Investigations on organolanthanide derivatives with the hydrazonido ( -NHN=CPh2) ligand: synthesis, crystal structure, and reactivity

Article abstract of DOI:10.1021/om900246b

Two organolanthanide complexes with the benzophenone hydrazonido(l-) ligand, [Cp₂Yb(MNHN=CPh₂)]₂ (1) and Cp ₂Er[η²-NHN=CPh₂](THF) (2), were synthesized by abstraction of cyclopentadienyl fr

Full text of DOI:10.1021/om900246b

3916 Organometallics 2009, 28, 3916–3921
DOI: 10.1021/om900246b
Investigations on Organolanthanide Derivatives with the Hydrazonido
(-NHNdCPh2) Ligand: Synthesis, Crystal Structure, and Reactivity
Yanan Han, Jie Zhang,* Fuyan Han, Zhengxing Zhang, Linhong Weng, and Xigeng Zhou*
Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials,
Fudan University, Shanghai 200433, People’s Republic of China
Received March 31, 2009
Two organolanthanide complexes with the benzophenone hydrazonido(1-) ligand, [Cp2Yb(μ-
NHNdCPh2)]2 (1) and Cp2Er[η2-NHNdCPh2](THF) (2), were synthesized by abstraction of cyclo-
pentadienyl from Cp3Ln with 1 equiv of benzophenone hydrazone in THF. Reaction of 1 and 2 with
phenyl isocyanate gives Ln-N bond insertion with the 1,3-H migration products Cp2Ln(η2-OC
(NHPh)NNdCPh2)(HMPA) (Ln = Yb (3), Er (4)). However, 1 and 2 react with PhNCS to give Ln-N
bond insertion without the 1,3-H migration products Cp2Ln(η2-SC(NHNdCPh2)NPh)(HMPA) (Ln =
Yb (5), Er (6)) under the same conditions. PhCN inserts into the Er-N bond of 2 with 1,3-hydrogen
migration to form the organolanthanide heterometallacycles Cp2Er[η2-NHC(Ph)NNdCPh2] (7).
However, tBuNC does not insert into the Er-N bond of 2 under the same conditions, and treatment
of 2 with tBuNC leads to the isolation of the solvent-free dimer [Cp2Er(μ-η1:η2-NHNdCPh2)]2 (20). All
new compounds have been characterized through X-ray single-crystal diffraction analysis.
Introduction
tion about their rare-earth complexes is rather limited. To
the best of our knowledge, only a few lanthanide and group 3
complexes with hydrazido ligands have been reported
to date.6a-6c The reactivity of the scandium hydrazido com-
plexes with acetonitrile has been described by Bercaw and co-
workers.6b
The activation of organolanthanides on unsaturated organic
small molecules is an important field in organolanthanide
chemistry.7,8 As one flourishing subdiscipline of this field,
insertion reactions have been studied extensively over the past
decade, because they permit unusual organolanthanide deriva-
tives to be prepared and provide new bond-forming methods for
organic synthesis with exquisite selectivity and effectiveness.9-11
Recently, our interest has been focused on the investigation
of the addition of the N-H bonds of organolanthanide
There has been considerable and growing interest in metal
hydrazido complexes and in their role as catalysts for the
stoichiometric and catalytic reduction of dinitrogen to ammo-
nia;1 further, the terminal hydrazido(2-) ligands are believed
to participate in alkyne hydrohydrazination2 and iminohydra-
zination3 catalysis. Although many transition-metal hydrazido
complexes have been synthesized in recent years,4,5 informa-
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r
pubs.acs.org/Organometallics
Published on Web 06/01/2009
2009 American Chemical Society

Article
Organometallics, Vol. 28, No. 13, 2009 3917
derivatives to some unsaturated organic small molecules to
construct a novel neutral or anionic ligand or an N-hetero-
cyclic skeleton.12 As part of this program, we were interested
in the reactivity of lanthanide hydrazonido complexes to-
ward heteroallenes. Therefore, herein we report the synthesis
of organolanthanide derivatives bearing the benzophenone
hydrazonido(1-) ligand and their reactions with PhNCO,
PhNCS, and PhCN.
(2H, C6H5), 17.96 (1H, C6H5), 17.61 (2H, C6H5), 12.49 (2H,
C6H5), 11.07 (2H, C6H5), 10.42 (1H, NH), 10.09 (1H, C6H5),
8.44 (18H, N(CH3)2), 3.39 (1H, C6H5), 2.43 (2H, C6H5), -7.06
(2H, C6H5), -9.74 (10H, C5H5); IR (Nujol): 3359 s, 1606 m,
1587 s, 1570 s, 1530 s, 1443 s, 1303 s, 1070 w, 1016 s, 941 m, 768 s,
707 m, 654 m cm-1
.
