Synthesis, structure, and reactivity of diamidophosphine complexes of yttrium and the lanthanides

Article abstract of DOI:10.1139/v01-087

The reaction of the dilithiodiamidophosphine ligand precursor PhP(CH₂SiMe₂NPh)₂Li₂(THF) ₂([NPN]Li₂(THF)₂) with LnCl₃(THF)₃ (Ln = Y, Sm, Ho, Yb, Lu; THF = te

Full text of DOI:10.1139/v01-087

1194
Synthesis, structure, and reactivity of
diamidophosphine complexes of yttrium and the
lanthanides
Michael D. Fryzuk, Peihua Yu, and Brian O. Patrick
Abstract: The reaction of the dilithiodiamidophosphine ligand precursor PhP(CH2SiMe2NPh)2Li2(THF)2([NPN]Li2(THF)2)
with LnCl3(THF)3 (Ln = Y, Sm, Ho, Yb, Lu; THF = tetrahydrofuran) in refluxing toluene generates the mononuclear
complexes [NPN]LnCl(THF) in good yield. The molecular structures have been shown to be five-coordinate in the
solid state and in solution. Attempts to prepare alkyl derivatives have only met with partial success; the reaction of
MeMgCl with [NPN]YCl(THF) generates the partially characterized mixed-metal derivative [NPN]YMe2MgCl. The re-
action with LiAlH4 results in complete ligand exchange and the formation of the tetranuclear lithium aluminum hydride
derivative {[NPN]AlH2Li(THF)}2. Reduction of the lutetium derivative with KC8 and naphthalene generated the
dinuclear naphthalene-bridged species {[NPN]Lu}2(µ-η4:η4-C10H8) wherein each Lu centre engages in η4-coordination
to opposite sides of the arene moiety. X-ray crystallography was used to characterize the four complexes.
Key words: lanthanides, yttrium, mixed-donor ligands, aluminum, lithium, naphthalene.
Résumé : La réaction du précurseur de ligand dilithiodiamidophosphine PhP(CH2SiMe2NPh)2Li2(THF)2([NPN]Li2(THF)2)
avec du LnCl3(THF)3 (Ln = Y, Sm, Ho, Yb, Lu; THF = tétrahydrofurane), dans du toluène au reflux, génère des com-
plexes mononucléaires [NPN]LnCl(THF) avec de bons rendements. Il a été démontré que, à l’état solide ainsi qu’en so-
lution, les structures moléculaires sont pentacoordinées. Les essais effectués en vue de préparer des dérivés alkylés
n’ont donné que des succès partiels; la réaction du MeMgCl avec le [NPN]YCl(THF) conduit à la formation du dérivé
métallique mixte [NPN]YMe2MgCl, qui a été partiellement caractérisé. La réaction avec le LiAlH4 donne lieu à un
échange complet de ligands et à la formation de l’hydrure de lithium et d’aluminium tétranucléaire
{[NPN]AlH2Li(THF)}2. La réduction du dérivé du lutécium avec du KC8 et du naphtalène génère l’espèce dinucléaire
ponté par du naphtalène, {[NPN]Lu}2(µ-η4:η4-C10H8) dans lequel chaque centre Lu est engagé dans une coordination η4
avec les côtés opposés de la portion arène. On a fait appel à la diffraction des rayons X pour caractériser quatre des
complexes.
Mots clés : lanthanides, yttrium, ligands à donneurs mixtes, aluminium, lithium, naphtalène.
[Traduit par la Rédaction] Fryzuk et al. 1200
Introduction
based on varying the number of amide and phosphine moi-
eties have been developed in our lab (5–7). Herein we report
on the preparation of a series of lanthanide complexes
[NPN]LnCl(THF) that incorporate a tridentate ligand con-
taining one phosphine and two amido donors ([NPN] =
[PhP(CH2SiMe2NPh)2]; Ln = Y (1), Sm (2), Ho (3), Yb (4),
Lu (5)).
Early transition metal complexes with formally d0 elec-
tronic configurations have been prominent as catalyst precur-
sors for the polymerization of α-olefins (1). While the
cyclopentadienyl ancillary ligand provided the initial surge
of activity, recent reports have focused on nonmetallocene
systems, and in particular, multidentate amido ligands (2–4).
Our strategy for ligand design has centred on the combina-
tion of two vastly different donor types in a chelate array in
an effort to allow access to a variety of different oxidation
states at the metal centre. Several new multidentate ligands
Experimental
All experimental manipulations were carried out under an
atmosphere of purified dinitrogen rigorously excluding air
and moisture using standard Schlenk or glovebox techniques
(Vacuum Atmospheres HE-553-2 glovebox equipped with a
MO-40-2H purification system and a –40°C freezer). Sol-
vents were purified according to conventional procedures
and were freshly distilled prior to use. Unless otherwise
Received January 30, 2001. Published on the NRC Research
Press Web site at http://canjchem.nrc.ca on August 10, 2001.
