Yttrium and lanthanide complexes having a chiral phosphanylamide in the coordination sphere

Article abstract of DOI:10.1021/ic051584e

The chiral phosphanylamides {N(R-*CHMePh)(PPh₂)} ^- and {N(S-*CHMePh)(PPh₂)}^- were introduced into rare earth chemistry. Transmetalation of the enantiomeric pure lithium compounds Li{N(R-*CHMePh)(PPh₂)} (1a) and Li{N(S-*CHMePh)(PPh₂)} (1b) with lanthanide bis(phosphinimino)methanide dichloride [{CH(PPh₂NSiMe ₃)₂}LnCl₂]₂ in a 2:1 molar ratio in THF afforded the enantiomeric pure complexes [{CH(PPh₂NSiMe ₃)₂}Ln(Cl){η²-N(R-*CHMePh)(PPh ₂)}] (Ln = Er (2a), Yb (3a), Lu (4a)) and [{CH(PPh ₂NSiMe₃)₂}Ln(Cl){η²-N(S- *CHMePh)(PPh₂)}] (Ln = Er (2b), Yb (3b), Lu (4b)). The solid-state structures of 2a and 3a,b were established by single-crystal X-ray diffraction. Attempts to synthesize compounds 3 in a one-pot reaction starting from K{CH(PPh₂NSiMe₃)₂}, YbCl₃, and 1 resulted in the lithium chloride incorporated complex [{(Me ₃SiNPPh₂)₂CH}Yb(μ-Cl)₂LiCl(THF) ₂] (5). In an alternative approach to give chiral rare earth compounds in a one-pot reaction 1a or 1b was reacted with LnCl₃ and K₂C₈H₈ to give the enantiomeric pure cyclooctatetraene compounds [{η²-N(R-*CHMePh)(PPh ₂)}Ln(η⁸-C₈H₈)] (Ln = Y (6a), Er (7a), Yb (8)) and [{η²-N(S-*CHMePh)(PPh ₂)}Ln(η⁸-C₈H₈)] (Ln = Y (6b), Er (7b)). The structures of 6a,b, 7a, and 8 were confirmed by single-crystal X-ray diffraction in the solid state.

Full text of DOI:10.1021/ic051584e

Inorg. Chem. 2006, 45, 910−916
Yttrium and Lanthanide Complexes Having a Chiral Phosphanylamide in
the Coordination Sphere
Tarun K. Panda, Michael T. Gamer, and Peter W. Roesky*
Institut fu¨r Chemie und Biochemie, Freie UniVersita¨t Berlin,
Fabeckstrasse 34-36, 14195 Berlin, Germany
Received September 15, 2005
-
-
The chiral phosphanylamides
{
N(R-*CHMePh)(PPh2)
}
and
{
N(S-*CHMePh)(PPh2)
N(R-*CHMePh)(PPh2)
(1b) with lanthanide bis(phosphinimino)methanide dichloride [ CH(PPh2NSiMe3)2
in a 2:1 molar ratio in THF afforded the enantiomeric pure complexes [ CH(PPh2NSiMe3)2
Ln(Cl){η2-N(R-*CHMePh)-
(PPh2) ] (Ln Er (2a), Yb (3a), Lu (4a)) and [ CH(PPh2NSiMe3)2 ] (Ln Er
Ln(Cl){η2-N(S-*CHMePh)(PPh2)
(2b), Yb (3b), Lu (4b)). The solid-state structures of 2a and 3a,b were established by single-crystal X-ray diffraction.
Attempts to synthesize compounds 3 in a one-pot reaction starting from K CH(PPh2NSiMe3)2 , YbCl3, and 1 resulted
in the lithium chloride incorporated complex [ (Me3SiNPPh2)2CH Yb( -Cl)2LiCl(THF)2] (5). In an alternative approach
to give chiral rare earth compounds in a one-pot reaction 1a or 1b was reacted with LnCl3 and K2C8H8 to give the
enantiomeric pure cyclooctatetraene compounds [{η2-N(R-*CHMePh)(PPh2) 8-C8H8)] (Ln
Ln( Y (6a), Er (7a),
Yb (8)) and [{η2-N(S-*CHMePh)(PPh2) 8-C8H8)] (Ln
Ln( Y (6b), Er (7b)). The structures of 6a,b, 7a, and 8
were confirmed by single-crystal X-ray diffraction in the solid state.
}
were introduced into rare
(1a) and
LnCl2]2
earth chemistry. Transmetalation of the enantiomeric pure lithium compounds Li
{
}
Li N(S-*CHMePh)(PPh2)
{
}
{
}
}
{
}
}
)
{
}
)
{
}
{
}
µ
}
η
)
}
η
)
Introduction
However little has appeared on the use of chiral amines as
backbone for chiral phosphorus ligands.4 These chiral P,N
ligands, which usually coordinate via the phosphorus atom
to the center metal, were basically used in late transition
metal chemistry.5,6,7,8 We have been working for some time
with P,N compounds such as amido (e.g. (Ph2P)2N-)9 or
imido ((Me3SiNPPh2)CH-) ligands10,11 in early transition
metal and lanthanide chemistry. These kinds of ligands
always coordinate via the nitrogen atom and only sometimes
via the phosphorus onto the metal center. Very recently we
Numerous families of chiral phosphorus ligands have been
synthesized over the years, and their coordination chemistry
on various metals is widely studied.1 In homogeneous
catalysis usually bidentate phosphine ligands especially those
having C2 symmetry have been employed. In most cases the
stereogenic centers are chiral phosphorus atoms or phos-
phines with chiral hydrocarbon substituents as derivative of
the chiral pool. The third widely used method is the use of
axial chirality in ligands such as BINAP.2 The synthesis and
limited use of heteroatom-substituted phosphines and their
transition metal complexes have received some attention
lately as a result of the search for new structural diversity.3
(4) Zijp, E. J.; van der Vlugt, J. I.; Tooke, D. M.; Spek, A. L.; Vogt, D.
Dalton Trans. 2005, 512-517.
(5) (a) Brunner, H.; Gastinger, R. G. J. Organomet. Chem. 1978, 145,
365-373. (b) Brunner, H.; G. O. Nelson J. Organomet. Chem. 1979,
173, 389-395. (c) Frauendorfer, E.; Brunner, H. J. Organomet. Chem.
1982, 240, 371-379.
(6) (a) Fiorini, M.; Giongo, G. M.; Marcati, F.; Marconi, W. J. Mol. Catal.
1976, 1, 451-453. (b) Fiorini, M.; Marcati, F.; Giongo, G. M. J. Mol.
Catal. 1978, 4, 125-134. (c) Fiorini M.; Giongo, G. M. J. Mol. Catal.
1979, 5, 303-310.
