Synthesis and structure of yttrium and lanthanide bis(phosphinimino)methanides

Article abstract of DOI:10.1021/om0102955

Reaction of K{CH(PPh₂NSiMe₃)₂} (1) with anhydrous yttrium or lanthanide trichlorides leads to [{CH(PPh₂NSiMe₃)₂}LnCl₂]₂ (Ln = Y (2a), Sm (2b), Er (2c), Dy (2d), Yb (2e), Lu (2f)). The single-crystal X-ray structures of these complexes show that the methine carbon is bound to the lanthanide atom. This is supported by DFT calculations, which show a comparable interaction. Due to the similar ion radii of the lanthanides, the single-crystal X-ray structures of 2a-f are isostructural. Further reaction of 2 with KNPh₂ afforded [{CH(PPh₂NSiMe₃)₂} Ln(NPh₂)₂] (Ln = Y (3a), Sm (3b)). These complexes show in comparison to 2 a similar coordination behavior of the {CH(PPh₂NSiMe₃)₂}^- ligand in the solid state and in solution.

Full text of DOI:10.1021/om0102955

4230
Organometallics 2001, 20, 4230-4236
Syn th esis a n d Str u ctu r e of Yttr iu m a n d La n th a n id e
Bis(p h osp h in im in o)m eth a n id es
Michael T. Gamer, Stefanie Dehnen, and Peter W. Roesky*
Institut fu¨r Anorganische Chemie, Engesserstrasse 15, D-76128 Karlsruhe, Germany
Received April 10, 2001
Reaction of K{CH(PPh2NSiMe3)2} (1) with anhydrous yttrium or lanthanide trichlorides
leads to [{CH(PPh2NSiMe3)2}LnCl2]2 (Ln ) Y (2a ), Sm (2b), Er (2c), Dy (2d ), Yb (2e), Lu
(2f)). The single-crystal X-ray structures of these complexes show that the methine carbon
is bound to the lanthanide atom. This is supported by DFT calculations, which show a
comparable interaction. Due to the similar ion radii of the lanthanides, the single-crystal
X-ray structures of 2a -f are isostructural. Further reaction of 2 with KNPh2 afforded
[{CH(PPh2NSiMe3)2}Ln(NPh2)2] (Ln ) Y (3a ), Sm (3b)). These complexes show in comparison
to 2 a similar coordination behavior of the {CH(PPh2NSiMe3)2}- ligand in the solid state
and in solution.
In tr od u ction
P-N ligands such as phosphinimines and phosphinim-
ides.13 Our attention is drawn to the phosphinimine
{CH(PPh2NSiMe3)2}- as a potential precursor to stable
lanthanide complexes. We anticipated that this ligand
system may combine the advantages of phosphinimines
and amidinates. The central carbon protons of CH2(PPh2-
NSiMe3)2 are expected to be acidic in analogy with the
inorganic ligands [N(EPPh2)2]- (E ) O, S, Se)14-16 and
[CH(EPPh2)2]- (E ) O, S, Se).17-19 It was shown that a
monoanionic20,21 and a dianionic species22,23 ({CH(PPh2-
NSiMe3)2}- and {C(PPh2NSiMe3)2}2-, respectively) can
be generated by deprotonation of the precursor CH2(PPh2-
Metallocenes of organolanthanides1 have proven to be
highly efficient catalysts2 for a variety of olefin trans-
formations including hydrogenation,3,4 polymerization,5
hydroamination,4,6 hydrosilylation,7 and hydroboration.8
Recently, there has been a significant research effort
by us and others to substitute the cyclopentadienyl
ligand9 by anionic nitrogen-based bidentate ligand
systems10 such as benzamidinates11 or aminotropon-
iminates.12 Another approach in this area is the use of
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10.1021/om0102955 CCC: $20.00 © 2001 American Chemical Society
Publication on Web 09/07/2001

Lanthanide Bis(phosphinimino)methanides
Organometallics, Vol. 20, No. 20, 2001 4231
δ 0.14 (s, 36H, SiMe3), 1.93 (dt, 2H, CH, 2J (H,P) ) 1.94 Hz,
2J (H,Y) ) 0.92 Hz), 6.88-7.05 (m, 8H, Ph), 7.07-7.27 (m, 12H,
Ph), 7.36-7.55 (m, 12H, Ph), 7.80-8.08 (br, 8H, Ph). 13C{1H}
NMR (THF-d8, 62.9 MHz, 25 °C): δ 4.3 (SiMe3), 17.6 (dt, CH,
1J (C,P) ) 89.1 Hz, 1J (C,Y) ) 3.6 Hz), 128.6 (d, Ph), 131.0 (Ph),
132.3 (m, Ph), 132.6 (m, Ph). 29Si NMR (THF-d8, 49.7 MHz,
25 °C): δ -1.6. 31P{1H} NMR (THF-d8, 101.3 MHz, 25 °C): δ
20.4 (d, 2J (P,Y) ) 5.8 Hz). C62H78Cl4N4P4Si4Y2 (1435.18): calcd
C 51.89, H 5.48, N 3.90; found C 51.57, H 5.40, N 3.78.
[{CH(P P h 2NSiMe3)2}Ln Cl2]2 (Ln ) Sm (2b), Dy (2c), Er
(2d )). THF (20 mL) was condensed at -196 °C onto a mixture
of 1.10 mmol LnCl3 and 600 mg (1.0 mmol) of 1, and the
mixture was stirred for 18 h at room temperature. The solvent
was then evaporated in vacuo and toluene condensed onto the
mixture. The mixture was shortly refluxed and then filtered
and the solvent taken off in vacuo. The remaining solid was
washed with pentane (3 × 10 mL) and dried in vacuo. Finally,
the product was crystallized from hot toluene.