M.D. Fryzuk,1 P. Yu, and B.O. Patrick.2 Department of
Chemistry, University of British Columbia, 2036 Main Mall,
Vancouver, BC V6T 1Z1, Canada.
1
stated, H and 31P{1H} NMR spectra were recorded on a
Bruker AC-200 instrument operating at 200 and 81.0 MHz,
respectively.
The compounds LnCl3(THF)3 (8), [NPN]Li2(THF)2 (9),
and KC8 (10) were prepared as described in the literature.
1Corresponding author (telephone: (604) 822-2897; fax: (604)
822-2847; e-mail: fryzuk@chem.ubc.ca).
2UBC X-ray crystallographic service.
Can. J. Chem. 79: 1194–1200 (2001)
DOI: 10.1139/cjc-79-7-1194
© 2001 NRC Canada

Fryzuk et al.
1195
MeMgCl (solution in THF), LiAlH4, and naphthalene were
purchased from Aldrich.
Elemental analyses were performed in the microanalysis
laboratory of this department by Mr. P. Borda.
Methylation of [NPN]YCl(THF) using MeMgCl
To a suspension of [NPN]YCl(THF) (1) (0.63 g, 1 mmol)
in toluene (30 mL) was added MeMgCl (0.7 mL, 3.0 M in
THF, 2.1 mmol) at room temperature, and the mixture was
stirred overnight. After removal of the volatiles, the residue
was extracted with hexane–toluene (1:1, 2 × 5 mL), and the
mixture was filtered through Celite. Upon cooling to –30°C
Preparation of [NPN]LnCl(THF) (Ln = Y, Sm, Ho, Yb,
Lu)
a
white
crystalline
product
formulated
as
General procedure for 1–5: at room temperature, toluene
(100 mL) was added to a mixture of [NPN]Li2(THF)2
(1.18 g, 2 mmol) and LnCl3(THF)3 (2 mmol) and the result-
ing slurry was heated under reflux overnight. After cooling
to room temperature, the mixture was filtered through Celite.
The solvent was evaporated to dryness and the residue
washed with hexane and dried under vacuum, yielding 1
(0.97 g, 70%), 3 (0.96 g, 68%), 5 (1.12 g, 71%) as white
powders, 2 (1.15 g, 75%) as a yellow powder, and 4 (1.18 g,
74%) as an orange powder.
[NPN]YMe2MgCl(THF) (6) could be obtained in 50% yield
(0.34 g). H NMR (C6D6, 200 MHz, 298 K) δ: 7.68 (m, 2H,
1
PPh o-H), 7.50 (m, 6H, NPh m-H and PPh m-H), 7.12 (m,
1H, PPh p-H), 6.97 (m, 4H, NPh o-H), 6.85 (m, 2H, NPh p-
H), 2.61 (m, 4H, THF), 1.18 (m, 2H, PCH2Si), 1.06 (m, 2H,
PCH2Si), 0.71 (m, 4H, THF), 0.45 and –0.02 (s, 12H total,
SiCH3), –0.14 (m, 3H, Me), –0.62 (m, 3H, Me). 31P{1H}
NMR (C6D6, 81 MHz, 298 K) δ: –46.5(s). Anal. calcd. for
C30H45ClN2OPSi2MgY: C 52.55, H 6.68, N 4.08; found:
C 52.98, H 6.59, N 4.02.
[NPN]YCl(THF) (1)
Reaction of [NPN]YCl(THF) with LiAlH4; synthesis of
{[NPN]AlH(α-H)Li(THF)}2 (7)
EI-MS m/z (%): 593 ([M – Cl]+, 10), 558 ([M – THF]+,
1
100). H NMR (C6D6, 200 MHz, 298 K) δ: 7.92 (m, 2H,
To a stirred mixture of [NPN]YCl(THF) (1) (1.26 g,
2 mmol) and LiAlH4 (0.1 g, 2.6 mmol) was added THF
(50 mL) at –78°C. After warming to room temperature, the
mixture was stirred overnight. After removal of the precipi-
tate by filtration, the solvent was evaporated to dryness un-
der vacuum, the white residue was extracted with toluene
(2 × 15 mL), and the mixture filtered through Celite. Partial
removal of the volatiles and cooling to –30°C to yield
PPh p-H), 7.40 (m, 4H, NPh o-H), 7.15 (m, 6H, NPh m-H
and PPh m-H), 6.80 (m, 2H, NPh p-H), 2.93 (m, 4H, THF),
1.60 (m, 2H, PCH2Si), 1.00 (m, 2H, PCH2Si), 0.76 (m, 4H,
THF), 0.30 and 0.24 (s, 12H total, SiCH3). 31P{1H} NMR
(C6D6, 81 MHz, 298 K) δ: –27.17 (d, JP,Y = 77.1 Hz). Anal.
calcd. for C28H39ClN2OPSi2Y: C 53.29, H 6.23, N 4.44;
found: C 53.56, H 6.26, N 4.43.