* To whom correspondence should be addressed. E-mail:
roesky@chemie.fu-berlin.de.
(1) For recent review on chiral phosphorous ligands, see: Tand, W.;
Zhang, X. Chem. ReV. 2003, 103, 3029-3069.
(2) Cotton, F. A.; Wilkinson, G.; Murillo, C. A.; Bochmann, M. AdVanced
Inorganic Chemistry, 6th ed.; Wiley: New York, 1999; p 1235.
(3) (a) Balakrishna, M. S.; Reddy, V. S.; Krishnamurthy, S. S.; Burckett
St. Laurent, J. C. T. R. Coord. Chem. ReV. 1994, 129, 1-90 and
references therein. (b) M. Rodriguez i Zubiri, M.; Clarke, M. L.; Foster,
D. F.; Cole-Hamilton, D. J.; Slawin A. M. Z.; Woollins, J. J. Chem.
Soc., Dalton Trans. 2001, 969-971. (c) Slawin, A. M. Z.; Wainwright
M.; Woollins, J. D. J. Chem. Soc., Dalton Trans. 2002, 513-519. (d)
Magee, M. P.; Li, H.-Q.; Morgan O.; Hersh, W. H. Dalton Trans.
2003, 387-394.
(7) Guo, R.; Li, X.; Wu, J.; Kwok, W. H.; Chen, J.; Choi, M. C. K.;
Chan, A. S. C. Tetrahedron Lett. 2002, 43, 6803-6806.
(8) Ansell, J.; Wills, M. Chem. Soc. ReV. 2002, 31, 259-268 and
references therein.
(9) (a) Roesky, P. W.; Gamer, M. T.; Puchner, M.; Greiner, A. Chem.s
Eur. J. 2002, 8, 5265-5271. (b) Roesky, P. W.; Gamer, M. T.;
Marinos, N. Chem. Eur. J. 2004, 10, 3537-3542. (c) Gamer, M. T.;
Roesky, P. W. Inorg. Chem. 2004, 43, 4903-4906.
(10) Gamer, M. T.; Dehnen S.; Roesky, P. W. Organometallics 2001, 20,
4230-4236.
910 Inorganic Chemistry, Vol. 45, No. 2, 2006
10.1021/ic051584e CCC: $33.50
© 2006 American Chemical Society
Published on Web 12/30/2005

Yttrium and Lanthanide Chiral Phosphanylamides
Ln ) Yb. Yields: 3a, 246 mg (45%), and 3b, 255 mg (47%)
(yellow crystals). IR (KBr, cm-1): 3053 (m), 2948 (m), 2894 (w),
2850 (w), 1949 (w), 1888 (w), 1809 (w), 1660 (w), 1589 (s), 1479
(s), 1434 (s), 1352 (w), 1307 (w), 1245 (m), 1168 (w), 1122 (br),
1093 (m), 1026 (m), 999 (m), 954 (m), 835 (s), 740 (s), 694 (s).
Anal. Calcd for C51H58ClN3P3Si2Yb (Mr ) 1070.62): C, 57.22; H,
5.46; N, 3.92. Found: C, 57.39; H, 5.60; N, 3.85.
introduced both enantiomers of a chiral phosphanylamide,
{N(R-*CHMePh)(PPh2)}- and {N(S-*CHMePh)(PPh2)}-,
into zirconium chemistry.12 The amido ligands were obtained
by deprotonation of the corresponding amines HN(R-
*CHMePh)(PPh2) and HN(S-*CHMePh)(PPh2), respectively.
The latter were originally introduced by Brunner into
coordination chemistry of the late transition metals.5
Herein we report on the coordination chemistry of both
enantiomers of the chiral phosphanylamide {N(*CHMePh)(P-
Ph2)}- in group 3 and lanthanide chemistry. As coligands,
cyclooctatetraene and the bis(phosphinimino)methanide,
(Me3SiNPPh2)CH-,13 were used.
Ln ) Lu. Yields: 4a, 232 mg (43%), and 4b, 236 mg (44%)
1
(colorless crystals). H NMR (THF-d8, 400 MHz, 25 °C): δ 0.14
2
(s, 9H, Me3Si), 0.18 (s, 9H, Me3Si), 0.88 (t, 1H, CH, J(H,P) )
3
7.2 Hz), 1.30 (d, 3H, CH3, J(H,H) ) 6.79 Hz), 4.38 (q, 1H, CH,
3J(H,H) ) 6.79 Hz), 6.73-7.09 (m, 15H, Ph), 7.20-7.35 (m, 13H,
Ph), 7.50-7.81 (m, 7H, Ph). 31P{1H} NMR (THF-d8, 161.7 MHz,
2
25 °C): δ 18.0, 18.8 (d, PCP, J(P,P) ) 8.89 Hz), 19.1 (d, PCP,
2J(P,P) ) 10.35). IR (KBr, cm-1): 3055 (m), 3020 (m), 2950 (m),
2893 (w), 1965 (w), 1888 (w), 1814 (w), 1589 (w), 1481 (s), 1436
(s), 1259 (m), 1245 (m), 1166 (w), 1120 (br), 1026 (m), 999 (m),
948 (m), 833 (s), 781 (m), 740 (s), 692 (s). Anal. Calcd for C51H58-
ClLuN3P3Si2Cl (Mr ) 1072.55): C, 57.11; H, 5.45; N, 3.92.
Found: C, 56.67; H, 5.86; N, 3.66.
Experimental Section
General Methods. All manipulations of air-sensitive materials
were performed with the rigorous exclusion of oxygen and moisture
in flame-dried Schlenk-type glassware either on a dual manifold
Schlenk line, interfaced to a high-vacuum (10-4 Torr) line, or in
an argon-filled M. Braun glovebox. Ether solvents (tetrahydrofuran
and ethyl ether) were predried over Na wire and distilled under
nitrogen from K (THF) or Na wire (ethyl ether) benzophenone ketyl
prior to use. Hydrocarbon solvents (toluene and pentane) were
distilled under nitrogen from LiAlH4. All solvents for vacuum line
manipulations were stored in vacuo over LiAlH4 in resealable flasks.
Deuterated solvents were obtained from Chemotrade Chemiehan-
delsgesellschaft mbH (all g99 atom % D) and were degassed, dried,
and stored in vacuo over Na/K alloy in resealable flasks. NMR
spectra were recorded on JNM-LA 400 FT-NMR spectrometer.
Chemical shifts are referenced to internal solvent resonances and
are reported relative to tetramethylsilane and 85% phosphoric acid
(31P NMR), respectively. Elemental analyses were carried out with
an Elementar vario EL. LnCl3,14 [{CH(PPh2NSiMe3)2}LnCl2]2,10
K{CH(PPh2NSiMe3)2},13 Li{N(R-*CHMePh)(PPh2)} (1a),12 and Li-
{N(S-*CHMePh)(PPh2)} (1b)12 were prepared according to litera-
ture procedures.