NSiMe3)2. The monoanionic species was used as ligands
in main group and transition metal chemistry,24-27
whereas the dianionic ligand was reported by Cavell and
co-workers to form carbene-like complexes with a series
of transition metals and samarium.27,28
In this paper we describe the synthesis of a series of
lanthanide bis(phosphinimino)methanide dichloride com-
plexes including yttrium, [{CH(PPh2NSiMe3)2}LnCl2]2
(Ln ) Y, Sm, Dy, Er, Yb, Lu). Their structures were
investigated in solution and in the solid state and
rationalized by quantum chemical investigations using
density functional theoretical (DFT)29 methods and
population analyses. Moreover, a further reaction of the
yttrium and the samarium compound to the amido
complexes [{CH(PPh2NSiMe3)2}Ln(NPh2)2] (Ln ) Y,
Sm) is reported.
2b (Ln ) Sm): Yield 535 mg (69%). IR (KBr [cm-1]): 1437
(s), 1262 (s), 1242 (s), 1170 (m), 1108 (s), 825 (s), 742 (m), 692
(s), 663 (m), 605 (m), 554 (m), 519 (m), 504 (m). 1H NMR (THF-
d8, 250 MHz, 25 °C): δ 0.32 (br, 36H, SiMe3), 2.61 (br, 2H,
CH), 6.80-7.05 (br, 8H, Ph), 7.05-7.50 (br, 24H, Ph), 7.60-
7.85 (br, 8H, Ph). 13C{1H} NMR (THF-d8, 62.9 MHz, 25 °C): δ
4.2 (SiMe3), 21.4 (br, CH), 128.7 (br, Ph), 131.1 (br, Ph), 132.6
(br, Ph), 138.3 (br, Ph). 31P{1H} NMR (THF-d8, 101.3 MHz,
25 °C): δ 31.2. C62H78Cl4N4P4Si4Sm2 (1558.10): calcd C 47.79,
H 5.05, N 3.60; found C 47.66, H 4.98, N 3.52.
Exp er im en ta l Section
Gen er a l P r oced u r es. 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
Na/K alloy benzophenone ketyl prior to use. Hydrocarbon
solvents (toluene and n-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 Aldrich Inc. (all 99 atom % D)
and were degassed, dried, and stored in vacuo over Na/K alloy
in resealable flasks. NMR spectra were recorded on Bruker
AC 250. Chemical shifts are referenced to internal solvent
resonances and are reported relative to tetramethylsilane and
85% phosphoric acid (31P NMR), respectively. K{CH(PPh2-
NSiMe3)2}20 was prepared according to literature procedures.
[{CH(P P h 2NSiMe3)2}YCl2]2 (2a ). THF (20 mL) was con-
densed at -196 °C onto a mixture of 107 mg (0.55 mmol) of
YCl3 and 300 mg (0.5 mmol) of 1, and the mixture was stirred
for 18 h at room temperature. The solution was then filtered
and the solvent removed in vacuo. The remaining solid was
washed with pentane (3 × 10 mL) and dried in vacuo. Finally,
the product was crystallized from hot toluene. Yield: 247 mg
(68%). IR (KBr [cm-1]): 1437 (s), 1263 (s), 1245 (s), 1160 (m),
1131 (s), 824 (s), 711 (m), 694 (s), 661 (m), 624 (m), 607 (m),
2c (Ln ) Dy): Yield 324 mg (41%). IR (KBr [cm-1]): 1437
(s), 1261 (s), 1246 (s), 1107 (m), 847 (s), 744 (m), 711 (m), 693
(s), 661 (m), 551 (m), 517 (m). EI/MS (70 eV) m/z (%): 791 ([M/
2]+, rel int. 17), 776 ([M/2 - Me]+, 12), 543 ([C30H36N2P2Si2]+,
97), 471 ([C28H31NP2Si]+, 100), 456 ([C27H28NP2Si]+, 90). C62H78
-
Cl4N4P4Si4Dy2 (1582.38): calcd C 47.06, H 4.97, N 3.54; found
C 47.01, H 4.82, N 3.45.
2d (Ln ) Er): Yield 270 mg (34%). IR (KBr [cm-1]): 1437
(s), 1262 (s), 1247 (s), 1125 (s), 828 (s), 743 (m), 711 (m), 693
(s), 661 (m), 624 (m), 551 (m), 517 (s), 504 (m). EI/MS (70 eV)
m/z (%): 795 ([M/2]+, rel int. 3), 780 ([M/2 - Me]+, 2), 558
([C31H39N2P2Si2]+, 57), 543 ([C30H36N2P2Si2]+, 100), 471 ([C28H31
-
NP2Si]+, 92). C62H78Cl4N4P4Si4Er2 (1591.90): calcd C 46.78, H
4.94, N 3.52; found C 46.46, H 5.25, N 3.18.
[{CH(P P h 2NSiMe3)2}Ln Cl2]2 (Ln ) Yb (2e), Lu (2f)).
THF (20 mL) was condensed at -196 °C onto a mixture of 0.44
mmol LnCl3 and 241 mg (0.40 mmol) of 1, and the mixture
was stirred for 18 h at room temperature. Then, the solution
was filtered and the solvent removed. The remaining solid was
washed with pentane (3 × 10 mL) and dried in vacuo. Finally,
the product was crystallized from hot toluene.
