422(3)
2.654(5)
2.659(5)
2.665(5)
2.667(5)
2.670(5)
2.7774(14)
2.789(5)
2.8372(14)
2.557(4)
2.612(7)
2.629(6)
2.634(7)
Y(2)–C(33)
Y(2)–C(34)
Y(2)–C(29)
Y(2)–C(31)
Y(2)–C(30)
Y(2)–C(25)
Y(2)–C(26)
Y(2)–S(1)
2.636(6)
2.650(6)
2.653(7)
2.655(6)
2.663(6)
2.676(7)
2.696(6)
2.8142(14)
1.770(5)
1.783(5)
1.441(5)
1.348(6)
1.382(6)
1.322(6)
S(1)–C(6)
Bond angles/◦
S(2)–C(12)
N(1)–C(11)
N(2)–C(18)
N(3)–C(18)
N(4)–C(18)
N(1)–Y(1)–N(2)
N(1)–Y(1)–S(1)
N(2)–Y(1)–S(1)
S(1)–Y(1)–S(1A)
C(12)–N(1)–Y(1)
C(12)–N(2)–Y(1)
56.23(10)
69.73(7)
125.92(8)
82.99(3)
96.5(2)
N(2)–C(12)–N(1)
N(2)–C(12)–N(3)
N(1)–C(12)–N(3)
N(2)–C(12)–Y(1)
N(1)–C(12)–Y(1)
N(3)–C(12)–Y(1)
113.1(3)
124.1(3)
122.9(3)
57.84(18)
55.24(17)
177.6(3)
94.2(2)
Bond angles/◦
Symmetry transformations used to generate equivalent atoms: -x + 1, -y
+ 2, -z + 1.
N(2)–Y(1)–N(4)
N(2)–Y(1)–S(2)
S(2)–Y(1)–S(1)
N(4)–C(18)–N(2)
56.80(13)
69.99(10)
79.78(4)
N(4)–C(18)–N(3)
N(2)–C(18)–N(3)
N(3)–C(18)–Y(1)
124.2(5)
122.6(5)
171.7(3)
113.2(4)
2
1
2
1
=
Fig. 2 Thermal ellipsoid plot of [CpY(m-h :h -SC6H4N C(NHCy)-
NCy)(THF)]2, 5, with ellipsoids at the 30% probability level. Hydrogen
atoms omitted for clarity.
=
Thermal ellipsoid plot of CpY(THF)[m-h :h -SC6H4N C-
2 1
Fig.
3
(NHiPr)NiPr)] (m-h :h -SC6H4NH2)YCp2·THF, 6, with ellipsoids at the
30% probability level. Hydrogen atoms omitted for clarity.
Fig. 3 and Table 3 shows complex 6 has a unique unsymmetrical
dinuclear structure, in which the CpY and Cp2Y fragments connect
The quality of the crystallographic data for 8 is poor with
the value of R on the high side (R1 = 0.0731, wR2 = 0.1835)
thus the bond distances and bond angles for 8 will not be
discussed. However, the overall structure of 8 was clearly
determined as shown in Fig. 5. The structure of 8 is consistent
i
i
2-
with the [SC6H4N C(NH Pr)N Pr] and [SC6H4NH2]- units.
=
i
i
2-
=
The dianionic ligand [SC6H4N C(NH Pr)N Pr] also connects
2
1
with two yttrium ions with the m-h :h -mode, similar to the
observation in 5. The residual NH2 group also connects with
one uncoordinated THF molecule through the intermolecular
N–H ◊ ◊ ◊ O hydrogen bond interaction.