[{(Me3SiNPPh2)2CH}Ln(Cl){N(R-*CHMePh)(PPh2)}] (Ln )
Er (2a), Yb (3a), Lu (4a)) and [{(Me3SiNPPh2)2CH}Ln(Cl){N(S-
*CHMePh)(PPh2)}] (Ln ) Er (2b), Yb (3b), Lu (4b)). A 0.5
mmol amount of [{CH(PPh2NSiMe3)2}LnCl2]2 was mixed with 156
mg (0.5 mmol) of 1 under argon atmosphere. A 15 mL volume of
THF was condensed onto it. The reaction solution was allowed to
come at room temperature and kept under stirring for 24 h. THF
was evaporated under vacuo, and the residue was dissolved in 15
mL of toluene and filtered. Toluene was removed, and the
compound was washed with 10 mL of pentane. Finally title
compounds were crystallized from THF/pentane (1:3).
[{(Me3SiNPPh2)2CH}Yb(µ-Cl)2LiCl(THF)2] (5). A 597 mg (1
mmol) amount of K{CH(PPh2NSiMe3)2} was mixed with 307 mg
(1.1 mmol) of anhydrous YbCl3 and 311 mg (1 mmol) of 1 under
inert atmosphere. To this mixture 15 mL of THF was added and
stirred for 24 h. Then THF was removed in vacuo, and the residue
was extracted from 15 mL of toluene. The solution was filtered,
and solvent was removed in vacuo. The compound was washed by
pentane (10 mL) and crystallized from THF/pentane as colorless
crystals.
Yield: 400 mg (37%). IR (KBr, cm-1): 3056 (m), 3016 (m),
2950 (m), 2898 (w), 1963 (w), 1888 (w), 1811 (w), 1589 (w), 1481
(s), 1433 (s), 1307 (w), 1247 (m), 1166 (w), 1122 (br), 1091 (m),
1029 (m), 999 (m), 954 (m), 840 (s), 744 (s), 700 (s). Anal. Calcd
for C43H55Cl3LiN2O3P2Si2Yb (Mr ) 1052.38): C, 49.08; H, 5.27;
N, 2.66. Found: C, 48.86; H, 5.36; N, 3.15.
[(η8-C8H8)Ln{N(R-*CHMePh)(PPh2)}] (Ln ) Y (6a), Er (7a),
Yb (8)) and [η8-(C8H8)Ln{N(S-*CHMePh)(PPh2)}] (Ln ) Y
(6b), Er (7b)). To a 50 mL reaction vessel, 1.1 mmol of anhydrous
LnCl3 was charged with 311 mg (1 mmol) of 1 in 15 mL of THF.
After 20 h of stirring under room temperature, a THF solution of
freshly prepared K2C8H8 (1 mmol) was added slowly at room
temperature to the reaction vessel and stirred for another 20 h. In
each case a color change was noticed. The THF was removed in
vacuo, and the residue was extracted with 15 mL of toluene. The
solution was filtered, and solvent was evaporated. After washing
of the compound by pentane, the title compounds were crystallized
from either hot toluene or THF/pentane.
Ln ) Y. Yields: 6a, 180 mg (37%), and 6b, 200 mg (35%)
Ln ) Er. Yields: 2a, 240 mg (45%), and 2b, 235 mg (44%)
(pink crystals). IR (KBr, cm-1): 3053 (m), 2950 (m), 2893 (w),
1951 (w), 1888 (w), 1814 (w), 1589 (s), 1434 (s), 1305 (w), 1245
(m), 1170 (w), 1120 (br), 1095 (m), 952 (m), 835 (s), 740 (s), 694
(s). Anal. Calcd for C51H58ErClN3P3Si2 (Mr ) 1064.84): C, 57.53;
H, 5.49; N, 3.95. Found: C, 57.21; H, 5.79; N, 3.55.
1
(yellow crystals). H NMR (C6D6, 400 MHz, 25 °C): δ 0.93 (br,
THF), 1.28 (d, 3H, CH3, 3J(H,H) 6.7 Hz), 2.90 (br, THF), 4.03 (q,
1H, CH, 3J(H,H) ) 6.67 Hz), 6.76 (s, 8H, C8H8), 7.0-7.7 (m, 15H,
2
Ph). 31P{H} NMR (C6D6, 161.7 MHz 25 °C): δ 19.3 (d, J(P,Y)
) 17.8 Hz). IR (KBr, cm-1): 3060 (m), 2964 (m), 2860 (m), 1593
(w), 1473 (s), 1456 (m), 1433 (s), 1363 (w), 1269 (m), 1184 (w),
1110 (br), 1091 (m), 1066 (w), 1026 (m), 962 (m), 869 (s), 798
(m), 744 (s), 700 (w), 628 (s). Anal. Calcd for C32H35NOPY (Mr
) 569.51): C, 67.49; H, 6.19; N, 2.45. Found: C, 66.61; H, 6.91;
N, 2.36.
(11) (a) Zulys, A.; Panda, T. K.; Gamer, M. T.; Roesky, P. W. Chem.
Commun. 2004, 2584-2585. (b) Zulys, A.; Panda, T. K.; Gamer, M.
T.; Roesky, P. W. Organometallics 2005, 24, 2197-2202. (c) Gamer,
M. T.; Rasta¨tter, M.; Roesky, P. W.; Steffens, A.; Glanz, M. Chem.
Eur. J. 2005, 11, 3165-3172.
Ln ) Er. Yields: 7a, 200 mg (31%), and 7b, 195 mg (30%)
(pink crystals). IR (KBr, cm-1): 3055 (m), 3022 (m), 3001 (m),
2970 (m), 2923 (m), 2862 (m), 1591 (w), 1479 (s), 1450 (m), 1436
(s), 1396 (w), 1363 (w), 1340 (m), 1311 (w), 1272 (m), 1245 (m),
1176 (w), 1122 (br), 1110 (m), 1068 (w), 1026 (m), 999 (m), 966
(12) Wiecko, M.; Girnt, D.; Rasta¨tter, M.; Panda, T. K.; Roesky, P. W.
Dalton Trans. 2005, 2147-2150.
(13) Gamer, M. T.; Roesky, P. W. Z. Anorg. Allg. Chem. 2001, 627, 877-
881.
(14) Taylor, M. D.; Carter, C. P. J. Inorg. Nucl. Chem. 1962, 24, 387-
391.
Inorganic Chemistry, Vol. 45, No. 2, 2006 911

Panda et al.