Synthesis of Cp2Er[η2-OC(NHPh)NNdCPh2](HMPA) (4).
Following the procedure described for 3, reaction of PhNCO
(0.055 g, 0.46 mmol) with 2 (0.260 g, 0.46 mmol) and HMPA
(0.083 g, 0.46 mmol) gave 4 as pink crystals. Yield: 0.276 g
(76%). Anal. Calcd for C36H44N6O2PEr: C, 54.66; H, 5.61; N,
10.62. Found: C, 54.53; H, 5.57; N, 10.66. IR (Nujol): 3351 m,
1605 m, 1589 s, 1571 s, 1530 s, 1443 s, 1071 w, 1011 s, 989 s, 748 s,
Experimental Section
General Procedure. All operations involving air- and moist-
ure-sensitive compounds were carried out under an inert atmo-
sphere of purified argon or nitrogen using standard Schlenk
techniques or a glovebox. The solvents THF, toluene, and n-
hexane were refluxed and distilled over sodium benzophenone
ketyl under nitrogen immediately prior to use. (C5H5)3Ln was
prepared by literature methods.13 PhNCO, PhNCS, PhCN,
tBuNC, Ph2CdNNH2, and HMPA (hexamethylphosphoric
triamide) 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 ob-
tained on a Nicolet FT-IR 360 spectrometer with samples
697 m, 658 w cm-1
.
Synthesis of Cp2Yb[η2-SC(NHNdCPh2)NPh](HMPA) (5).
Following the procedure described for 3, reaction of 1 (0.339 g,
0.34 mmol) with phenyl isothiocyanate (0.092 g, 0.68 mmol) and
HMPA (0.122 g, 0.68 mmol) gave 5 as orange crystals. Yield:
0.370 g (67%). Anal. Calcd for C36H44N6OSPYb: C, 53.20;
H, 5.46; N, 10.34. Found: C, 53.12; H, 5.47; N, 10.43. IR (Nujol):
3299 m, 1589 m, 1562 w, 1531s, 1445 s, 1400 m, 1169 s,
1073 w, 1012 s, 984 s, 770 s, 745 s, 705 m, 665 w cm-1. No
valuable 1H NMR spectra on this ytterbium compound could be
obtained.
1
Synthesis of Cp2Er[η2-SC(NHNdCPh2)NPh](HMPA) (6).
Following the procedure described for 3, reaction of 2 (0.327
g, 0.58 mmol) with phenyl isothiocyanate (0.079 g, 0.58 mmol)
and HMPA (0.104 g, 0.58 mmol) gave 6 as pink crystals. Yield:
0.300 g (64%). Anal. Calcd for C36H44N6OSPEr: C, 53.58; H,
5.49; N, 10.41. Found: C, 53.43; H, 5.43; N, 10.54. IR (Nujol):
3300 s, 1588 m, 1573 w, 1562 w, 1530 s, 1445 s, 1399 s, 1167s,
prepared as Nujol mulls. H NMR data were obtained on a
Bruker DMX-400 NMR spectrometer.
Synthesis of [Cp2Yb(μ-NHNdCPh2)]2 (1). (C5H5)3Yb (0.943
g, 2.56 mmol) and Ph2CdNNH2 (0.504 g, 2.56 mmol) were
mixed in 50 mL of THF. After the mixture was stirred for 24 h at
room temperature, all volatile substances were removed under
vacuum to give an orange powder. Red crystals of 1 were
obtained by recrystallization from THF at -20 °C for several
days. Yield: 1.12 g (87%). Anal. Calcd for C46H42N4Yb2: C,
1071 w, 1006 s, 994 s, 778 s, 745 s, 705 m, 665 w cm-1
.
Synthesis of Cp2Er[η2-NHC(Ph)NNdCPh2] (7). PhCN (0.046
g, 0.45 mmol) was slowly added to a 20 mL THF solution of 2
(0.254 g, 0.45 mmol) at room temperature, and the mixture was
stirred for 24 h. The reaction solution was concentrated to ca. 5
mL by reduced pressure. Pink crystals of 7 were obtained by
slow diffusion of n-hexane. Yield: 0.212 g (79%). Anal. Calcd
for C30H26N3Er: C, 60.48; H, 4.40; N, 7.05. Found: C, 60.41; H,
4.37; N, 7.11. IR (Nujol): 3366 m, 1584 s, 1529 s, 1502 s, 1426 m,
1
55.42, H, 4.25; N, 5.62. Found: C, 55.31; H, 4.21; N, 5.69. H
NMR (C6D6, 7.16): δ 64.25 (4H, C6H5), 26.43 (4H, C6H5), 23.39
(4H, C6H5), 18.87 (2H, NH), 12.49 (4H, C6H5), 11.85 (4H,
C6H5), -17.37 (20H, C5H5). IR (Nujol): 3178 m, 1598 w, 1574
m, 1549 m, 1535 m, 1493 s, 1440 s, 1391 s, 1158 m, 1074 w, 1010 s,
955 s, 777 s, 704 m, 661 m cm-1
.