1
(0.58 g, 54%) compound 7 as colorless crystals. H NMR
[NPN]SmCl(THF) (2)
(C6D6, 200 MHz, 298 K) δ: 7.75 (m, 2H, PPh o-H), 7.05 (m,
10H, NPh o-H and m-H, and PPh m-H), 6.81 (m, 2H, NPh
p-H), 3.61 (m, 4H, THF), 1.68 (m, 2H, PCH2Si), 1.25 (m,
4H, THF), 0.95 (m, 2H, PCH2Si), 0.52 and –0.21 (s, 12H to-
tal, SiCH3). 31P{1H} NMR (C6D6, 81 MHz, 298 K) δ: –36.01
(q, JP,Li = 66.4 Hz). Anal. calcd. for C28H41N2OPSi2AlLi:
C 61.97, H 7.61, N 5.16; found: C 61.68, H 7.24, N 5.30.
EI-MS m/z (%): 623 ([M – THF]+, 100), 558 ([M – THF –
Cl]+, 15). 1H NMR (C6D6, 200 MHz, 298 K) δ: 6.42 (m, 1H,
PPh p-H), 6.05 (m, 6H, NPh m-H and PPh m-H), 5.76 (m,
4H, NPh o-H), 4.80 (m, 2H, NPh p-H), 4.42 (m, 2H,
PCH2Si), 2.35 and 2.21 (s, 12H total, SiCH3), 2.60 (m, 2H,
PCH2Si), 1.13 (m, 4H, THF), 0.05 (m, 4H, THF). Anal.
calcd. for C28H39ClN2OPSi2Sm: C 48.56, H 5.68, N 4.04;
found: C 48.85, H 5.75, N 4.01.
Reaction of [NPN]LuCl(THF) with KC8 and
naphthalene (C10H8); preparation of {[NPN]Lu}2(µ-
[NPN]HoCl(THF) (3)
η4:η4-C10H8) (8)
EI-MS m/z (%): 634 ([M – THF]+, 100), 599 ([M – THF –
Cl]+, 25). Anal. calcd. for C28H39ClN2OPSi2Ho: C 47.56,
H 5.50, N 3.96; found: C 47.72, H 5.63, N 3.87.
To a mixture of [NPN]LuCl(THF) (5) (1.43 g, 2 mmol),
KC8 (0.27 g, 2 mmol), and naphthalene (0.128 g, 1 mmol)
was added toluene at –78°C, leading the immediate develop-
ment of a purple colour. The mixture was warmed to room
temperature and stirred overnight to generate a dark purple
colour. After filtration, the volatiles were removed under
vacuum, the residue was washed with hexane (3 × 15 mL),
and then the remaining solid was recrystallized from tolu-
ene. Compound 8 was obtained as dark red crystals by
slowly evaporating the solvent at room temperature. Yield
35% (0.47 g). 1H NMR (C6D6, 200 MHz, 298 K) δ: 7.25 (m,
4H, PPh o-H), 7.02 (m, 20H, NPh o-H and m-H, and PPh m-
H), 6.78 (m, 4H, NPh p-H), 4.12 (m, 4H, C10H8), 2.51 (m,
4H, C10H8), 1.24 (m, 4H, PCH2Si), 0.65 (m, 4H, PCH2Si),
0.21 and 0.02 (s, 24H total, SiCH3). 31P{1H} NMR (C6D6,
81 MHz, 298 K) δ: –9.1 (s). 13C NMR (C6D6, 75.45 MHz,
298 K) δ: 159.7 (m, ipso-C6H5N), 131.6 (m, o-C6H5N),
129.6 (s, m/p-C6H5N), 122.9 (m, ipso-C6H5P), 120.6 (m, o-
C6H5P), 105.8 (m, ipso-C10H8), 104.4 (s, m/p-C6H5P), 89.8
[NPN]YbCl(THF) (4)
EI-MS m/z (%): 643 ([M – THF]+, 100), 607 ([M – THF –
Cl]+, 18). Anal. calcd. for C28H39ClN2OPSi2Yb: C 47.02,
H 5.50, N 3.92; found: C 47.22, H 5.60, N 3.86.