=
of two independent units of Cp2Gd[SC6H4N C(NHCy)2]
2
1
=
(8a) and {CpGd(THF)[m-h :h -SC6H4N C(NHCy)NCy)][m-
2
1
h :h -SC6H4NH2]GdCp2}(8b). In 8a, the gadolinium atom is
5
Complex 7 (Fig. 4, Table 4) is a centrosymmetric dimeric
structure, with the o-aminothiophenolate ligand as both a bridging
and side-on donating group. Each gadolinium atom is coordinated
by two cyclopentadienyl rings, two bridging sulfur atoms and one
chelating nitrogen atom to form an edge-bridged tetrahedral ge-
ometry. No intermolecular N–H ◊ ◊ ◊ O hydrogen bond interaction
has been found due to the lack of THF molecules in the crystal
lattice of 7, which is different from the observed result of 1.9
coordinated to two h -cyclopentadienyl groups and one
=
chelated ligand [SC6H4N C(NHCy)2], similar to 2. In 8b, the
Cp2Gd and CpGd moieties are connected by one m-h :h -
2
1
2
1
=
SC6H4N C(NHCy)NCy guanidinate ligand and one m-h :h -
SC6H4NH2 aminothiophenolate ligand. The gadolinium atom
is also coordinated to one oxygen atom from the solvent THF
molecule in CpGd moiety. The overall structure of 8b is similar
to 6.
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◦
◦
˚
˚
Table 5 Selected bond lengths (A) and angles ( ) for 9
Table 4 Selected bond lengths (A) and angles ( ) for 7
˚
˚
Bond lengths/A
Bond lengths/A
Gd(1)–N(1)
Gd(1)–C(1)
Gd(1)–C(2)
Gd(1)–C(8)
Gd(1)–C(5)
Gd(1)–C(9)
Gd(1)–C(3)
Gd(1)–C(4)
Gd(1)–C(7)
Gd(1)–C(10)
Gd(1)–C(6)
Gd(1)–S(1)
Gd(2)–N(2)
Gd(2)–C(23)
2.545(5)
2.645(7)
2.666(7)
2.669(6)
2.679(7)
2.682(6)
2.687(6)
2.697(7)
2.701(6)
2.708(6)
2.708(6)
2.8307(18)
2.541(5)
2.653(6)
Gd(2)–C(22)
Gd(2)–C(19)
Gd(2)–C(18)
Gd(2)–C(24)
Gd(2)–C(20)
Gd(2)–C(26)
Gd(2)–C(21)
Gd(2)–C(17)
Gd(2)–C(25)
Gd(2)–S(2)
S(1)–C(16)
2.671(6)
2.670(8)
2.680(8)
2.677(8)
2.692(7)
2.706(6)
2.706(7)
2.711(7)
2.715(6)
2.826(2)
1.764(6)
1.758(7)
1.424(7)
1.431(8)
Yb(1)–O(1)
Yb(1)–N(1)
Yb(1)–N(4)
Yb(1)–C(28)
Yb(1)–C(30)
Yb(1)–C(31)
Yb(1)–C(27)
Yb(1)–C(29)
2.354(6)
2.356(7)
2.480(8)
2.634(11)
2.661(12)
2.663(11)
2.663(12)
2.672(11)
Yb(1)–S(2)
Yb(1)–S(1)
N(1)–C(7)
N(2)–C(7)
N(3)–C(7)
N(4)–C(20)
N(5)–C(20)
N(6)–C(20)
2.703(3)
2.709(3)
1.318(11)
1.340(10)
1.321(11)
1.321(12)
1.374(12)
1.333(12)
Bond angles/◦
S(2)–C(32)
N(1)–C(11)
N(2)–C(27)
N(3)–C(7)–N(2)
N(3)–C(7)–N(1)
N(2)–C(7)–N(1)
118.4(8)
116.7(8)
124.9(8)
N(4)–C(20)–N(5)
N(4)–C(20)–N(6)
N(5)–C(20)–N(6)
125.4(9)
119.0(9)
115.6(9)
Bond angles/◦
N(1)–Gd(1)–S(1)
N(2)–Gd(2)–S(2)
Gd(1)–S(1)–Gd(2)
C(32)–S(2)–Gd(2)
C(32)–S(2)–Gd(1)
65.25(11)
65.06(12)
103.12(6)
96.8(2)
C(16)–S(1)–Gd(1)
C(16)–S(1)–Gd(2)
Gd(2)–S(2)–Gd(1)
C(11)–N(1)–Gd(1)
C(27)–N(2)–Gd(2)
94.7(2)
126.9(2)
103.66(6)
110.8(3)
112.9(4)
128.2(2)
=
Fig. 5 Thermal ellipsoid plot of {Cp2Gd[SC6H4N(H)C(NHCy) NCy]}·
2
1
2
1
=
{CpGd(THF)[m-h :h -SC6H4N C(NHCy)NCy)][m-h :h -SC6H4NH2 ]-
GdCp2·THF}, 8, with ellipsoids at the 30% probability level. Hydrogen
atoms and solvent molecules in the lattices omitted for clarity.