Synthesis of Cp2Er[η2-NHNdCPh2](THF) (2). Following the
procedure described for 1, reaction of (C5H5)3Er (0.972 g, 2.68
mmol) with Ph2CdNNH2 (0.528 g, 2.68 mmol) gave 2 as pink
crystals. Yield: 1.26 g (83%). Anal. Calcd for C27H29ON2Er: C,
57.42; H, 5.17; N, 4.96. Found: C, 57.33; H, 5.15; N, 5.05. IR
(Nujol): 3548 s, 3422 m, 3260 m, 1574 s, 1436 s, 1194 s, 1071 s,
1406 w, 1215 m, 1016 s, 785 s, 768 s, 705 m, 660 w cm-1
.
Synthesis of [Cp2Er(μ-η1:η2-NHNdCPh2)]2 (20). tBuNC
(0.034 g, 0.40 mmol) was slowly added to a 20 mL THF solution
of 2 (0.226 g, 0.40 mmol) at room temperature, and the mixture
was stirred for 24 h. The reaction solution was concentrated to ca.
5 mL by reduced pressure. Pink crystals of 20 were obtained by
slow diffusion of n-hexane. Yield: 0.124 g (63%). Anal. Calcd
for C46H42N4Er2: C, 56.07; H, 4.30; N, 5.69. Found: C, 55.95;
H, 4.27; N, 5.77. IR (Nujol): 3251 m, 3243 w, 1598 w, 1574 w,
1529 m, 1514 m, 1494 s, 1442 s, 1041 s, 1021 s, 959 m, 770 s, 697 m,
1009 s, 950 m, 913 m, 866 s, 769 s, 707 m, 656 w cm-1
.
Synthesis of Cp2Yb[η2-OC(NHPh)NNdCPh2](HMPA) (3).
PhNCO (0.081 g, 0.67 mmol) was slowly added to a 20 mL THF
solution of 1 (0.332 g, 0.33 mmol) at room temperature, and the
mixture was stirred for 1 h. Then HMPA (0.120 g, 0.66 mmol)
was added into the solution, and this mixture was continuously
stirred overnight. The reaction solution was concentrated to ca.
5 mL under reduced pressure. Orange crystals of 3 were
obtained by slow diffusion of n-hexane. Yield: 0.373 g (71%).
Anal. Calcd for C36H44N6O2PYb: C, 54.27; H, 5.57; N, 10.55.
660 w cm-1
.
Structure Determination of Complexes 1-7 and 20. X-ray
structure determination details and crystallographic refinement
parameters of complexes 1-7 and 20 are given in the Supporting
Information.
1
Found: C, 54.21; H, 5.53; N, 10.61. H NMR (C6D6): δ 26.01
Results and Discussion
(12) (a) Zhang, J.; Cai, R. F.; Weng, L. H.; Zhou, X. G. Organome-
tallics 2004, 23, 3303. (b) Ma, L. P.; Zhang, J.; Zhang, Z. X.; Cai, R. F.;
Chen, Z. X.; Zhou, X. G. Organometallics 2006, 25, 4571. (c) Ma, L. P.;
Zhang, J.; Cai, R. F.; Chen, Z. X.; Zhou, X. G. Dalton Trans. 2007, 2718.
(d) Zhang, J.; Cai, R. F.; Chen, Z. X.; Zhou, X. G. Inorg. Chem.
Commun. 2007, 10, 1265. (e) Zhang, J.; Ma, L. P.; Cai, R. F.; Weng,
L. H.; Zhou, X. G. Organometallics 2005, 24, 738. (f) Zhang, J.; Han, Y.
N.; Han, F. Y.; Chen, Z. X.; Weng, L. H.; Zhou, X. G. Inorg. Chem.
2008, 47, 5552. (g) Pi, C. F.; Liu, R. T.; Zheng, P. Z.; Chen, Z. X.; Zhou,
X. G. Inorg. Chem. 2007, 46, 5252–5259. (h) Pi, C. F.; Zhu, Z. Y.; Weng,
L. H.; Chen, Z. X.; Zhou, X. G. Chem. Commun. 2007, 2190. (i) Pi, C. F.;
Zhang, Z. X.; Pang, Z.; Luo, J.; Chen, Z. X.; Weng, L. H.; Zhou, X. G.