1
551 (m), 518 (s), 503 (m). H NMR (THF-d8, 250 MHz, 25 °C):
2e (Ln ) Yb): Yield 205 mg (64%). IR (KBr [cm-1]): 1437
(s), 1263 (s), 1246 (s), 1160 (m), 1131 (s), 824 (s), 711 (m), 694
(s), 661 (m), 624 (m), 607 (m), 551 (m), 518 (s), 503 (m). EI/MS
(70 eV) m/z (%): 801 ([M/2]+, rel int 0.8), 786 ([M/2 - Me]+,
(24) Imhoff, P.; Guelpen, J . H.; Vrieze, K.; Smeets, W. J . J .; Spek,
A. L.; Elsevier, C. J . Inorg. Chim. Acta 1995, 235, 77-88.
(25) (a) Avis, M. W.; van der Boom, M. E.; Elsevier, C. J .; Smeets,
W. J . J .; Spek, A. L. J . Organomet. Chem. 1997, 527, 263-276. (b)
Avis, M. W.; Elsevier: C. J .; Ernsting, J . M.; Vrieze, K.; Veldman, N.;
Spek, A. L.; Katti, K. V.; Barnes, C. L. Organometallics 1996, 15, 2376-
2392. (c) Avis, M. W.; Vrieze, K.; Kooijman, H.; Veldman, N.; Spek, A.
L.; Elsevier: C. J . Inorg. Chem. 1995, 34, 4092-4105. (d) Imhoff, P.;
van Asselt, R.; Ernsting, J . M.; Vrieze, K.; Elsevier, C. J .; Smeets, W.
J . J .; Spek, A. L.; Kentgens, A. P. M. Organometallics 1993, 12, 1523-
1536.
2), 558 ([C31H39N2P2Si2]+, 34), 543 ([C30H36P2Si2]+, 100). C62H78
-
Cl4N4P4Si4Yb2 (1603.46): calcd C 46.44, H 4.90, N 3.49; found
C 46.27, H 5.19, N 3.15.
1
2f (Ln ) Lu): Yield 189 mg (59%). H NMR (THF-d8, 250
2
MHz, 25 °C): δ 0.14 (s, 36H, SiMe3), 1.97 (t, 2H, CH, J (H,P)
) 1.95 Hz), 6.90-7.04 (br, 8H, Ph), 7.11-7.26 (m, 12H, Ph),
7.36-7.54 (m, 12H, Ph), 7.90-8.06 (m, 8H, Ph). 13C{1H} NMR
(THF-d8, 62.9 MHz, 25 °C): δ 4.5 (SiMe3), 17.6 (t, CH, 1J (H,C)
) 87.5 Hz), 128.7 (d, Ph), 132.0 (d, Ph), 132.6 (d, Ph), 138.0
(d, Ph). 29Si NMR (THF-d8, 49.7 MHz, 25 °C): δ -0.5. 31P{1H}
NMR (THF-d8, 101.3 MHz, 25 °C): δ 20.5. C62H78Cl4N4P4Si4-
Lu2 (1607.32): calcd C 46.44, H 4.90, N 3.49; found C 46.68,
H 5.12, N 3.11.
[{CH(P P h 2NSiMe3)2}Ln (NP h 2)2] (Ln ) Y (3a ), Sm (3b)).
THF (20 mL) was condensed at -196 °C onto a mixture of 0.50
mmol of 2 and 207 mg (1.0 mmol) of KNPh2, and the mixture
was stirred for 18 h at room temperature. The solvent was
then evaporated in vacuo and toluene (20 mL) condensed onto
(26) Ong, C. M.; McKarns, P.; Stephan, D. W. Organometallics 1999,
18, 4197-4208.
(27) (a) Kasani, A.; Kamalesh Babu, R. P.; McDonald, R.; Cavell, R.
G. Organometallics 1999, 18, 3775-3777. (b) Aparna, K.; McDonald,
R.; Fuerguson, M.; Cavell, R. G. Organometallics 1999, 18, 4241-4243.
(28) (a) Kamalesh Babu, R. P.; McDonald, R.; Decker, S. A.;
Klobukowski, M.; Cavell, R. G. Organometallics 1999, 18, 4226-4229.
(b) Cavell, R. G.; Kamalesh Babu, R. P.; Kasani, A.; McDonald, R. J .
Am. Chem. Soc 1999, 121, 5805-5806. (c) Kamalesh Babu, R. P.;
McDonald, R.; Cavell, R. G. Chem. Commun. 2000, 481-482. (d)
Kasani, A.; Furguson, M.; Cavell, R. G. J . Am. Chem. Soc. 2000, 112,
726-727.
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and Molecules; Oxford University Press: New York, 1988. (b) Ziegler,
T. Chem. Rev. 1991, 91, 651-667.

4232 Organometallics, Vol. 20, No. 20, 2001
Ta ble 1. Cr ysta llogr a p h ic Deta ils of [{CH(P P h 2NSiMe3)2}Ln Cl2]2 (2a -f)a
Gamer et al.