[NPN]LuCl(THF) (5)
EI-MS m/z (%): 644 ([M – THF]+, 100), 558 ([M – THF –
Cl]+, 20). 1H NMR (C6D6, 200 MHz, 298 K) δ: 7.90 (m, 2H,
PPh o-H), 7.41 (m, 4H, NPh o-H), 7.15 (m, 6H, NPh m-H
and PPh m-H), 6.81 (m, 2H, NPh p-H), 2.98 (m, 4H, THF),
1.58 (m, 2H, PCH2Si), 0.97 (m, 2H, PCH2Si), 0.69 (m, 4H,
THF), 0.32 and 0.25 (s, 12H total, SiCH3). 31P{1H} NMR
(C6D6, 81 MHz, 298 K) δ: –22.70 (s). Anal. calcd. for
C28H39ClN2OPSi2Lu: C 46.89, H 5.48, N 3.91; found:
C 46.63, H 5.90, N 4.02.
© 2001 NRC Canada

1196
Can. J. Chem. Vol. 79, 2001
Table 1. Crystallographic data for 1, 4, 7, and 8.
1
4
7
8
Chemical formula
FW
Crystal Size (mm)
Crystal system
Space group
T (°C)
C28H39ClN2OPSi2Y
631.13
0.40 × 0.25 × 0.10
Monoclinic
P21/n (No. 14)
–100
C28H39ClN2OPSi2Yb
715.27
0.30 × 0.20 × 0.20
Monoclinic
P21/n (No. 14)
–100
C63H90N4O2P2Si4Al2Li2
1177.56
0.35 × 0.20 × 0.12
Triclinic
P1 (No. 2)
–100
C58H70N4P2Si4Lu2
1347.44
0.30 × 0.25 × 0.10
Triclinic
P1 (No. 2)
–100
λ (Å)
a (Å)
b (Å)
c (Å)
α (°)
β (°)
γ (°)
V (Å3)
0.71069
0.71069
0.71069
12.8490(9)
16.146(2)
19.415(2)
68.498(2)
121.518 (2)
66.523(2)
3355.5(5)
2
1.165
1260
2.05
55.9
0.71069
10.033(1)
11.2951(4)
13.711(1)
98.892(1)
96.494(2)
109.255(2)
1426.5(2)
1
1.568
674
36.21
56.8
15.3199(7)
12.0338(5)
17.432(1)
15.1656(5)
12.0402(3)
17.5551(6)
100.906(3)
101.027(3)
3155.7(2)
4
1.328
1312
20.84
55.8
0.93
0.028
0.077
3146.3(2)
4
1.510
1436
32.07
55.8
0.97
0.025
0.074
Z
Dcalcd. (g cm–3)
F(000)
µ (cm–1)
2θmax. (°)
GoF
1.37
0.039
0.107
1.23
0.027
0.074
a
R1
b
wR2
aR1 = (*Fo – Fc*/ Σ*Fo*[I > 3σ(I)].
bwR2 = [Σw(Fo2 – Fc2)2/ΣwFo4 ]1/2 (all data).
(s, CH, C10H8), 31.9 (s, CH, C10H8), 22.9 (s, SiCH2P), 14.8
(s, (CH3)2Si). Anal. calcd. for C58H70N4P2Si4Lu2: C 51.71,
H 5.20, N 4.16; found: C 51.58, H 5.34, N 4.30.
Results and discussion
A series of complexes of the formula [NPN]LnCl(THF)
([NPN] = [PhP(CH2SiMe2NPh)2]; Ln = Y (1), Sm (2), Ho
(3), Yb (4), Lu (5)) were prepared in high yield (>70%) by
reaction of [NPN]Li2(THF)2 with LnCl3(THF)3 in molar ra-
tio of 1:1 in toluene under reflux (eq. [1]).
X-ray crystallography
Single crystals of compounds 1, 4, 7, and 8 suitable for X-
ray diffraction studies were selected and mounted on a glass
fiber using Paratone oil. The crystallographic data appear in
Table 1.3 All measurements were made on a Rigaku/ADSC
CCD area detector at 173 K, with graphite monochromated
Mo Kα radiation (λ = 0.71069 Å), performing 2θ–ω scans.
The structures of 1, 4, and 7 were solved by direct methods
using SIR97 (11) and 8 by the Patterson method (12) and re-
fined by full-matrix least-squares methods on F2 for all data.
Unless otherwise stated, all nonhydrogen atoms were refined
anisotropically. All hydrogen atoms were included in the
model at geometrically calculated positions with C—H dis-
tances of 0.98 Å and the isotropic thermal parameter for
each H atom (BH) is equal to 1.2 times Biso of the atom to
which it is bonded. Unmodified statistical weights (w =
Me2
Si
Ph
S
O
Ph
Ph
N
LnCl3(THF)3
N
N
Ln
Cl
Li
[1]
Ph
P
Li
toluene
reflux
(–2 LiCl)
Me2Si
S
N
Me2Si
P
Si
Me2
Ph
Ph
S = THF
Ln = Y
1
Ln = Sm
Ln = Ho
Ln = Yb
Ln = Lu
2
3
4
5
1/σ2(F2)) were employed for all structures. The coordinated
o
THF molecules in 1 and 4 were found to be disordered and
were subsequently refined isotropically in two separate ori-
entations.