Organometallics 2007, 26, 1934.
Synthesis and Characterization of Organolanthanide Hy-
drazonido Complexes [Cp2Yb(μ-NHNdCPh2)]2 (1) and Cp2Er
(η2-NHNdCPh2) THF (2). The known samarium and scan-
3
dium hydrazido complexes were synthesized by the oxida-
tion reaction of Cp*2Sm with excess hydrazine (H2NNH2)6a
or the protonolysis reaction of Cp*2ScCH3 with 1 equiv of
the hydrazine H2NNH2 or H2NN(CH3)2.6b Here we synthe-
sized the complexes [Cp2Yb(μ-NHNdCPh2)]2 (1) and Cp2Er
(η2-NHNdCPh2) THF (2) by the protonolysis reaction of
3
Cp3Ln with 1 equiv of H2NNdCPh2 in THF at room
temperature, as shown in Scheme 1. The structural analysis
(13) Magin, R. E.; Manastyrskyj, S.; Dubeck, M. J. Am. Chem. Soc.
1963, 85, 672.

3918 Organometallics, Vol. 28, No. 13, 2009
Han et al.
Scheme 1
results show that 1 is a solvent-free dimer, while 2 is a
solvated monomer.
the Ln-N bond insertion with 1,3-H migration products
Cp2Ln(η2-OC(NHPh)NNdCPh2)(HMPA) (Ln = Yb (3),
Er (4)) were obtained in moderate yields, as shown in
Scheme 2.
Both 1 and 2 are sensitive to air and moisture and are
soluble in THF and toluene and slightly soluble in n-hexane.
They have been characterized by elemental analysis, IR, and
1H NMR. In the IR spectra, 1 exhibits two characteristic
absorptions at 3178 and 1574 cm-1, which can be attributed
to the hydrazonido ligand;5a 2 exhibits three absorptions at
3548, 3422, and 3260 cm-1 attributable to the N-H bond and
two well-defined bands at 1071 and 913 cm-1 for the co-
ordinated THF. The solid-state structures of complexes 1 and
2 have been identified by X-ray single-crystal diffraction
analysis, as shown in Figures 1 and 2. Crystal data confirm
the centrosymmetric dimeric structure of 1, with the hydra-
zonido(1-) group as a monodentate bridging ligand. Each
Yb atom is coordinated by two η5-cyclopentadienyl rings and
two bridging nitrogen atoms to form a distorted-tetrahedral
geometry. The coordination number of the central Yb3+ is 8.
To gain more insight into the reactivity of 1 and 2, the
reactions of them with phenyl isothiocyanate (PhNCS)
were also investigated. Interestingly, treatment of 1 and 2 with
PhNCS under the same conditions yields the Ln-N
bond insertion products Cp2Ln(η2-SC(NPh)NHNdCPh2)
(HMPA) (Ln = Yb (5), Er (6)). X-ray analysis results indicate
that PhNCS simply inserts into the Ln-N bond without any
hydrogen migration, which is significantly different from the
observations in the formation of 3 and 4. It is yet unclear why
complexes 5 and 6 do not undergo the subsequent 1,3-hydro-
gen migration as observed in complexes 3 and 4.
It should be noted that complexes 3-6 are almost inso-
luble in THF and other organic solvents without HMPA.
Complexes 3-6 have been characterized by elemental ana-
lysis, IR, and 1H NMR, and their structures were also
identified by X-ray single-crystal diffraction analysis. The
X-ray analysis shows that, although the cell parameters of
complexes 3 and 4 are different (Table 1, Supporting In-
formation), their structures are similar and that both of them
are monomeric structures (Figure 3) in which the newly
formed ureido ligand (OC(NHPh)NNdCPh2) contacts the
lanthanide atom in a η2-bonding mode. The Ln atom is
coordinated by two η5-cyclopentadienyl groups, one chelat-
ing OC(NHPh)NNdCPh2 ligand, and one oxygen atom
from the HMPA molecule, such that the Ln atom has a
˚
Two Yb-N bond distances (Yb1-N1 = 2.349(10) A; Yb1-
N1A = 2.340(10) A) are almost equivalent and are between
˚
those expected for an Yb3+-N single bond and an Yb3+r:
N donor bond (2.19-2.69 A).9,12 The C1-N2 double-bond
˚
˚
distance (1.289(15) A) is comparable to the accepted value for
2
2
the N(sp )dC(sp ) double bond (1.28 A).
14
˚
In 2, the hydrazonido ligand is coordinated to the erbium
ion in a side-on bonding mode. The metal ion is bonded to
two Cp rings, one chelating hydrazonido ligand, and one
THF molecule to form a distorted-bipyramidal geometry.