2a ‚(2 toluene)
2b‚(2 toluene)
2c‚(2 toluene)
formula
fw
space group
a, Å
b, Å
c, Å
C
76H94Cl4N4P4Si4Y2
C76H94Cl4N4P4Si4Sm2
1742.30
C76H94Cl4N4P4Si4Dy2
1766.60
1619.42
P1h (No. 2)
11.6542(5)
14.3959(5)
14.7218(7)
63.758(3)
73.465(4)
74.811(4)
2096.9(2)
1
1.282
Mo KR
(λ ) 0.71073 Å)
1.679
ψ-scan
7429
7429
6344
P1h (No. 2)
11.579(8)
14.371(8)
14.751(13)
63.37(8)
73.36(9)
74.89(7)
2077(3)
1
1.393
Mo KR
(λ ) 0.71073 Å)
1.705
none
18 290
7456 [Rint ) 0.0689]
6863
P1h (No. 2)
11.5748(9)
14.3016(12)
14.6348(12)
63.715(9)
73.456(9)
74.816(9)
2056.0(3)
1
1.427
Ag KR
(λ ) 0.56087 Å)
1.427
none
19 253
9021 [Rint ) 0.0291]
7885
9021, 378
0.0357; 0.1003
R,deg
â, deg
γ, deg
V, Å3
Z
density (g/cm3)
radiation
µ, mm-1
abs corr
no. of reflns collected
no. of unique reflns
no. of obsd reflns
no. of data; params
R1;b wR2c
7418; 390
0.0492; 0.1529
7456; 378
0.0407; 0.1250
2d ‚(2 toluene)
2e‚(2 toluene)
2f‚(2 toluene)
formula
fw
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C
76H94Cl4N4P4Si4Er2
C76H94Cl4N4P4Si4Yb2
1787.68
C76H94Cl4N4P4Si4Lu2
1791.54
1776.12
P1h (No. 2)
11.663(2)
14.377(2)
14.7310(12)
63.84(4)
73.49(2)
74.750(15)
2098.2(5)
1
1.406
Mo KR
(λ ) 0.71073 Å)
2.288
ψ-scan
6817
6816
5625
P1h (No. 2)
11.654(3)
14.340(2)
14.687(3)
64.000(3)
73.45(2)
73.45(2)
2088.2(7)
1
1.422
Mo KR
(λ ) 0.71073 Å)
2.529
ψ-scan
8244
7373 [Rint ) 0.0498]
6451
7373; 378
0.0374; 0.1081
P1h (No. 2)
11.6426(2)
14.33340(14)
14.67890(13)
64.048(8)
73.538(10)
74.842(15)
2085.27(4)
1
1.427
Mo KR
(λ ) 0.71073 Å)
2.657
ψ-scan
7954
7407 [Rint ) 0.0651]
6500
7407; 378
0.0376; 0.1103
Z
density (g/cm3)
radiation
µ, mm-1
abs corr
no. of reflns collected
no. of unique reflns
no. of obsd reflns
no. of data; params
R1;b wR2c
6816; 378
0.0490; 0.1422
All data collected at 203 K. R1 ) ∑|Fo| - |Fc|/∑|Fo|. c wR2 ) {∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2
.
a
b
2
the mixture. The solution was filtered and concentrated until
N2 stream of a Stoe IPDS or a Stoe STADI 4 diffractometer.
Subsequent computations were carried out on a Intel Pentium
III PC.
a precipitate is formed (about 3 mL of solution). The precipitate
was dissolved in boiling toluene. Crystals were obtained after
1 day.
All structures were solved by the Patterson method
(SHELXS-9730). The remaining non-hydrogen atoms were
located from successive difference Fourier map calculations.
The refinements were carried out by using full-matrix least-
squares techniques on F, minimizing the function (Fo - Fc)2,
where the weight is defined as 4Fo2/2(Fo2) and Fo and Fc are
the observed and calculated structure factor amplitudes using
the program SHELXL-97.31 In the final cycles of each refine-
ment, all non-hydrogen atoms except the toluene molecules
were assigned anisotropic temperature factors. Carbon-bound
hydrogen atom positions were calculated and allowed to ride
on the carbon to which they are bonded 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 3. 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 significance. Positional param-
eters, hydrogen atom parameters, thermal parameters, and
3a (Ln ) Y): Yield 100 mg (22%). 1H NMR (C6D6, 250 MHz,
25 °C): δ -0.06 (s, 18H, SiMe3), 2.20 (t, 1H, CH, 2J (H,P) )
4.9 Hz), 6.70-7.75 (m, 40H, Ph). 29Si NMR (C6D6, 49.7 MHz,
25 °C): δ -1.0. 31P{1H} NMR (C6D6, 101.3 MHz, 25 °C): δ
2
22.1 (d, J (P,Y) ) 6.2 Hz). EI/MS (70 eV) m/z (%): 982 ([M]+,
rel int 0.1), 814 ([M - NPh2]+, 20), 735 ([M - (NPh2)PhH]+,
100), 543 ([C30H36N2P2Si2]+, 76), 169 ([NPh2]+, 63). C55H59N4P2-
Si2Y (983.12): calcd C 67.19, H 6.05, N 5.70; found C 66.92, H
5.95, N 5.80.
3b (Ln ) Sm): Yield 220 mg (42%). 1H NMR (C6D6, 250
MHz, 25 °C): δ -0.76 (s, 18H, SiMe3), 4.98 (br, 1H, CH), 6.60-
7.20 (m, 40H, Ph). 29Si NMR (C6D6, 49.7 MHz, 25 °C): δ -1.0.
31P{1H} NMR (C6D6, 101.3 MHz, 25 °C): δ 33.4. EI/MS (70
eV) m/z (%): 1045 ([M]+, rel int 0.1), 877 ([M - NPh2]+, 5) 798
([M - (NPh2)PhH]+, 40), 543 ([C30H36N2P2Si2]+, 76), 169
([NPh2]+, 100). C55H59N4P2Si2Sm (1044.58): calcd C 63.24, H
5.69, N 5.36; found C 63.01, H 5.37, N 5.57.
X-r a y Cr ysta llogr a p h ic Stu d ies of 2a -f a n d 3a . Crystals
of 2a -f and 3a were grown from 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
(30) Sheldrick, G. M. SHELXS-97, Program of Crystal Structure
Solution; University of Go¨ttingen: Germany, 1997.
(31) Sheldrick, G. M. SHELXL-97, Program of Crystal Structure
Refinement; University of Go¨ttingen, Germany, 1997.