Fig. 4 Thermal ellipsoid plot of [Cp2Gd(o-H2NC6H4S)]2, 7, with ellip-
soids at the 30% probability level. Hydrogen atoms omitted for clarity.
The X-ray analysis (Fig. 6 and Table 5) shows 9 is a
solvated monomer, and the neutral guanidine group of the
[SC6H4NC(NHiPr)2]- ligands is coordinated to the central metal
1
with the h -bonding mode. The ytterbium atom carries with one
5
h -cyclopentadienyl group and one THF molecule and is chelated
by two [SC6H4NC(NHiPr)2]- ligands. The coordination number of
the central metal ion is eight. The overall structure of 9 is similar
to that of the complex CpEr[SC6H4NC(NHiPr)2]2(THF).10a
Fig. 6 Thermal ellipsoid plot of CpYb[SC6H4NC(NHiPr)2]2(THF), 9,
with ellipsoids at the 30% probability level. Hydrogen atoms omitted for
clarity.
Conclusion
ligands. The N–H bonds of the amino group can selectively add to
=
The present results demonstrate that the nucleophilic addition of
the adjacent amino group with carbodiimide takes readily place
to construct the guanidine substituents or guanidinate anionic
the C N bond of carbodiimide molecule, and provide some new
2-
=
methods for the construction of novel [SC6H4N C(NHR)NR]
or [SC6H4N C(NHR)2] ligands. Further study indicate that the
-
=
3302 | Dalton Trans., 2009, 3298–3305
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
=
selectivity of the amino group addition to C N bonds of car-
DCCI (0.248 g, 1.20 mmol) with 4 (0.496 g, 0.60 mmol) gave
5 as colourless crystals. Yield: 0.433 g (65%). C, H, N analysis
(%): calcd for C56H80N6O2S2Y2: C 60.53, H 7.26, N 7.56; found:
bodiimide and/or elimination of cyclopentadienyl group can be
strongly affected by the factors of metal ionic characters/radii and
the steric hindrance of the substituted groups of carbodiimide, and
reveals the N–H bonds addition to the C N bond of carbodiimide
molecules is prior to the elimination of the cyclopentadienyl
group.
1
C 60.74, H 7.22, N 7.69. H NMR d/ppm: 7.00–7.18 (m, 8H,
=
C6H4), 6.03 (s, 10H, C5H5), 3.55–3.59 (m, 12H, O(CH2)2(CH2)2,
unique CH), 2.69 (m, 20H, C6H10), 2.22 (2H, NH), 0.87–1.42 (br,
28H, O(CH2)2(CH2)2, C6H10). IR (Nujol) n/cm-1: 3380 s, 3040 s,
1530 s, 1423 s, 1400 s, 1345 m, 1300 s, 1238 s, 1146 m, 1068 s,
1030 s, 881 s, 772 s, 741 s. MS (70 eV): m/z (%): 483 (24) [1/2M -
THF].
