Bismuth coordination chemistry with allyl, alkoxide, aryloxide, and tetraphenylborate ligands and the {[2,6-(Me2NCH2) 2C6H3]2Bi}+ cation

Article abstract of DOI:10.1021/ic102119y

A series of bis(aryl) bismuth compounds containing (N,C,N)-pincer ligands, [2,6-(Me₂NCH₂)₂C₆H₃] ^- (Ar?), have been synthesized and structurally characterized to compare the coordination che

Full text of DOI:10.1021/ic102119y

Inorg. Chem. 2011, 50, 1513–1520 1513
DOI: 10.1021/ic102119y
Bismuth Coordination Chemistry with Allyl, Alkoxide, Aryloxide, and
Tetraphenylborate Ligands and the {[2,6-(Me2NCH2)2C6H3]2Bi}þ Cation
Ian J. Casely,† Joseph W. Ziller,† Bruce J. Mincher,‡ and William J. Evans*,†
†Department of Chemistry, University of California, Irvine, California 92697-2025, United States, and
‡Aqueous Separations and Radiochemistry Department, Idaho National Laboratory, Idaho Falls,
Idaho 83415-6180, United States
Received October 20, 2010
A series of bis(aryl) bismuth compounds containing (N,C,N)-pincer ligands, [2,6-(Me2NCH2)2C6H3]- (Ar0), have been
synthesized and structurally characterized to compare the coordination chemistry of Bi3þ with similarly sized
lanthanide ions, Ln3þ. Treatment of Ar02BiCl, 1, with ClMg(CH2CHdCH2) affords the allyl complex Ar02Bi(η1-
CH2CHdCH2), 2, in which only one allyl carbon atom coordinates to bismuth. Complex 1 reacts with KOtBu and
KOC6H3Me2-2,6 to yield the alkoxide Ar02Bi(OtBu), 3, and aryloxide Ar02Bi(OC6H3Me2-2,6), 4, respectively, but the
t
t
analogous reaction with the larger KOC6H3 Bu2-2,6 forms [Ar02Bi][OC6H3 Bu2-2,6], 6, in which the aryloxide ligand
acts as an outer sphere anion. Chloride is removed from 1 by NaBPh4 to form [Ar02Bi][BPh4], 5, which crystallizes from
THF in an unsolvated form with tetraphenylborate as an outer sphere counteranion.
Introduction
in the separation process. The Shannon ionic radii of Bi3þ
˚
(1.03 and 1.17 A for six and eight-coordination, respectively)
Bismuth has many interesting medical and technological
applications1-3 that include treatment of gastrointestinal
disorders,4 applications in radioisotope therapy,5 and assem-
bly of advanced materials such as superconductors,6 ferro-
electric devices,7,8 and specialized pigments.2 Additionally,
the use of its oxidative capacity9 to achieve separations in
nuclear waste streams has been investigated.10,11 Specifically,
NaBiO3 has been examined as a convenient oxidant to
convert Am3þ to Am6þ and allow separation of americium
from the trivalent lanthanides in nuclear waste streams.12
Surprisingly, in the presence of this bismuth oxidant the
separation efficiency has been observed to decrease.13 It is
possible that this is due to interference by the trivalent
oxidation byproduct, Bi3þ, in competition with Ln3þ ions
14
are similar to those of La3þ (1.032 and 1.16 A, respectively)
˚
and consequently these ions have the same charge-to-radius
ratio. Accordingly, to a first approximation based on elec-
trostatic and steric factors, analogous complexes of bismuth
and the lanthanides could adopt similar coordination
geometries.2,15 However, it is well established that the co-
ordination chemistry of bismuth can be influenced by a stereo-
chemically active lone pair,16,17 and bismuth has a very
different Pauling electronegativity, 1.9, compared to 1.10-
1.25 for the lanthanides.18
We report here synthetic and structural results in organo-
bismuth chemistry that allow comparisons to be made between
the coordination geometries of bismuth and the lanthanides.
Specifically, we have examined Bi3þ complexes ligated by
the (N,C,N)-pincer ligand, [2,6-(Me2NCH2)2C6H3]- (Ar0),
originally studied with the transition metals by van Koten
et al.19-26 The bismuth chemistry of the Ar0 ligand was initially
investigated by Cowley and co-workers,27 and subsequent
*To whom correspondence should be addressed. E-mail: wevans@uci.
edu.
(1) Briand, G. G.; Burford, N. Chem. Rev. 1999, 99, 2601.
(2) Mehring, M. Coord. Chem. Rev. 2007, 251, 974.
(3) Hanna, T. A. Coord. Chem. Rev. 2004, 248, 429.
(4) Sadler, P. J.; Li, H.; Sun, H. Coord. Chem. Rev. 1999, 185-186, 689.
(5) Deb, S.; Abdulghani, S.; Behiri, J. C. Biomaterials 2002, 23, 3387.
(6) Rao, G. V. R.; Swaminathan, K.; Sreedharan, O. M.; Venkadesan, S.;
Mannan, S. L.; Varadaraju, U. V. J. Mater. Sci. 1998, 33, 1511.
(7) Isupov, V. A. Ferroelectrics 1996, 189, 211.
(14) Shannon, R. D. Acta Crystallogr., Sect. A: Found. Crystallogr. 1976,
32, 751.
(15) Mansfield, D.; Mehring, M. Z. Anorg. Allg. Chem. 2005, 631, 2429.
(16) Norman, N. C. Chemistry of Arsenic, Antimony and Bismuth, 1st ed.;
Blackie Academic Professional: London, 1998.
(8) Park, B. H.; Kang, B. S.; Bu, S. D.; Noh, T. W.; Lee, J.; Jo, W. Nature
(London) 1999, 401, 682.
(9) Postel, M.; Dunach, E. Coord. Chem. Rev. 1996, 155, 127.
(10) Hara, M.; Suzuki, S. Bull. Chem. Soc. Jpn. 1979, 52, 1041.
(11) Hara, M.; Suzuki, S. J. Radioanal. Chem. 1977, 36, 95.
(12) Mincher, B. J.; Martin, L. R.; Schmitt, N. C. Inorg. Chem. 2008, 47,
6984.
(13) Mincher, B. J.; Schmitt, N. C.; Case, M. E. Solvent Extr. Ion Exch.
2011, in press.
(17) Silvestru, C.; Breunig, H. J.; Althaus, H. Chem. Rev. 1999, 99, 3277.
(18) Lide, D. R., Ed.; CRC Handbook of Chemistry and Physics, 90th ed.;
CRC Press/Taylor and Francis: Boca Raton, FL, Internet Version 2010.
(19) van Koten, G. Pure Appl. Chem. 1989, 61, 1681.
(20) van Koten, G. Pure Appl. Chem. 1990, 62, 1155.
