Isocyanate diinsertion into the N-H bond of the 2-pyridylamino ligand of organolanthanides

Article abstract of DOI:10.1039/b918181d

[Cp₂LnNHPy]₂ (Py = 2-pyridyl) (1a-e) react with phenyl isocyanate to form the N-H diinsertion products Cp₂Ln [η²:η¹-PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d), Gd (3e)). It has been proven that ⁿ Pr ₂NH can abstract one PhNCO unit from 3c to form Cp₂ Y[η³-OC(NHPh)NPy] (2c) and ⁿPr₂ NHCONHPh (4), representing a rare example of selective release of a functional group of ligands in organolanthanide chemistry. Hydrolysis of 2c gives the organic nitrogen-containing product PyNHCONHPh (5). Moreover, 3c can also be obtained by the reaction of 2c with PhNCO. These results demonstrate that the diinsertion of PhNCO into the N-H bond of coordinated amino ligands might proceed in a stepwise manner. All the compounds were characterized by elemental analysis and spectroscopic properties. The structures of compounds 3a-e and 4 are also determined through X-ray single-crystal diffraction analysis. The Royal Society of Chemistry 2010.

Full text of DOI:10.1039/b918181d

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Isocyanate diinsertion into the N–H bond of the 2-pyridylamino ligand
of organolanthanides†
Yan Sun,a Zhengxing Zhang,a Xu Wang,a Xiaoqing Li,a Linhong Wenga and Xigeng Zhou*a,b
Received 3rd September 2009, Accepted 22nd September 2009
First published as an Advance Article on the web 3rd November 2009
DOI: 10.1039/b918181d
[Cp2LnNHPy]2 (Py = 2-pyridyl) (1a–e) react with phenyl isocyanate to form the N–H diinsertion
2
1
products Cp2Ln[h :h -PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d),
Gd (3e)). It has been proven that nPr2NH can abstract one PhNCO unit from 3c to form
3
Cp2Y[h -OC(NHPh)NPy] (2c) and nPr2NHCONHPh (4), representing a rare example of selective
release of a functional group of ligands in organolanthanide chemistry. Hydrolysis of 2c gives the
organic nitrogen-containing product PyNHCONHPh (5). Moreover, 3c can also be obtained by the
= =
reaction of 2c with PhNCO. These results demonstrate that the diinsertion of PhN C O into the
N–H bond of coordinated amino ligands might proceed in a stepwise manner. All the compounds were
characterized by elemental analysis and spectroscopic properties. The structures of compounds 3a–e
and 4 are also determined through X-ray single-crystal diffraction analysis.
two decades, many organolanthanides have proven their abilities
Introduction
to act as catalysts in the intramolecular diinsertion of unsaturated
C–C functionalities into the N–H bond.1b,3a The catalysis may be
initiated by metallization of a N–H bond followed by tandem
intramolecular Ln–N and Ln–C bond insertion and protonation
to complete the catalytic cycle.
Insertion reactions identify an efficient, atom-economical, and
desirable route to form chemical bonds. Nevertheless, the direct
insertion of unsaturated molecules into unreactive organic nu-
cleophiles is generally difficult, and usually requires the use of
appropriate catalyst or initiator.1 Among a variety of approaches
to activation of these unreactive nucleophiles, metal-catalyzed
cleavage of C–H, E–H (E = heteroatom) and C–C bonds followed
by addition of the resulting M–C(E) bond across unsaturated
bonds is especially an attractive strategy.2 Despite significant
advances in this area, the efficient control of diinsertion remains
a major challenge since less reactive substrates preferentially give
rise to mono-inserted species, whereas the more reactive ones lead
to mixtures of mono- and poly-inserted derivatives.1a–c,3 The major
reason can be attributed to the reaction mechanism, which results
a similar reactivity toward unsaturated functionalities between
monoinsertion species and diinsertion ones. If a coordination
insertion process is viable for monoinsertion intermediate, it
usually has a tendency for multiple insertion to further take place.
