New types of group 4 and 13 metal complexes stabilized by homo- or hetero-donor functionalized dicarbollide ligands: Syntheses, characterizations, and structural studies of [{η5-C2B9H 9(D)}(η1-NMe2CH2)]M(NMe 2)2 (D = CH2NMe2, PPh2; M = Ti, Zr)

Article abstract of DOI:10.1021/om100199n

A series of group 4 and 13 metal complexes coordinated to either a homo- or hetero-donor and a dicarbollyl ligand derived from N,N′- or P,N-chelated ligands were synthesized and characterized. Two homo- and hetero-donor tethered ligands of the type 7,8-(Me₂NCH₂)(μ-H)(Me ₂NCH₂)-7,8-C₂B₉H₁₀ (Dcab^NNH, 3) and 7-PPh₂-8-Me₂NHCH ₂-7,8-C₂B₉H₁₀ (Dcab^PNH, 6) were prepared using the standard deborination methods from 1,2-(NMe ₂CH₂)₂-1,2-C₂B₁₀H ₁₀ (2) and 1-PPh₂-2-Me₂NCH₂-1,2- C₂B₁₀H₁₀ (5), respectively. Subsequent reactions of 3 with M(NMe₂)₄ (M = Ti, Zr) produced single nitrogen donors involving φ,δ-dicarbollides of the type [{- ⁵-C₂B₉H₉(CH₂NMe ₂)}(-¹-NMe₂CH₂)]M(NMe ₂)₂ (M = Ti (4), Zr (5)). Structurally similar nitrogen donor stabilized φ,δ-dicarbollides of the type [{-⁵-C ₂B₉H₉(PPh₂)}(-¹-NMe ₂CH₂)]M(NMe₂)₂ (M = Ti (7), Zr (8)) were produced from the reaction of 6 with M(NMe₂)₄ (M = Ti, Zr). When group 13 metals were attempted with dissimilar ligands, 3 and 6, δ,δ-type complexes were formed with the engagement of two tethered donors at the dicarbollide ligand in an exo-polyhedral manner irrespective of the dissimilar donor properties, nitrogen or phosphine. As a result, a series of group 13 metal complexes bearing ligands 3 and 6, [(-¹-NMe ₂CH₂)₂C₂B₉H ₁₀]MMe₂ (M = Al (11), Ga (12)) and [(-¹- PPh₂)(-¹-NMe₂CH₂)C₂B ₉H₁₀]MMe₂ (M = Al (13), Ga (14)), were prepared by reacting 3 and 6 with trimethylaluminum (TMA) and trimethylgallium (TMG), respectively. New types of φ,δ- and δ,δ-coordination were established by extensive structural studies of each metal complex comprising N,N′- or P,N-chelated dicarbollide: 7, 9, 10, 11, 13, and 14.

Full text of DOI:10.1021/om100199n

2348 Organometallics 2010, 29, 2348–2356
DOI: 10.1021/om100199n
New Types of Group 4 and 13 Metal Complexes Stabilized by
Homo- or Hetero-Donor Functionalized Dicarbollide Ligands: Syntheses,
Characterizations, and Structural Studies of [{η5-C2B9H9(D)}-
(η1-NMe2CH2)]M(NMe2)2 (D=CH2NMe2, PPh2; M=Ti, Zr)
and [(η1-D)(η1-NMe2CH2)C2B9H10]MMe2 (D=CH2NMe2, PPh2;
M=Al, Ga)
Jong-Dae Lee,*,† Ha-Yeon Kim,† Won-Sik Han,‡ and Sang Ook Kang*,‡
‡
†Department of Chemistry, Chosun University, Gwangju 501-759, Korea, and Department of Advanced
Materials Chemistry, Sejong Campus, Korea University, Chungnam 339-700, Korea
Received March 14, 2010
A series of group 4 and 13 metal complexes coordinated to either a homo- or hetero-donor and a
dicarbollyl ligand derived from N,N0- or P,N-chelatedligands were synthesized and characterized. Two
homo- and hetero-donor tethered ligands of the type 7,8-(Me2NCH2)(μ-H)(Me2NCH2)-7,8-C2B9H10
(DcabNNH, 3) and 7-PPh2-8-Me2NHCH2-7,8-C2B9H10 (DcabPNH, 6) were prepared using the stan-
dard deborination methods from 1,2-(NMe2CH2)2-1,2-C2B10H10 (2) and 1-PPh2-2-Me2NCH2-1,2-
C2B10H10 (5), respectively. Subsequent reactions of 3 with M(NMe2)4 (M=Ti, Zr) produced single
nitrogen donors involving π,σ-dicarbollides of the type [{η5-C2B9H9(CH2NMe2)}(η1-NMe2CH2)]M-
(NMe2)2 (M=Ti (4), Zr (5)). Structurally similar nitrogen donor stabilizedπ,σ-dicarbollides of the type
[{η5-C2B9H9(PPh2)}(η1-NMe2CH2)]M(NMe2)2 (M=Ti (7), Zr (8)) were produced from the reaction of
6 with M(NMe2)4 (M=Ti, Zr). When group 13 metals were attempted with dissimilar ligands, 3 and 6,
σ,σ-type complexes were formed with the engagement of two tethered donors at the dicarbollide ligand
in an exo-polyhedral manner irrespective of the dissimilar donor properties, nitrogen or phosphine. As
a result, a series of group 13 metal complexes bearing ligands 3 and 6, [(η1-NMe2CH2)2C2B9H10]MMe2
(M=Al (11), Ga (12)) and [(η1-PPh2)(η1-NMe2CH2)C2B9H10]MMe2 (M=Al (13), Ga (14)), were pre-
pared by reacting 3 and 6 with trimethylaluminum (TMA) and trimethylgallium (TMG), respectively.
New types of π,σ- and σ,σ-coordination were established by extensive structural studies of each metal
complex comprising N,N0- or P,N-chelated dicarbollide: 7, 9, 10, 11, 13, and 14.
Introduction
In the search fornew types of ligand systems capable of π,σ-
coordination, the dicarbollyl moiety appears to be a suitable
candidate as a π-bonding group instead of the cyclopentadie-
nyl ligand (Cp). The dicarbollide dianion, (C2B9H11)2-, is a
versatile ligand that is an isolobal inorganic analogue of the
Cp- ion. The preparation of π,σ-coordination complexes
with this dicarbollyl functionality is a challenging project,
because the incorporation of a dicarbollyl fragment into the
ligand frameworkwillcreate new metal/charge combinations.