(21) van Koten, G.; Jastrzebski, J. T. B. H.; Noh, J. G.; Spek, A. L.;
Shoone, I. C. J. Organomet. Chem. 1978, 148, 233.
r
2010 American Chemical Society
Published on Web 12/30/2010
pubs.acs.org/IC

1514 Inorganic Chemistry, Vol. 50, No. 4, 2011
Casely et al.
studies have been reported by Breunig, Silvestru, and co-
workers.28-30 This ligand was chosen for our comparative
studies since it provides a favorable bismuth-aryl bond with
chelating nitrogen donor groups that can fill the coordination
sphere of bismuth if needed. The synthesis of the bis(aryl)
Bi3þ complexes, (Ar0)2BiX, was examined since the two Ar0
ligands provide a stable coordination environment for bis-
muth while leaving a single anionic X site for evaluation.31
Comparisons will be made with (C5Me5)2LnX lanthanide
complexes since the bis(pentamethylcyclopentadienyl) ligand
set also provides a stable coordination environment to lantha-
nides with one X site, and an extensive set of complexes is
known with lanthanum through lutetium. Lanthanide com-
plexes of the [2,6-(Me2NCH2)2C6H3]- ligand are known,32,33
but the set of compounds is insufficient for the comparisons
of X ligand binding desired in this study. In fact, crystal-
lographically characterized complexes are known only for
species containing one of these ligands: {[2,6-(Me2NCH2)2-
C6H3]LuCl2(μ-Cl)[μ-Li(THF)2]}2, {[2,6-(Me2NCH2)2C6H3]-
Lu(μ-Cl)(CH2SiMe3)}2, and (η5-C5H5)2La[2,6-(Me2N-
CH2)2C6H3].32,33 It has previously been noted that the
bis(dimethylaminomethyl)phenyl (N,C,N) ligand may be
considered as a replacement for cyclopentadienyl-based li-
gands in terms of both the number of coordination sites it can
occupy and the bonding electrons it provides.32
capillary melting point apparatus. [2,6-(Me2NCH2)2C6H3]2-
BiCl, 1, was synthesized according to literature procedures.28
KOC6H3Me2-2,6 and KOC6H3 Bu2-2,6 were synthesized by
treatment of the parent phenol with 1 equiv of KN(SiMe3)2 in
toluene. [HNEt3][BPh4] was synthesized by treatment of
t
NEt3 HCl with NaBPh4 in water followed by filtration,
3
washing, and drying under vacuum (10-5 Torr) overnight.
ClMg(CH2CHdCH2) (2.0 M solution in THF) and all other
reagents were purchased from Aldrich and used as received.
KOtBu was sublimed and NaBPh4 placed under vacuum
(10-5 Torr) overnight prior to use.
[2,6-(Me2NCH2)2C6H3]2Bi(CH2CHdCH2), 2. A tetrahydro-
furan (THF) solution of ClMg(CH2CHdCH2) (0.40 mL,
0.80 mmol) was added to a stirred THF (10 mL) solution of
[2,6-(Me2NCH2)2C6H3]2BiCl (500 mg, 0.80 mmol) at room
temperature. The yellow reaction mixture was stirred for 12 h,
and the solvent was removed under reduced pressure to afford
an off-white solid that was subsequently stirred in hexanes
(10 mL) for 0.5 h. Following centrifugation, filtration, and
removal of the volatiles, 2 was obtained as a yellow solid (495 mg,
98%). This crude product was analytically pure. Single crystals
suitable for an X-ray diffraction study were grown by slow
evaporation of a hexane solution at room temperature. 1H
3
NMR (CD3CN): δ 7.25 (d, 4H, JH-H =7.4 Hz, m-Ar-CH),
3
7.15 (t, 2H, JH-H = 7.4 Hz, p-Ar-CH), 5.96 (m, 1H,
3
2
CH2CH=CH2), 4.43 (dd, 1H, Jtrans =16.8 Hz, JH-H =2.4
Hz, CH2CHdCH2), 4.23 (dd, 1H, 3Jcis=10.0 Hz, 2JH-H=2.4
Hz, CH2CHdCH2), 3.33 and 3.14 (d, 4H each, 2JH-H=13.2 Hz,
NCH2), 2.75 (d, 2H, 3JH-H = 8.6 Hz, CH2CHdCH2), 1.97 [s,
24H, N(CH3)2]. 13C (CD3CN): δ 167.7 [Bi-C(Ar)], 147.7
(quaternary o-Ar-C), 138.6 (CH2CHdCH2), 128.5 and 126.5
(Ar-CH), 110.2 (CH2CH=CH2), 68.4 (NCH2), 44.4 [N(CH3)2],
35.7 (CH2CHdCH2). Mp 89-90 °C. Anal. Calcd for C27H43-
BiN4: C, 51.25; H, 6.86; N, 8.86. Found: C, 51.22; H, 6.59;
N, 8.77.
Experimental Section
All manipulations and syntheses described below were
conducted with the rigorous exclusion of air and water using
standard Schlenk line and glovebox techniques, under an
argon or dinitrogen atmosphere. Solvents were sparged with
UHP argon and dried by passage through columns contain-
ing Q-5 and molecular sieves prior to use. Deuterated NMR
solvents were purchased from Cambridge Isotope Labora-
tories, dried over NaK alloy, degassed by three freeze-
[2,6-(Me2NCH2)2C6H3]2Bi(OtBu), 3. Separate solutions of
[2,6-(Me2NCH2)2C6H3]2BiCl (200 mg, 0.32 mmol) and KOtBu
(36 mg, 0.32 mmol) in THF (5 mL each) were cooled to -30 °C,
and the KOtBu solution was added dropwise to the stirred bis-
muthsolution. Thereactionmixturewasallowedtowarmtoroom
temperature and stirred for 2.5 h. The solution remained colorless,
and a fine white precipitate formed which was removed by
filtration beforesolvent evaporation. The resulting colorlesssolids
were extracted by stirring in hexane (10 mL) for 0.5 h, after which
centrifugation, filtration, and removal of the volatiles under
reduced pressure yielded crude 3 (150 mg, 70%). Recrystallization
from hexanes(2mL) at-30 °C afforded colorless 3(133 mg, 62%)
as single crystals suitable for an X-ray diffraction study. 1H NMR
(C6D6): δ 7.43 (bd, 4H, m-Ar-CH), 7.21 (t, 2H, 3JH-H=7.4 Hz,
p-Ar-CH), 3.75 (bs, 4H, NCH2), 3.39 (bd, 4H, 2JH-H=12.3 Hz,
NCH2), 2.06 [s, 24H, N(CH3)2], 1.39 [s, 9H, OC(CH3)3]. 13C
(C6D6): δ 185.4 (Bi-C), 148.6 (quaternary o-Ar-C), 129.4 (m-Ar-
CH), 126.8 (p-Ar-CH), 71.1 (NCH2), 66.8 [OC(CH3)3], 45.2
[N(CH3)2], 33.4 [OC(CH3)3]. Mp 99-100 °C. Purple color ob-
served at 75 °C. Anal. Calcd for C28H47BiN4O: C, 50.59; H, 7.14;
N, 8.43. Found: C, 50.29; H, 7.05; N, 8.36.