Consequently, development of a new strategy for metal-induced
diinsertion of unsaturated substrates into nucleophiles would be
of particular value, but remains a significant challenge in organic
syntheses.
We have recently shown that the chelating effect not only
facilitates a direct addition of N–H bonds to heteroallenes (such as
carbodiimides) but delicately induces some unusual tandem N–H
activations of lanthanide-bound neutral NH2 and anionic NH-
containing fragments.5 These kinds of reactions identify a new
path to form C–N bonds and offer a certain degree of selectivity
due to the steric hindrance around the central metal ion, which
increases with the insertion degree, so limiting multiple insertion.
We were interested in the possibility of developing a ligand-
based diinsertion reaction of the N–H bond on lanthanide amido
complexes. Herein, we report details of the diaddition reaction of
lanthanocene pyridylamido complexes across phenyl isocyanate
to give the diureido complexes and the present contribution also
demonstrates that the resulting diureido ligand is a potential
provider of isocyanates which are of use in organic syntheses.
Results and discussion
N–H bonds are among the most ubiquitous and inexpensive
chemical linkages in nature and the direct conversion of N–H
bonds to N–C bonds through insertion reactions is an efficient and
economical strategy for fine chemical production.1b,2b,3,4 In the last
Synthesis of Cp2Ln[g2:g1-PyNCON(Ph)CONHPh](THF) (3)
Treatment of [Cp2LnNHPy]2 (Py = 2-pyridyl) 1a–e5a with
four equiv. of phenyl isocyanate in THF at ambient
2
1
temperature gave the unexpected products Cp2Ln[h :h -
PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c),
aDepartment of Chemistry, Shanghai Key Laboratory of Molecular Catalysis
and Innovative Materials, Fudan University, Shanghai, 200433, People’s
Republic of China. E-mail: xgzhou@fudan.edu.cn; Fax: +86 21 65641740;
Tel: +86 21 65643769
= =
Dy (3d), Gd (3e)), indicating that PhN C O diinserted into the
N–H bond of the coordinated amido group of 1 (Scheme 1).
Surprisingly, even in the reaction of 1a–e with two equiv. of
PhNCO, 3a–e were still obtained as the main products.
bState Key Laboratory of Organometallic Chemistry, Shanghai, 200032,
People’s Republic of China
The selective ligand-based insertion of organometallic com-
plexes is a much greater challenge as compared with insertion
into metal–ligand single bonds.5 Although amido metal complexes
† CCDC reference numbers 723138, 723135, 723136, 723137 and 745890
for compounds 3a, 3b, 3c, 3d, 3e and 4. For crystallographic data in CIF
or other electronic format see DOI: 10.1039/b918181d
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◦
˚
Table 1 Selected bond distances (A) and angles ( ) for 3
3a
3b
3c
3d
3e
Ln–O(2)
Ln–N(1)
Ln–N(2)
2.243(3)
2.413(4)
2.341(3)
1.342(5)
1.387(5)
1.245(5)
1.318(5)
1.424(6)
1.388(5)
1.434(5)
1.454(5)
1.339(5)
1.216(5)
2.259(3)
2.437(3)
2.364(3)
1.344(5)
1.383(5)
1.243(5)
1.322(5)
1.423(5)
1.387(5)
1.434(5)
1.456(5)
1.342(5)
1.214(4)
2.275(4)
2.459(4)
2.371(5)
1.343(5)
1.386(5)
1.237(5)
1.331(6)