The formal replacement of the monoanionic Cp- ligand in
The preparation of new types of π,σ-coordination com-
plexes with various donor groups is currently of interest in
both academia and industry because of the remarkable acti-
vity for the copolymerization of ethylene with R-olefins.1-3 The
concept“π,σ-coordination” came from a uniqueligand layout
designed from the array of two dissimilar coordinating func-
tionalities: π-cyclopentadienide and σ-amide.4-6 One such
reference is a titanium complex of the type [(η5-Me4C5)Me2Si-
(η1-t-BuN)]TiCl2, which represents a characteristic π,σ-bond-
ing interaction at the titanium metal center.
[CpMIII 2þ
]
with the isolobal, dianionic (C2B9H11)2- ligand to
fragment reduces the overall charge
give a [(C2B9H11)MIII þ
]
by one unit but leaves the gross structural and metal frontier
orbitalproperties unchanged. Furthermore, secondarymetal/
ligand interactions with σ-coordination appeared to play an
important role in improving the capability of π-bonding in a
dicarbollide unit. It should be noted that the weaker ionic
character of the pendant neutral amino group enhances the
metal’s π-binding capability with the dicarbollyl ligand
through η5 coordination.
*To whom correspondence should be addressed. Tel: þ82-41-860-
1334. Fax: þ82-41-867-5396. E-mail: sangok@korea.ac.kr.
(1) Siemeling, U. Chem. Rev. 2000, 100, 1495.
(2) Butenschon, H. Chem. Rev. 2000, 100, 1527.
(3) Li, X.; Nishiura, M.; Hu, L.; Mori, K.; Hou, Z. J. Am. Chem. Soc.
2009, 131, 13870.
(4) Bunel, E. E.; Burger, B. J.; Bercaw, J. E. J. Am. Chem. Soc. 1988,
110, 976.
(5) Shapiro, P. J.; Bunel, E. E.; Schaefer, P. J.; Bercaw, J. E.
Organometallics 1990, 9, 867.
(6) Shapiro, P. J.; Cotter, W. D.; Schaefer, W. P.; Labinger, J. A.;
Bercaw, J. E. J. Am. Chem. Soc. 1994, 116, 4623.
€
As part of our ongoing efforts to induce π,σ-bonding, a
wide variety of pendant donors have been incorporated to
r
pubs.acs.org/Organometallics
Published on Web 04/27/2010
2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 10, 2010 2349
Figure 1. Single side arm enhancing the metal’s π-bonding capability.
Scheme 1. Synthesis of 3 and π,σ-Type Group 4 Metal Complexes (7 and 8)
the parent dicarbollyl compounds.7-10 Recently, chelating
dicarbollide ligands with a nitrogen donor were investigated
in the context of the production of π,σ-group 4 metal
complexes.11-15 In such ligand systems, the amine or amide
donors were found to be the most effective ancillary func-
tionalities to form π,σ-bonds with group 4 metals. Moreover,
we recently reported the preparation of π,σ-type group 13
metal complexes,16,17 in which the amine donor was a key
ingredient that induced the primary π-interaction with di-
carbollide, as shown in Figure 1. As an extension of this
work, two donor groups with homo and hetero functional-
ities were engaged to the dicarbollide to determine the scope
of π,σ-coordination with transition and main-group metals.
Similar to monofunctionalized group 4 metal dicarbollides,
difunctionalized dicarbollyl ligand systems with N,N0 (3) and
N,P (6) tethers formed the expected π,σ-group 4 metal
complexes, whereas group 13 metals completed their tetra-
hedral geometry with σ,σ-bonding with the disubstituted
donors. Therefore, π,σ- and σ,σ-type coordination was
demonstrated in the structures of 7, 9, and 10 and 11, 13,
and 14, respectively.
Figure 2. Molecular structure of 3 with thermal ellipsoids drawn
at the 30% level. Hydrogen atoms are omitted for clarity, except
for H100 and H101 atoms.
Results and Discussion
DcabNNH (3). Treatment of o-carborane (1), 1,2-C2B10H12,
with 2 equiv of n-BuLi and then Eschenmoser’s salt, H2Cd
NMe2þI-, afforded 1,2-(Me2NCH2)2-1,2-C2B10H10 (2) in ex-
cellent yield. The complete conversion of 2 into 7,8-(Me2-
NCH2)(μ-H)(Me2NCH2)-7,8-C2B9H10 (3) was then achieved
Scheme 1 summarizes the syntheses of group 4 metal com-
plexes of the zwitterionic dicarbollyl ligand, abbreviated as
(7) Hosmane, N. S.; Maguire, J. A.; Yinghuai, Z. Main Group Chem.
2006, 5, 251.
(8) Yinghuai, Z.; Yulin, Z.; Carpenter, K.; Maguire, J. A.; Hosmane,
1
by heating in neat methanol. The H NMR spectrum of 3
N. S. J. Organomet. Chem. 2005, 690, 2802.
(9) Wang, H.; Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2008,
27, 3964.
(10) Shen, H.; Chan, H.-S.; Xie, Z. Organometallics 2007, 26, 2694.
(11) Lee, J.-D.; Lee, Y.-J.; Son, K.-C.; Cheong, M.; Ko, J.; Kang,
S. O. Organometallics 2007, 26, 3374.
(12) Lee, J.-D.; Lee, Y.-J.; Son, K.-C.; Han, W.-S.; Cheong, M.;
Ko, J.; Kang, S. O. J. Organomet. Chem. 2007, 692, 5403.
(13) Gao, M.; Tang, Y.; Xie, M.; Qian, C.; Xie, Z. Organometallics
2006, 25, 2578.
(14) Xie, Z. Coord. Chem. Rev. 2006, 250, 259.
(15) Lee, Y.-J.; Lee, J.-D.; Ko, J.; Kim, S.-H.; Kang, S. O. Chem.
Commun. 2003, 1364.
(16) Lee, J.-D.; Kim, S.-K.; Kim, T.-J.; Han, W.-S.; Lee, Y.-J.; Yoo,
D.-H.; Cheong, M.; Ko, J.; Kang, S. O. J. Am. Chem. Soc. 2008, 130,
9904.
showed a singlet pattern for methyl protons of the NMe2
group at δ 2.69. However, the methylene protons of the NCH2
group are diastereotopic, each giving rise to an AB spin pattern
(δ 3.07, 3.53). A single-crystal X-ray structural determination
of 3 revealed the formula of the salt to be the zwitterionic form
of 3 with a NMe2 unit linked to the HNMe2 cation by an
N
H-N hydrogen bond (Figure 2).
