The (β-diketiminato)bismuth(III) complex [LBiCl(μ-Cl)]2 {L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H 3} and its derivatives: The presence of versatile ligand ligation modes

Article abstract of DOI:10.1002/ejic.201100821

The reaction of BiCl₃ with LLi {L = HC[(CMe)(NAr)]₂, Ar = 2,6-iPr₂C₆H₃} in a molar ratio of 1:1 was carried out under various conditions and afforded [LBiCl(μ-Cl)]₂ (1), [L′BiCl(μ-Cl)]

Full text of DOI:10.1002/ejic.201100821

FULL PAPER
DOI: 10.1002/ejic.201100821
The (β-Diketiminato)bismuth(III) Complex [LBiCl(μ-Cl)]2
{L = HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3} and Its Derivatives:
The Presence of Versatile Ligand Ligation Modes
Yan Li,[a] Hongping Zhu,*[a] Gengwen Tan,[a] Tao Zhu,[a] and Jinyuan Zhang[a]
Keywords: β-Diketiminato ligands / Bismuth / Isomerization / Ligation modes / N ligands
The reaction of BiCl3 with LLi {L = HC[(CMe)(NAr)]2, Ar =
2,6-iPr2C6H3} in a molar ratio of 1:1 was carried out under
various conditions and afforded [LBiCl(μ-Cl)]2 (1), [LЈBiCl(μ-
Cl)]2 [4; LЈ = N(Ar)=C(Me)CH=C(NHAr)CH2], and LЈЈBi2Cl4
[5; LЈЈ = N(Ar)=C(Me)CC(Me)=N(Ar)]. Compounds 1 and 4
are isomers, and a thermal conversion of 1 to 4 was realized.
In this reaction system, when a little excess nBuLi and BiCl3
were used, [LBiCl(μ-Cl)Bi(nBu)Cl(μ-Cl)]2 (2) was isolated as
side product after the isolation of 1. The reaction of 1 with
AgOOCCF3 in the absence of light from –15 °C to room tem-
perature generated LBi(OOCCF3)2 (3). Finally, the solvent-
free reaction of BiCl3 and LH at elevated temperature
(125 °C) under vacuum gave [LH2]+[BiCl4(THF)]– (6) in a low
yield. The formulations of all these complexes have been
1
confirmed by H and 13C NMR spectroscopy and X-ray crys-
tallography, except for 6, which was only identified by X-
ray crystallography due to its insolubility in organic solvents.
These complexes exhibit versatile L ligation modes at the
metal atom and reveal the complexity of the reaction be-
tween BiCl3 and LLi.
β-diketiminato ligands and reflects the intriguing interac-
tions of the ligand with a target element. However, a gene-
ral viewpoint on the coordination mode of L towards
Introduction
β-Diketiminato ligands have been widely employed in the
synthesis of main-group, transition-metal, and lanthanide
complexes. This is due to the relatively rigid N,N-chelation
backbone and the demanding N-substituents, which stabi-
lize the target center electronically and/or sterically, espe-
cially with low coordination numbers and low oxidation
states.[1,2] Some of these complexes can be used as precur-
sors in reactions with various small-molecule substrates at
the center,[3] efficient homogeneous catalysts,[3g,4,5] and as
models for bioinorganic enzyme systems.[6] These examples
prove further that β-diketiminates are promising ligands.
In recent years, progress on approaches to group 15 β-
diketiminates have revealed that HC[(CMe)(NAr)][(CMe)-
(NHAr)] (LH) displays a variety of coordination modes in
addition to N,N-chelation.[7] These ligation modes are sum-
marized in Scheme 1 and include α-C,N-chelation (II-
1),[7a,7b,8] α-C,N-chelation and α-C-ligation (II-2),[7c] α-C-
ligation and N,N-chelation (II-3),[9] γ-C-ligation (III-1),[10]
γ-CH-ligation (III-2),[7a] γ-C-ligation and N,N-ligation (III-
3),[10c] γ-C-ligation and N-ligation (III-4),[9,10b] and γ-C-lig-
ation and α-C-ligation (IV-1).[10a,10c] In other main-group
compounds several other coordination features are also ob-
served.[11–13] This indicates a rich coordination chemistry of
[a] State Key Laboratory of Physical Chemistry of Solid Surfaces,
National Engineering Laboratory for Green Chemical
Productions of Alcohols–Ethers–Esters, College of Chemistry
and Chemical Engineering, Xiamen University,
Xiamen, Fujian 361005, China