1.427(6)
1.392(6)
1.450(5)
1.449(6)
1.344(6)
1.212(5)
2.292(4)
2.461(5)
2.393(5)
1.340(7)
1.381(7)
1.249(7)
1.307(7)
1.414(7)
1.388(8)
1.452(7)
1.457(7)
1.331(7)
1.211(7)
2.307(4)
2.415(5)
2.481(5)
1.357(8)
1.387(7)
1.237(7)
1.336(8)
1.432(8)
1.394(8)
1.459(7)
1.432(8)
1.337(8)
1.184(7)
C(11)–N(1)
C(11)–N(2)
C(23)–O(2)
C(23)–N(4)
C(24)–N(4)
C(23)–N(3)
C(16)–N(3)
C(17)–N(3)
C(16)–N(2)
C(16)–O(1)
O(2)–C(23)–N(3)
C(23)–N(3)–C(16)
N(3)–C(16)–N(2)
Ln–O(2)–C(23)
O(2)–Ln–N(1)
C(16)–N(2)–C(11)
N(2)–C(11)–N(1)
123.7(4)
123.3(4)
126.6(3)
115.0(3)
139.4(3)
124.81(10)
120.6(3)
109.1(3)
123.7(4)
126.2(4)
115.1(4)
139.5(3)
124.61(15)
120.4(3)
109.6(4)
122.8(5)
127.0(5)
114.7(5)
139.7(4)
123.61(16)
120.3(5)
109.9(5)
124.8(5)
125.6(5)
114.5(5)
139.5(4)
122.57(17)
119.4(5)
109.0(7)
126.2(4)
114.9(4)
138.9(3)
125.63(12)
120.5(3)
108.7(3)
Scheme 1
have been studied extensively,5–7 to the best of our knowledge, the
analogous coupling diinsertion pattern has not yet been reported.
Complexes 3a–e are moderately sensitive toward moisture and
air. They are soluble in THF, but less soluble in n-hexane. All
these complexes have been characterized by elemental analysis
and spectroscopic methods. In the IR spectra of complexes 3a–e,
a band at ca. 3406–3411 cm–1 attributable to the n(N–H) vibration
is observed. The carbonyl characteristic stretching frequency was
observed at 1650–1670 cm-1, and slightly red-shifted as compared
with that of free delocalized carbonyl group. Moreover, the
medium band at about 1075–1070 cm-1 could be assigned to the
pendent THF molecule.8
2
1
Fig.
1 Thermal ellipsoid (30%) plot of complexes Cp2Ln[h :h -
PyNCON(Ph)CONHPh](THF) (Ln = Yb (3a), Er (3b), Y (3c), Dy (3d),
Gd (3e)). Hydrogen atoms, except the H atom at the nitrogen atom, are
omitted for clarity.
rigorously coplanar. Within this extended ligand, there are four
short bonds, C(23)–O(2), C(23)–N(4), C(16)–O(1) and C(16)–
˚
N(2). For example, in 3a the C(16)–O(1) distance of 1.216(5) A is
The molecular structures of 3a–e were confirmed by X-ray struc-
tural analysis. Complexes 3a, 3b, 3c, 3d and 3e are isostructural,
and the lanthanide ion possesses a distorted trigonal-bipyramidal
geometry surrounded by two rings, one oxygen and two nitrogen
atoms (Fig. 1). It can be seen that two PhNCO molecules
have been formally inserted into the N–H bond, and that the
resultant phenylcarbamoyl ureido ligand is coordinated through
two nitrogen and one oxygen atoms to the Cp2Ln fragment.
The differences of lanthanide iron radii lead to slight changes
in the bond distances and angles of complexes 3a–e (Table 1).
There are no unusual distances or angles in the metallocene unit.
The bond distances in the chelating ligand indicate considerable
delocalization. The bond angles around C(16), C(23), N(2),
N(3) and N(4) are consistent with sp2 hybridization, although
Ln, O(2), C(11), C(16), C(23), N(1), N(2) and N(3) are not
in the typical double bond range, while the C(23)–O(2) distance
2
˚
˚
=
of 1.245(5) A is between the 1.192–1.23 A range of C(sp ) O and
2
9
˚
the 1.30–1.39 A range of C(sp )–O distances in the literature.