3 3 3
As shown in Scheme 1, reaction of 3 with 1 equiv of
M(NMe2)4 (M=Ti, Zr) in toluene gave the expected π,σ-co-
ordination products [{η5-C2B9H9(CH2NMe2)}(η1-NMe2-
CH2)]M(NMe2)2 (M = Ti (7), Zr (8)) in 84 and 78% yield,
respectively.
Compounds 7 and 8 were characterized by 1H, 11B,
and 13C NMR spectroscopy and elemental analyses. The
(17) Son, K.-C.; Lee, Y.-J.; Cheong, M.; Ko, J.; Kang, S. O. J. Am.
Chem. Soc. 2006, 128, 12086.

2350 Organometallics, Vol. 29, No. 10, 2010
Lee et al.
Table 1. Comparison of the NMR Spectroscopic Data for 3, 6, and 7-14
1H NMR (δ) 13C NMR (δ)
M-NMe2 M-NMe2
compd
CH2
NMe2
2.69
2.66
M-Me
CH2
65.0
64.2
NMe2
43.4
42.6
M-Me
3a
6a
7b
3.07, 3.53
2.99, 3.42
2.93, 4.12
3.56 (free)
2.94, 4.10
3.55 (free)
2.93, 4.13
2.88, 4.09
2.34, 2.51
2.40, 2.54
2.38, 3.03
2.41, 3.11
2.64, 2.88
2.33 (free)
2.64, 2.86
2.31 (free)
2.72, 2.94
2.68, 2.91
1.54
3.48, 3.66
3.45, 3.58
69.6
64.4 (free)
68.2
64.1 (free)
69.5
68.7
71.5
71.8
71.8
71.3
52.3
47.8 (free)
51.4
47.5 (free)
52.1
51.9
56.8
57.1
57.2
56.8
47.2, 52.6
48.1, 53.0
8b
9b
3.46, 3.63
3.40, 3.58
47.2, 52.3
48.0, 52.8
10b
11c
12c
13c
14c
-0.19, -0.22
0.58, 0.60
-0.21, -0.49
0.56, 0.84
-8.70, -8.71
1.48, 1.49
-7.47, -9.51
1.51, 2.97
1.62
1.61
1.66
a (CD3)2SO was used as the solvent, and the chemical shifts are reported relative to the residual H of the solvent. b C6D6 was used as the solvent, and the
chemical shifts are reported relative to the residual H of the solvent. c CD3C6D5 was used as the solvent, and the chemical shifts are reported relative to the
residual H of the solvent.
deprotonation of 3 was evident from the disappearance
of the bridge hydrogen atoms of B-H-B and N-H-N
(1H NMR, δ -2.05 and 3.49). As shown in Table 1, the 1H
NMR spectra of 7 and 8 showed two singlets (δ 3.48, 3.66
for 7 and δ 3.45, 3.58 for 8) corresponding to the methyl
protons of each M-NMe2 due to the asymmetric group 4
metal center. The coordination of the nitrogen atom of
one of the side arms to the central metal atom was evident
from the downfield shift of methyl protons in the 1H NMR
spectrum. The methylene protons of the CH2 group in 7 and
8 were diastereotopic, each giving rise to an AB pattern and a
broad singlet for the noncoordinated NCH2 unit. In com-
parison with the parent ligand 3, the downfield shift was
apparent for the methylene protons of NCH2 and methyl
protons of NMe2 in the side arms of 7 and 8, appearing at
δ 2.93, 4.12 and 2.64, 2.88 for 7 and δ 2.94, 4.10 and 2.64,
2.86 for 8, respectively. These shifts are consistent with the
findings for other intramolecularly coordinated group 4
metal complexes containing methylene spacers, such as
(DcabN)M(NMe2)2, (M = Ti, Zr).18 Their 13C NMR spectra
1
were consistent with the results derived from the H NMR
spectrum. The 11B NMR spectrum showed a similar splitting
Figure 3. Molecular structure of 7 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
pattern for the asymmetric η5-dicarbollyl metal complexes.
The solid-state IR spectra of 7 and 8 revealed a characteristic
B-H absorption at approximately 2522 cm-1
.
single bond ([η2-(C6H5CH2)2C2B9H9]Ti(NEt2)2(NHEt2),
19
2.225(2) A ) confirms that the N atom is coordinated to
A single-crystal X-ray structural determination confirmed
7 to be a monomeric π,σ-coordination complex, in which
the Ti atom is π-bound to a pentagonal C2B3 bonding face,
σ-bound to two terminal NMe2 ligands, and coordinated by
the nitrogen atom of one of the side arms in a stable piano-
stool structure (Figure 3). Table 2 gives the crystallographic
data for 7. Table 3 and the Supporting Information give
the selected bond lengths and angles. The molecule is a
Ti(NMe2)2 unit that is bonded to a η5-dicarbollyl ligand.
The dimethylamino fragment coordinates to the titanium in
the remaining basal site of the overall three-legged piano-
stool conformation, giving a five-membered ring. As shown
in Table 3, the central Ti atom is coordinated pseudotetra-
hedrally to a pair of NMe2 ligands (Ti-N(1)/N(2) =
1.889(4)/1.901(4) A), the NMe2 side arm, and the C2B3 plane
of the dicarbollyl ligand. The observation of a Ti-N(3)
˚
the metal in a strain-free manner. The central Ti atom is η5-
coordinated to the dicarbollide ligand with Ti-cage atom
distances ranging from 2.344(5) to 2.534(4) A with an
˚
˚
average value of 2.432 A, indicating a highly asymmetric
bonding mode. The titanium atom is centered approximately
over the ring, giving rise to a Ti(1)-C2B3 face (centroid)
distance of 1.964 A. Such slip distortion may be due to
˚
intramolecular interactions between Ti and the nitrogen
atom of the side arm. The corresponding C2B3(centroid)-
C(1)-C(3) angle is 146.7°. The endocyclic C(1)-C(3)-N(3)
bond angle is 107.0(3)°, which departs from the tetrahedral
sp3-C value. The π,σ-type coordination character in a series
of related compounds is probably best characterized by the
C2B3(centroid)-Ti-N(side arm) angle (R angle in Table 3),
which responds sensitively to steric and electronic geometry
changes. In 7, this angle is 97.6°. We recently communicated
3
˚
distance of 2.240(3) A, which is consistent with a Ti-N(sp )
(18) Lee, J.-D.; Lee, Y.-J.; Son, K.-C.; Cheong, M.; Ko, J.; Kang,
S. O. Organometallics 2007, 26, 3374.
(19) Kwong, W.-C.; Chan, H. -S.; Tang, Y.; Xie, Z. Organometallics
2004, 23, 4301.