Table 1. Crystallographic Details of [{(Me3SiNPPh2)2CH}Er(Cl){N(R-*CHMePh)(PPh2)}] (Ln ) Er (2a), Yb (3a))),
[{(Me3SiNPPh2)2CH}Yb(Cl){N(S-*CHMePh)(PPh2)}] (3b), and [{(Me3SiNPPh2)2CH}Yb(Cl2)LiCl(THF)2] (5)a
param
2a
3a
3b
5‚THF
formula
fw
C51H58ClErN3P3Si2
1072.8
C51H58ClN3P3Si2Yb
1078.6
C51H58ClN3P3Si2Yb
1078.6
C43H55Cl3LiN2O3P2Si2Yb
1060.4
space group
a, Å
P1 (No. 1)
9.960(2)
P1 (No. 1)
9.9874(4)
P1 (No. 1)
9.978(3)
Pna21 (No. 33)
18.843(5)
b, Å
c, Å
11.612(2)
12.478(3)
66.605(4)
72.437(4)
78.481(4)
2011.1(6)
1
11.6417(5)
12.5038(5)
66.475(3)
72.140(3)
78.311(3)
1263.38(9)
1
1.407
11.624(3)
12.495(4)
66.644(5)
72.282(6)
78.429(6)
1262.0(6)
1
13.206(4)
20.044(6)
R,deg
â, deg
γ, deg
V, Å3
4987(2)
4
1.412
Z
d, g/cm3
1.406
1.409
radiatn (λ, Å)
µ, mm-1
abs corr
reflcns collcd
unique reflcns
obsd reflcns
data, params
R1,b wR2c
absolute struct param (Flack)
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
1.901
2.082
2.085
2.185
empirical (SADABS)
15 394
11 138 (Rint ) 0.0128)
11 108
11 138, 557
0.0233, 0.0572
-0.013(3)
integration (X-shape)
36 476
16 088 (Rint ) 0.0420)
15 973
16 088, 557
0.0259, 0.0593
-0.014(3)
empirical (SADABS)
15 709
12 454 (Rint ) 0.0110)
12 438
12 454, 557
0.0196, 0.0497
-0.016(3)
empirical (SADABS)
59 949
15 158 (Rint ) 0.0800)
10 256
15 158, 459
0.0456, 0.1078
-0.005(7)
a All data collected at 173 K except for 3a (at 200 K) and 5‚THF (at 203 K). b R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
2
2
2
(m), 910 (m), 850 (s), 800 (m), 746 (s), 725 (m), 698 (s), 628 (s).
Anal. Calcd for C32H35ErNOP (Mr ) 647.87): C, 59.33; H, 5.45;
N, 2.16. Found: C, 59.38; H, 6.09; N, 2.02.
significance. Positional parameters, hydrogen atom parameters,
thermal parameters, and bond distances and angles have been
deposited as Supporting Information. Crystallographic data (exclud-
ing structure factors) for the structures reported in this paper have
been deposited with the Cambridge Crystallographic Data Centre
as supplementary publication nos. CCDC-281366-281373. Copies
of the data can be obtained free of charge on application to CCDC,
12 Union Road, Cambridge CB21EZ, U.K. (fax, (+(44)1223-336-
033; E-mail, deposit@ccdc.cam.ac.uk).
Ln ) Yb. Yield of 8: 175 mg (27%) (green crystals). IR (KBr,
cm-1): 3055 (m), 3022 (m), 2958 (m), 2921 (m), 2856 (m), 1959
(m), 1886 (w), 1812 (w), 1591 (w), 1490 (s), 1479 (s), 1450 (m),
1434 (s), 1363 (w), 1307 (w), 1272 (m), 1251 (m), 1203 (m), 1157
(w), 1122 (br), 1110 (m), 1091 (w), 1066 (w), 1022 (m), 999 (m),
960 (m), 852 (s), 802 (m), 740 (s), 725 (m), 696 (s), 628 (s).Anal.
Calcd for C32H35NOPYb (Mr ) 653.65): C, 58.80; H, 5.40; N,
2.14. Found: C, 58.78; H, 5.55; N, 2.48.
Results and Discussion
X-ray Crystallographic Studies of 2a, 3a,b, 5, 6a,b, 7a, and
8. Single crystals of 2a, 3a,b, 5, 6a,b, 7a, and 8 were grown from
THF/pentane (1:3). Single crystals were obtained from THF/pentane
(1:3) or hot toluene. A suitable crystal was covered in mineral oil
(Aldrich) and mounted onto a glass fiber. The crystal was transferred
directly to the -73 °C cold N2 stream of a Stoe IPDS 2T or a
Bruker Smart 1000 CCD diffractometer. Subsequent computations
were carried out on an Intel Pentium IV PC.
To introduce the chiral phosphanylamides {N(R-*CHMePh)-
(PPh2)}- and {N(S-*CHMePh)(PPh2)}- into rare earth
chemistry, we tried first to synthesize homoleptic complexes
of composition [Ln{N(*CHMePh)(PPh2)}3] via a salt me-
tathesis of Li{N(R-*CHMePh)(PPh2)} (1a) and Li{N(S-
*CHMePh)(PPh2)} (1b) with LnCl3. A mixture of products
was obtained. Up to now we were not able to isolate a
definite product. Therefore, we implemented two different
coligands into the coordination sphere of the metal to
stabilize the corresponding chiral phosphanylamide com-
plexes. The coligands are the well-established cyclo-
octatetraene17 and the bis(phosphinimino)methanide,
(Me3SiNPPh2)CH-.18
Bis(phosphinimino)methanide Complexes. Transmeta-
lation of the enantiomeric pure lithium compounds 1a,b with
lanthanide bis(phosphinimino)methanide dichloride, [{CH-
(PPh2NSiMe3)2}LnCl2]2,10 in a 2:1 molar ratio in THF
followed by extraction with toluene afforded the expected
enantiomeric pure complexes [{CH(PPh2NSiMe3)2}Ln(Cl)-
{η2-N(R-*CHMePh)(PPh2)}] (Ln ) Er (2a), Yb (3a), Lu
(4a)) and [{CH(PPh2NSiMe3)2}Ln(Cl){η2-N(S-*CHMePh)-
(PPh2)}] (Ln ) Er (2b), Yb (3b), Lu (4b)) (Scheme 1). The
All structures were solved by the Patterson method (SHELXS-
9715). The remaining non-hydrogen atoms were located from
successive difference Fourier map calculations. The refinements
were carried out by using the full-matrix least-squares techniques
on F, minimizing the function (Fo - Fc)2, where the weight is
2
2
defined as 4Fo /2(Fo ) and Fo and Fc are the observed and calculated
structure factor amplitudes using the program SHELXL-97.16 In
the final cycles of each refinement, all non-hydrogen atoms except
the pentane molecules in C32-C43 and O3 in 5 and C30 and C31
in 6a,b and 7a were assigned anisotropic temperature factors.