1
pump-thaw cycles and vacuum transferred before use. H
NMR spectra were recorded on Bruker DR400, GN500, or
CRYO500 MHz spectrometers (13C spectra on 500 MHz
spectrometer operating at 125 MHz) at 298 K unless other-
wise stated and referenced internally to residual protio-solvent
resonances. Elemental analyses were conducted on a Perkin-
Elmer2400SeriesIICHNSelementalanalyzer. Meltingpoint
measurements were determined on a Thomas Scientific Unimelt
(22) van Koten, G.; Terheijden, J.; van Beek, J. A. M.; Wehman-
Ooyevaar, I. C. M.; Muller, F.; Stan, C. H. Organometallics 1990, 9, 903.
(23) Mehendale, N. C.; Lutz, M.; Spek, A. L.; Gebbink, R. J. M. K.; van
Koten, G. J. Organomet. Chem. 2008, 693, 2971.
(24) Steenwinkel, P.; Grove, D. M.; Veldman, N.; Spek, A. L.; van Koten,
G. Organometallics 1998, 17, 5647.
(25) Kleij, A. W.; Gossage, R. A.; Gebbink, R. J. M. K.; Brinkmann, N.;
Reijerse, E. J.; Kragl, U.; Lutz, M.; Spek, A. L.; van Koten, G. J. Am. Chem.
Soc. 2000, 122, 12112.
(26) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 40, 3750.
(27) Atwood, D. A.; Cowley, A. H.; Ruiz, J. Inorg. Chim. Acta 1992,
198-200, 271.
(28) Soran, A. P.; Silvestru, C.; Breunig, H. J.; Balazs, G.; Green, J. C.
Organometallics 2007, 26, 1196.
(29) Balazs, L.; Breunig, H. J.; Lork, E.; Soran, A. P.; Silvestru, C. Inorg.
Chem. 2006, 45, 2341.
(30) Breunig, H. J.; Koenigsmann, L.; Lork, E.; Nema, M.; Philipp, N.;
Silvestru, C.; Soran, A. P.; Varga, R. A.; Wagner, R. Dalton Trans. 2008,
1831.
[2,6-(Me2NCH2)2C6H3]2Bi(OC6H3Me2-2,6), 4. Separate solu-
tions of [2,6-(Me2NCH2)2C6H3]2BiCl (200 mg, 0.32 mmol) and
KOC6H3Me2-2,6 (51 mg, 0.32 mmol) in THF (5 mL each) were
cooled to -30 °C, and the KOC6H3Me2-2,6 solution was added
dropwise to the stirred bismuth solution. The reaction mixture was
allowed to warm to room temperature, whereupon a pale yellow
solution and fine white precipitate formed. The mixture was stirred
for 12 h, centrifuged, and the solution filtered. The solvent was
removed under reduced pressure yielding a yellow solid. Recrys-
tallization from hexanes (2 mL) at -30 °C afforded yellow 4 (163
mg, 71%) as single crystals suitable for an X-ray diffraction study.
1H NMR (CD3CN): δ 7.53 (d, 4H, 3JH-H=7.5 Hz, m-Ar-CH),
7.36 (t, 2H, 3JH-H=7.5 Hz, p-Ar-CH), 6.72 (d, 2H, 3JH-H=7.3
(31) Crabtree, R. H. The Organometallic Chemistry of the Transition
Metals, 4th ed.; Wiley: New York, 2005. pp 25-35.
(32) Hogerheide, M. P.; Grove, D. M.; Boersma, J.; Jastrzebski, J. T. B.
H.; Kooijman, H.; Spek, A. L.; van Koten, G. Chem.;Eur. J. 1995, 1, 343.
(33) Hogerheide, M. P.; Boersma, J.; Spek, A. L.; van Koten, G.
Organometallics 1996, 15, 1505.

Article
Inorganic Chemistry, Vol. 50, No. 4, 2011 1515
Scheme 1. Synthesis of Ar02BiX Complexes
Hz, m-OAr-CH), 6.21 (t, 1H, 3JH-H = 7.3 Hz, p-OAr-CH), 3.60
(s, 8H, NCH2), 2.08 [s, 6H, OAr-(CH3)2], 2.03 [s, 24H, N(CH3)2].
13C (CD3CN): δ 192.0 (Bi-C), 162.1 and 127.3 (quaternary i/o-
OAr-C), 149.4 (quaternary o-Ar-C), 129.7 (m-Ar-CH), 127.9
( p-Ar-CH), 127.7 (m-OAr-CH), 113.7 (p-OAr-CH), 67.3
(NCH2), 44.9 [N(CH3)2], 17.8 [OAr-(CH3)2]. Mp 97-99 °C.
Anal. Calcd for C32H47BiN4O: C, 53.92; H, 6.66; N, 7.86.
Found: C, 53.31; H, 6.65; N, 7.49.
122.8 (m-OAr-CH), 106.4 (p-OAr-CH), 67.8 (NCH2), 45.6
[N(CH3)2], 34.7 [C(CH3)3], 29.9 [C(CH3)3]. Mp 145-146 °C.
Color changes observed at 85 °C (brown) and at 110 °C (purple).
Anal. Calcd for C38H59BiN4O: C, 57.26; H, 7.48; N, 7.03. Found:
C, 57.06; H, 7.60; N, 6.85.
Results
Synthesis. The [2,6-(Me2NCH2)2C6H3]2BiX complexes
(Ar02BiX), 2-6, were prepared by reacting the previously
reported bismuth chloride complex, Ar02BiCl, 1,28 with alkali
and alkaline earth metal salts of allyl, alkoxide, aryloxide,
and tetraphenylborate reagents as shown in Scheme 1.
The bismuth products were isolated in good to excellent
{[2,6-(Me2NCH2)2C6H3]2Bi}[BPh4], 5. Separate solutions of
[2,6-(Me2NCH2)2C6H3]2BiCl (300 mg, 0.48 mmol) and NaBPh4
(164 mg, 0.48 mmol) in THF (5 mL each) were cooled to -30 °C
and the NaBPh4 solution was added dropwise to the stirred
bismuth solution. The reaction mixture was allowed to warm to
room temperature, whereupon a pale yellow solution and fine
white precipitate formed. After the mixture was stirred for 30 h,
centrifuged, and filtered, the solvent was removed under reduced
pressure to yield an off white foamy solid. Recrystallization from
THF (2 mL) at -30 °C afforded colorless 5 (312 mg, 72%) as
X-ray quality single crystals. 1H NMR (CD3CN): δ 7.61 (d, 4H,
3JH-H=7.5 Hz, m-Ar-CH), 7.52 (t, 2H, 3JH-H=7.5 Hz, p-Ar-
CH), 7.27 (bm, 8H, m-BPh4), 6.99 (t, 8H, 3JH-H=7.4 Hz, o-BPh4),
1
yields of 60-98% and were characterized using H and
13C NMR spectroscopy, elemental analysis, and X-ray
diffraction. Structural and spectroscopic details are pre-
sented in the following sections.