Article
Organometallics, Vol. 29, No. 10, 2010 2351
syntheses and structural studies of the zwitterionic dicarbol-
lylamino ligand 3 and the corresponding titanium metal
complex 7.15
P,N-functionalized dicarbollyl systems were studied as
an extension of ligand variation. The new type of 7-PPh2-8-
Me2N(H)CH2-7,8-C2B9H10 ligand, abbreviated as DcabPN
H
(6), was prepared by applying a standard deborination pro-
cedure11 to 1-PPh2-2-Me2NCH2-1,2-C2B10H10 (5) (Scheme 2).
In this procedure, the reaction of 5 with 3 equiv of KOH in
ethanol at 78 °C and subsequent protonation with phospho-
ric acid led to the formation of the deborinated zwitterionic
compound 6. The characteristic asymmetric pattern in the
11B NMR spectrum in the range from δ -8.4 to -34.6 and
1
the presence of an absorption peak at δ -2.48 in the H
NMR spectrum indicate a B-H-B interaction on the C2B3
open face. Similar to the case for 3, the 1H NMR spectrum of
6 showed an AB spin pattern for the methylene protons at
δ 2.99 and 3.42 for the NCH2 unit and a singlet for the methyl
protons at δ 2.66 for the NMe2 unit. Figure 4 shows the
ORTEP diagram of 6. It is clearly a zwitterionic structure, in
which the N atom is bonded to two methyl groups and one
hydrogen atom.
As shown in Scheme 2, reaction of 6 with M(NMe2)4 in
toluene gave π,σ-type group 4 metal complexes of the type
[{η5-C2B9H9(PPh2)}(η1-NMe2CH2)]M(NMe2)2 (M = Ti (9),
Zr (10)) in good yield (87% for 9, 65% for 10). The 1H NMR
spectrum was similar to that of the parent ligand 6, except
for the B-H-B and N-H proton resonances centered at
δ -2.48 and 8.08, respectively. The 1H NMR spectra of 9 and
10 revealed a pair of singlets for the methyl protons of the
M-NMe2 group due to the asymmetric metal center, cen-
tered at δ 3.46, 3.63 (9) and δ 3.40, 3.58 (10), respectively. The
methylene protons of the NCH2 unit in 9 and 10 were
diastereotopic, each giving rise to an AB spin pattern. In
comparison with the parent ligand 6, the downfield shift was
apparent for the methylene protons of NCH2 and methyl
protons of NMe2 in the side arms of 9 and 10, appearing at δ
2.93, 4.13 and 2.72, 2.94 for 9 and δ 2.88, 4.09 and 2.68, 2.91
for 10, respectively. Their 13C NMR spectra are consistent
1
with the H NMR data. The 11B NMR spectra exhibited
splitting patterns similar to those for asymmetric η5-dicar-
bollyl metal complexes. The solid-state IR spectra of 9 and 10
showed characteristic B-H absorptions at approximately
2521 cm-1
.
An X-ray structural analysis of 9 showed that the Ti atom
exhibited π,σ-type coordination with difunctional dicarbol-
lide, having a π-bonding mode with the C2B3 open cage and a
σ-bonding mode with the NMe2 side arm (Figure 5). Table 2
gives the crystallographic data for 9. Table 3 and the Sup-
porting Information give selected bond lengths and angles.
The structure of 9 is similar to that of 7, except for the pre-
sence of an uncoordinated phosphine tether. The Ti-N(2)/
˚
N(3) distances are 1.910(3)/1.889(3) A, and the Ti-N(1)
5
˚
distance is 2.276(3) A. The central Ti atom is η -coordinated
to the dicarbollide ligand, where Ti-cage atom distances
range from 2.394(4) to 2.484(3) A with an average value of
˚
˚
2.437 A, indicating a highly asymmetric bonding mode. The
C2B3(centroid)-Ti-N(side arm) angle of 9 is 97.6°.
)
)
As shown in Figure 6, the structure of zirconium complex
10 reveals it to be isomorphous and isostructural with 9. The
central Zr atom is π-bound to the C2B3 ligand with a C2B3-
˚
(centroid)-Zr distance of 2.112 A. The Zr-N(1) distance of
2.377(6) A confirms that the N-donor atom is coordinated to
the metal in a strain-free manner and is consistent with a
˚

2352 Organometallics, Vol. 29, No. 10, 2010
Lee et al.
Table 3. Compilation of the Characteristic Structural Parameters of 7, 9 CH3C6H5, 10, 11 CH3C6H5, 13, and 14a
3
11 CH3C6H5 (M = Al)
3
7 (M = Ti)
9 CH3C6H5 (M = Ti)
3
10 (M = Zr)
13 (M = Al)
14 (M = Ga)
3
M-C7
2.406(4)
2.534(4)
2.458(5)
2.418(5)
2.344(5)
1.964
1.889(4), 1.901(4)
2.240(3)
2.399(3)
2.484(3)
2.462(4)
2.444(4)
2.394(4)
1.966
1.910(3), 1.889(3)
2.276(3)
97.6
2.534(7)
M-C8
2.580(8)
2.592(1)
2.557(9)
2.512(9)
2.112
2.040(7), 2.016(7)
2.377(6)
93.6
M-B9
M-B10
M-B11
M-Cent
M-N/C(ligand)
M-N(side arm)
1.939(5), 1.944(5)
1.985(4), 1.988(4)
1.939(4), 1.937(4) 1.964(3), 1.959(4)
2.475(1), 2.019(3) 2.446(7), 2.096(2)
Cent-M-N (R angle) 97.6
N(P)-M-N
105.5(1)
97.7(9)
97.0(6)
a Distances are given in angstroms and angles in degrees.
Scheme 2. Synthesis of 6 and the π,σ-Type Group 4 Metal Complexes 9 and 10
Figure 5. Molecular structure of 9 CH3C6H5 with thermal
ellipsoids drawn at the 30% level. Hydrogen atoms and solvent
molecules are omitted for clarity.