˚
The 1.318(5) A C(23)–N(4) bond distance is near the high end of
2
10
˚
=
the 1.279–1.329 A range of reported C(sp ) N distances. The
C(16)–N(3) bond distance of 1.434(5) A is between the C(sp )–
N distance and the typical C(sp3)–N single bond distance. The
2
˚
˚
N–C(ipso) bonds, N(3)–C(17) 1.454(5) A and N(4)–C(24) 1.424(6)
˚
˚
A, also have lengths indicative of single bonds. The 1.339(5) A
C(16)–N(2) bond is clearly shorter than this typical single bond
˚
range. The Yb–O(2) distance of 2.243(3) A is in the low end of the
range of observed Yb3+←:OR2.11 Moreover, the H atom at N(4)
atom can be distinctly identified by the hydrogen bond interaction
with the oxygen atom of the solvent THF molecule, as shown in
Fig. 1.
222 | Dalton Trans., 2010, 39, 221–226
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Reactivity of complexes 3
In contrast to the previously reported insertion of isocyanate
into metal–ligand bonds, where the presence of excess isocyanate
often leads to the formation of cyclotrimers and polymers of
isocyanates,6a,b,12 we have found that complex 3a is inert to the
isocyanate. This might be attributed to the difference of the steric
crowding of the center metal in the two cases. For the former
the approach of the third PhNCO to the metal center is less
hindered, which should prevent the insertion from stopping at the
1 : 2 adduct stage and catalyzing the excess PhNCO to cyanurates
(PhNCO)3 and polymers, while for the latter the steric hindrance
around the central metal ion depends on the level of insertion
and the insertion of a third PhNCO molecule into sterically
saturated 3a is prevented, so that the diinsertion product is
isolated.
Fig. 2 Thermal ellipsoid (30%) plot of the compound nPr2NC(O)NHPh.
(4) Hydrogen atoms, except the H atom ◦at nitrogen atom, are omitted for
˚
clarity. Key bond lengths (A) and angles ( ): C(1)–N(1) 1.411(3), C(7)–N(1)
As few stoichiometric diinsertion reactions of organolan-
thanides had been hitherto reported and the reactions of the
resulting metal-containing diinsertion products remained almost
unexplored,13,14 with the aim of establishing whether the diureido
ligand imparts to their lanthanocene complexes an enhanced
reactivity we then turned our attention to the reaction of these
diinsertion products with amines. Surprisingly, the treatment of
3c with an excess of nPr2NH led to the abstraction of one
PhNCO unit by amine, giving Cp2Y[OC(NHPh)NPy] (2c) and
nPr2NC(O)NHPh (4) in 96 and 41% yield, respectively, indicating
that the second insertion reaction is reversible under certain
conditions (Scheme 2). The hydrolysis of 2c produced the nitrogen-
containing organic product PyNHC(O)NHPh (5). Compounds
1.366(3), C(7)–N(2) 1.354(3), C(8)–N(2) 1.462(3), C(11)–N(2) 1.3465(3),
C(7)–O(1) 1.231(3); C(1) –N(1)–C(7) 124.4(2), N(1)–C(7) –N(2) 117.1(2),
C(7)–N(2)–C(8) 117.7(2), C(7)–N(2)–C(11) 125.7(2).