Structure. X-ray crystallographic data on 2-6 are sum-
marized in Tables 1 and 2 and compared below with the
previously published structure of Ar02BiCl, 1.28 Complexes
1-6 are similar in that only three of the four amine donor
arms of the two aryldiamine ligands coordinate to bismuth.
Hence, one [2,6-(Me2NCH2)2C6H3]- ligand functions as
an (N,C,N) pincer ligand through binding of N1, C1, and
N2, whereas the other coordinates in an (N,C) mode via
binding of N4 and C13.
3
6.84 (t, 4H, JH-H=7.4 Hz, p-BPh4), 3.74 (s, 8H, NCH2), 2.27
[s, 24H, N(CH3)2]. 13C (CD3CN): δ 189.5 (Bi-C), 165.0 (4-line
multiplet, JC-B = 49.1 Hz, B-C), 151.3 (quaternary o-Ar-C),
1
137.0 (m-BPh4), 131.4 (m-Ar-CH), 130.7 (p-Ar-CH), 126.9
(o-BPh4), 123.0 (p-BPh4), 69.0 (NCH2), 47.0 [N(CH3)2]. Mp
154-156 °C. Anal. Calcd for C48H58BBiN4: C, 63.29; H, 6.43;
N, 6.15. Found: C, 63.10; H, 6.31; N, 6.07.
Compound 5 can also be synthesized by treatment of 2 with 1
equiv of [HNEt3][BPh4] in toluene. However, since the isolated
product contained residual 2 that could not be removed, even
with multiple washings, this method was not pursued further.
In complexes 1, 2 (Figure 1), 3 (Figure 2), and 4 (Figure
3) of general formula Ar02BiX where X = Cl, CH2CHd
CH2, OtBu, and OC6H3Me2-2,6, respectively, the X
ligand completes the coordination sphere such that six
donor atoms surround the bismuth in a highly distorted
octahedral geometry. The three nitrogen donor atoms are
facial such that two are trans to the two aryl ligands and
the third is trans to the X ligand. The distortion in the
octahedral geometry can be seen in the deviation of the
137.93(6)-166.82(10)° N-Bi-C and N-Bi-X angles
from 180° in a regular octahedron. The cis angles in these
structures range from 59.95(6)-135.14(4)°, that is, sig-
nificantly different from the octahedral 90°. In 2 the “cis”
N-Bi-N angles are 94.03(5), 114.03(5), and 134.87(5)°
compared to 65.61(7)-101.95(8)° for all the other cis
angles in this complex. This means that looking down
the pseudo 3-fold axis through Bi and perpendicular to
the plane of N1, N2, and N4, the three nitrogen ligands
are distorted away from octahedral more than the other
three ligands C1, C13, and C25. Hence, the most likely
place for lone pair electron density to be stereochemically
active would be in the middle of the triangle defined by the
three nitrogen atoms.
t
{[2,6-(Me2NCH2)2C6H3]2Bi}[OC6H3 Bu2-2,6], 6. A solution
of [2,6-(Me2NCH2)2C6H3]2BiCl (100 mg, 0.16 mmol) was added
t
to a solution of KOC6H3 Bu2-2,6 (39 mg, 0.16 mmol) in THF
(5 mL each) at room temperature. A dark yellow solution formed
immediately, accompanied by a fine white precipitate. The mix-
ture was stirred for 3 h, centrifuged, and filtered. The solvent was
removed under reduced pressure yielding a yellow solid which
was recrystallized from THF (2 mL) at -30 °C to afford yellow 6
(110 mg, 86%) as single crystals suitable for an X-ray diffrac-
tion study. 1HNMR(CD3CN): δ7.60 (bsv1/2=26 Hz, 4H, m-Ar-
3
CH), 7.51 (bs, 2H, p-Ar-CH), 6.76 (d, 2H, JH-H = 7.6 Hz,
m-OAr-CH), 5.81 (t, 1H, 3JH-H=7.6 Hz, p-OAr-CH), 3.73 (bs
v
1/2=25 Hz, 8H, NCH2), 2.26 [bs v1/2= 26 Hz, 24H, N(CH3)2],
1.37 [s, 18H, OAr-C(CH3)3]. 13C (CD3CN): δ 188.2 (Bi-C), 169.1
and 136.2 (quaternary i/o-OAr-C), 149.8 (quaternary o-Ar-C),
130.1 (v1/2= 22 Hz, m-Ar-CH), 129.4 (v1/2=18 Hz, p-Ar-CH),
123.2 (m-OAr-CH), 105.1 (p-OAr-CH), 67.6 (NCH2), 45.7 [v1/2=
27 Hz, N(CH3)2], 34.5 [C(CH3)3], 29.5 [C(CH3)3]. 1H NMR
3
(C4D8O): δ 7.60 (d, 4H, JH-H = 7.4 Hz, m-Ar-CH), 7.44 (t,
2H, 3JH-H=7.4 Hz, p-Ar-CH), 6.73 (d, 2H, 3JH-H=7.5 Hz, m-
OAr-CH), 5.84 (t, 1H, 3JH-H=7.5 Hz, p-OAr-CH), 3.75 (s, 8H,
NCH2), 2.28 [s, 24H, N(CH3)2], 1.39 [s, 18H, OAr-C(CH3)3]. 13
C
All eight Bi-C(aryl) distances in 1-4 fall in the narrow
(C4D8O): δ 188.8 (Bi-C), 167.7 and 136.0 (quaternary i/o-OAr-C),
149.9 (quaternary o-Ar-C), 130.0 (m-Ar-CH), 128.9 (p-Ar-CH),
˚
range 2.278(4)-2.310(2) A. For 1, 3, and 4, the Bi-N

1516 Inorganic Chemistry, Vol. 50, No. 4, 2011
Casely et al.