3
Figure 4. Molecular structure of 6 (CH3)2CO with thermal
3
the second donor tether. Due to the availability of the extra
donor site, a π-interaction with remote dicarbollide was not
foreseeable. Such exo-polyhedral bis-donor interactions stabi-
lized the group 13 metal center with a uninegative dicarbollide,
as evidenced by the bridge hydrogen on the open face of the
C2B3 pentagon. Formally, 11, 13, and 14 are charge-balanced
between anionic (DcabH)- and cationic [Me2Al(D)(NMe2-
CH2)]þ (D=Me2NCH2, PPh2) units.
ellipsoids drawn at the 30% level. Hydrogen atoms and solvent
molecules are omitted for clarity, except for H100 and H101
atoms.
Zr-N(sp3) single bond.20,21 As shown in Table 3, all other
bond distances and angles around the Zr and the N atoms
were similar to those found in 9.
Previously, we reported the use of monofunctionalized
dicarbollyl ligand systems to prepare π,σ-coordinated group
13 metal complexes.16,17 In comparison with previous results
derived from the monofunctional group, difunctional dicar-
bollides proceeded with a different metal coordination mode:
an σ,σ-fashion. The initial interaction of group 13 metals with
the first donor tether brought the metal into a favorable
position to form a tetrahedral geometry by interacting with
As shown in Scheme 3, reaction of 3 or 6 with 1 equiv of
MMe3 (M=Al, Ga) produced the exo-polyhedral σ,σ-type
complexes 11-14 in good yield (91-74%).
Treatment of 3 with 1 equiv of MMe3 (M = Al, Ga) in tol-
uene under reflux for 12 h gave the σ,σ-type complexes in
good to high yield, [(η1-NMe2CH2)2C2B9H10]MMe2 (M =
Al (11), 91%; M = Ga (12), 71%). As shown in Table 1, the
1H NMR spectra of 11 and 12 show two M-Me peaks at
δ -0.19, -0.22 (11) and δ 0.58, 0.60 (12) and a bridging
hydrogen of the C2B3 cage at δ -2.14 (11) and δ -2.17 (12),
indicating that only one methyl group on MMe3 had been
(20) Carpenetti, D. W.; Kloppenburg, L.; Kupec, J. T.; Petersen, J. L.
Organometallics 1996, 15, 1572.
(21) Bowen, D. E.; Jordan, R. F.; Rogers, R. D. Organometallics
1995, 14, 3630.
removed. Disappearance of the N H-N proton and
3 3 3

Article
Organometallics, Vol. 29, No. 10, 2010 2353
Figure 6. Molecular structure of 10 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity.
Figure 7. Molecular structure of 11 CH3C6H5 with thermal
3
ellipsoids drawn at the 30% level. Hydrogen atoms and solvent
molecules are omitted for clarity, except for the H101 atom.
Scheme 3. Synthesis of the σ,σ-Type Dicarbollyl Group 13 Metal
Complexes 11-14
t
angle is larger than [Me2Al(NH2 Bu)2]I (98.2(3)°).23 Indeed,
this value is similar to that for the distorted triangular Al
compound reported elsewhere.24
A similar protocol was applied to the preparation of [(η1-
PPh2)(η1-NMe2CH2)C2B9H10]MMe2 (M = Al (13), Ga (14)),
asshown in Scheme3. The additionof MMe3 (M =Al, Ga) to
the toluene solution of 6 resulted in the formation of σ,σ-bon-
ded group 13 metal complexes as observed in 11. As shown in
Table 1, compounds 13 and 14 exhibit characteristic shifts and
splitting patterns of M-Me, NCH2, NMe2, and PPh2 units.
The 27Al NMR chemical shift of 13 (δ þ150) confirms that the
central aluminum atom is a four-coordinated compound.22
Single-crystal X-ray structural studies of 13 confirmed the
σ,σ-coordination between the Al atom and the PPh2 and
NMe2 side arm (Figure 8). Table 2 gives the crystallographic
data for 13. Table 3 and the Supporting Information give
selected bond lengths and angles. The six-membered chelate
ring was formed by the ligand bound to AlMe2. The Al-P/N
the upfield shift of methyl protons in the NMe2 side arm
indicated the presence of two dative σ-bonds of NfMrN.
Furthermore, σ,σ-bonded structures were proposed on the
basis of the observation of a diastereotopic splitting pattern
of the methylene protons of NCH2 and two separate methyl
resonances for the coordinated nitrogen functionality of
NMe2. The 27Al NMR chemical shift of 11 (δ þ154) confirms
that the central aluminum atom is a four-coordinated
compound.22
Single-crystal X-ray structural studies authenticated the
σ,σ-type interactions at the aluminum metal center (Figure 7
for 11). Table 2 gives the crystallographic data for 11. Table 3
and the Supporting Information give selected bond lengths
and angles. The seven-membered chelate ring was formed
by the ligand bound to AlMe2. This species is believed to be
a kinetically stabilized complex, in which there is an initial
σ-electronic interaction of the aluminum atom with the
amine side arm and concomitant η1-type coordination with
the neighboring second amine side arm. The central alumi-
num atom in 11 is coordinated to a pair of methyl ligands and
two nitrogen atoms of the side arm in a σ-bonding manner.
˚
bond lengths of 13 are 2.475(1)/2.019(3) A, respectively. The
Al-P bond distance confirmed that the P-donor atom is
coordinated to the metal in a strain-free manner and the
bond distance is consistent with a four-coordinated Al-P
single bond.25 The chelate bite angle P-Al-N of 97.7(9)° is
significantly smaller than that in the corresponding four-
coordinated cationic Al compound [η2(O,P)-(2-PPh2-4-Me-
6-tBu-C6H2O)]2Alþ (120.0(3)°),25 reflecting the electronic
and size effects of P,N-donor atoms with differing P,O-
donors.
˚
Compound 14 was also produced from the same synthetic
protocol (Scheme 3). Similar to the case for 13, the 1H NMR
spectral pattern for the NCH2, NMe2, Ga-Me, and PPh2
units were observed in 14. The X-ray crystal structure of 14
(Figure 9) showed that the Al atom essentially adopts an σ,σ-
bonding posture with the NMe2 groups. Similar to 13, the
The Al-C bond lengths (1.939(5) and 1.944(5) A) are shorter
t
than the corresponding Al-C σ-bond, [Me2Al(NH2 Bu)2]I,
(1.960(8) and 1.929(9) A).23 The Al-N(1)/N(2) bond lengths
˚
˚
of the NMe2 side arm (1.985(4)/1.988(4) A) are shorter than
for the corresponding four-coordinated cationic Al com-
t
pound [Me2Al(NH2 Bu)2]I, (1.988(7) and 1.996(6) A).23 The
˚
˚
Ga-P bond length (2.446(7) A) is in the range of a typical
shorter Al-N distances reflect the positive charge on Al in
11. The chelate bite angle N-Al-N in 11 is 105.5(1)°. This
(24) Radzewich, C. E.; Guzei, I. A.; Jordan, R. F. J. Am. Chem. Soc.