Lanthanide Bis(phosphinimino)methanides
Organometallics, Vol. 20, No. 20, 2001 4233
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles (d eg) of [{CH(P P h 2NSiMe3)2}Ln Cl2]2 (2a -f)
2a
2b
2c
2d
2e
2f
Bond Lengths (Å)
2.641(3)
Ln-C1
Ln-N1
Ln-N2
Ln-Cl1
Ln-Cl2
Ln-Cl2′
P1-N1
P2-N2
P1-C1
P2-C1
2.642(4)
2.335(3)
2.357(3)
2.5484(13)
2.7170(11)
2.6826(12)
1.608(3)
1.606(3)
1.751(4)
1.749(4)
2.720(5)
2.391(4)
2.400(4)
2.614(3)
2.777(2)
2.732(2)
1.607(4)
1.611(4)
1.751(4)
1.734(4)
2.625(7)
2.327(6)
2.344(6)
2.541(3)
2.699(2)
2.668(2)
1.616(6)
1.610(6)
1.749(7)
1.743(7)
2.607(5)
2.301(4)
2.317(4)
2.511(2)
2.677(2)
2.643(2)
1.611(4)
1.609(4)
1.756(5)
1.747(5)
2.596(5)
2.291(4)
2.313(4)
2.500(2)
2.6667(15)
2.6309(15)
1.607(4)
1.606(4)
1.761(5)
1.740(5)
2.330(3)
2.344(3)
2.5452(11)
2.7077(10)
2.6743(10)
1.598(3)
1.598(3)
1.741(3)
1.737(4)
Bond Angles (deg)
77.46(3)
Cl2-Ln-Cl2′
Cl1-Ln-Cl2
N1-Ln-Cl1
N1-Ln-Cl2
N2-Ln-Cl1
N2-Ln-Cl2
N1-Ln-N2
Ln-Cl2-Ln′
P1-C1-P2
P1-N1-Ln
P2-N2-Ln
77.51(4)
98.38(5)
99.32(9)
160.41(9)
105.17(9)
86.91(9)
96.47(12)
102.49(4)
124.5(2)
99.7(2)
76.99(6)
77.63(6)
98.28(9)
99.0(2)
160.84(15)
104.56(15)
87.11(14)
96.6(2)
102.37(6)
124.7(4)
100.2(3)
99.6(3)
78.00(5)
97.48(6)
99.07(11)
161.48(11)
104.18(12)
86.72(11)
97.21(15)
102.00(1)
124.1(3)
100.2(2)
99.5(2)
77.96(5)
97.57(6)
99.01(12)
161.51(12)
103.74(11)
86.80(11)
97.1(2)
102.04(1)
123.8(3)
100.5(2)
99.2(2)
99.40(10)
100.45(13)
158.35(9)
107.94(12)
86.91(10)
95.09(12)
103.01(4)
124.7(2)
100.04(4)
99.38(8)
160.12(8)
105.47(7)
86.90(7)
96.18(11)
102.54(3)
124.5(2)
100.89(14)
99.94(14)
101.7(2)
100.5(2)
99.7(2)
been developed based on the DFT program,35 approximating
the coulomb part of the two-electron interactions. Basis sets
were of SV(P) quality (SV(P) ) split valence plus polarization
for all non-hydrogen atoms, split valence for hydrogen atoms).36
The Y atom was treated with the effective core potential ECP-
28,37 which serves as approximation for 28 inner electrons
considering relativistic effects. The shared electron numbers
(SEN) were calculated pursuant to a method based on occupa-
tion numbers that was reported by Ehrhardt and Ahlrichs.38
The calculation was performed by means of the program
Moloch equally implemented in Turbomole.
Ta ble 3. Cr ysta llogr a p h ic Deta ils of
[{CH(P P h 2NSiMe3)2}Y(NP h 2)2] (3a )a
3a ‚(toluene)
formula
fw
C62H67N4P2Si2Y
1075.23
space group
a, Å
P1h (No. 2)
12.3776(9)
12.6813(9)
20.9540(13)
90.128(8)
99.638(8)
117.207(7)
2872.2(3)
2
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Resu lts a n d Discu ssion
Z
density (g/cm3)
radiation
1.243
Mo KR
La n th a n id e Ch lor id e Com p lexes. Transmetala-
tion of the potassium methanide complex K{CH(PPh2-
NSiMe3)2} (1) with anhydrous yttrium or lanthanide
trichlorides in a 1:1.1 molar ratio in THF followed by
crystallization from hot toluene afforded the corre-
sponding yttrium and lanthanide complexes [{CH(PPh2-
NSiMe3)2}LnCl2]2 (Ln ) Y (2a ), Sm (2b), Er (2c), Dy
(2d ), Yb (2e) Lu (2f)) as large crystals in good yields
(eq 1).39 Whereas the complexes 2a , 2e, and 2f were
already obtained at room temperature, due to a de-
creased solubility of the lighter lanthanide trichlorides
for 2b, 2c, and 2d , an additional heating of the reaction
mixture was necessary to ensure a quantitative reac-
tion. The potassium reagent 1, which was described
earlier,20 was used as starting material to avoid coor-
dination of lighter alkali halides such as lithium chlo-
ride. The new complexes have been characterized by
standard analytical/spectroscopic techniques, and the
solid-state structures of all six compounds were estab-
lished by single-crystal X-ray diffraction.
(λ ) 0.71073 Å)
1.154
ψ-scan
10 766
10 174 [Rint ) 0.0684]
8678
10 174; 624
0.0476; 0.1338
µ, mm-1
abs corr
no. of reflns collected
no. of unique reflns
no. of obsd reflns
no. of data; params
R1;b wR2c
a
b
All data collected at 203 K. R1 ) ∑|Fo| - |Fc|/∑|Fo|. c wR2 )
{∑[w(Fo - Fc2)2]/∑[w(Fo2)2]}1/2
.