reaction of 2c with one equiv. of PhNCO. Therefore, the above
= =
diinsertion of PhN C O into the N–H bond of coordinated
amino ligands might proceed in a stepwise manner. The driving
force for the subsequent insertion reaction of the ureido complex
intermediate (2) probably results from the acidity of the newly
formed N–H proton and its accessibility to another isocyanate,
making a favorable tropism of the nucleophilic nitrogen adjacent
to the carbon atom of the incoming isocyanate, a position which
is generally electrophilic.13
1
2c, 4 and 5 were characterized by IR, elemental analysis and H
NMR. The elemental analysis data for these compounds were
consistent with the assigned structures. The 1H NMR spectrum of
2c showed the cyclopentadienyl, pyridyl and phenyl resonances in
the expected 10 : 4 : 5 ratio. In the IR spectra of complex 2c, a band
at ca, 3403 cm-1 attributable to n(N–H) is observed. The carbonyl
characteristic stretching frequency was observed at 1657 cm-1. The
molecular structure of compound 4 was also identified by X-ray
diffraction analysis, as shown in Fig. 2.15
In contrast to the extensive studies on the reversibility of
insertions of transition-metal complexes, reports on well-defined
reverse insertions of organolanthanides are scarce.16 Presumably,
the driving force for the abstraction of one PhNCO unit by
an amine might be the fluxionality of the proton of the NH
group (Scheme 3), analogous to that already observed in other
polynitrogen systems such as pyridyl-linked diguanidinate mono-
and dianionic ligands.5 Obviously, the transformation of 3c to 2c
represents a rare example of selective release of a functional group
of ligands in organolanthanide chemistry, and provides a new
insight into the ligand-forming and transformation behavior of
organolanthanides. Furthermore, these results demonstrate that
the diinsertion products are a potential provider of isocyanates.
Since isocyanates are important building blocks in synthetic
organic chemistry,17 the particular value of compound 3 as a
precursor of isocyanates lies its mild in situ formation and
reactivity.
Scheme 2
The lack of precedent for such group transfer reaction of
organolanthanides prompted us to further investigate the reaction
of 2c with PhNCO. It was found that 3c could be obtained by the
Scheme 3
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(0.357 g, 3.00 mmol) afforded 3c as light yellow crystals. Yield:
0.481 g (51.5%). Anal. Calc. for C33H33N4O3Y: C, 63.67; H, 5.34;
N, 9.00; Y, 13.42. Found: C, 63.60; H, 5.38; N, 9.08; Y, 13.33.
IR (Nujol, cm-1): 3411 (m), 1655 (s), 1588 (s), 1465 (m), 1377
(m), 1255 (m), 1109 (m), 1012 (m), 735 (m). 1H NMR (400 MHz,
C6D6) of 3c: d 8.50 (d, Py, 1H), 7.45 (m, Py, 1H), 6.96–6.88 (m,
Py, Ph, 12H), 6.14 (s, C5H5, 10H), 3.50 (t, THF, 4H), 1.34 (m,
THF, 4H).
Conclusion
In conclusion, we have demonstrated that selective diinsertion
of isocyanates into the N–H bond is a viable fundamental
reaction for organolanthanide complexes, which represents an
unusual reactivity pattern of air-sensitive organolanthanide com-
plexes with unsaturated organic molecules. Moreover, it has
been unexpectedly revealed that the insertion of the second
isocyanate molecule is reversible and dipropylamine can abstract
one isocyanate unit from the diinsertion product Cp2Ln[h :h -
PyNCON(Ph)CONHPh](THF). These results highlight the value
of the ligand-based diinsertion and have proved that the
N–H moiety of organolanthanides may act as a depository of
isocyanates.
Preparation of Cp2Dy[g2:g1-PyNCON(Ph)CONHPh](THF)
(3d). Following the procedure described for 3a, using
[Cp2DyNHPy]2 1d (0.386 g, 0.50 mmol) and phenyl isocyanate
(0.238 g, 2.00 mmol) afforded 3d as light yellow crystals. Yield:
0.412 g (59.1%). Anal. Calc. for C33H33N4O3Dy: C, 56.94; H, 4.78;
N, 8.05; Dy, 22.07. Found: C, 56.76; H, 4.72; N, 7.92; Dy, 22.07%.
IR (Nujol, cm-1): 3411 (m), 1655 (s), 1618 (m), 1587 (s), 1448 (m),
1376 (m), 916 (m), 723 (m).
2
1
Experimental
General remarks
Preparation of Cp2Gd[g2:g1-PyNCON(Ph)CONHPh](THF)
(3e). Following the procedure described for 3a, using
[Cp2GdNHPy]2 1e (0.407 g, 0.54 mmol) and phenyl isocyanate
(0.257 g, 2.16 mmol) afforded 3e as light yellow crystals. Yield:
0.415 g (56.1%). Anal. Calc. for C33H33N4O3Gd: C, 57.37; H, 4.81;
N, 8.11; Gd, 21.51. Found: C, 57.88; H, 5.12; N, 8.54; Gd, 19.65%.