1999, 121, 8673.
(25) Haddad, M.; Laghzaoui, M.; Welter, R.; Dagorne, S. Organo-
(22) Benn, R.; Janssen, E.; Lehmkuhl, H.; Rufihska, A. J. Organo-
met. Chem. 1987, 333, 155.
(23) Atwood, D.; Jegier, J. Inorg. Chem. 1996, 35, 4277.
metallics 2009, 28, 4584.

2354 Organometallics, Vol. 29, No. 10, 2010
Lee et al.
Group 4 metals (Ti and Zr) preferred π,σ-coordination with
the involvement of a dicarbollyl ligand and one of the donor
groups in the N,N0- and P,N-functionalized units, whereas
group 13 metals (Al and Ga) completed their four-coordina-
tion only with tethered donors through both nitrogen atoms
and a nitrogen and phosphine combination in a σ,σ-coordi-
nation manner. This study shows that the two side arm
donors dictate the formation of σ,σ-coordination with group
13 metals. Therefore, a monotethering strategy is desirable
for forming π,σ-type coordination with group 13 metals.
Experimental Section
General Procedures. All manipulations were performed under
a dry, oxygen-free nitrogen or argon atmosphere using stan-
dard Schlenk techniques or in a Vacuum Atmospheres HE-493
drybox. THF was freshly distilled over potassium benzophe-
none. Toluene, n-hexane, and n-pentane were dried and distilled
over sodium benzophenone. Dichloromethane and hexane were
1
dried and distilled over CaH2. The H, 11B, 13C, 31P, and 27Al
NMR spectra were recorded on a Varian Mercury 300 spectro-
meter operating at 300.1, 96.3, 75.4, 121.4, and 78.2 MHz,
respectively. All 11B chemical shifts were referenced to BF3
Figure 8. Molecular structure of 13 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity,
except for the H101 atom.
3
O(C2H5)2, with a negative sign indicating an upfield shift. All
proton and carbon chemical shifts were measured relative to
internal residual benzene from the lock solvent (99.5% C6D6)
and then referenced to tetramethylsilane (Me4Si). The IR spec-
tra were recorded on a Biorad FTS-165 spectrophotometer.
Elemental analyses were performed with a Carlo Erba Instru-
ments CHNS-O EA1108 analyzer. All melting points were
uncorrected. o-Carborane was purchased from Katchem and
used as received. All other reagents were obtained from com-
mercial suppliers (Aldrich and TCI) and used as received.
Preparation of [closo-1,2-(CH2NMe2)2-1,2-C2B10H10] (2).
n-BuLi (2.5 M, 4.4 mL) was added to a stirred solution of
o-carborane 1 (0.72 g, 5 mmol) in toluene (100 mL) via a syringe
through a serum cap at 0 °C. The resulting white suspension was
stirred at 25 °C for 10 min and placed in an ice bath. When the
toluene solution was cold, Eschenmoser’s salt, CH2dNMe2þI-
(2.03 g, 11.1 mmol), was added to the lithio-o-carborane. The
reaction temperature was maintained at 0 °C for 1 h. The
reaction mixture was then warmed slowly to room temperature.
After it was stirred for an additional 12 h under reflux, the
reaction mixture was filtered and dried in vacuo to give a white
crystalline powder. The resulting residue was taken up in a
minimum of n-pentane and recrystallized from solution by
cooling to -5 °C to afford 2 as colorless crystals. Yield: 86%
(1.1 g, 4.3 mmol). Mp: 87 °C. Anal. Calcd for C8H26B10N2: C,
37.18; H, 10.14; N, 10.84. Found: C, 37.30; H, 10.12; N, 10.80.
IR spectrum (KBr pellet, cm-1): ν(B-H) 2640, 2580, ν(C-H)
3001, 2829, 2781. 1H NMR (300 MHz, CDCl3): δ 2.32 (s, 12H,
NMe2), 3.11 (s, 4H, NCH2). 13C NMR (75.4 MHz, CDCl3):
δ 46.7 (NMe2), 62.6 (NCH2). 11B NMR (96.3 MHz, CDCl3):
δ -3.9 (4B), -10.8 (6B).
Figure 9. Molecular structure of 14 with thermal ellipsoids
drawn at the 30% level. Hydrogen atoms are omitted for clarity,
except for the H101 atom.
Ga-P single bond26,27 in a four-coordinated tetrahedral
geometry. The P-Ga-N bite angle of 14 is 97.0(6)°, which
is similar to 13.
Preparation of [nido-7,8-(NMe2CH2)2-7,8-C2B9H10] (3).
Compound 2 (0.78 g, 3.0 mmol) was dissolved in degassed
methanol (20 mL) and heated under reflux under N2 for 12 h.
Methanol was removed under reduced pressure, and the residue
was washed with Et2O (10 mL ꢀ 3). The volatiles were removed
under vacuum to provide the final crude product. The pro-
duct was purified by recrystallization from ethanol in 95% yield
(0.95 g, 3.8 mmol). Mp: 294 °C dec. Anal. Calcd for C8H27B9N2:
C, 38.65; H, 10.95; N, 11.25. Found: C, 38.52; H, 10.98; N, 11.30.
IR spectrum (KBr pellet, cm-1): ν(B-H) 2515, ν(C-H) 3025,
2989, 2963. 11B NMR (96.3 MHz, acetone-d6): δ -7.5 (2B),
-10.8 (1B), -13.4 (1B), -15.5 (1B), -19.5 (2B), -33.1 (1B),
-35.8 (1B).
Conclusions
Apparently similar electrophilic early-transition and
main-group metals were examined for the formation of
new types of coordination compounds consisting of a N,
N0- and P,N-donor unit tethered to a dicarbollyl ligand.
ꢀ
ꢁ
€
(26) Valean, A. M.;Gomez-Ruiz, S.; Lonnecke, P.; Silaghi-Dumitrescu,
I.; Silaghi-Dumitrescu, L.; Hey-Hawkins, E. Inorg. Chem. 2008, 47,
11284.