Experimental
General procedures
2
1
i
i
=
Synthesis of CpY(THF)[l-g :g -SC6H4N C(NH Pr)N Pr)](l-
g2:g1-SC6H4-NH2)YCp2·THF (6). Complex 6 was prepared sim-
ilarly to 5 from the reaction of N,N¢-diisopropylcarbodiimide
(0.156 g, 1.24 mmol) with 4 (0.516 g, 0.62 mmol) to give colourless
crystals 6. Yield: 0.376 g (68%). C, H, N analysis (%): calcd for
C42H56N4O2S2Y2: C 56.63, H 6.34, N 6.29; found: C 56.42, H
6.45, N 6.29. 1H NMR d/ppm: 6.94–7.22 (8H, C6H4), 6.05 (15H,
C5H5), 3.35–3.58 (10H, O(CH2)2(CH2)2, CH(CH3)2), 2.18 (2H,
NH2), 0.82–1.43 (20H, O(CH2)2(CH2)2, CH(CH3)2). IR (Nujol)
n/cm-1: 3382 m, 3047 w, 1598 s, 1535 s, 1404 m, 1271 s, 1243 s,
1059 m, 1028 s, 914 m, 881 s, 762 w, 679 w. MS (70 eV): m/z (%):
All operations involving air- and moisture-sensitive compounds
were carried out under an inert atmosphere of purified argon or
nitrogen using standard Schlenk techniques. The solvents of THF,
toluene, n-hexane were refluxed and distilled from sodium ben-
zophenone ketyl under nitrogen immediately prior to use. Cp3Ln14
and [Cp2Yb(o-H2NC6H4S)]2·2THF (1).10a were prepared by the
literature methods, respectively. N,N¢-Dicyclohexylcarbodiimide
(DCCI), N,N¢-diisopropylcarbodiimide and o-aminothiophenol
were purchased from Aldrich and were used without purification.
Elemental analyses for C, H and N were carried out on a Rapid
CHN-O analyzer. Infrared spectra were obtained on a NICOLET
FT-IR 360 spectrometer with samples prepared as Nujol mulls.
Mass spectra were recorded on a Philips HP5989A instrument
operating in EI mode. Crystalline samples of the respective
complexes were rapidly introduced by the direct inlet techniques
with a source temperature of 200 ◦C. The values of m/z refer to the
isotopes 12C, 1H, 14N, 16O, 32S, 158Gd, 89Y and 174Yb. 1H NMR data
were obtained on a Bruker DMX-500 NMR spectrometer and
were referenced to residual aryl protons in C6H6 (d = 7.16 ppm).
i
i
=
644 (18) [M - 2THF - L] (L = SC6H4N C(NH Pr)N Pr).
Synthesis of [Cp2Gd(o-H2NC6H4S)]2 (7). Following the pro-
cedure described for 4, reaction of Cp3Gd (0.978 g, 2.78 mmol)
with o-aminothiophenol (0.348 g, 2.78 mmol) gave 7 as colourless
crystals. Yield: 0.891 g (78%). C, H, N analysis (%): calcd for
C32H32N2S2Gd2: C 46.69, H 3.92, N 3.40; found: C 46.93, H 4.10,
N 3.18. IR (Nujol) n/cm-1: 3306 s, 3238 m, 1591 s, 1555 m, 1447 s,
1440 s, 1270 m, 1057 s, 1014 s, 906 m, 781 s, 754 s, 679 m. MS
(70 eV): m/z (%): 824(7) [M].
=
Synthesis of Cp2Yb[SC6H4N C(NHCy)2] (2). A THF solution
of DCCI (0.239 g, 1.16 mmol in 10 mL THF) was slowly added to a
30 mL THF solution of 1 (0.579 g, 0.58 mmol) at room temperature
and stirred for 24 h. The reaction solution was concentrated to ca.