IR (Nujol, cm-1): 3410 (m), 1659 (s), 1589 (s), 1511 (m), 1462 (m),
1377 (m), 1322 (w), 1246 (m), 1211 (m), 1169 (m), 1107 (s), 1013
(m), 907 (m), 753 (m).
All operations involving air- and moisture-sensitive compounds
were carried out under an inert atmosphere of purified nitrogen
gas using standard Schlenk techniques. All organic solvents (THF,
toluene and n-hexane) were refluxed and distilled over sodium
benzophenone ketyl under nitrogen gas prior to use. Complexes
[Cp2LnNHPy]2 (Py = 2-pyridyl, 1) were prepared according to
the procedures described in the literatures.5a Phenyl isocyanate
and diisopropylamine were purchased from commercial sources
and used without further purification. Elemental analyses for C,
H and N were carried out by using a Rapid CHN-O analyzer.
Metal analyses for lanthanides were accomplished using a liter-
ature method.18 Infrared spectra for air- and moisture-sensitive
compounds were obtained on a Nicolet FTIR 360 spectrometer
with samples prepared as Nujol mulls, while for other common
organic compounds KBr disks were prepared. 1H NMR data were
obtained on a Bruker DMX-400 NMR spectrometer.
Reaction of 3c with dipropylamine. To a THF solution (10 mL)
of 3c (0.104 g, 0.166 mmol) was added nPr2NH (0.084 g,
0.830 mmol) at room temperature. After being stirred overnight,
the solvent was removed under reduced pressure. The solid was ex-
tracted with n-hexane (20 mL), and compound nPr2NC(O)NHPh
(4) (0.015 g, 41.0%) was obtained as a crystalline solid from the
hexane solution. The residual solid was washed with n-hexane
and dried to afford Cp2Y[OC(NHPh)NPy] (2c) as a white powder
(0.069 g, 96.4%); 2c was then hydrolyzed and extracted with
chloroform. The organic layer was separated, dried over anhydrous
MgSO4, concentrated under reduced pressure, and purified by
flash column chromatography to afford PyNHC(O)NHPh (5)
(0.032 g, 90.4% based on the pyridyl). Anal. Calc. for 2c,
C22H20N3OY: C, 61.26; H, 4.67; N, 9.74; Y, 20.61. Found: C, 61.19;
H, 4.61; N, 9.68; Y, 20.53%. IR (Nujol, cm-1): 3403 (m), 1657 (m),
1594 (s), 1546 (s), 1461 (m), 1377 (m), 1260 (m), 1155 (m), 1016
(m), 723 (m). 1H NMR (400 MHz, C6D6) of 2c: d 8.11 (d, Py, 1H),
6.90–7.75 (m, Py, Ph, 8H), 6.24 (s, C5H5, 10H). Anal. Calc. for 4,
C13H20N2O: C, 70.87; H, 9.15; N, 12.72. Found: C, 70.84; H, 9.14;
N, 12.68%. IR (KBr, cm-1): 3309 (m), 2958 (m), 2926 (w), 1715
(vs), 1665 (m), 1588 (w), 1509 (m), 1447 (s), 1375 (m), 1245 (m),
1163 (m), 1035 (w), 912 (m), 756 (m). 1H NMR (400 MHz, CDCl3)
d 7.39–7.00 (m, 5H), 6.33 (s, 1H), 3.26 (t, J = 7.56 Hz, 4H), 1.65
(m, 4H), 0.94 (t, J = 7.34 Hz, 6H); 13C NMR (100 MHz, CDCl3)
d 155.0, 139.2, 128.8, 122.7, 119.7, 49.4, 21.8, 11.4.19a Anal. Calc.