The coordination number of the central Er3+ is 9. As
˚
˚
expected, the Er1-N1 bond distance, 2.227(4) A, is shorter
coordination number of 9. In 3, the 1.271(13) A C1-O1
2
˚
than the average Yb-N(bridging) distance observed in 1 and
distance is between the 1.293-1.407 A range of C(sp )-O
is similar to the values found in Yb(NHC6Hi3Pr2-
distances and the 1.192-1.256 A range of C(sp )dO dis-
2
˚
15
2,6)3(THF)2 (average 2.17 A), when the difference in the
tances.17 The distance of C1-N2 (1.337(14) A) is also
˚
˚
metal ionic radii and the effect of coordination number are
considered.16 The Er1-N2 distance of 2.372(4) A is compar-
between the values observed for a C-N single-bond distance
˚
˚
(1.321-1.416 A) and a CdN double-bond distance (1.279-
1.329 A).20 The bond angles around C14 are consistent with
˚
able to the Ln-N donor bond distance. Notably, the N1-
N2 distance of 1.339(5) A in 2 is much shorter than that
sp2 hybridization. This suggests some electronic delocaliza-
tion over the O-C-N unit. Consistent with this observation,
the Yb-O1 and the Yb-N2 distances, 2.233(8) and 2.593(9)
˚
˚
observed in 1 (N1-N2 = 1.432(13) A), while the C1-N2
distance of 1.311(5) A is slightly longer than the correspond-
˚
˚
ing value in 1, 1.289(15) A.
˚
A, both lie between the values observed for a Yb-
Reactions of Complexes 1 and 2 with PhNCO and PhNCS.
To explore the reactivity of complexes 1 and 2, we
first investigate their reactions with phenyl isocyanate.
PhNCO was dropped into a clear THF solution of 1 or 2
at room temperature, and after the mixture was stirred for 1
h, a small amount of precipitate was formed. Then 1 equiv of
HMPA was added to the turbid solution, and after it was
stirred overnight, the solution became clear. After workup,
O(N) single-bond distance and a Yb-O(N) donor-bond
distance.9a,9c,11b Interestingly, the C1-N3 distance (1.338
˚
(14) A) is significantly shorter than the expected value for
C(sp2)-N(sp3) single bonds (C-Nav = 1.416),18 indicating a
strong p-π conjugation between the lone-pair electron on
noncoordinated nitrogen and the N-C-N unit. The C8-
˚
N1 and N1-N2 distances (1.309(13), 1.401(12) A) are in the
expected range.
(14) March, J. In Advanced Organic Chemistry; McGraw-Hill: New
York, 1997; Vol. 2, p 24.
(15) Evans, W. J.; Ansari, M. A.; Ziller, J. W. Inorg. Chem. 1996, 35,
(17) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G. J. Chem. Soc., Perkin Trans. 1 1987, S1.
(18) Evans, W. J.; Fujimoto, C; Ziller, H. Organometallics 2001, 20,
4529.
5435.
(16) Shannon, R. D. Acta Crystallogr. 1976, A32, 751.

Article
Organometallics, Vol. 28, No. 13, 2009 3919
Scheme 2
Cp2Er fragment connects with one SC(NPh)NHNdCPh2
unit and one HMPA molecule. The N3-C1 and S1-C1 bond
lengths, 1.360(12) and 1.722(10) A, are between the corre-
˚
Figure 1. Thermal ellipsoid plot of [Cp2Yb(μ-NHNdCPh2)]2
(1), with ellipsoids at the 30% probability level. Selected bond
lengths (A): Yb(1)-N(1A) = 2.340(10), Yb(1)-N(1) = 2.349-
(10), N(1)-N(2) = 1.432(13), N(2)-C(1) = 1.289(15). Selected
bond angles (deg): N(1A)-Yb(1)-N(1) 80.0(4), N(2)-N(1)-
Yb(1A) = 122.3(7), N(2)-N(1)-Yb(1) = 111.6(7), C(1)-N-
(2)-N(1) = 117.3(10).
sponding C-N and C-S single- and double-bond distances,
respectively.9b,11a These bond parameters indicate substantial
electronic delocalization over the S-C-N unit. Significantly,
˚
˚
the distance of N2-C1 (1.360(12) A) in 7 is slightly shorter
than the corresponding value found in Cp2Yb(SC(Ptz)NPh)
˚
(THF) (N2-C17 = 1.395(7) A), which may indicate that the
lone-pairelectronson the N2atomare partially delocalizedon
the S-C-N unit. The C8-N1 and N1-N2 distances (1.291
˚
(11), 1.369(11) A) are also in the normal ranges. The Er-O1
distance is 2.237(7) A, significantly shorter than that of the
˚
Err:OR donor bond.19
Complex 5 is isostructural with 6. The central metal also
contacts the nitrogen and sulfur atoms from the PhNCS unit,
whereas the hydrazonido group shifts to the center carbon of
PhNCS and is not coordinated to the metal atom. Its bond
lengths and angles are comparable to the corresponding
values observed in 6, when the differences in the metal ionic
radii are considered.