5 mL under reduced pressure. Yellow crystals of 2 were obtained
at -20 ◦C after several days. Yield: 0.493 g (67%). C, H, N analysis
(%): calcd for C29H38N3SYb: C 54.96, H 6.04, N 6.63; found: C
=
Synthesis of {Cp2Gd[SC6H4N C(NHCy)2]}·{CpGd(THF)[l-
2
1
2
1
=
g :g -SC6H4N C(NHCy)NCy)][l-g :g -SC6H4NH2 ]GdCp2 ·
THF} (8). A THF solution of DCCI (0.310 g, 1.50 mmol in
10 mL THF) was slowly dropped into a 30 mL THF solution of 7
(0.616 g, 0.75 mmol) at room temperature. After stirring for 24 h,
the solution was clear. All volatile substances were removed under
vacuum to give white powder. The colourless crystal samples of
complex 8 have been obtained from the mixture solvent of n-
hexane and THF. Yield: 0.496 g (55%). C, H, N analysis (%): calcd
for C81H110N7O2S3Gd3: C 54.12, H 6.17, N 5.45; found: C 53.75, H
6.04, N 5.80. IR (Nujol) n/cm-1: 3354 m, 3285 w, 1573 m, 1540 s,
1315 s, 1259 s, 1237 s, 1146 s, 1062 s, 1013 s, 890 s, 762 s. MS
(70 eV): m/z (%): 618 (17) [M1], 964 (3) [M2 - 2THF] (M1,8a;
M2, 8b).
1
54.73, H 6.44, N 5.96. H NMR d/ppm: 6.94–7.20 (4H, C6H4),
6.46 (10H, C5H5), 4.20 (2H, NH), 3.55–3.60 (2H, unique CH),
0.90–1.43 (20H, C6H10). IR (Nujol) n/cm-1: 3382 m, 1591 w, 1570
m, 1534 s, 1424 s, 1064 m, 1033 s, 920 m, 774 s, 742 s, 598 w. MS
(70 eV): m/z (%): 634 (7) [M].
Synthesis of [Cp2Y(o-H2NC6H4S)]2·2THF (4). Cp3Y (0.748 g,
2.63 mmol) and o-aminothiophenol (0.330 g, 2.63 mmol) were
mixed in 50 mL of THF. After stirring for 24 h at room
temperature, all volatile substances were removed under vacuum
to give yellow powder. Colourless crystals of 4 were obtained by
recrystallization from THF at -20 ◦C during several days. Yield:
0.829 g (76%). C, H, N analysis (%): calcd for C40H48N2O2S2Y2: C
57.83, H 5.82, N 3.37; found: C 57.49, H 5.63, N 3.56. 1H NMR
d/ppm: 7.00–7.24 (m, 8H, C6H4), 6.01 (s, 20H, C5H5), 4.01 (4H,
NH), 3.57 (m, 8H, O(CH2)2(CH2)2), 1.41 (m, 8H, O(CH2)2(CH2)2).
IR (Nujol) n/cm-1: 3572 s, 3300 w, 3220 m, 1590 s, 1556 m, 1306
m, 1267 s, 1153 m, 1061 s, 1010 s, 906 m, 784 s, 700 m, 642 w. MS
(70 eV): m/z (%): 686 (27) [M - 2THF].
Synthesis of CpYb[SC6H4NC(NHiPr)2]2(THF) (9). Cp3Yb
(0.453 g, 1.23 mmol) and o-aminothiophenol (0.308 g, 2.46 mmol)
were mixed in 20 mL of THF. After stirring for 12 h at room
temperature, N,N¢-diisopropylcarbodiimide (0.310 g, 2.46 mmol)
was added into the solution. After stirring for 48h, all volatile
substances were removed under vacuum to give orange powder.