Table 1. X-ray Data Collection Parameters for [2,6-(Me2NCH2)2C6H3]2Bi(CH2CHdCH2), 2, [2,6-(Me2NCH2)2C6H3]2Bi(OtBu), 3, [2,6-(Me2NCH2)2C6H3]2Bi(OC6H3Me2-
2,6), 4, {[2,6-(Me2NCH2)2C6H3]2Bi}[BPh4], 5, and {[2,6-(Me2NCH2)2C6H3]2Bi}[OC6H3tBu2-2,6], 6
2
3
4
5
6
empirical formula
formula weight
temperature (K)
crystal system
space group
C
27H43BiN4
C28H47BiN4O
664.68
93(2)
monoclinic
P21/n
16.5591(9)
10.7987(6)
16.9911(9)
90
94.5780(7)
90
3028.6(3)
4
1.458
5.846
0.0150
0.0354
C32H47BiN4O • 1/2 C6H14
C48H58BBiN4
910.77
148(2)
monoclinic
P21/c
15.9493(9)
13.0162(7)
20.7895(11)
90
101.1256(7)
90
4234.8(4)
4
1.429
4.201
0.0208
0.0528
C38H59BiN4O
796.87
143(2)
triclinic
P1
9.6863(6)
10.5364(6)
18.3169(11)
92.3499(7)
97.9458(7)
99.2711(6)
1823.43(19)
2
632.63
148(2)
monoclinic
P21/c
9.9777(5)
17.5299(9)
16.9668(8)
90
106.7253(5)
90
2842.1(2)
4
1.479
755.80
98(2)
monoclinic
P21/c
9.5132(5)
14.5142(8)
25.4014(13)
90
91.4692(6)
90
3506.2(3)
4
1.432
˚
a (A)
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
volume (A )
Z
3
˚
F
calcd (Mg/m3)
1.451
4.868
0.0289
0.0706
μ (mm-1
)
6.223
0.0182
0.0445
5.059
0.0183
0.0446
R1 [I > 2σ(I)]a
wR2 (all data)a
P
P
P
P
a Definitions: R1 = ||Fo| - |Fc||/ |Fo|,wR2 = [ w(Fo2 - Fc2)2/ w(Fo2)2]1/2
.
Table 2. Metrical Data for [2,6-(Me2NCH2)2C6H3]2Bi(CH2CHdCH2), 2, [2,6-(Me2NCH2)2C6H3]2Bi(OtBu), 3, [2,6-(Me2NCH2)2C6H3]2Bi(OC6H3Me2-2,6), 4,
{[2,6-(Me2NCH2)2C6H3]2Bi}[BPh4], 5, and {[2,6-(Me2NCH2)2C6H3]2Bi}[OC6H3tBu2-2,6], 6
2
3
4
5
6
X = C25
X = O1
X = O1
X = O1
Bi-C1/-C13
Bi1-X
2.304(2)/ 2.310(2)
2.331(2)
3.102(2)
3.064(2)
4.998
3.176(2)
2.283(2)/ 2.314(2)
2.151(1)
2.916(2)
3.064(2)
5.015
2.309(2)/ 2.308(2)
2.228(1)
2.708(2)
3.552(2)
5.043
2.210(2)/ 2.283(2)
2.210(3)/ 2.311(3)
3.455(2)
2.579(3)
2.494(3)
4.218
Bi1-N1
2.509(2)
2.552(2)
4.329
Bi1-N2
Bi1-N3
Bi1-N4
3.321(2)
1.426(2)
3.052(2)
1.337(3)
3.003(2)
3.025(3)
1.293(4)
O1-C25
C25-C26
1.453(4)
1.282(5)
96.70(8)
66.48(7)
74.83(7)
114.03(5)
94.30(5)
65.61(7)
151.41(7)
134.87(5)
158.27(7)
67.24(7)
101.95(8)
87.97(8)
157.39(7)
74.95(7)
92.36(7)
(C26-C27)
C1-Bi1-C13
N1-Bi1-C1
N1-Bi1-C13
N1-Bi1-N2
N1-Bi1-N4
N2-Bi1-C1
N2-Bi1-C13
N2-Bi1-N4
N4-Bi1-C1
N4-Bi1-C13
X-Bi1-C1
X-Bi1-C13
X-Bi1-N1
X-Bi1-N2
X-Bi1-N4
Bi1-X-C25
97.58(6)
67.57(5)
77.45(5)
110.64(4)
95.54(4)
64.56(5)
152.99(5)
135.14(4)
159.41(5)
66.15(5)
92.99(5)
91.22(5)
155.52(5)
70.84(5)
99.62(4)
123.79(10)
97.88(7)
70.50(6)
85.50(6)
114.74(5)
105.79(5)
59.95(6)
137.93(6)
131.80(5)
165.41(6)
67.57(6)
95.91(6)
87.38(6)
163.57(5)
62.66(5)
85.02(5)
126.12(14)
106.83(8)
73.71(7)
95.34(7)
146.12(6)
82.61(5)
72.42(7)
93.54(7)
130.97(5)
155.73(7)
69.64(7)
102.07(12)
71.23(11)
90.90(10)
144.97(9)
132.96(8)
74.27(11)
102.11(10)
81.85(8)
151.38(10)
67.49(10)
93.21(9)
164.27(9)
97.61(8)
78.28(7)
97.21(7)
149.8(2)
bonds trans to aryl ligands are in the range 3.052(2)-3.552-
in the literature to compare with 2: Bi(C3H5)3, a liquid at
room temperature,34 and [C(SiMe3)2C5H4N-2]BiCl-
[CH2CHdC(SiMe3)C5H4N-2],35 which was isolated as a
decomposition product from the reaction of BiCl3 and 2
equiv of Li[C(SiMe3)2C5H4N-2] in THF. The Bi-C(allyl)
bond length in the latter compound was measured as
t
˚
(2) A, but the Bi1-N1 bonds trans to the Cl, O Bu, and
OC6H3Me2-2,6 ligands are significantly shorter, 2.699(3),
˚
2.916(2), and 2.708(2) A, respectively. For 2, however, the
˚
3.102(2) A Bi1-N1 bond trans to the allyl ligand is not the
shortest Bi-N distance since the Bi1-N2 distance trans to
an aryl ligand is 3.064(2) A. This is consistent with the fact
˚
˚
2.23(2) A.
[2,6-(Me2NCH2)2C6H3]2Bi(O Bu), 3. The 2.151(1) A
t
˚
that the allyl carbon donor atom would be more similar to
the aryl carbon in its effect on the trans nitrogen ligand. The
Bi1-O1(OtBu) bond length in 3 is similar to the 2.117(4)
t
37
˚
˚
and 2.159(5) A analogs in {(C5H4Me)2Mo[Bi(O Bu)2]2},
and is within the broad range of distances found for these
2.331(2) A Bi-C(allyl) distance is similar to0 the 2.304(2)
[2,6-(Me2NCH2)2C6H3]2Bi(CH2CHdCH2), 2. Only
two other bismuth allyl compounds have been reported
˚
and 2.310(2) A Bi-C(aryl) distances of the Ar ligands in 2.
(35) Jones, C.; Engelhardt, L. M.; Junk, P. C.; Hutchings, D. S.;
Patalinghug, W. C.; Raston, C. L.; White, A. H. J. Chem. Soc., Chem.