2
bond distances and angles have been deposited as Supporting
Information. Crystallographic data (excluding structure fac-
tors) for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data Centre
as supplementary publication no. CCDC-164392-164398. Cop-
ies 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; email: deposit@ccdc.cam.ac.uk).
Meth od s of th e Th eor etica l In vestiga tion s. It has been
formerly proved that density functional theoretical (DFT)29
calculations are suitable for the theoretical investigation of
yttrium and lanthanide systems.13 The program system Tur-
bomole32 was employed to carry out the DFT investigations
using the efficient Ridft program33 with the Becke-Perdew
(B-P) functional34 and the gridsize m3. The Ridft program has
(34) (a) Becke, A. D. Phys. Rev. A 1988, 38, 3098-3109. (b) Vosko,
S. H.; Wilk, L.; Nusair, M. Can. J . Phys. 1980, 58, 1200-1205. (c)
Perdew, J . P. Phys. Rev. B 1986, 33, 8822-8837.
(35) Treutler, O.; Ahlrichs, R. J . Chem. Phys. 1995, 102, 346-354.
(36) Scha¨fer, A.; Horn, H.; Ahlrichs, R. J . Chem Phys. 1992, 97,
2571-2577.
(37) Dolg, M.; Stoll, H.; Savin, A.; Preuss, H. Theor. Chim. Acta 1989,
75, 173-194.
(32) Ahlrichs, R.; Ba¨r, M.; Ha¨ser, M.; Horn, H.; Ko¨lmel, C. Chem.
Phys. Lett. 1995, 242, 652-657.
(33) (a) Eichkorn, K.; Treutler, O.; O¨ hm, H.; Ha¨ser, M.; Ahlrichs,
R. Chem. Phys. Lett. 1995, 242, 652-660. (b) Eichkorn, K.; Weigend,
F.; Treutler, O.; Ahlrichs, R. Theor. Chim. Acta 1997, 97, 119-124.
(38) Ehrhardt, C.; Ahlrichs, R. Theor. Chim. Acta 1985, 68, 231-
245.
(39) The bonding situation in the drawings of the ligand system in
eqs 1 and 2 is simplified for clarity.

4234 Organometallics, Vol. 20, No. 20, 2001
Gamer et al.
F igu r e 1. Perspective ORTEP view of the molecular
structure of 2f. Thermal ellipsoids are drawn to encompass
50% probability. Hydrogen atoms are omitted for clarity.
having one molecule of 2 and two molecules of toluene
in the unit cell. 2a -f are dimeric complexes in which
the metal centers are bridged asymmetrically by two
µ-chlorine atoms. In the center of the Ln-Cl2-Ln′-Cl2′
plane, a crystallographic inversion center is observed.
A comparison of the Ln-Cl2-Ln′ (102.00(1)° (2e) to
103.01(4)° (2b)) and Cl2-Ln-Cl2′ angles (76.99(6)° (2b)
to 78.00(5)° (2e)) of the central Ln-Cl-Ln′-Cl′ four-
membered ring of 2a -f shows only a small influence of
the center atom onto the observed geometry. The ligand
geometry is as expected. The P-N and P-C bond
distances as well as the P1-C1-P2 angles vary only
slightly within the series 2a -f. A six-membered met-
allacycle (N1-P1-C1-P2-N2-Ln) is formed by che-
lation of the two trimethlysilylimine groups to the
lanthanide atom. The Ln-N distances as well as the
Ln-Cl1 bond length increase as expected with increas-
ing ion radius of the center metal in a linear fashion.
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. The dis-
tance between the central carbon atom (C1) and the
lanthanide atom (2.596(5) (2f) to 2.720(5) Å (2b)) is
longer than usual Ln-C distances;1 however the folding
of the six-membered ring toward the lanthanide atom
is caused by a weak interaction. The Ln-C1 bond
lengths increase with increasing ion radius of the center
metal in a linear fashion. The resultant tridentate
coordination of the ligand was observed in 1,20 [Li(THF)]-
[CH(PPh2NSiMe3)2],20 [Al(CH3)2{CH(PPh2NSiMe3)2}],26
[GaCl2{CH(PPh2NSiMe3)2}],26 and [Ir{CH(PPh2N(p-
tolyl))2}(COD)].24 The Sm-C1 bond length of 2b (2.720-
(5) Å) is significantly longer than that observed in the
carbene-like complex [Cy2NSm(THF){C(PPh2NSiMe3)2}]
(2.467(4) Å) (Cy ) cyclohexyl).28d This clearly indicates
the difference in coordination chemistry of the monoan-
ionic {CH(PPh2NSiMe3)2}- and the dianionic {C(PPh2-
NSiMe3)2}2- ligand. The endocyclic P-C bond distances
(1.734(4)-1.761(5) Å) are significantly shortened com-
pared to the exoclyclic ones (1.808(4)-1.831(5) Å),
suggesting that there is a considerable delocalization
throughout the backbone of the ligand.
1
The H NMR spectra of the diamagnetic compounds
2a ,f show a slight downfield shift of the methine proton
(δ 1.93 (2a ), 1.97 (2f)) compared to 1 (δ 1.58). The
2J (H,P) coupling constant of the methine proton (e.g.,
2
2f J (H,P) ) 1.9 Hz) is smaller than that of 1 (2.8 Hz).