Carbon-bound hydrogen atom positions were calculated and allowed
to ride on the carbon to which they are bonded by assuming a C-H
bond length of 0.95 Å. The hydrogen atom contributions were
calculated but not refined. The final values of refinement parameters
are given in Tables 1 and 2. The locations of the largest peaks in
the final difference Fourier map calculation as well as the magnitude
of the residual electron densities in each case were of no chemical
(17) Review: (a) Edelmann, F. T. Angew. Chem. 1995, 107, 2647-2669;
Angew. Chem., Int. Ed. Engl. 1995, 34, 2466-2488. (b) Edelmann,
F. T.; Freckmann D. M. M.; Schumann H. Chem. ReV. 2002, 102,
1851-1896.
(15) Sheldrick, G. M. SHELXS-97, Program of Crystal Structure Solution;
University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(16) Sheldrick, G. M. SHELXL-97, Program of Crystal Structure Refine-
ment; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(18) Review: Roesky, P. W. Heteroatom Chem. 2002, 13, 514-520.
912 Inorganic Chemistry, Vol. 45, No. 2, 2006

Yttrium and Lanthanide Chiral Phosphanylamides
Table 2. Crystallographic Details of [(η8-C8H8)Ln{N(R-*CHMePh)(PPh2)}] (Ln ) Y (6a), Er (7a), Yb (8)) and [η8-(C8H8)Ln{N(S-*CHMePh)(PPh2)}]
(Ln ) Y (6b))a
param
6a
6b
7a
8
formula
fw
C32H35NOPY
569.49
C32H35NOPY
569.49
C32H35ErNOP
647.84
C32H35NOPYb
653.62
space group
a, Å
P212121 (No. 19)
11.710(4)
P212121 (No. 19)
11.714(3)
P212121 (No. 19)
11.679(2)
P212121 (No. 19)
11.728(2)
b, Å
13.453(4)
13.445(3)
13.395(2)
13.378(2)
c, Å
17.967(6)
2830(2)
4
17.967(4)
2829.9(10)
4
17.920(3)
2803.3(7)
4
17.880(3)
2805.1(7)
4
V, Å3
Z
d, g/cm3
1.336
1.337
1.535
1.548
radiatn (λ, Å)
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
Mo KR (0.71073)
µ, mm-1
2.141
2.142
3.075
3.415
abs corr
empirical (SADABS)
25 497
8633 (Rint ) 0.0372)
7086
8633, 316
0.0397, 0.0929
-0.026(4)
empirical (SADABS)
35 445
8690 (Rint ) 0.0291)
7870
8690, 316
0.0344, 0.0845
-0.027(4)
empirical (SADABS)
30 078
8169 (Rint ) 0.0534)
6977
8169, 316
0.0332, 0.0626
-0.034(8)
empirical (SADABS)
35 038
8576 (Rint ) 0.0227)
8203
8576, 326
0.0177, 0.0410
-0.024(5)
reflcns collcd
unique reflcns
obsd reflcns
data, params
R1,b wR2c
absolute struct param (Flack)
a All data collected at 173 K. b R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
2
2
2
Scheme 1
NMR spectrum, the phosphorus atoms of the bis(phosphin-
imino)methanide ligand are not chemically equivalent in
solution and show two doublets at 18.8 and 19.1 ppm. The
phosphorus atom of the ligand {N(*CHMePh)(PPh2)}-
shows a sharp singlet at 18.0 ppm. Thus, no coupling with
the other two phosphorus atoms was noticed for the
phosphorus atom of the {N(*CHMePh)(PPh2)}- ligand.
The structures of 2a and 3a,b were confirmed by single-
crystal X-ray diffraction in the solid state. Data collection
parameters and selected bond lengths and angles are given
in Tables 1 and 3. As a result of the similar ionic radii of
the lanthanides, the single-crystal X-ray structures of 2a and
3a are isostructural, whereas 3b forms the corresponding
enantiomer (Figure 1). All the compounds crystallize in the
triclinic space group P1 having one molecule in the unit cell.
The coordination polyhedron is formed by the chlorine atom
and the {N(*CHMePh)(PPh2)}- and {CH(PPh2NSiMe3)2}-
ligands. As observed in zirconium chemistry, the {N(CHMe-
Ph)(PPh2)}- ligand is coordinated to the metal atom in a
chelating (η2) fashion.12 Thus, the {N(*CHMePh)(PPh2)}-
ligand coordinates to the center metal through nitrogen atom
(N3) and the phosphorus atom (P3) forming a azaphospha-
metallacyclopropane structure featuring Ln-P3 distances of
2.7985(8) Å (2a), 2.7782(7) Å (3a), and 2.7849(8) Å (3b)
and Ln-N3 distances of 2.254(2) Å (2a), 2.216(2) Å (2b),
and 2.225(2) Å (3b), respectively. The observed long Ln-
P3 distances are in the range of other lanthanide phosphanyl-
compounds were crystallized from THF/pentane (1:3). All
complexes have been characterized by standard analytical/
spectroscopic techniques, and the solid-state structures of 2a
and 3a,b were established by single-crystal X-ray diffraction.
The 1H NMR spectra of the diamagnetic compounds 4a,b
show characteristic signals. Two sharp singlets (δ 0.14 and
0.18 ppm) are observed for two Me3Si groups of the bis-
(phosphinimino)methanide ligand as the Me3Si groups are
chemically nonequivalent due to the asymmetric nature of
the molecule. Because of the presence of a chiral phosphanyl
group, there is no symmetry element through the molecule
and thus gives three nonequivalent phosphorus atoms. As
the chemical shift of methine protons is more sensitive
toward the chemical surrounding, a triplet (δ 0.88 ppm) was
observed which is upfield shifted compared to the chlorine
-
amide (R-N-PPh2 ) compounds, e.g., an average 2.762-
(8) Å in [Er{N(PPh2)2}3] and 2.885(2)-3.031(2) Å in [Li-
(THF)4][(Ph2PNPh)4Yb].19 Values for the N-Ln-P bite
angles (N3-Ln-P3 36.22(7)° (2b), 36.76(6)° (3a), and
36.70(5)° (3b)) show that the angle is rather small.
A six-membered metallacycle (N1-P1-C1-P2-N2-Ln)
is formed by chelation of the two trimethlysilylimine groups
to the lanthanide atom. The ring adopts a twist boat
conformation, in which the central carbon atom and the
lanthanide atom are displaced from the N2P2 least-squares
precursor [{CH(PPh2NSiMe3)2}LuCl2]2 (δ 1.97 ppm).10
A
2J(H,P) coupling constant of 7.2 Hz of the methine proton
1
is observed. In the H NMR spectra, the {N(*CHMePh)-
(PPh2)}- ligand shows a characteristic doublet for the CH3
group (δ 1.30 ppm), which is downfield shifted compared
to 1a,b (δ 1.08 ppm), and a quartet for the proton of the
chiral CH group (δ 4.38 ppm), which is in the range of the
corresponding signal of 1a,b (δ 4.30 ppm).12 In the 31P{1H}
(19) Wetzel, T. G.; Dehnen, S.; Roesky, P. W. Angew. Chem. 1999, 111,
1155-1158; Angew. Chem., Int. Ed. 1999, 38, 1086-1088.