Commun. 1991, 1560.
(34) Hyeon, J.-Y.; Lisker, M.; Silinskas, M.; Burte, E.; Edelmann, F. T.
Chem. Vap. Deposition 2005, 11, 213.
(36) Farrugia, L. J. J. Appl. Crystallogr. 1997, 30, 565.

Article
Inorganic Chemistry, Vol. 50, No. 4, 2011 1517
Figure 3. ORTEP representation of [2,6-(Me2NCH2)2C6H3]2Bi(OC6-
H3Me2-2,6), 4, drawn at the 50% probability level. Hydrogen atoms
and solvent are omitted for clarity.
Figure 1. ORTEP36 representation of [2,6-(Me2NCH2)2C6H3]2Bi(CH2-
CHdCH2), 2, drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
Figure 4. ORTEP representation of {[2,6-(Me2NCH2)2C6H3]2Bi}-
[BPh4], 5, drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
these complexes are 126.12(14)°, 123(4)° (average), and
122.8(3)-127.5(2)°, respectively.
{[2,6-(Me2NCH2)2C6H3t]2Bi}[BPh4], 5, and {[2,6-(Me2-
NCH2)2C6H3]2Bi}[OC6H3 Bu2-2,6], 6. The [Ar02Bi][X]
complexes 5 (Figure 4) and 6 (Figure 5) differ from the
Ar02BiX compounds, 1-4, in that the X ligands are outer
sphere anions. As a consequence, there are only five donor
atoms around bismuth. Since the largest ligand-Bi-
ligand angles in 5 and 6 are the 155.73(7)° and 151.4(1)°
C1-Bi-N4 angles, respectively, and since C1, N1, and
N2 are nearly coplanar with bismuth in a plane that
Figure 2. ORTEP representation of [2,6-(Me2NCH2)2C6H3]2Bi-
(OtBu), 3, drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity.
˚
bonds, for example, 2.215(5) A in {(C5H4Me)2Mo[ μ-Bi-
(OtBu)]}2,37 and 2.061(3) A in (calix[4]arene)BiO Bu.38 The
t
˚
123.79(10)° Bi1-O1-C25 angle in 3 is in the range of
values found for the examples above, 128.3(4)°, 121.9(4)°,
118.5(5)°, and 121.4(2)°, respectively.
contains the C1 N4 vector, there is no regular five
3 3 3
coordinate geometry that closely matches the ligand
arrangement in these complexes. A distorted octahedral
geometry with a vacant vertex (Ψ-octahedral) may be the
best description of these complexes.41 The structure of the
cation in [Ar02Bi][W(CO)5Cl], which was reported online
while this paper was under review,42 is similar to the
cation in 5.
[2,6-(Me2NCH2)2C6H3]2Bi(OC6H3Me2-2,6), 4. The
˚
2.228(1) A Bi1-O1(OAr) bond length in the aryloxide
complex 4 is longer than that observed in 3, in Bi-
39
˚
(OC6H3Me2-2,6)3 [2.085(11)-2.097(9) A], and in the
repeat unit of polymeric {Bi[OC6H3-2-OMe-4-(CH2CHd
CH2)]3}n [2.135(3)-2.201(3) A].40 The Bi-O-C angles in
˚
In contrast to 1-4, there are two types of Bi-C distances:
˚
the 2.283(2) and 2.311(3) A Bi-C13 distances in 5 and 6,
(37) Roggan, S.; Limberg, C.; Ziemer, B.; Brandt, M. Angew. Chem., Int.
Ed. 2004, 43, 2846.
(38) Liu, L.; Zakharov, L. N.; Golen, J. A.; Rheingold, A. L.; Hanna,
T. A. Inorg. Chem. 2008, 47, 11143.
respectively, are similar to those in 1-4, whereasthe2.210(2)
and 2.210(3) A Bi-C1 distances, respectively, are shorter.
˚
(39) Evans, W. J.; Hain, J. H.; Ziller, J. W. J. Chem. Soc., Chem. Commun.
1989, 1628.
(40) Kou, X.; Wang, X.; Mendoza-Espinosa, D.; Zakharov, L. N.;
Rheingold, A. L.; Watson, W. H.; Brien, K. A.; Jayarathna, L. K.; Hanna,
T. A. Inorg. Chem. 2009, 48, 11002.
(41) Davidovich, R. L.; Stavila, V.; Marinin, D. V.; Voit, E. I.; Whitmire,
K. H. Coord. Chem. Rev. 2009, 253, 1316.
(42) Breunig, H. J.; Nema, M. G.; Silvestru, C.; Soran, A. P.; Varga, R. A.
Dalton Trans. 2010, 39, 11277.

1518 Inorganic Chemistry, Vol. 50, No. 4, 2011
Casely et al.
and X=BF4, PF6;46,47 Donor=PPh3 and X = PF648] are
also known and have been structurally characterized.
The structure of 6 differs from that of 5 in that the oxygen
of the counteranion points toward a vacant site on bismuth.
˚
The 3.455(2) A Bi1 O1 distance is much longer than the
˚
3 3 3
2.151(1) and 2.228(1) A Bi-O distances in 3 and 4,
respectively, although it is still within the sum of the van
˚
der Waals radii for bismuth and oxygen (3.80 A), a
similar situation to that observed for the cationic complexes
29,30
containing Bi F interactions. For comparison, another
3 3 3
bismuth complex with 2,6-di-tert-butyl aryloxide ligands,
Bi[OC6H2 Bu3-2,4,6]2Cl,40 has an average Bi-O bond
t
˚
length of 2.093(3) A, well within the sum of covalent radii
30
˚
for bismuth and oxygen (2.18 A).
˚
The 1.293(4) A C25-O1 bond length in 6 is shorter than
˚
˚
the 1.337(3) A distance observed in 4 and the 1.345(6) A
value in [LiOArtBu,Me(OEt2)]2,49 but it is similar to values
found in complexes containing aryloxide anions not at-
Figure 5. ORTEP representation of {[2,6-(Me2NCH2)2C6H3]2Bi}[OC6-
H3 Bu2-2,6], 6, drawn at the 50% probability level. Hydrogen atoms are
omitted for clarity, except H34b and H12b.
t
˚
tached to metal ions such as 1.302(3) A in {(C5Me5)2-
O
[iPrNC(Me)NiPr]U}(ArtBu,Me
˚
HOArtBu,Me 50
)
and
3 3 3
1.306(2) A in [HC(MesNCH)2][OArtBu,Me],51 both of which
are stabilized by hydrogen bonding. There may be a long-
˚
Similarly, the 3.003(2) and 3.025(3) A Bi-N4 distances in 5
and 6, respectively, for the amine trans to C1 are similar to
those in 1-4, but the Bi-N1 and Bi-N2 distances are much
˚
range contact in 6 between Bi1 H34b (3.1822 A) and a
3 3 3
˚
˚
shorter, 2.494(3)-2.579(3) A. Hence, both lower coordinate
complexes have some closer metal ligand contacts.
weak C-H12b O1 hydrogen bond of 2.476 A, which is
3 3 3
longer than OH O and NH O hydrogen bonds, but
3 3 3
3 3 3
typical for weaker CH O interactions.52 The Bi1-
In complexes 5 and 6, neither N1 nor N2 has a ligand
directly trans: the N1-Bi1-N2 angles are 146.12(6)° and
144.97(9)°, respectively. These angles are similar to the
analogous 144.18(11)° angle in Ar0BiCl2.28 Further simi-
larities are seen with five-coordinate Ar0BiCl2 in that it
3 3 3
H34b-C34 and O1-H12b-C12 angles are 160.25 and
156.73°, respectively.