Preparation of [closo-1-PPh2-2-CH2NMe2-1,2-C2B10H10] (5).
n-BuLi (2.5 M, 1.3 mL, 3.3 mmol) was added to a stirred
(27) Lee, J.-D.; Ko, J.; Cheong, M.; Kang, S. O. Organometallics
2005, 24, 5845.

Article
Organometallics, Vol. 29, No. 10, 2010 2355
solution of 1-PPh2-o-carborane 4 (1.64 g, 5.0 mmol) in toluene
(100 mL) via a syringe through a serum cap at 0 °C. The resulting
white suspension was stirred at 25 °C for 10 min and placed in an
ice bath. When the toluene solution was cold, Eschenmoser’s
salt, CH2dNMe2þI- (1.02 g, 5.5 mmol), was added to the
1-lithio-2-PPh2-o-carborane. The reaction temperature was
maintained at 0 °C for 1 h. The reaction mixture was then
warmed slowly to room temperature. After it was stirred for an
additional 12 h under reflux, the reaction mixture was filtered
and dried in vacuo to give a white crystalline powder. The
resulting residue was taken up in a minimum of n-pentane and
recrystallized from this solution by cooling to -5 °C to afford 5
as colorless crystalline solids. Yield: 81% (1.56 g, 4.05 mmol).
Mp: 86 °C. Anal. Calcd for C17H28B10NP: C, 52.97; H, 7.32; N,
3.63. Found: C, 53.01; H, 7.28; N, 3.60. IR spectrum (KBr pellet,
cm-1): ν(B-H) 2638, 2584, ν(C-H) 2988, 2780. 1H NMR (300
MHz, CDCl3): δ 2.32 (s, 6H, NMe2), 3.13 (s, 2H, NCH2),
7.28-7.34 (m, 10H, PPh2). 13C NMR (75.4 MHz, CDCl3): δ
47.2 (NMe2), 63.1 (NCH2), 125.7 (PPh2), 128.4 (PPh2), 134.6
(PPh2). 11B NMR (96.3 MHz, CDCl3): δ -4.5 (2B), -6.2 (1B),
-9.7 (2B), -11.2 (3B), -12.5 (2B). 31P NMR (121.4 MHz,
CDCl3): δ -11.8 (PPh2).
Preparation of [nido-7-PPh2-8-CH2NMe2-7,8-C2B9H10] (6).
Compound 5 (1.16 g, 3.0 mmol) and KOH (0.22 g, 4.0 mmol)
were dissolved in degassed ethanol (20 mL) and then heated
under reflux in N2 for 12 h. Ethanol was removed under reduced
pressure, and the residue was suspended in benzene (60 mL).
Azeotropic distillation was then performed to remove the H2O
and ethanol, and the remaining white solid was dried overnight
under vacuum. The solid was mixed with benzene (30 mL) under
N2 to form a slurry, and H3PO4 was then added. The resulting
two-phase mixture was stirred vigorously for 15 h. The volatiles
were removed by rotary evaporation under reduced pressure,
and the residue was washed with H2O to yield an off-white solid.
The product was purified by recrystallization from acetone to
yield 6 as colorless crystals. Yield: 94% (1.06 g, 2.8 mmol). Mp:
268 °C dec. Anal. Calcd for C17H29B9NP: C, 54.35; H, 7.78; N,
3.73. Found: C, 54.31; H, 7.73; N, 3.70. IR spectrum (KBr pellet,
cm-1): ν(B-H) 2517, ν(C-H) 3020, 2982, 2887. 11B NMR (96.3
MHz, acetone-d6): δ -8.4 (2B), -11.3 (1B), -13.7 (1B), -18.6
(1B), -19.2 (2B), -31.8 (1B), -34.6 (1B). 31P NMR (121.4
MHz, acetone-d6): δ -21.7 (PPh2).
(1B), -7.9 (1B), -11.7 (2B), -17.2 (2B), -31.8 (1B), -34.3 (2B).
31P NMR (121.4 MHz, C6D6): δ -27.4 (PPh2).
Compound 10. A procedure analogous to that used to prepare
7 was employed, but instead with the zwitterion 6 (0.75 g,
2.0 mmol) and Zr(NMe2)4 (0.72 g, 2.0 mmol). Yield: 65%
(0.72 g, 1.3 mmol). Mp: 128 °C dec. Anal. Calcd for
C21B9H39N3PZr: C, 45.61; H, 7.11; N, 7.60. Found: C, 45.58;
H, 7.14; N, 7.63. IR spectrum (KBr pellet, cm-1): ν(B-H) 2522,
ν(C-H) 2984, 2955, 2948. 11B NMR (96.3 MHz, C6D6): δ -4.6
(1B), -7.1 (2B), -11.6 (1B), -19.4 (3B), -33.7 (1B), -36.8 (1B).
31P NMR (121.4 MHz, C6D6): δ -26.8 (PPh2).
Preparation of [(η1-NMe2CH2)2C2B9H10]AlMe2 (11). A 5 mL
portion of a toluene solution of AlMe3 (0.14 g, 2.0 mmol) was
added to 20 mL of a stirred toluene solution containing 3 (0.50 g,
2.0 mmol) by cannula at -78 °C. Subsequently, the dry ice/
acetone bath was removed and the solution was heated under
reflux in N2 for 12 h. The formation of 3 was demonstrated by
1H NMR spectroscopy. The volatiles were removed under
vacuum, and the residue was purified by recrystallization with
a toluene at -15 °C. Yield: 91% (0.55 g, 1.82 mmol). Mp: 135 °C
dec. Anal. Calcd for C10B9H32AlN2: C, 39.42; H, 10.59; N, 9.20.
Found: C, 39.18; H, 10.54; N, 9.27. IR spectrum (KBr pellet,
cm-1): ν(B-H) 2518, ν(C-H) 3105, 2993, 2951. 11B NMR (96.3
MHz, CD3C6D5): δ -8.4 (2B), -10.2 (1B), -18.6 (1B), -20.8
(3B), -30.8 (1B), -33.7 (1B).
Compound 12. A procedure analogous to that used to prepare
11 was employed, but instead with the zwitterion 3 (0.50 g, 2.0
mmol) and GaMe3 (0.23 g, 2.0 mmol). Yield: 71% (0.49 g, 1.42
mmol). Mp: 130 °C dec. Anal. Calcd for C10B9H32GaN2: C,
34.57; H, 9.28; N, 8.06. Found: C, 34.60; H, 9.33; N, 8.00. IR
spectrum (KBr pellet, cm-1): ν(B-H) 2518, ν(C-H) 2994, 2972.