Reaction of 2 with PhCN. In recent years, organic nitriles
have been useful reagents in organic synthesis for the con-
struction of many important N-heterocyclic compounds,
and thus their reactivity toward organometallic complexes
is of fundamental interest in organometallic chemistry.20
Upon comparison with the investigations on the reactivity
of organolanthanide hydrides and alkyl complexes with
nitriles, which have provided many important organometal-
lic reactions and interesting structures,21,22 examples of
Figure 2. Thermal ellipsoid plot of Cp2Er[η2-NHNdCPh2]
(THF), (2), with ellipsoids at the 30% probability level. Selected
bond lengths (A): Er(1)-N(1) = 2.227(4), Er(1)-N(2) = 2.372
(4), Er(1)-O(1) = 2.376(4), N(1)-N(2) = 1.339(5), C(1)-N-
(2) = 1.311(5). Selected bond angles (deg): N(1)-Er(1)-N(2) =
33.66(13), C(1)-N(2)-N(1) = 124.9(4), C(1)-N(2)-Er(1) =
164.3(3), N(1)-N(2)-Er(1) = 67.2(2).
˚
(19) Day, C. S.; Day, V. W.; Ernst, R. D.; Vollmer, S. H. Organome-
tallics 1982, 1, 998.
(20) (a) Kukushkin, V. Y.; Pombeiro, A. J. L. Chem. Rev. 2002, 102,
1771. (b) Michelin, R. A.; Mozzon, M.; Bertani, R. Coord. Chem. Rev.
1996, 147, 299.
(21) (a) Evans, W. J.; Meadows, J. H.; Hunter, W. E.; Atwood, J. L. J.
Am. Chem. Soc. 1984, 106, 1291. (b) Hultzsch, K. C.; Spaniol, T. P.;
Okuda, J. Angew. Chem., Int. Ed. 1999, 38, 227. (c) Cui, D.; Nishiura,
M.; Hou, Z. M. Angew. Chem., Int. Ed. 2006, 44, 959.
The bond parameters for 4 are also in normal ranges
(Figure 3), indicating that the hydrazonido ligand is trans-
formed to the ureido ligand via a formal insertion of a phenyl
isocyanate into the N-H bond. Complex 4 is also a mono-
mer, in which the ureido ligand is chelated to the erbium ion
Er3+ in a η2-bonding mode. The bond distances and angles
in 4 are similar to the corresponding values in 3, if the
difference in metal radii is considered.
(22) (a) Beetstra, D. J.; Meetsma, A.; Hessen, B.; Tueben, J. H.
Organometallics 2003, 22, 4372. (b) Duchateau, R.; Brussee, E. A. C.;
Meetsma, A.; Teuben, J. H. Organometallics 1997, 16, 5506. (c) Duch-
ateau, R.; Tuinstra, T.; Brussee, E. A. C.; Meetsma, A.; van Duijnen, P.
T.; Teuben, J. H. Organometallics 1997, 16, 3511. (d) Heeres, H. J.;
Meetsma, A.; Teuben, J. H. Angew. Chem., Int. Ed. 1990, 29, 420. (e)
Bercaw, J. E.; Davies, D. L.; Wolczanski, P. T. Organometallics 1986, 5,
443. (f) Den Haan, K. H.; Luinstra, G. A.; Meetsma, A.; Teuben, J. H.
Organometallics 1987, 6, 1509. (g) Wang, C. F.; Xu, F.; Cai, T.; Shen, Q.
Org. Lett. 2008, 10, 445.
The X-ray determination indicates that complex 6 is a
solvent-free monomeric structure. As shown in Figure 4, the

3920 Organometallics, Vol. 28, No. 13, 2009
Han et al.