Inorganic Chemistry, Vol. 45, No. 2, 2006 913

Panda et al.
Table 3. Selected Bond Lengths (Å) and Angles (deg) of
[{(Me3SiNPPh2)2CH}Er(Cl){N(R-*CHMePh)(PPh2)}] (Ln ) Er (2a), Yb
(3a)) and [{(Me3SiNPPh2)2CH}Yb(Cl){N(S-*CHMePh)(PPh2)}] (3b)
param
2a
3a
3b
Bond Lengths (Å)
Ln-N1
Ln-N2
Ln-N3
Ln-P3
Ln-Cl
Ln-C1
N1-P1
N2-P2
P1-C1
P2-C1
P3-N3
N3-C32
2.339(2)
2.369(2)
2.254(2)
2.7985(8)
2.5416(1)
2.615(3)
1.607(3)
1.593(2)
173.9(3)
1.739(3)
1.653(3)
1.468(4)
2.325(2)
2.343(2)
2.216(2)
2.7782(7)
2.5208(7)
2.592(2)
1.602(2)
1.600(2)
1.740(3)
1.743(3)
1.663(2)
1.466(3)
2.332(2)
2.345(2)
2.225(2)
2.7849(8)
2.5226(1)
2.596(2)
1.603(2)
1.598(2)
1.741(2)
1.744(2)
1.664(2)
1.473(3)
Figure 1. Perspective ORTEP view of the molecular structure of the
enantiomers 3a (left) and 3b (right). Thermal ellipsoids are drawn to
encompass 50% probability. Hydrogen atoms are omitted for clarity.
Bond Angles (deg)
96.06(8)
N1-Ln-N2
N1-Ln-N3
N2-Ln-N3
N1-Ln-Cl
N2-Ln-Cl
N3-Ln-Cl
N1-Ln-C1
N2-Ln-C1
N3-Ln-C1
N1-Ln-P3
N2-Ln-P3
N3-Ln-P3
Cl-Ln-C1
Cl-Ln-P3
C1-Ln-P3
C32-N3-P3
C32-N3-Ln
P3-N3-Ln
96.46(8)
113.17(8)
136.45(8)
103.11(6)
99.68(6)
103.49(6)
66.34(8)
65.71(8)
96.92(8)
138.94(6)
100.40(5)
36.76(6)
159.50(6)
110.47(3)
87.11(6)
121.5(2)
147.5(2)
90.34(10)
96.24(7)
112.91(7)
136.79(7)
102.80(5)
100.01(6)
103.49(6)
66.36(7)
65.58(7)
96.85(8)
138.89(5)
100.89(5)
36.70(5)
159.52(5)
110.49(3)
87.32(5)
121.56(2)
147.58(2)
90.28(9)
112.87(9)
135.54(8)
103.50(6)
100.67(6)
104.18(7)
65.95(8)
64.91(8)
96.08(8)
138.19(6)
100.27(6)
36.22(7)
159.64(6)
110.78(3)
86.79(6)
122.13(2)
147.24(2)
90.12(1)
Figure 2. Perspective ORTEP view of the molecular structure of 5.
Thermal ellipsoids are drawn to encompass 50% probability. Hydrogen
atoms are omitted for clarity.
plane. The distance between the central carbon atom (C1)
and the lanthanide atom (2.615(3) Å (2a), 2.592(2) Å (3a),
and 2.596(9) Å (3b)) is longer than usual Ln-C distances;20
however, resultant tridentate coordination of the ligand was
observed like before.10,11,21 The {CH(PPh2NSiMe3)2}- ligand
shows a slight asymmetrical attachment to the metal center
(Ln-N1 2.339(2) Å (2a), 2.325(2) Å (3a), and 2.332(2) Å
(3b); Ln-N2 2.369(2) Å (2a), 2.343(2) Å (3a), and 2.345-
(2) Å (3b)).
Recently, we discovered that many substituted bis(phos-
phinimino)methanide complexes such as [{CH(PPh2NSi-
Me3)2}Ln(η8-C8H8)] (Ln ) Y, Sm, Er, Yb, Lu) and [{CH-
(PPh2NSiMe3)2}Ln{(Ph2P)2N}Cl] (Ln ) Y, La, Nd, Yb) can
be obtained in a one-pot reaction starting from K{CH(PPh2-
NSiMe3)2}, LnCl3, and the potassium salt of the correspond-
ing coligand, e.g. K2C8H8 and [K(THF)nN(PPh2)2] (n ) 1.25,
1.5), respectively.11b,c In this context we also tried to obtain
compound 3 in a one-pot reaction starting from K{CH(PPh2-
NSiMe3)2}, YbCl3, and 1. Performing the reaction in THF
and subsequent extractions from toluene and crystallization
from THF/pentane yielded not the desired product. Instead,
the lithium chloride incorporated complex [{(Me3SiNPPh2)2-
CH}Yb(µ-Cl)2LiCl(THF)2] (5) was obtained. The incorpora-
tion of lithium chloride into the coordination sphere of
lanthanide complexes is common in the literature.20 Thus,
complexes such as [(η5-C5Me5)2Nd(µ-Cl)2Li(THF)2] have
been known for many years.22
Complex 5 has been characterized by standard analytical
techniques, and the solid-state structure was established by
single-crystal X-ray diffraction (Figure 2). Data collection
parameters and selected bond lengths and angles are given
in Tables 1 and 4. In the solid-state structure the lighter alkali
metal lithium coordinates to the ytterbium through two µ-
chlorine atoms along with two solvent THF molecules to
the lithium atom. Like before, the ligand, {CH(PPh2NSi-
Me3)2}-, forms a six-membered metallacycle (N1-P1-C1-
P2-N2-Yb) by chelation of the two trimethylsilylimine
groups to the lanthanide atom. The ring adopts a twist boat
conformation in which the central carbon atom and the
lanthanide atom are displaced from the N2P2 least-squares
plane. A four-membered metallacyle (Yb-Cl(2)-Li-Cl(3))
was observed by µ-bridging of two chlorine atoms toward
(21) (a) Imhoff, P.; Guelpen, J. H.; Vrieze, K.; Smeets, W. J. J.; Spek, A.
L.; Elsevier, C. J. Inorg. Chim. Acta 1995, 235, 77-88. (b) Ong, C.