11B NMR (96.3 MHz, CD3C6D5): δ -7.8 (2B), -10.7 (1B),
-15.5 (2B), -19.4 (2B), -32.8 (1B), -35.7 (1B).
Compound 13. A procedure analogous to that used to prepare
11 was employed, but instead with the zwitterion 6 (0.75 g,
2.0 mmol) and AlMe3 (0.14 g, 2.0 mmol). Yield: 80% (0.69 g,
1.6 mmol). Mp: 125 °C dec. Anal. Calcd for C19B9H34AlNP: C,
52.86; H, 7.94; N, 3.24. Found: C, 52.81; H, 8.00; N, 3.21. IR
spectrum (KBr pellet, cm-1): ν(B-H) 2520, ν(C-H) 3100, 2986,
2980. 11B NMR (96.3 MHz, CD3C6D5): δ -8.5 (1B), -11.4
(1B), -18.6 (3B), -20.4 (2B), -32.4 (1B), -36.1 (1B). 31P NMR
(121.4 MHz, CD3C6D5): δ -38.7 (PPh2).
Preparation of [(η5-C2B9H9CH2NMe2)(η1-NMe2CH2)]Ti-
(NMe2)2 (7). Over a period of 30 min, a 20 mL toluene solution
of Ti(NMe2)4 (0.45 g, 2.0 mmol) was added to a stirred solution
of 3 (0.50 g, 2.0 mmol) in toluene (20 mL) at 0 °C. Subsequently,
the cold bath was removed and the solution was stirred at room
temperature for 36 h. The solvent was removed in vacuo, and the
residue was purified by recrystallization with a CH2Cl2/toluene
mixture at -30 °C. Yield: 84% (0.64 g, 1.68 mmol). Mp: 131 °C
dec. Anal. Calcd for C12H37B9N4Ti: C, 37.67; H, 9.75; N, 14.64.
Found: C, 37.74; H, 9.77; N, 14.69. IR (KBr, pellet, cm-1):
ν(B-H) 2521, ν(C-H) 2989, 2964, 2855. 11B NMR (96.3 MHz,
C6D6): δ -4.5 (1B), -6.8 (1B), -7.2 (2B), -10.6 (1B), -15.9
(1B), -31.8 (2B), -34.7 (1B).
Compound 8. A procedure analogous to that used to prepare
7 was employed, but instead with the zwitterion 3 (0.50 g,
2.0 mmol) and Zr(NMe2)4 (0.54 g, 2.0 mmol). Yield: 78%
(0.66 g, 1.56 mmol). Mp: 138 °C dec. Anal. Calcd for
C12H37B9N4Zr: C, 33.84; H, 8.75; N, 13.15. Found: C, 33.86;
H, 8.80; N, 13.26. IR spectrum (KBr pellet, cm-1): ν(B-H) 2523,
ν(C-H) 2994, 2950, 2880. 11B NMR (96.3 MHz, C6D6): δ -5.1
(2B), -8.6 (1B), -10.4 (1B), -18.4 (3B), -32.1 (1B), -35.3 (1B).
Compound 9. A procedure analogous to that used to prepare 7
was employed, but instead with the zwitterions 6 (0.75 g,
2.0 mmol) and Ti(NMe2)4 (0.45 g, 2.0 mmol). Yield: 87%
(0.88 g, 1.74 mmol). Mp: 133 °C dec. Anal. Calcd for
C21B9H39N3PTi: C, 49.49; H, 7.71; N, 8.24. Found: C, 49.53;
H, 7.68; N, 8.29. IR spectrum (KBr pellet, cm-1): ν(B-H) 2520,
ν(C-H) 3002, 2978, 2951. 11B NMR (96.3 MHz, C6D6): δ -3.7
Compound 14. A procedure analogous to that used to prepare
11 was employed, but instead with the zwitterion 6 (0.75 g,
2.0 mmol) and GaMe3 (0.23 g, 2.0 mmol). Yield: 74% (0.70 g,
1.48 mmol). Mp: 122 °C dec. Anal. Calcd for C19B9H34GaNP:
C, 48.10; H, 7.22; N, 2.95. Found: C, 48.06; H, 7.17; N, 2.98. IR
spectrum (KBr pellet, cm-1): ν(B-H) 2519, ν(C-H) 3104, 2988,
2961. 11B NMR (96.3 MHz, CD3C6D5): δ -7.7 (2B), -12.8
(1B), -17.5 (3B), -19.7 (1B), -30.4 (1B), -35.3 (1B). 31P NMR
(121.4 MHz, CD3C6D5): δ -35.8 (PPh2).
Crystal Structure Determination. Crystals of 3, 6-11, 13, and
14 were obtained from toluene at -15 °C, sealed in glass
capillaries under argon, and mounted on the diffractometer.
A preliminary examination and data collection were performed
using a Bruker SMART CCD detector system single-crystal
X-ray diffractometer equipped with a sealed-tube X-ray source
(40 kV ꢀ 50 mA) using graphite-monochromated Mo KR radia-
˚
tion (λ = 0.7107 A). Preliminary unit cell constants were deter-
mined with a set of 45 narrow-frame (0.3° in ω) scans. The
double-pass method of scanning was used to exclude noise.
The collected frames were integrated using an orientation
matrix determined from the narrow-frame scans. The SMART
software package was used for data collection, and SAINT was
used for frame integration.28 The final cell constants were
determined by a global refinement of the xyz centroids of
reflections harvested from the entire data set. Structure solution
(28) SMART and SAINT; Bruker Analytical X-ray Division, Madison,
WI, 2002.

2356 Organometallics, Vol. 29, No. 10, 2010
Lee et al.
and refinement were carried out using the SHELXTL-PLUS
software package.29
the Korea government (MEST) (No. 2010-0018456). We also
thank the support from WCU and BK-21 programs.
Acknowledgment. This study was supported by a Natio-
nal Research Foundation of Korea (NRF) grant funded by
Supporting Information Available: Text giving additional
details of the syntheses, and tables and CIF files giving
crystallographic data for 3, 6, 7, 9, 10, 11, 13, and 14. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(29) Sheldrick, G. M. SHELXTL-PLUS Software Package; Bruker
Analytical X-ray Division, Madison, WI, 2002.