for 5, C12H11N3O: C, 67.59; H, 5.20; N, 19.71. Found: C, 67.58; H,
5.17; N, 19.68%. IR (KBr, cm-1): 3310 (m), 1709 (vs), 1675 (m),
1598 (w), 1530 (s), 1499 (m), 1440 (s), 1322 (m), 1265 (m), 1183
Preparation of Cp2Yb[g2:g1-PyNCON(Ph)CONHPh](THF)
(3a). To a THF solution (30 mL) of [Cp2YbNHPy]2 1a (0.538 g,
0.68 mmol) was added phenyl isocyanate (0.324 g, 2.72 mmol) with
stirring at 0 ◦C. Then the reaction mixture was allowed to warm to
room temperature and stirred for 36 h. The solution changed from
yellow to brown–yellow during the course of the reaction. The
◦
solution was concentrated and cooled at -15 C for several days
to give 3a as yellow crystals. Yield: 0.585 g (60.9%). Anal. Calc.
for C33H33N4O3Yb: C, 56.09; H, 4.71; N, 7.93; Yb, 23.17. Found:
C, 56.01; H, 4.76; N, 7.87; Yb, 23.04%. IR (Nujol, cm-1): 3405 (m),
1672 (s), 1634 (m), 1588 (m), 1554 (m), 1511 (vs), 1462 (m), 1376
(s), 1250 (m), 1211 (m), 1109 (m), 1074 (m), 1016 (s), 728 (m).
Preparation of Cp2Er[[g2:g1-PyNCON(Ph)CONHPh](THF)
(3b). Following the procedure described for 3a, using
[Cp2ErNHPy]2 1b (0.683 g, 0.875 mmol) and phenyl isocyanate
(0.416 g, 3.50 mmol) afforded 3b as light pink crystals. Yield:
0.790 g (64.6%). Anal. Calc. for C33H33N4O3Er: C, 56.55; H, 4.75;
N, 7.99; Er, 23.86. Found: C, 56.48; H, 4.78; N, 7.96; Er, 23.79%.
IR (Nujol, cm-1): 3410 (m), 1653 (s), 1590 (s), 1463 (m), 1375 (m),
1253 (m), 1112 (m), 1016 (m), 728 (m).
1
(m), 1030 (w), 902 (m), 753 (m). H NMR (400 MHz, CDCl3) d
Preparation of Cp2Y[g2:g1-PyNCON(Ph)CONHPh](THF)
(3c). Following the procedure described for 3a, using
[Cp2YNHPy]2 1c (0.468 g, 0.75 mmol) and phenyl isocyanate
11.81 (s, 1H), 9.35 (s, 1H), 8.26 (d, J = 4.4 Hz, 1H), 7.66–6.92 (m,
8H); 13C NMR (100 MHz, CDCl3) d 153.9, 153.1, 145.8, 138.6,
128.9, 123.4, 120.3, 117.2, 112.4.19b
224 | Dalton Trans., 2010, 39, 221–226
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Table 2 Crystal and data collection parameters of complexes 3a–e
3a
3b
3c
3d
3e
Formula
Mr
C33H33N4O3Yb
706.67
C33H33N4O3Er
700.89
C33H33N4O3Y
622.54
C33H33N4O3Dy
696.13
C33H33N4O3Gd
690.88
Crystal dimensions/mm
Crystal system
Space group
0.30 ¥ 0.25 ¥ 0.15
Monoclinic
P21/n
0.30 ¥ 0.25 ¥ 0.15
Monoclinic
P21/n
0.20 ¥ 0.15 ¥ 0.12
Monoclinic
P21/n
9.795(16)
11.88(2)
26.18(4)
94.61(3)
3037(9)
4
1.362
1.959
1288
293(2)
1.88–25.01
12541
5342
0.20 ¥ 0.10 ¥ 0.10
Monoclinic
P21/n
0.20 ¥ 0.15 ¥ 0.14
Monoclinic
P21/n
˚
a/A
9.809(4)
9.799(3)
9.821(4)
9.811(6)
˚
b/A
11.794(5)
26.003(10)
94.882(5)
2997(2)
11.819(3)
26.044(8)
94.795(4)
3005.6(15)
4
1.549
2.832
1404
293(2)
11.862(4)
26.143(9)
94.762(5)
3035.2(19)
4
1.523
2.501
1396
293(2)
11.851(7)
26.149(16)
94.670(7)
3030(3)
˚
c/A
b/o
3
˚
V/A
Z
4
4
Dc/g cm-3
1.566
3.160
1412
293(2)
1.57–25.01
12228
5259
1.514
2.228
1388
293(2)
1.89–25.00
12065
5279
m(Mo-Ka)/mm-1