Using THF as the solvent led to lower yields of the prod-
ucts. Compounds 1–5 are moisture sensitive, moderately sol-
uble in toluene and Et2O, but very soluble in THF. The
3 Supplementary material may be purchased from the Depository of Unpublished Data, Document Delivery, CISTI, National Research
Council Canada, Ottawa, ON K1A 0S2, Canada. For information on obtaining material electronically go to
http://www.nrc.ca/cisti/irm/unpub_e.shtml. Crystallographic information has also been deposited with the Cambridge Crystallographic Data
Centre. Copies of the data can be obtained, free of charge, on application to the Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
U.K. (Fax: 44-1223-336033 or e-mail: deposit@ccdc.cam.ac.uk).
© 2001 NRC Canada

Fryzuk et al.
1197
Table 2. Selected bond distances (Å) and angles (°) for com-
Fig. 1. Molecular structure of [NPN]YCl(THF) (1).
pound 1.
Bond distances (Å)
Y(1)—Cl(1)
Y(1)—N(1)
Y(1)—O(1)
N(1)—C(13)
2.7561(6) Y(1)—P(1)
2.9276(6)
2.240(2)
1.826(2)
1.421(3)
2.260(2)
2.350(2)
1.407(3)
Y(1)—N(2)
P(1)—C(7)
N(2)—C(19)
Bond angles (°)
Cl(1)-Y(1)-O(1)
Cl(1)-Y(1)-N(2)
O(1)-Y(1)-N(2)
N(1)-Y(1)-N(2)
P (1)-Y(1)-N(1)
91.54(5)
94.95(5)
94.39(7)
105.30(7)
68.09(5)
Cl(1)-Y(1)-P(1)
Cl(1)-Y(1)-N(1) 145.98(5)
O(1)-Y(1)-N(1)
P(1)-Y(1)-O(1)
P(1)-Y(1)-N(2)
90.82(2)
113.35(6)
171.44(5)
77.20(5)
Y(1)-N(2)-C(19) 117.6(1)
Y(1)-N(1)-C(13) 103.8(1)
Y(1)-P(1)-C(2)
Y(1)-P(1)-C(7)
95.06(8)
135.45(8)
Y(1)-P(1)-C(1)
C(1)-P(1)-C(2)
109.46(8)
103.5(1)
Table 3. Selected bond distances (Å) and angles (°) for com-
pound 4.
Fig. 2. Molecular structure of [NPN]YbCl(THF) (4).
Bond distances (Å)
Yb(1)—Cl(1)
Yb(1)—N(1)
Yb(1)—O(1)
N(2)—C(19)
2.7188(9)
2.213(3)
2.325(3)
1.421(5)
Yb(1)—P(1)
Yb(1)—N(2)
P(1)—C(7)
2.8809(9)
2.199(3)
1.825(4)
1.412(5)
N(1)—C(13)
Bond angles (°)
Cl(1)-Yb(1)-O(1)
Cl(1)-Yb(1)-N(2)
O(1)-Yb(1)-N(2)
N(1)-Yb(1)-N(2)
P(1)-Yb(1)-N(1)
92.67(7)
95.70(8)
91.9(1)
104.7(1)
69.68(8)
Cl(1)-Yb(1)-P(1)
Cl(1)-Yb(1)-N(1)
O(1)-Yb(1)-N(1)
P(1)-Yb(1)-O(1)
P(1)-Yb(1)-N(2)
90.62(3)
147.55(8)
111.2(1)
170.01(8)
78.38(8)
Yb(1)-N(1)-C(13) 107.6(2)
Yb(1)-N(2)-C(19) 118.3(2)
Yb(1)-P(1)-C(1)
Yb(1)-P(1)-C(7)
108.8(1)
135.3(1)
Yb(1)-P(1)-C(2)
C(1)-P(1)-C(2)
95.7(1)
103.6(2)
five-coordinate environments around the central metals with
the coordinated THF occupying the position opposite to the
phosphorus atom. Overall, the geometries around each cen-
tral metal are very similar and can be described as distorted
square pyramidal by defining the base of the pyramid by
P(1), O(1), N(1), and Cl(1), with N(2) in the apical position.
This rather unsymmetrical geometry observed in the solid
state cannot account for the solution data; in fact, the solu-
tion data are more consistent with a trigonal bipyramidal
structure wherein the two amide donors and the chloride oc-
cupy the equatorial plane with the phosphine and THF moi-
eties are apical resulting is Cs molecular symmetry.
Presumably the small structural differences between the
solid state and in solution are a result of crystal packing in
the former.