Figure 4. Thermal ellipsoid plot of Cp2Ln(η2-SC(NHNdCPh2)
NPh)(HMPA) (Ln = Yb (5), Er (6)), with ellipsoids at the 30%
probability level. Selected bond lengths for 5 (A): Yb(1)-O-
Figure 3. Thermal ellipsoid plot of Cp2Ln(η2-OC(NHPh)
NNdCPh2)(HMPA) (Ln = Yb (3), Er (4)), with ellipsoids at
˚
(1) = 2.215(8), Yb(1)-N(3) = 2.520(9), Yb(1)-S(1) = 3.146
(3), N(1)-N(2) = 1.442(8), N(1)-C(8) = 1.497(14), N(2)-C-
(1) = 1.534(14), N(3)-C(1) = 1.471(15), O(1)-P(1) = 1.437
(8), S(1)-C(1) = 1.676(12). Selected bond angles for 5 (deg): N-
(3)-Yb(1)-S(1) = 54.9(2), N(2)-N(1)-C(8) = 131.2(9), N-
(1)-N(2)-C(1) = 128.0(9), C(1)-N(3)-Yb(1) = 108.2(6), C-
(1)-S(1)-Yb(1) = 79.8(4), N(3)-C(1)-N(2) = 130.3(9), N-
(3)-C(1)-S(1) = 116.0(8), N(2)-C(1)-S(1) = 113.7(8). Se-
˚
the 30% probability level. Selected bond lengths in 3 (A): Yb-
(1)-O(2) = 2.230(7), Yb(1)-O(1) = 2.233(8), Yb(1)-N(2) =
2.593(9), N(1)-C(8) = 1.309(13), N(1)-N(2) = 1.401(12), N-
(2)-C(1) = 1.337(14), N(3)-C(1) = 1.338(14), O(1)-C(1) =
1.271(13), O(2)-P(1) = 1.474(7). Selected bond angles in 3
(deg): O(1)-Yb(1)-N(2) = 53.7(3), C(8)-N(1)-N(2) = 121.6
(9), C(1)-N(2)-N(1) = 108.5(9), C(1)-N(2)-Yb(1) = 86.1(7),
˚
˚
N(1)-N(2)-Yb(1) = 164.0(7). Selected bond lengths in 4 (A):
lected bond lengths for 6 (A): Er(1)-O(1) = 2.237(7), Er(1)-N-
Er(1)-O(2) = 2.244(9), Er(1)-O(1) = 2.332(8), Er(1)-N(2) =
2.486(10), N(1)-C(8) = 1.314(15), N(1)-N(2) = 1.376(14), N-
(2)-C(1) = 1.329(15), N(3)-C(1) = 1.390(16), O(1)-C(1) =
1.248(15), O(2)-P(1) = 1.466(9). Selected bond angles in 4
(deg): O(1)-Er(1)-N(2) = 54.7(3), C(8)-N(1)-N(2) = 118(1),
C(1)-N(2)-N(1) = 111(1), C(1)-N(2)-Er(1) = 87(1), O(1)-
C(1)-N(2) = 119(1), O(1)-C(1)-N(3) = 120(1), N(2)-C(1)-
N(3) = 121(1), O(1)-C(1)-N(2) = 115(1), O(1)-C(1)-N-
(3) = 120(1), N(2)-C(1)-N(3) = 125(1), N(1)-N(2)-Er-
(1) = 144(1).
(3) = 2.500(8), Er(1)-S(1) = 2.744(3), S(1)-C(1) = 1.722(10),
N(1)-C(8) = 1.291(11), N(1)-N(2) = 1.369(11), N(2)-C(1) =
1.360(12), N(3)-C(1) = 1.312(12), O(1)-P(1) = 1.491(7).
Selected bond angles for 6 (deg): N(3)-Er(1)-S(1) = 58.9(2),
C(1)-S(1)-Er(1) = 82.4(3), C(8)-N(1)-N(2) = 117.0(8),
C(1)-N(2)-N(1) = 119.1(8), C(1)-N(3)-Er(1) = 101.1(6), N-
(3)-C(1)-N(2) = 122.7(9), N(3)-C(1)-S(1) = 116.5(7), N-
(2)-C(1)-S(1) = 120.8(8).
Scheme 3
reactions of organolanthanide amides with nitriles have
scarcely been reported.22c,22e,22g Recently, we found that
the cyano group of anthranilonitrile can continuously insert
into the Ln-N(primary amide) bond to construct a quina-
zolinate moiety.12f With the organolanthanide hydrazonido
complex 2 in hand, we also explored its reactivity toward
benzonitrile and tert-butyl isocyanide. As shown in
Scheme 3, when phenyl isocyanate was added to a THF
solution of 2 at room temperature, the new organolantha-
nide heterometallacycle Cp2Er[η2-NHC(Ph)NNdCPh2] (7)
was obtained, indicating that PhCN inserts into the lantha-
nide-nitrogen (hydrazonido) bond in concert with a 1,3-
hydrogen migration.6b However, treatment of 2 with tBuNC
gave only the solvent-free dimer [Cp2Er(μ-η1:η2-
comparable to the accepted value for the N(sp2)dC(sp2)
double bond.14 The N1-N2 and C1-N1 distances, 1.388
(13) and 1.268(14)A, are in the normal ranges. Consistent
˚
with this observation, two different Er-N distances have
t
NHNdCPh2)]2 (20), indicating that BuNC cannot insert
been observed in 7. The Er1-N1 distance of 2.407(10) A is
˚
into the lanthanide-nitrogen bond of 2.
significantly longer than the Er1-N3 distance of 2.156(10)
˚
The molecular structure and important bond lengths and
angles of 7 ares shown in Figure 5. The X-ray crystal analysis
shows that the hydrazonido group in 7 has combined with
benzonitrile, forming a five-membered heterometallacycle.