Furthermore, for 2a a small splitting of the signals in
the 1H and 13C NMR spectra is seen for the methine
group. We suggest that this splitting is caused by a
2J (H,Y) coupling (0.92 Hz) and a J (C,Y) coupling (3.6
1
Hz). The coupling constants are much smaller than the
ones observed for Y-CH2SiMe3 groups ([Y(CH2SiMe3)3-
(THF)2]: 1J (C,Y) ) 35.7 Hz; J (H,Y) ) 2.3 Hz),40 but
2
the 1J (C,Y) coupling is in the range of a (η8-C8H8)Y
group ([(η8-C8H8)Y{Ph2P(NSiMe3)2}(THF)]: 1J (C,Y) )
2 Hz).41 The small coupling constants observed for 2a
may be caused by the very long Y-Cmethine bond length
(see below). The observed couplings suggest a rigid
structure of 2 in solution.
The signals of the phenyl protons are broadened in
the 1H NMR spectrum. Complexes 2a ,f each show a
sharp signal in the 31P{1H} NMR spectra (δ 20.4 (2a ),
20.5 (2f)) shifted downfield by about 10 ppm relative to
1 (δ 13.0), showing that the phosphorus atoms in each
case are chemically equivalent in solution. In the 31P-
{1H} NMR spectrum of 2a a J (P,Y) coupling of 5.8 Hz
2
is observed. Also for 2b 1H, 13C, and 31P NMR spectra
were obtained, which are quantitatively comparable to
those of 2a ,f. Nevertheless, due to the influence of the
paramagnetic samarium center, the observed chemical
shifts are significantly different, e.g., δ(31P{1H}) 31.2.
The solid-state IR spectra of 2 are quite similar to each
other. They show an intense νPdN absorption around
1245 cm-1
.
The structures of 2a -f were confirmed by single-
crystal X-ray diffraction in the solid state. Data collec-
tion parameters and selected bond lengths and angles
are given in Tables 1 and 2. Due to the similar ion radii
of the lanthanides, the single-crystal X-ray structures
of 2a -f are isostructural. As a representative example,
the structure of 2f is shown in Figure 1. In this series,
samarium was the largest center metal for which single
crystals could be obtained. Attempts to obtain crystals
from reactions of neodymium or lanthanum trichloride
failed. 2a -f crystallize in the trigonal space group P1h,
DF T In vestiga tion s. To rationalize and to better
understand the nature of the Ln-C1 contacts, quantum
chemical investigations of the asymmetric unit of 2a
were carried out at the density functional theory (DFT)29
level (see Experimental Section). The calculations were
undertaken by means of the program system Turbo-
mole.32 The structure optimizations with the DFT
(40) Hultsch, K. C.; Voth, P.; Spanoil, T. P.; Okuda, J . Organome-
tallics 2000, 19, 228-243.
(41) Kilimann, U.; Edelmann, F. T. J . Organomet. Chem. 1994, 469,
C5-C9.

Lanthanide Bis(phosphinimino)methanides
Organometallics, Vol. 20, No. 20, 2001 4235
F igu r e 2. Schematic view of the calculated monomeric
unit of 2a . SEN values are denoted. Note that the latter
only represent relative values, which have to be compared
with SEN for reliable bonds in the same or in related
structures. Selected bond lengths [Å] or angles [deg]
(labeling corresponding to that given in Figure 1 or Table
2): Y-C1 2.726, Y-N1 2.318, Y-N2 2.323, Y-Cl1 2.537,
Y-Cl2 2.538, P1-N1 1.645, P2-N2 1.645, P1-C1 1.769,
P2-C1 1.767; Cl1-Y-Cl2 111.11, N1-Y-Cl1 101.81, N1-
Y-Cl2 115.83, N2-Y-Cl1 101.62, N2-Y-Cl2 116.80, N1-
Y-N2 107.74, P1-C1-P2 130.99, P1-N1-Y 101.79, P2-
N2-Y 101.78.
F igu r e 3. Perspective ORTEP view of the molecular
structure of 3a . Thermal ellipsoids are drawn to encompass
50% probability. Hydrogen atoms are omitted for clarity.
Ta ble 4. Selected Bon d Len gth s (Å) a n d An gles
(d eg) of [{CH(P P h 2NSiMe3)2}Y(NP h 2)2] (3a )
bond lengths (Å)
bond angles (deg)
Y-C1
2.724(3)
2.348(2)
2.364(3)
2.250(3)
2.278(3)
1.615(2)
1.621(3)
1.746(3)
1.736(3)
1.817(3)
1.830(3)
N1-Y-N2
108.58(9)
117.84(10)
104.36(9)
117.29(10)
101.90(10)
104.63(10)
128.2(2)
Y-N1
N1-Y-N3
N1-Y-N4
N2-Y-N3
N2-Y-N4
N3-Y-N4
P1-C1-P2
P1-N1-Y
P2-N2-Y
N1-Y-C1
N2-Y-C2
method were followed by a population analysis based
on occupation numbers after Ehrhardt and Ahlrichs.38
Due to the reduction of a dimeric to a monomeric species
(coordination number 5 instead of 6), the coordination
sphere around the metal center was not perfectly
reproduced regarding the bond angles. However, most
of the calculated bond distances are in good agreement
with the experimentally observed ones (maximum dif-
ference ca. 0.04 Å). One exception is one of the Y-Cl
bonds, which can be due to differing steric as well as
electronic situations due to differing coordination envi-
ronments. Another exception is the Y-C1 contact, which
is computed to be about 0.075 Å too long. This is,
however, a typical result for the DFT investigations of
a weaker or more dispersive interaction since DFT
methods do not explicitly consider dispersion interac-
tions. Therefore, we used the optimized monomeric
structure to perform a population analysis. As a result,
we present a shared electron number (SEN) of 0.40 for
the Y-C contact that matches the values for the Y-N
bonds in the monomer (SENY-N: 0.40 and 0.41) and
thus reveals the existence of a Y-C binding interaction.