F(000)
T/K
q range/◦
1.57–27.01
14254
6428
1.56–25.01
14735
5331
No. reflns measured
No. unique reflns
Rint
0.0218
0.0410
0.0554
0.0259
0.0340
Completeness to q (%)
Max./min. transmission
Data/restraints/params
GOF
97.7 (q = 25.01)
0.6486/0.4508
5259/25/374
1.146
R1 = 0.0312,
wR2 = 0.0739
R1 = 0.0383,
wR2 = 0.0765
0.722/-0.969
97.7 (q = 27.01)
0.6761/0.4838
6428/30/373
0.911
R1 = 0.0319,
wR2 = 0.0678
R1 = 0.0485,
wR2 = 0.0708
1.279/-0.730
99.7 (q = 25.01)
0.7989/0.6953
5342/6/373
0.981
R1 = 0.0498,
wR2 = 0.1094
R1 = 0.0879,
wR2 = 0.1242
0.603/-0.409
99.6 (q = 25.01)
0.7881/0.6347
5331/1/373
1.091
R1 = 0.0390,
wR2 = 0.1299
R1 = 0.0477,
wR2 = 0.1372
1.021/-1.060
99.0 (q = 25.00)
0.7456/0.6642
5279/1/348
0.999
R1 = 0.0423,
wR2 = 0.1125
R1 = 0.0551,
wR2 = 0.1215
0.983/-0.851
Final R indices [I > 2s(I)]
R indices (all data)
-3
˚
Drmax/min/e A
Reaction of 2c with phenyl isocyanate. To a THF solution
(10 mL) of 2c (0.114 g, 0.264 mmol) was added PhNCO
(0.032 g, 0.264 mmol) at -20 C, then the reaction mixture was
Acknowledgements
◦
This work was supported by the NNSF of China, 973 program
(2009CB825300), NSF of Shanghai, and Shanghai Leading Aca-
demic Discipline Project for financial support (B108).
allowed to warm to room temperature and stirred overnight.
The solution was removed under reduced pressure. The light
2
1
yellow solid Cp2Y[h :h -PyNCON(Ph)CONHPh] (3c) was ob-
tained by recrystallization from its THF solution. Yield: 0.104 g
(63.3%).
Notes and references
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Crystal data and refinement details
Suitable single crystals of compounds 3 and 4 were sealed under
N2 in thin-walled glass capillaries for X-ray structural analysis. X-
Ray diffraction data were collected on a SMART APEX CCD
diffractometer (graphite-monochromated Mo-Ka radiation,
˚
q–w scan technique, l = 0.71073 A). The intensity data were
integrated by means of the SAINT program.20 SADABS21 was
used to perform area-detector scaling and absorption corrections.
The structures were solved by direct methods and were refined
against F2 using all reflections with the aid of the SHELXTL
package.22 All nonhydrogen atoms were refined anisotropically.
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 non-hydrogen
atoms were found from the difference Fourier syntheses. All
calculations were performed using the Bruker Smart program.
Selected bond lengths and angles of complexes 3 are listed in
Table 1. A summary of crystallographic parameters along with
details of the data collection and refinement for complexes 3a–e
are collected in Table 2.
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226 | Dalton Trans., 2010, 39, 221–226
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The Royal Society of Chemistry 2010
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