The Y—Cl (2.7561(6) Å) bond distance in 1 is longer
than that reported for the mononuclear diamido complex
[DADMB]YCl(THF)2 (Y—Cl 2.574(2) Å), while Y—N (av-
erage 2.250 Å) and Y—O (2.350(2) Å) in compound 1 are
comparable to those in compound [DADMB]YCl(THF)2
(DADMB = [6,6′-Me2-(C6H3)2](2,2′-NSiMe2-t-Bu)2) (aver-
age Y—N 2.250 Å, average Y—O 2.376 Å) (2). The bond
distances Yb—Cl (2.710 Å), Yb—N (average 2.212 Å), and
compounds were characterized by elemental analyses, mass
spectrometry, and 1H and 31P NMR spectroscopy where pos-
sible. The most intense peaks observed in the mass spectra
correspond to the fragments [NPN]LnCl ([M – THF]+) and
[NPN]Ln ([M – THF – Cl]+). Although the Sm(III), Ho(III),
and Yb(III) derivatives (2, 3, and 4, respectively) are para-
magnetic, the samarium derivative [NPN]SmCl(THF) (2)
1
exhibited H NMR signals (although no 31P NMR resonance
could be detected); no diagnostic signals could be detected
1
in both the H and 31P NMR spectra for compounds 3 and 4.
1
For complexes 1 and 5, the H NMR spectra each show two
signals due to coordinated THF at ca. 2.9 and 0.7 ppm, re-
spectively. More importantly, both diamagnetic derivatives 1
and 5 show very symmetrical NMR patterns in solution sug-
gestive of at least Cs symmetry; for example, only two envi-
ronments for the silylmethyl protons (SiMe2) are observed
and the phenyl groups attached to nitrogen are equivalent.
The molecular structures of 1 and 4 were determined by
X-ray crystallography and are shown in Figs. 1 and 2, re-
spectively; selected bond distances and angles are given in
Tables 2 and 3. These two derivatives are isostructural and
isomorphous in the solid state. Both compounds display
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Can. J. Chem. Vol. 79, 2001
Fig. 3. Molecular structure of {[NPN]AlH(µ-H)Li(THF)}2 (7).
For clarity the Ph groups at N and P are omitted.
[2]
tances and angles are given in Table 4. The Li atoms are
each coordinated by three atoms (P, O, H) and the angles of
P-Li-O (113.7(3)°), P-Li-H (109.5°), and O-Li-H (105.2°)
are in agreement with those expected for pseudo-tetrahedral
geometries. The average Al—N (1.85 Å), Al—H (1.57 Å),
and Li—H (1.84 Å) distances are comparable to those in the
related
disilylamido
aluminate,
[(Me3Si)2N]2Al(µ-
H)2Li·2Et2O (Al—N 1.86, Al—H 1.58, and Li—H 1.93 Å)
(15). Stoichiometry requires that YClH2(THF)x also be gen-
erated; however, the identity of the yttrium side-product was
not pursued.
Recently, we have reported the formation of yttrium and
lutetium complexes with polycyclic aromatic compounds
that were formulated as {[P2N2]Ln}2(µ-η4:η4-C10H8) by re-
ducing {[P2N2]LnCl}2 (Ln = Y, Lu) using KC8 in the pres-
ence of aromatic compounds such as naphthalene and
anthracene (16). A similar reaction of [NPN]LuCl(THF)
with KC8 and naphthalene resulted in the generation of
{[NPN]Lu}2(µ-η4:η4-C10H8) (8) in moderate yield (eq. [3]).
Yb—P (2.881 Å) in compound 4 can be compared to other
Yb(III)
phosphine
complexes;
for
example,
in
Cp*2YbCl(dmpm), the Yb—Cl bond distance of 2.532 Å is
considerably shorter than that found in 4, while the Yb—P
bond length in 4 is slightly shorter than 2.941 Å found in the
aforementioned permethylytterbocene derivative (13). The
Yb(II) derivative [(Me2Si)2N]2Yb(dmpe) shows Yb—N and
Yb—P bond distances of 2.331 and 3.012 Å, respectively,
which are both longer than that found in 4 (14).
Attempts to generate metal–carbon bonds by metathesis of
the remaining chloride ligands of [NPN]LnCl(THF) have not
met with success. Generally mixtures of products are ob-
tained upon addition of RLi (R = Me, CH2SiMe3) to
[NPN]YCl(THF) (1). However, it was found that the addi-
tion of MeMgCl to 1 did result in the formation of an adduct
of the empirical formula [NPN]YMe2MgCl (6). This mate-
rial is clearly not the expected product, [NPN]YMe(THF).
The proposed formulation of 6 is from elemental analyses;
[3]
1
while H and 31P NMR spectroscopy could be obtained, a
definitive structure has so far eluded us, as have suitable
crystals for single crystal X-ray diffraction studies. From the
solution NMR data, it is clear that phosphorus is not bound
to Y (no coupling between yttrium-89 and phosphorus-31)
and there are two metal–methyl environments. Further spec-
ulation on the structure of 6 must await additional data.