In contrast, SENs of the ones next to the neighbors, P
or Si, amount to 0.19 and 0.20 (P) or 0.09 (Si), which
shows the expected decrease. Figure 2 schematically
shows the calculated molecule. Structural parameters
are given in the caption; SEN values are denoted.
La n th a n id e Am id e Com p lexes. Transmetalation
of the yttrium and the samarium chloro complex 2a and
2b, respectively, with an excess of KNPh2 in toluene
afforded the corresponding bisamido complexes [{CH-
(PPh2NSiMe3)2}Ln(NPh2)2] (Ln ) Y (3a ), Sm (3b)) as
crystalline solids (eq 2).39 The new complexes have been
characterized by standard analytical/spectroscopic tech-
niques, and the solid-state structure of the yttrium
compound was established by single-crystal X-ray dif-
fraction (Figure 3). 3a crystallizes in the trigonal space
group P1h, having two molecules of 3a and two molecules
of toluene in the unit cell. Data collection parameters
and selected bond lengths and angles are given in
Tables 3 and 4. The structure reveals a distorted
tetrahedral arrangement of the nitrogen atoms around
the yttrium atom, having N-Y-N angles in the range
of 101.90(10)° (N2-Y-N4) to 117.84(10)° (N1-Y-N3).
Y-N2
Y-N3
Y-N4
P1-N1
P2-N2
P1-C1
P2-C1
P1-C2
P2-C14
101.14(12)
101.20(12)
64.64(9)
64.09(9)
The Y-N distance of the {CH(PPh2NSiMe3)2}- ligand
is about 0.1 Å longer (N1-Y 2.348(2) Å; N2-Y 2.364(3)
Å) than the Y-NPh2 bond length (Y-N3 2.250(3) Å;
Y-N4 2.278(3) Å). Other yttrium complexes having
comparable mulitdentate monoanionic ligands such as
[{(iPr)2ATI}Y(C5Me5)2] (N-Y 2.398(2) and 2.390(3) Å)42
((iPr)2ATI ) N-isopropyl-2-(isopropylamino)troponimi-
nate) or [{(Ph)NdC(Ph)C(Ph)dN(Ph)}Y(C5Me5)2] (2.408-
(4) Å)43 feature similar bond lengths. The Y-NPh2
distance is in agreement with other Y-N compounds,
like the homoleptic amide [Y{N(SiMe3)}3]44 (2.211(9) Å)
and [{tBu(Ar)2SiO}Y{N(SiMe3)2}2] (Ar ) 2-C6H4(CH2-
NMe2)) (2.237(9) Å).45 As observed for 2a -f a six-
membered ring (N1-P1-C1-P2-N2-Y), which adopts
a twist-boat conformation, is formed by the {CH(PPh2-
NSiMe3)2}- ligand and the yttrium atom. The distance
between the central carbon atom C1 and the yttrium
atom (2.724(3) Å) is significantly longer than in 2a
(2.642(4) Å).

4236 Organometallics, Vol. 20, No. 20, 2001
Gamer et al.
The multinuclear NMR data of 3 are consistent with
the solid-state structure. The H NMR spectrum of 3a
ionic {CH(PPh2NSiMe3)2}- ligand in the coordination
sphere were reported. These are the first lanthanide
complexes having this ligand in the coordination sphere.
The single-crystal X-ray structures of these complexes
show that the methine carbon atom is bound to the
lanthanide atom. This is supported by DFT calculations,
which show a similar interaction. Due to the similar ion
radii of the lanthanides, the single-crystal X-ray struc-
tures of 2a -f are isostructural. The Ln-Cmethine bond
length increases linearly with increasing ion radius of
the center metal. Further reaction of 2 with KNPh2 led
to new amide complexes. These complexes show in
comparison to 2 a comparable coordination behavior of
the {CH(PPh2NSiMe3)2}- ligand in the solid state.
1
shows a downfield shift of the methine proton (δ 2.20)
compared to the starting material 2a (δ 1.93). In
2
contrast to 2a no J (H,Y) coupling is seen. This effect
might be caused by an increased Y-C bond length.
Thus, the methine signal is split into a triplet, which is
caused by a 2J (H,P) coupling of 4.9 Hz. Complex 3a
shows a doublet in the 31P{1H} NMR spectrum (δ 22.1;
2J (P,Y) ) 6.2 Hz), which is in the same range as the
one observed in 2a . As a result of the paramagnetic
influence of the samarium(III) atom, the NMR signals
of 3b are distributed over a wider range. Thus the
1
resonance of the Si(CH3)3 group in the H NMR spec-
trum is observed at δ -0.76. The 31P{1H} NMR reso-
nance of 3b (δ 33.4) is, in comparison to [Cy2NSm(THF)-
{C(PPh2NSiMe3)2}] (δ 43.3), about 10 ppm upfield
shifted.28d In the EI mass spectra of 3a ,b the molecular
ions as well as their characteristic fragmentation pat-
tern were observed.
Ack n ow led gm en t. This work was supported by the
Deutsche Forschungsgemeinschaft (Heisenberg fellow-
ship) and the Fonds der Chemischen Industrie. Ad-
ditionally, a lot of generous support from Prof. Dr. D.
Fenske is gratefully acknowledged.
Su m m a r y
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files in CIF format for the structure determinations
of 2a -f and 3a are available free of charge via the Internet at
http://pubs.acs.org.
In summary, it can be emphasized that a series of
lanthanide dichloride complexes having the monoan-
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(44) Westerhausen, M.; Hartmann, M.; Pfitzner, A.; Schwarz, W.
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