NMR Studies. NMR data on 2-6 are shown in Table 3.
The resonances of the Ar0 ligand in each complex are similar.
One resonance that differentiates the Ar02BiX complexes
2, 3, and 4 from the [Ar02Bi][X] complexes 5 and 6 is the
p-Ar0-CH resonances which are within the range 7.15-
7.36 ppm for the former complexes and 7.51-7.52 ppm
for the latter.
˚
has 2.561(3) and 2.570(4) A Bi-N(amine) distances
28
˚
and a 2.224(4) A Bi-C(aryl) bond length.
The (BPh4)- anion in 5 acts as an outer sphere anion
and has no close interactions with the bismuth center. A
similar outer sphere unsolvated complex was previously
structurally characterized with an unsymmetrically sub-
stituted 1,4,7-triazacyclononane ligand, [{cyclo[N(CH2)2]3-
1-(CH2COO)-4,7-[2-CH2(MeNCHCHN)]2}BiCl][BPh4].43
However, most of the other bismuth cations reported in
the literature have some interaction of either solvent or
the counteranion with the metal center. For example, in
In 2, the methylene groups of the ligand arms are split
into two doublets at 3.33 and 3.14 ppm (2JH-H =13.2
Hz). A variable temperature NMR study on 2 in MeCN-
d3 up to 80 °C elicited no change in the 1H NMR
spectrum. In contrast, for 3 in benzene-d6, the methylene
groups appear as two broad resonances, one of which
manifests as a doublet (2JH-H = 12.3 Hz). Unfortu-
nately, this complex decomposes upon heating and is
insoluble in MeCN-d3, so direct comparison was not
possible. The broadening seen in benzene-d6 may result
from exchange of the three coordinated amines with the
amine that is not oriented toward bismuth. However, in
4, only a single resonance for the methylene groups is
observed at 3.60 ppm. Single methylene resonances are
also found for 5 and 6, but the amine arms in these
compounds are all oriented toward bismuth in the solid
state structures. In the case of 6, the Ar0 ligand reso-
nances are substantially broadened in MeCN-d3. Heat-
ing the sample to 80 °C elicited no change, but changing
{[2-(Me2CH2)C6H4]2Bi}{PF6},44 there is a short Bi
F
3 3 3
contact to one of the fluorine atoms in the (PF6)- counter-
ion. Similarly, in [tBuN(CH2C6H4)2Bi][B(C6F5)4] a vacant
site at bismuth is filled by one of the fluorine atoms of the
anion.45 The Bi F lengths in these complexes are 3.49
3 3 3
˚
and 2.971(2) A, respectively, within the sum of the van
˚
der Waals radii (3.75 A) and much longer than the range
of reported covalent Bi-F bond distances (2.088(8)-
2.59(1) A). Upon addition of neutral donor solvents,
45
˚
this interaction is displaced and a range of solvated
cations, [tBuN(CH2C6H4)2BiL][B(C6F5)4] (L=MeCHO,
MeOH, MeCN, and CH2Cl2), were isolated and structu-
rally characterized.45 Cationic bismuth complexes of for-
mula [Ph2Bi(Donor)2][X] [Donor=OP(NMe2)3, OPPh3,
(48) Kilah, N. L.; Petrie, S.; Stranger, R.; Wielandt, J. W.; Willis, A. C.;
Wild, S. B. Organometallics 2007, 26, 6106.
(49) Cetinkaya, B.; Gumrukcu, I.; Lappert, M. F.; Atwood, J. L.; Shakir,
R. J. Am. Chem. Soc. 1980, 102, 2086.
(50) Evans, W. J.; Walensky, J. R.; Ziller, J. W. Chem. Commun. 2009,
7342.
(43) Di Vaira, M.; Mani, F.; Stoppioni, P. Eur. J. Inorg. Chem. 1999, 833.
(44) Carmalt, C. J.; Walsh, D.; Cowley, A. H.; Norman, N. C. Organo-
metallics 1997, 16, 3597.
(45) Bao, M.; Hayashi, T.; Shimada, S. Organometallics 2007, 26, 1816.
(46) Carmalt, C. J.; Farrugia, L. J.; Norman, N. C. J. Chem. Soc., Dalton
Trans. 1996, 443.
(51) Cowan, J. A.; Clyburne, J. A. C.; Davidson, M. G.; Harris, R. L. W.;
Howard, J. A. K.; Kupper, P.; Leech, M. A.; Richards, S. P. Angew. Chem.,
Int. Ed. 2002, 41, 1432.
(47) Carmalt, C. J.; Norman, N. C.; Orpen, A. G.; Stratford, S. E.
J. Organomet. Chem. 1993, 460, C22.
(52) Steiner, T. Chem. Commun. 1997, 727.

Article
Inorganic Chemistry, Vol. 50, No. 4, 2011 1519
Table 3. Selected 1H and 13C NMR Chemical Shift (ppm), J Coupling Constant, and Peak Width (Hz) Data for Complexes 2-6 in CD3CN
complex
m-Ar-CH
p-Ar-CH
NCH2
N(CH3)2
Bi-C(Ar)
2
7.25, d, 3J = 7.4
7.15, t, 3J = 7.4
3.33, d, 2J = 13.2
3.14, d, 2J = 13.2
3.75, bs
1.97
2.06
167.7
3a
7.43, bd
7.21, t, 3J = 7.4
185.4
3.39, bs, 2J = 12.3
3.60
3.74
4
5
6
7.53, d, 3J = 7.5
7.61, d, 3J = 7.5
7.60, bs v1/2 = 26
7.36, t, 3J = 7.5
7.52, t, 3J = 7.5
7.51
2.03
2.27
192.0
189.5
188.2
3.73, bs v1/2 = 25
2.26, bs v1/2 = 26
a 3 run in C6D6.
the solvent to THF-d8 produces a much more resolved
spectrum.