Attempts to prepare a hydride of the general formula
{[NPN]YH(THF)}x by the reaction of 1 with LiAlH4 in THF
instead resulted in ligand transfer from yttrium to aluminum
and the production in reasonable yield of the air-, moisture-,
and slightly light-sensitive dinuclear aluminate 7 (eq. [2]).
The molecular structure of 7 was determined by X-ray
crystallography. As shown in Fig. 3, the Al atoms are each
coordinated by two amido donors and two hydrides in a dis-
torted tetrahedral coordination mode. Selected bond dis-
Exactly analogous transformations are also evident for the
reaction of the holmium and yttrium analogues, although
these reactions were not examined in detail. While the
lutetium reaction provides proof of concept for this process
for some of the lanthanides, it is interesting to note that this
kind of reductive process completely fails to provide any
kind of isolable product for the samarium and ytterbium de-
rivatives 2 and 4, despite the fact that divalent states are
known for these particular lanthanide elements; it is not
© 2001 NRC Canada

Fryzuk et al.
1199
Table 5. Selected bond distances (Å) and angles (°) for com-
Table 4. Selected bond distances (Å) and angles (°) for com-
pound 7.
pound 8.
Bond distances (Å)
P(1)—Li(1)
Al(1)—N(1)
Al(1)—H(79)
Bond distances (Å)
Lu(1)—P(1)
Lu(1)—N(1)
Lu(1)—C(26)
Lu(1)—C(28)
C(25)—C(26)
C(28)—C(29)
C(25)*—C(29)
Bond angles (°)
P(1)-Lu(1)-N(1)
N(1)-Lu(1)-N(2)
P(1)-Lu(1)-C(26)
P(1)-Lu(1)-C(27)
P(1)-Lu(1)-C(29)
N(1)-Lu(1)-C(28)
N(1)-Lu(1)-C(29)
C(7)-Lu(1)-C(28)
C(7)-Lu(1)-C(29)
N(2)-Lu(1)-C(26)
N(2)-Lu(1)-C(28)
Lu(1)-N(1)-C(7)
C(25)-C(25)*-C(29)
C(26)-C(25)-C(29)*
C(26)-C(27)-C(28)
2.7538(8)
2.214(3)
2.551(3)
2.612(4)
1.438(5)
1.450(5)
1.414(5)
Lu(1)—C(7)
Lu(1)—N(2)
Lu(1)—C(27)
Lu(1)—C(29)
C(26)—C(27)
C(27)—C(28)
C(25)—C(25)*
2.755(3)
2.174(3)
2.614(4)
2.605(3)
1.426(5)
1.372(5)
1.451(6)
2.575(4)
1.847(2)
1.55
Li(1)—O(1)
Al(1)—N(2)
Al(1)—H(80)
1.904(5)
1.863(2)
1.56
Li(1)—H(80)
1.84
Bond angles (°)
H(79)-Al(1)-H(80)
H(79)-Al(1)-N(1)
H(80)-Al(1)-N(2)
P(1)-Li(1)-O(1)
H(80)-Li(1)-O(1)
107.0
108.4(5)
111.5
113.7(3)
105.2
N(1)-Al(1)-N(2)
H(79)-Al(1)-N(2)
H(80)-Al(1)-N(1)
P(1)-Li(1)-H(80)
116.80(8)
101.0
111.3
72.49(7)
113.0(1)
85.40(8)
113.16(9)
135.52(7)
130.8(1)
99.5(1)
106.6(1)
80.7(1)
107.6(1)
108.4(1)
96.7(2)
P(1)-Lu(1)-N(2)
C(7)-Lu(1)-N(1)
C(7)-Lu(1)-N(2)
P(1)-Lu(1)-C(28)
N(1)-Lu(1)-C(26)
N(1)-Lu(1)-C(27)
N(1)-Lu(1)-C(26)
C(7)-Lu(1)-C(27)
C(7)-Lu(1)-C(26)
N(2)-Lu(1)-C(27)
N(2)-Lu(1)-C(29)
Lu(1)-C(7)-N(1)
C(25)*-C(25)-C(26)
C(25)-C(26)-C(27)
C(27)-C(28)-C(29)
80.49(8)
30.4(1)
109.5
115.4(1)
141.25(9)
129.0(1)
151.1(1)
129.0(1)
95.9(1)
136.9(1)
95.9(1)
138.6(1)
53.0(2)
Fig. 4. Molecular structure of {[NPN]Lu}2(µ-η4:η4-C10H8) (8).
For clarity the Ph groups at N(2) and P(1) are omitted.