Orange crystals of 9 were obtained by recrystallization from THF
at -20 ◦C for several days. Yield: 0.855 g (86%). C, H, N analysis
(%): calcd for C35H53N6OS2Yb: C 51.84, H 6.59, N 10.36; found: C
51.98, H 6.53, N 10.21; 1H NMR d/ppm: 7.00–7.28 (8H, C6H4),
6.53 (5H, C5H5), 3.10–3.57 (8H, O(CH2)2(CH2)2, CH(CH3)2),
4.00 (4H, NH), 0.83–1.41 (O(CH2)2(CH2)2, 28H, CH(CH3)2). IR
2
1
=
Synthesis of [CpY(l-g :g -SC6H4N C(NHCy)NCy)(THF)]2
(5). Following the procedure described for 2, the reaction of
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©

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Table 6 Crystal and data collection parameters of complexes 2, 5 and 6
2
5
6
Formula
C29H38N3SYb
633.72
Orange
C56H80N6O2S2Y2
1111.20
colorless
0.15 ¥ 0.10 ¥ 0.08
Monoclinic
P21/n
10.340(3)
20.754(5)
15.309(4)
99.351(3)
3241.6(13)
2
1.138
1.884
1168
MoKa
293(2)
w - 2q
1.96–25.01
C42H56N4O2S2Y2
890.85
colorless
0.10 ¥ 0.15 ¥ 0.20
Monoclinic
C2/c
14.520(4)
19.120(5)
30.856(8)
96.055(4)
8518(4)
Molecular weight/g mol-1
Crystal colour
Crystal dimensions/mm
Crystal system
0.10 ¥ 0.08 ¥ 0.05
Monoclinic
P21/c
15.321(4)
11.728(3)
15.762(4)
103.182 (4)
2757.7(13)
4
1.526
3.488
1276
MoKa
297(2)
w - 2q
1.37–26.01
Space group
˚
a/A
˚
b/A
˚
c/A
b/◦
3
˚
V/A
Z
8
Dc/g cm-3
m/mm-1
F(000)
1.389
2.848
3696
MoKa
298(2)
w - 2q
1.77–25.01
˚
Radiation (l = 0.710730 A)
T/K
Scan type
q range/◦
h,k,l range
-18 ≤ h ≤ 17, -14 ≤ k ≤ 12 -19 ≤ -12 ≤ h ≤ 12 0 ≤ k ≤ 24 0 ≤ l ≤ 18 -14 ≤ h ≤ 17 -15 ≤ k ≤ 22 -36 ≤
l ≤ 18
l ≤ 29
No. of reflections measured
No. of unique reflections completeness
to q
15 818
5702
17 785
5412 (Rint = 0.0604) 99.7% (q =
5702 (Rint = 0.0000) 99.7% (q =
7524 (Rint = 0.0700) 100.0% (q =
26.01)
25.01)
25.01)
Refinement method
Full-matrix least-squares on F2
5412/2/291
Full-matrix least-squares on F2
5702/2/310
Full-matrix least-squares on F2
7524/0/469
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2s(I)]
1.004
0.934
0.968
R1 = 0.0453, wR2 = 0.1158
R1 = 0.0470, wR2 = 0.1069
R1 = 0.0517, R1 = 0.0453, wR2 =
0.1158, wR2 = 0.0918
R1 = 0.1125, R1 = 0.0453, wR2 =
0.1158, wR2 = 0.1087
0.417 and -0.267
R indices (all data)
R1 = 0.0782, R1 = 0.0453, wR2 = R1 = 0.0791, R1 = 0.0453, wR2 =
0.1158, wR2 = 0.1416
0.1158, wR2 = 0.1157
0.518 and -0.364
-3
˚
Largest diffraction peak and hole (e A ) 2.530 and -1.059
Table 7 Crystal and data collection parameters of complexes 7, 8 and 9
7
8
9
Formula
C32H32N2S2Gd2
823.22
Colourless
0.15 ¥ 0.10 ¥ 0.10
Monoclinic
P21/n
16.413(6)
10.832(4)
17.526(6)
111.808(4)
2890.5(18)
4
1.892
4.718
1592
MoKa
293(2)
C81H110N7S3O2Gd3
1797.69
Colourless
0.15 ¥ 0.10 ¥ 0.10
Monoclinic
P21/n
25.853(9)