M.; McKarns, P.; Stephan, D. W. Organometallics 1999, 18, 4197-
4208. (c) Kasani, A.; Kamalesh Babu, R. P.; McDonald, R.; Cavell,
R. G. Organometallics 1999, 18, 3775-3777. (d) Aparna, K.;
McDonald, R.; Fuerguson, M.; Cavell, R. G. Organometallics 1999,
18, 4241-4243. (e) Wei, P.; Stephan, D. W. Organometallics 2002,
21, 1308-1310. (f) Gamer, M. T.; Roesky, P. W. J. Organomet. Chem.
2002, 647, 123-127. (g) Sarsfield, M. J.; Steele, H.; Helliwell, M.;
Teat, S. J. Dalton Trans. 2003, 3443-3449. (h) Hill, M. S.; Hitchcock,
P. B. Dalton Trans. 2003, 4570-4571. (i) Bibal, C.; Pink, M.;
Smurnyy, Y. D.; Tomaszewski, J.; Caulton, K. G. J. Am. Chem. Soc.
2004, 126, 2312-2313.
(20) Review: (a) Schumann, H.; Meese-Marktscheffel, J. A.; Esser, L.
Chem. ReV. 1995, 95, 865-986. (b) Schaverien, C. J. AdV. Organomet.
Chem. 1994, 36, 283-363. (c) Schumann, H. Angew. Chem. 1984,
96, 475-493; Angew. Chem., Int. Ed. Engl. 1984, 23, 474-493.
(22) Wayda, A. L.; Evans, W. J. Inorg. Chem. 1980, 19, 2190-2191.
914 Inorganic Chemistry, Vol. 45, No. 2, 2006

Yttrium and Lanthanide Chiral Phosphanylamides
Table 4. Selected Bond Lengths (Å) and Angles (deg) of
[{(Me3SiNPPh2)2CH}Yb(Cl2)LiCl(THF)2] (5)
Table 5. Selected Bond Lengths (Å) and Angles (deg) of
[(η8-C8H8)Ln{N(R-*CHMePh)(PPh2)}] (Ln ) Y (6a), Er (7a), Yb (8))
and [η8-(C8H8)Ln{N(S-*CHMePh)(PPh2)}] (Ln ) Y (6b), Er (7b))a
Bond Lengths (Å)
Yb-N1
Yb-N2
Yb-C1
Yb-Cl1
Yb-Cl2
Yb-Cl3
N1-P1
2.350(4)
2.309(4)
2.617(5)
2.5185(2)
2.6253(2)
2.6187(2)
1.608(5)
N2-P2
C1-P1
C1-P2
Li-O1
Li-Cl2
Li-Cl3
Li-Yb
1.607(5)
1.739(5)
1.758(5)
1.894(1)
2.341(1)
2.374(1)
3.582(1)
param
6a
6b
7a
8
Bond Lengths (Å)
2.567(3)
Ln-C1
Ln-C2
Ln-C3
Ln-C4
Ln-C5
Ln-C6
Ln-C7
Ln-C8
Ln-N
Ln-P
2.564(3)
2.549(3)
2.541(3)
2.568(3)
2.607(4)
2.579(4)
2.554(4)
2.542(3)
2.242(2)
2.8471(1)
2.388(2)
1.81(1)
2.555(4)
2.532(4)
2.534(4)
2.557(5)
2.590(5)
2.573(5)
2.543(5)
2.524(4)
2.233(3)
2.8279(10)
2.370(3)
1.78(10)
1.661(3)
1.467(5)
2.538(3)
2.525(2)
2.514(2)
2.537(3)
2.577(3)
2.547(3)
2.518(3)
2.518(3)
2.2047(2)
2.8035(6)
2.3422(2)
1.757(10)
1.6626(2)
1.469(3)
2.551(3)
2.545(3)
2.571(3)
2.610(3)
2.581(3)
2.552(3)
2.540(3)
2.2452(2)
2.8468(7)
2.3885(2)
1.88(10)
1.6580(2)
1.472(3)
Bond Angles (deg)
N1-Yb-N2
N1-Yb-Cl1
N2-Yb-Cl1
N1-Yb-C1
N2-Yb-C1
N1-Yb-Cl1
N2-Yb-Cl1
N1-Yb-Cl2
N2-Yb-Cl2
N1-Yb-Cl3
N2-Yb-Cl3
P1-C1-P2
98.21(2)
95.73(1)
95.41(1)
65.76(2)
66.13(2)
95.73(11)
95.41(12)
90.17(12)
162.19(1)
160.67(1)
85.45(1)
125.2(3)
86.5(2)
P2-N2-Yb
Yb-Cl2-Li
Yb-Cl3-Li
Cl2-Li-Cl3
O1-Li-O2
O1-Li-Cl2
O2-Li-Cl2
O1-Li-Cl3
O2-Li-Cl3
Cl1-Yb-C1
Cl2-Yb-C1
Cl3-Yb-C1
Cl1-Yb-Cl2
Cl1-Yb-Cl3
Cl2-Yb-Cl3
99.8(2)
92.1(3)
91.5(3)
93.3(5)
Ln-O
Ln-Cg
P-N
119.7(8)
115.9(6)
111.3(6)
101.9(6)
110.8(6)
150.01(1)
103.83(12)
99.12(1)
99.38(6)
102.84(6)
81.64(5)
1.659(2)
1.474(3)
N-C9
Bond Angles (deg)
88.56(7)
N-Ln-O
N-Ln-P
O-Ln-P
N-P-Ln
N-Ln-Cg
P-Ln-Cg
O-Ln-Cg
C9-N-P
C9-N-Ln
P-N-Ln
88.58(8)
35.59(6)
79.78(5)
51.87(7)
147.08(1)
142.40(1)
124.21(1)
123.33(2)
144.13(2)
92.54(9)
88.30(12)
35.94(9)
79.69(7)
52.11(11)
146.34(1)
142.81(1)
125.06(1)
123.6(3)
144.5(3)
91.95(14)
89.03(7)
36.35(5)
80.17(4)
51.81(6)
145.52(1)
142.16(1)
125.22(1)
123.32(2)
144.83(1)
91.84(7)
35.58(5)
79.75(5)
52.00(6)
147.26(1)
142.43(1)
124.07(1)
123.47(14)
144.11(14)
92.42(7)
P1-C(1)-Yb
P2-C(1)-Yb
P1-N1-Yb
85.26(2)
99.2(2)
Scheme 2
a Cg ) C8H8-ring centroid.
acterized by standard spectroscopic techniques, and the solid-
state structures of compounds 6a,b, 7a, and 8 were estab-
lished in the single-crystal X-ray diffraction. In the 1H NMR
spectra, the diamagnetic compounds 6a,b show a sharp signal
at 6.76 ppm for the cyclooctatetraene ring. This is in the
same range of previously observed [{CH(PPh2NSiMe3)2}-
Y(η8-C8H8)] (δ 6.54 ppm).11b For the {N(*CHMePh)(PPh2)}-
1
ligand, the H NMR spectra show a characteristic doublet
for the CH3 group (δ 1.28 ppm), which is in the range of
4a,b, and a quartet for the CH proton (δ 4.03 ppm), which
is shifted high-field with respect to 4a,b (δ 4.38 ppm). The
31P{1H} NMR spectrum is also typical. At room temperature
6a,b each show one doublet in the 31P{1H} NMR spectrum
(δ 19.3 ppm) for the phosphorus atom. The 2J(P,Y) coupling
constant of 17.8 Hz is in the expected range.9b,19,23 Compared
to complex 4a,b there is slight high-field shifting in the 31P-
{1H} NMR spectrum for 6a,b.