118.7(4)
123.9(4)
119.7(3)
117.4(4)
120.8(3)
119.5(3)
Conclusions
The results of this study indicate that the NPN ligand sys-
tem can be incorporated onto certain Group 3 and lanthanide
derivatives to generate five-coordinate, mononuclear com-
plexes. However, these materials are not especially versatile
as starting materials for entry into organometallic chemistry
as most of the attempts to generate metal–carbon bonds re-
sult in mixtures of complexes. The only successful transfor-
mation so far is the incorporation of naphthalene under
reducing conditions to give a bridging naphthalene unit.
Since incorporation of alkyl species has proven difficult, it is
likely that the use of these ligand systems with Group 3 and
the lanthanides as catalyst precursors for polymerization of
α-olefins will not be optimal.
clear if reduction to a putative “Ln(II)[NPN]” species com-
plicates these latter reactions. The H NMR spectroscopic
data of 8 show only two sets of signals for the C10H8 moi-
ety, which indicate that the bridging naphthalene unit is
symmetrically bound. In addition, only one signal for its
31P{1H} NMR spectrum also demonstrates equivalent phos-
phine donors on both Lu(III) centers.
1
The crystal structure of 8 has been determined and is
shown in Fig. 4. Selected bond distances and angles are
given in Table 5. The conformation of 8 is very similar to
that of compound {[P2N2]Y}2(µ-η4:η4-C10H8). Each
[NPN]Lu unit binds in an η4 fashion on the opposite sides of
the different rings of the naphthalene unit. The naphthalene
moiety is distorted slightly with elongated bond lengths, and
its rings become nonplanar (16). The average Lu—C
(2.59 Å) π-bond distances in compound 8 is found similar to
the average π-bond distance of Lu—C(Cp) (2.63 Å) in com-
pound (C5H5)2Lu-t-Bu(THF) (17). It is interesting to note
that the short distance between Lu(1) and C(7) (2.75 Å) ap-
pears to indicate a η2-N,C interaction of the amide in solid
state. However, the 13C NMR spectrum shows no evidence
of any asymmetry and both ipso carbons resonate at
159.7 ppm, a shift typical for uncoordinated NPh linkages
(2).
Acknowledgment
Funding was provided by the Natural Sciences and Engi-
neering Research Council of Canada (NSERC).
References
1. H.H. Brintzinger, D. Fischer, R. Mulhaupt, B. Rieger, and R.
Waymouth. Angew. Chem. Int. Ed. Engl. 34, 1143 (1995).
2. T.I. Gountchev and T.D. Tilley. Organometallics, 18, 2896
(1999).
3. R.R. Schrock. Acc. Chem. Res. 30, 9 (1997).
4. G.J.P. Britovsek, V.C. Gibson, and D.F. Wess. Angew. Chem.
Int. Ed. Engl. 38, 429 (1999).
5. M.D. Fryzuk, J.B. Love, S.J. Rettig, and V.G. Young. Science,
275, 1445 (1997).
6. M.D. Fryzuk, J.B. Love, and S.J. Rettig, Organometallics, 17,
846 (1998).
© 2001 NRC Canada

1200
Can. J. Chem. Vol. 79, 2001
7. J.D. Cohen, M.D. Fryzuk, T.M. Loehr, M. Mylvaganam, and
S.J. Rettig. Inorg. Chem. 37, 112 (1998).
The DIRDIF program system, technical report of the crystal-
lography laboratory. University of Nijmegen, The Netherlands.
8. K.H. den Haan, J.L. de Boer, J.H. Teuben, A.L. Spek, B.
Kojic-Prodic, G.R. Hays, and R. Huis. Organometallics, 5,
1726 (1986).
9. M.D. Fryzuk, S.A. Johnson, and S.J. Rettig. J. Am. Chem.
Soc. 120, 11024 (1998).
10. A. Fürstner, and D.N. Jumbam. Tetrahedron, 48, 5991 (1992).
11. A. Altomare, M.C. Burla, G. Cammalli, M. Cascarano, C.
Giacovazzo, A. Guagliardi, A.G.G. Moliterni, G. Polidori, and
A. Spagna. J. Appl. Crystallogr. 32, 115 (1999).
12. P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, S.
Garcia-Granda, R.O. Gould, J.M.M. Smits, and C. Smykalla.
1992.
13. T.D. Tilley, R.A. Andersen, and A. Zalkin. Inorg. Chem. 22,
856 (1983).
14. T.D. Tilley, R.A. Andersen, and A. Zalkin. J. A. Chem. Soc.
104, 3725 (1982).
15. A. Heine and D. Stalke. Angew. Chem. Int. Ed. Engl. 31, 854
(1992).
16. M.D. Fryzuk, L. Jafarpour, F.M. Kerton, J.B. Love, and S.J.
Rettig. Angew. Chem. Int. Ed. Engl. 39, 767 (2000).
17. W.J. Evans, A.L. Wayda, W.E. Hunter, and J.L. Atwood. J.
Chem. Soc. Chem. Commun. 292 (1981).
© 2001 NRC Canada