12.257(4)
28.459(10)
91.485(5)
9015(5)
C35H53N6S2OYb
810.99
Red
Molecular weight/g mol-1
Crystal colour
Crystal dimensions/mm
Crystal system
0.20 ¥ 0.15 ¥ 0.15
Monoclinic
P21/n
16.186(8)
14.485(7)
16.207(8)
98.977(8)
3753(3)
Space group
˚
a/A
˚
b/A
˚
c/A
b/◦
3
˚
V/A
Z
4
4
Dc/g cm-3
m/mm-1
F(000)
1.271
2.292
3476
MoKa
293(2)
w - 2q
1.05–20.59
-25 ≤ h ≤ 22
-11 ≤ k ≤ 12
-28 ≤ l ≤ 25
30 400
1.435
2.683
1660
MoKa
293(2)
w - 2q
1.65–25.01
-19 ≤ h ≤ 16
-17 ≤ k ≤ 17
-17 ≤ l ≤ 19
15 596
˚
Radiation (l = 0.710730 A)
T/K
Scan type
w - 2q
q range/◦
1.45–25.01
-18 ≤ h ≤ 19
-11 ≤ k ≤ 12
-20 ≤ l ≤ 20
11 749
h,k,l range
No. of reflections measured
No. of unique reflections
Completeness to q
5077 (Rint = 0.0327)
99.6% (q = 25.01)
Full-matrix least-squares on F2
5077/0/343
0.950
9117 (Rint = 0.1800)
6610 (Rint = 0.0837)
99.7% (q = 20.59)
99.8% (q = 25.01)
Refinement method
Full-matrix least-squares on F2 Full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I > 2s(I)]
R indices (all data)
9117/44/403
1.010
R1 = 0.0731, wR2 = 0.1835
R1 = 0.1929, wR2 = 0.2705
1.348 and -1.298
6610/13/406
0.909
R1 = 0.0619, wR2 = 0.1456
R1 = 0.0980, wR2 = 0.1581
3.807 and -2.319
R1 = 0.0333, wR2 = 0.0684
R1 = 0.0595, wR2 = 0.0765
-3
˚
Largest diffraction peak and hole (e A ) 1.460 and -0.661
3304 | Dalton Trans., 2009, 3298–3305
This journal is
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©

View Article Online
(Nujol) n/cm-1: 3409 s, 3051 m, 1591 s, 1568 s, 1528 s, 1428 s,
1032 s, 882 m, 769 s, 733 s. m/z (%): 811 (29) [M].
References
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2
1
i
i
=
Synthesis of [CpYb(THF)(l-g :g -SC6H4N C(NH Pr)N Pr)]2
(3). A 20 mL THF solution of Cp3Yb (0.196 g, 0.53 mmol) was
slowly added to a 20 mL THF solution of 9 (0.559 g, 0.53 mmol) at
room temperature and stirred for 24 h. The reaction solution was
concentrated to ca. 5 mL by reduced pressure. Orange crystals of
3 were obtained at -20 ◦C for several days. Yield: 0.439 g (74%). C,
H, N analysis (%): calcd for C44H64N6O2S2Yb2: C 47.22, H 5.76,
N 7.51; found: C 47.19, H 5.80, N 7.74. IR (Nujol) n/cm-1: 3380
m, 1533 s, 1423 s, 1066 m, 1031 s, 922 m, 773 s, 744 s, 598 w. MS
(70 eV): m/z (%): 488 (13) [1/2M - THF]. The identify of 3 was
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Bailey, S. F. Bone, L. A. Mitchell, S. Parsons, K. J. Taylor and L. J.
Yellowlees, Inorg. Chem., 1997, 36, 867; (e) P. J. Bailey, L. A. Mitchell
and S. Parsons, J. Chem. Soc., Dalton Trans., 1996, 2389; (f) M. B.
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A. L. Blake, M. Kryszczuk, S. Parsons and D. Reed, J. Chem. Soc.,
Chem. Commun., 1995, 1647.