As expected, the bond angles around C14 are consistent with
sp2 hybridization, and the resulting heterometallacycle is
planar within experimental error (the sum of angles in this
A. The former falls in the range of Er-N donor-bond
lengths, while the latter is consistent with the Er-N single-
bond length. The relative bond parameters reveal that the
hydrogen atom of the hydrazido group is shifted toward the
nitrogen atom on the benzonitrile moiety.6b
Positive structural verification of 20 was also provided by a
single-crystal X-ray analysis. The solid-state structural ana-
lysis shows that 20 has a solvent-free centrosymmetric
˚
ring is 537.5°). The C14-N2 bond distance, 1.295(14) A, is

Article
Organometallics, Vol. 28, No. 13, 2009 3921
Figure 5. Thermal ellipsoid plot of Cp2Er[η2-NHC(Ph)
NNdCPh2] (7), with ellipsoids at the 30% probability level.
Selected bond lengths (A): Er(1)-N(3) = 2.156(10), Er(1)-N-
(1) = 2.407(10), N(1)-C(1) = 1.268(14), N(1)-N(2) = 1.388
(13), N(2)-C(14) = 1.295(14), N(3)-C(14) = 1.333(16), C-
(14)-C(15) = 1.504(14). Selected bond angles (deg): N(3)-Er-
(1)-N(1) = 66.7(4), N(2)-N(1)-Er(1) = 116.4(8), C(14)-
N(2)-N(1) = 110.9(10), C(14)-N(3)-Er(1) = 121.6(8),
N(2)-C(14)-N(3) = 121.9(11), N(2)-C(14)-C(15) = 113.3
(11), N(3)-C(14)-C(15) = 124.7(11).
Figure 6. Thermal ellipsoid plot of [Cp2Er(μ-η1:η2-NHNdCPh2)]2
(20), with ellipsoids at the 30% probability level. Selected bond
lengths (A): Er(1)-N(1) = 2.37(2), Er(1)-N(2) = 2.40(2),
˚
˚
Er(1)-N(1A) = 2.41(2), N(1)-N(2) = 1.36(3), N(2)-C(1) =
1.29(3). Selected bond angles (deg): N(1)-Er(1)-N(2) = 33.2
(7), N(1)-Er(1)-N(1A) = 80.8(7), N(2)-Er(1)-N(1A) =
109.9(7), N(2)-N(1)-Er(1) = 74.6(13), N(2)-N(1)-Er(1A) =
151.3(17), Er(1)-N(1)-Er(1A)
=
99.2(7), C(1)-N(2)-
N(1) = 120(2), C(1)-N(2)-Er(1) = 158(2), N(1)-N(2)-Er-
(1) = 72.3(13).
dimeric structure (Figure 6) in which the hydrazido ligand
acts as both a bridging and a side-on chelating group. The
bonding mode of the hydrazonido groups in 20 is signifi-
cantly different from those observed in 1 and 2. The six atoms
Er1, N1, N2, Er1A, N1A, and N2A form an interlinked
tricyclic structure via two bridged nitrogen atoms.
only insert the lanthanide-nitrogen bond. These results
clearly demonstrate that the hydrazonido(1-) ligand bound
to the lanthanide metal can undergo versatile reactions to
afford a variety of novel organolanthanide complexes.
Acknowledgment. We thank the NNSF of China, the
NSF of Shanghai, the 973 program (No. 2009CB825300),
and the Shanghai Leading Academic Discipline Project
(B108) for financial support.
Conclusions
We have synthesized three new organolanthanide hydra-
zonido(1-) complexes, wherein three kinds of bonding
modes of the hydrazonido ligand to lanthanide metals were
observed. Further studies on their reactivity toward unsatu-
rated organic molecules indicate that PhNCO and PhCN can
formally monoinsert into the N-H bond of these organo-
lanthanide hydrazonido(1-) complexes, while PhNCS can
Supporting Information Available: Text, tables, and CIF files
giving X-ray structure determination details for 1-7 and 20. This
material is available free of charge via the Internet at http://
pubs.acs.org.