To the best of our knowledge, there are no examples of
structurally characterized (C5Me5)2Ln(OtBu) complexes,
although examples of [(C5Me5)Ln(OtBu)( μ-OtBu)]2 (Ln =
Ce64 and Eu65) are known. The Ln-O-C angles for the
terminal alkoxide ligands in these cyclopentadienyl complexes
are 176.9(7)° and 174.5°, respectively, considerably more
linear than the corresponding 123.79(10)° angle observed in
3. These angles would allow the oxygen atom to donate more
electron density to the more Lewis acidic lanthanide metal
centers. The closest (C5Me5)2Ln(OArR) complexes to 4 are
the samarium complexes (C5Me5)2Sm(OC6HMe4-2,3,5,6)66
The 1H and 13C NMR spectra of 2 indicate that the allyl
ligand binds in an η1-mode in solution as was found in the
solid state. The splittings and couplings are characteristic
of η1-allyl ligands.53 The NMR data of the other X
ligands in compounds 2-6 are unexceptional.
Discussion
The syntheses shown in Scheme 1 have similarities between
bismuth and lanthanides in that they involve ionic metathesis
between metal chlorides and alkali and alkaline earth metal
reagents. An important difference is that the bismuth starting
material, Ar02BiCl, 1, is a monomer with only three amines
coordinated (like 2, 3, and 4), whereas the analogous bis-
(pentamethylcyclopentadienyl) lanthanide chloride exists
as a Lewis acid base adduct with KCl, (C5Me5)2LnCl2K-
(THF)2.54,55 Although [(C5Me5)2LnCl]x complexes are
known, they are not easy to generate and are generally at
least dimeric.56,57 In contrast to Ar02BiCl, the (C5Me5)2LnCl
unit typically either adds a ligand such as a solvent like THF
or binds a residual alkali metal halide, that is, it is a much
stronger Lewis acid. As described in the following sections,
this difference between bismuth and the lanthanides became
established as a trend in this study.
Although the allyl complex 2 is synthesized in the same
manner as (C5Me5)2Ln(η3-C3H5) complexes,58-63 its η1-
structure is quite different. Structural and NMR studies of
the eight (C5Me5)2Ln(η3-C3H5) complexes in the literature
indicate that all have the allyl ligand bound in an η3-manner.
Since allyl is a rather small chelating ligand, it should be
sterically possible for it to bind η3 to bismuth. However, this
is not observed.
and (C5Me5)2Sm(OC6H2 Bu3-2,4,6).67 The latter complexes
t
have 172.3(13)° and 165.8(5)° Sm-O-C angles, respectively,
that again are larger than the analogous angle in the bismuth
aryloxide, 4, of 126.12(14)°.
Complex 5 differs from [(C5Me5)2Ln][( μ-Ph)2BPh2] com-
plexes in both synthesis and structure. [(C5Me5)2Ln][( μ-
Ph)2BPh2] complexes are not known to form by ionic
metathesis between NaBPh4 and chloride precursors. Instead,
they are typically generated from [HNEt3][BPh4] and(C5Me5)2-
Ln(C3H5) complexes in a halide free environment.58,62 An
analogous bismuth reaction occurs in the conversion of 2 to 5.
The structural difference between [(C5Me5)2Ln][( μ-Ph)2-
BPh2] and 5 is that some of the C-H bonds of the phenyl
groups of the (BPh4)- anion are oriented toward the Lewis
˚
acidic lanthanide centers at distances within 0.12 A of
a typical Ln-C(C5Me5) bond distance. In contrast, the
(BPh4)- ligand in 5 is neither close nor oriented toward
the bismuth center. A further difference in the lanthanide
cations is that addition of any coordinating solvent, L, to
[(C5Me5)2Ln][( μ-Ph)2BPh2] immediately displaces the
(BPh4)- anion and forms a solvated complex with an outer
sphere anion, [(C5Me5)2Ln(L)2][BPh4]. In contrast, 5 is
crystallized from THF, and no THF adduct forms.
There is no analogue to the structure of 6 in lanthanide
chemistry. The closest example is found with uranium in
{(C5Me5)2U[iPrNC(Me)NiPr-κN,N0]}(4-Me-2,6-tBu2C6-
(53) Casely, I. J.; Suh, Y. S.; Ziller, J. W.; Evans, W. J. Organometallics
2010, 29, 5209.
(54) Evans, W. J.; Keyer, R. A.; Ziller, J. W. Organometallics 1993, 12,
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3 3 3
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1520 Inorganic Chemistry, Vol. 50, No. 4, 2011
Casely et al.
(C5Me5)2LnX complexes. Since the supporting ligands in
these two sets of complexes are different, the ligand to metal
electron density donation and steric effects are not identical.
However, the differences in both of these categories should
make the lanthanides less likely to bind X, a result that is not
observed. Specifically, since the cyclopentadienyl ligands in
the (C5Me5)2LnX complexes are always bound in a penta-
hapto mode, they could provide more electron density to the
lanthanide than the pincer ligands provide to bismuth when
some of the nitrogen donor arms are not directed toward the
bismuth. This should reduce the Lewis acidity of the lantha-
nides. Likewise, the fully coordinated cyclopentadienyl li-
gands provide less room around the metal than the partially
bound pincer ligands. This should decrease the tendency for
the X ligands to coordinate, but the opposite trend is observed.
the [Ar02Bi]þ cation and the outer sphere (BPh4)- ion,
whereas the lanthanide cations, [(C5Me5)2Ln]þ, orient to
interact with two of thephenylrings of the tetraphenylborate.
Similarly, the [Ar02Bi]þ cation does not bind THF, whereas
the lanthanide cation readily forms [(C5Me5)2Ln(THF)x]þ
species. Evidently, the charge-to-radius ratio is not the
dominating feature in this chemistry. The markedly different
chemistry can be understood in terms of the differences in
electronegativity and the presence of an inert pair of electrons
on bismuth. The Bi3þ ion in Ar02BiX complexes is much less
Lewis acidic than Ln3þ ions in (C5Me5)2LnX species, and this
significantly affects both reactivity and structure.
Acknowledgment. For support, we thank the Idaho
National Laboratory and the Chemical Sciences, Geo-
sciences, and Biosciences Division of the Office of Basic
Energy Sciences of the Department of Energy. We also
thank Dr. Michael K. Takase for assistance with X-ray
crystallography.
Conclusion
Despite identical charge and similar ionic radii, Bi3þ and
Ln3þ ions display significantly different chemistry in their
interactions with X ligands in Ar02BiX and (C5Me5)2LnX
complexes. When X = allyl, bismuth adopts η1 binding
despite room to form the η3-mode always found with the
lanthanides. When X=BPh4, there is no interaction between
Supporting Information Available: CIF files giving crystal-
lographic data for all complexes. This material is available free
of charge via the Internet at http://pubs.acs.org.