The structures of 6a,b, 7a, and 8 were confirmed by single-
crystal X-ray diffraction in the solid state. Data collection
parameters and selected bond lengths and angles are given
in Tables 2 and 5. All the crystals were grown from THF/
pentane (1:3). As a result of the similar ionic radii of the
lanthanides, the single-crystal X-ray structures of 6a, 7a, and
8 are isostructural, whereas 6b forms the corresponding
enantiomer (Figure 3). All compounds crystallize in the chiral
orthorhombic space group P212121 having four molecules
in the unit cell. The three leg piano stool of 6a,b, 7a, and 8
is formed by the η8-coordinated cyclooctatetraene ring, which
is located on top of the coordination polyhedron, one THF
molecule, and the η2-{N(*CHMePh)(PPh2)}- ligand. Thus,
lithium and ytterbium atoms having a distance of 3.582(1)
Å between ytterbium and lithium atoms.
Cyclooctatetraene Complexes. To learn more about the
reactivity of complexes 1a,b, we were interested in synthe-
sizing some cyclooctatetraene derivatives. Cyclooctatetraene
is besides cyclopentadienyl the most important π-perimeter
ligand in f-element chemistry. Today it is well-accepted that
the large flat cyclooctatetraene ligand represents an especially
valuable alternative to the popular cyclopentadienyl ligands.
Among non-cyclopentadienyl organolanthanide complexes,
cyclooctatetraene derivatives form a large and well-
investigated group of compounds.17a
The enantiomeric pure compounds [{η2-N(R-*CHMePh)-
(PPh2)}Ln(η8-C8H8)] (Ln ) Y (6a), Er (7a), Yb (8)) and
[{η2-N(S-*CHMePh)(PPh2)}Ln(η8-C8H8)] (Ln ) Y (6b), Er
(7b)) can be obtained by one-pot synthesis. The reaction
between the lithium salt of the chiral phosphanylamine 1a
or 1b with anhydrous lanthanide chloride in 1:1 ratio
generates the phosphanylamide lanthanide dichloride in situ,
which further reacts with dipotassium salt of cyclooctatet-
raene to produce the desired compounds (Scheme 2). Several
attempts to isolate the phosphanylamide lanthanide dichloride
were not successful. The new complexes have been char-
(23) Coan, P. S.; Hubert-Pfalzgraf, L. G.; Caulton, K. G. Inorg. Chem.
1992, 31, 1262-1267.
Inorganic Chemistry, Vol. 45, No. 2, 2006 915

Panda et al.
Summary
The chiral phosphanylamides {N(R-*CHMePh)(PPh2)}-
and {N(S-*CHMePh)(PPh2)}- were introduced into rare earth
chemistry. Since we were not able to isolate homoleptic
complexes of composition [Ln{N(*CHMePh)(PPh2)}3], we
implemented two different coligands into the coordination
sphere of the metal to stabilize the corresponding chiral
phosphanylamide complexes. The coligands are the well-
established cyclooctatetraene and the bis(phosphinimino)-
methanide, {CH(PPh2NSiMe3)2}-. By using these coligands,
the enantiomeric pure complexes [{CH(PPh2NSiMe3)2}Ln-
(Cl){η2-N(R-*CHMePh)(PPh2)}] (Ln ) Er, Yb, Lu), [{CH-
(PPh2NSiMe3)2}Ln(Cl){η2-N(S-*CHMePh)(PPh2)}] (Ln )
Er, Yb, Lu), [{η2-N(R-*CHMePh)(PPh2)}Ln(η8-C8H8)] (Ln
) Y, Er, Yb), and [{η2-N(S-*CHMePh)(PPh2)}Ln(η8-C8H8)]
(Ln ) Y, Er) were obtained. The structures of selected
examples of all four different kinds of complexes were
confirmed by single-crystal X-ray diffraction in the solid
state.
Figure 3. Perspective ORTEP view of the molecular structure of the
enantiomers 6a (left) and 6b (right). Thermal ellipsoids are drawn to
encompass 50% probability. Hydrogen atoms are omitted for clarity.
the lanthanide atom is 11-fold coordinated if η8-cyclooc-
tatetraene is considered as an octadentate ligand. The
cyclooctatetraene ring is slightly asymmetrically bound to
the lanthanide atom. The Ln-C bond lengths vary in the
expected range of 2.541(3)-2.607(4) Å (6a), 2.540(3)-
2.610(3) Å (6b), 2.524(4)-2.590(5) Å (7a), and 2.514(2)-
2.577(3) Å (8). Beside the cyclooctatetraene ring, the
{N(CHMePh)(PPh2)}- ligand is coordinated to the central
metal in a chelating η2-fashion through nitrogen and phos-
phorus atom, thus forming a three-membered metallacycle.
The Ln-N distances of 2.242(2) Å (6a), 2.2452(2) Å (6b),
2.233(3) Å (7a), and 2.2047(2) Å (8) are in the same range
observed for 2a (2.254(2) Å) and 3b (2.225(2) Å). Also the
Ln-P distances of 2.8471(1) Å (6a), 2.8468(7) Å (6b),
2.8279(10) Å (7a), and 2.8035(6) Å (8) are in a comparative
range with 2a (2.7985(8) Å) and 3b (2.7848(8) Å).
Acknowledgment. This work was supported by the
Deutsche Forschungsgemeinschaft (DFG Schwerpunktpro-
gramm (SPP 1166): Lanthanoidspezifische Funktionalita¨ten
in Moleku¨l und Material). We thank Prof. Dr. G. Schro¨der
(Karlsruhe, Germany) for the gift of cyclooctatetraene.
Supporting Information Available: X-ray crystallographic files
in CIF format for the structure determinations of 2a, 3a,b, 5, 6a,b,
7a, and 8. This material is available free of charge via the Internet
at http:// pubs.acs.org.
IC051584E
916 Inorganic Chemistry, Vol. 45, No. 2, 2006