Crystal data and refinement details
Suitable single crystals of complexes 2, and 5–9 were sealed
under argon in Lindemann glass capillaries for X-ray structural
analysis. Diffraction data were collected on a Bruker SMART
Apex CCD diffractometer using graphite-monochromated MoKa
˚
(l = 0.71073 A) radiation. During the intensity data collection,
no significant decay was observed. The intensities were corrected
for Lorentz-polarization effects and empirical absorption with
SADABS program.15 The structures were solved by the direct
method using the SHELXL-97 program.16 All non-hydrogen
atoms were found from the difference Fourier syntheses. The
H atoms were included in calculated positions with isotropic
thermal parameters related to those of the supporting carbon
atoms, but were not included in the refinement. All calculations
were performed using the SHELXL program. A summary of the
crystallographic data and selected experimental information are
given in Tables 6 and 7.
7 (a) J. Zhang, X. G. Zhou, R. F. Cai and L. H. Weng, Inorg. Chem., 2005,
44, 716; (b) L. P. Ma, J. Zhang, R. F. Cai, Z. X. Chen, L. H. Weng and
X. G. Zhou, J. Organomet. Chem., 2005, 690, 4926; (c) J. Zhang, R. F.
Cai, L. H. Weng and X. G. Zhou, Organometallics, 2004, 23, 3303; (d) J.
Zhang, R. F. Cai, L. H. Weng and X. G. Zhou, J. Organomet. Chem.,
2003, 672, 94.
8 (a) W. X. Zhang, M. Nishiura and Z. M. Hou, Synlett., 2006, 1213;
(b) H. Shen, H.-S. Chan and Z. Xie, J. Am. Chem. Soc., 2007, 129,
12934; (c) W. X. Zhang, M. Nishiura and Z. M. Hou, Chem.–Eur. J.,
2007, 13, 4037.
9 J. Zhang, L. P. Ma, R. F. Cai, L. H. Weng and X. G. Zhou,
Organometallics, 2005, 24, 738.
10 (a) L. P. Ma, J. Zhang, Z. X. Zhang, R. F. Cai, Z. X. Chen and X. G.
Zhou, Organometallics, 2006, 25, 4571; (b) L. P. Ma, J. Zhang, R. F. Cai,
Z. X. Chen and X. G. Zhou, Dalton Trans., 2007, 2718; (c) J. Zhang,
R. F. Cai, Z. X. Chen and X. G. Zhou, Inorg. Chem. Commun., 2007,
10, 1265.
11 N. Yamamoto and M. Isobe, Chem. Lett., 1994, 2299.
12 J. March, Advanced Organic Chemistry, McGraw-Hill, New York, 1997,
vol. 2, p. 24.
Due to the poor quality of data for compound 8 that it was
appropriate to leave most of the atoms isotropic as could only
show the overall connectivity. The diffraction intensity is too
weak in the remote sets during the crystal data collection due
to the poor quality of crystal sample 8. In 2, the disorder and
isotropic of the atoms C6–C10 (one Cp ring) have been done.
Compounds 5 and 8 have large voids in the crystal structure
should be the result of the highly disordered solvent. However, this
problem cannot be solved by the use of the SQUEEZE program.
It maybe attributed to the low occupations of these solvent
molecules.
13 Handbook of Chemistry and Physics, ed. D. R. Lide, CRC press, Boca
Raton, 1996.
14 R. E. Magin, S. Manastyrskyj and M. Dubeck, J. Am. Chem. Soc.,
1963, 85, 672.
Acknowledgements
15 G. M. Sheldrick, SADABS, A Program for Empirical Absorption
Correction, Go¨ttingen, Germany, 1998.
We thank the National Natural Science Foundation of China,
973 program and Shanghai Leading Academic Discipline Project
(B108) for financial support.
16 G. M. Sheldrick, SHELXL-97, Program for the refinement of the crystal
structure, University of G
o¨ttingen, Germany, 1997.
This journal is
The Royal Society of Chemistry 2009
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