Scheme 1. Ligation modes of L in group 15 complexes (I: normal
N–H activation, II: backbone Me C–H activation, III: backbone
γ-CH ligation or γ-C–H activation, IV: both backbone Me and γ-
CH C–H activation).
Fax: +86-592-2183047
E-mail: hpzhu@xmu.edu.cn
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Y. Li, H. Zhu, G. Tan, T. Zhu, J. Zhang
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group 15 elements has not been reached, and the reaction
mechanisms still remain speculative, although many experi-
ments have been investigated, which include the use of dif-
ferent precursors and changing the reaction and/or isola-
tion conditions.[7b,7c] Moreover, As and Bi complexes of L
are unknown to date.[14] Recently, we successfully synthe-
sized a series of CuI, CrIII, and BiIII complexes with an
N,N,P ligand.[15] According to this methodology, we further
investigated the reaction of BiCl3 with LLi. This reaction
has been reported; however, positive results have not been
described.[7c] By careful control of the reaction and isola-
tion conditions, we prepared a series of BiIII compounds,
which were structurally characterized and exhibited versa-
tile L ligation modes. Herein we report these results, the
isomerization of [LBiCl(μ-Cl)]2 (1), and a possible forma-
tion mechanism for LЈЈBi2Cl4 [5; LЈЈ = N(Ar)=C(Me)-
CC(Me)= N(Ar), Ar = 2,6-iPr2C6H3].
Results and Discussion
It has been suggested that LMCl2-type complexes {L =
HC[(CMe)(NAr)]2, Ar = 2,6-iPr2C6H3 or 2,4,6-Me3C6H2;
M = As or Bi} are formed in a similar way to LSbCl2 by
the reaction of LLi and MCl3 in tetrahydrofuran (THF)
from –78 °C to room temperature. However, this has not
been confirmed spectroscopically.[7c] We initially examined
the synthesis by treating LLi, which was prepared in situ,[16]
with BiCl3 in a mixture of toluene and THF from –15 °C
to room temperature. After a routine workup, which in-
cluded the removal of volatiles, extraction with toluene, and
concentration under vacuum, an orange-yellow solid was
obtained and identified as a mixture on the basis of 1H
NMR spectroscopy. An attempt to crystallize a pure com-
pound failed. Thus, we altered the treatment of this reac-
tion. A mixture of a precooled (–15 °C) toluene solution of
LLi and a precooled (–15 °C) THF solution of BiCl3·
(THF)2 was kept at –15 °C without stirring for 48 h.
Scheme 2. Synthesis of 1–5.
at δ = 2.00 and 5.30 ppm for 1, δ = 2.03 and 5.38 ppm for
2, and δ = 2.03 and 5.34 ppm for 3, which suggests an N,N-
chelation mode of L at Bi. This appears to be the normal
bonding feature, which is commonly known for other
main group metal β-diketiminate complexes.[2a,2b,3d–3h,16]
The structures of 1–3 are shown in Figures 1, 2, and 3,
respectively, and clearly prove such a coordination mode.
[LBiCl(μ-Cl)]2 {1; L = HC[(CMe)(NAr)]2, Ar = 2,6-
iPr2C6H3} was formed as red crystals in 64% yield
[Scheme 2, Equation (1)]. In a similar manner, [LBiCl(μ-
Cl)Bi(nBu)Cl(μ-Cl)]2 (2) was obtained as orange-red crys-
tals from LH, nBuLi, and BiCl3·(THF)2 in a molar ratio of
2.5:3.0:3.0 [Equation (2)],[17] in which 1 was isolated from
the first crop in 42% yield and 2 from the second crop in a
relatively low yield of 22%. This may indicate that 1 is
formed during the reaction and further reacts with
BiCl2(nBu), which could be generated by metathesis be-
tween BiCl3 and nBuLi, to produce 2. The use of excess
nBuLi in the reaction to obtain LBi(nBu)2 was not success-
Figure 1. Crystal structure of 1 with the thermal ellipsoids at 50%
probability. H atoms are omitted for clarity. Selected bond lengths
[Å] and angles [°]: Bi(1)–N(1) 2.242(3), Bi(1)–N(2) 2.283(3), Bi(1)–
Cl(1) 2.5901(12), Bi(1)–Cl(2) 2.8513(12), Bi(1)–Cl(2A) 2.8720(15),
C(1)–C(2) 1.510(6), C(2)–C(3) 1.398(5), C(3)–C(4) 1.411(5), C(4)–
C(5) 1.505(5), C(2)–N(1) 1.349(5), C(4)–N(2) 1.335(5); N(1)–Bi(1)–
N(2) 83.40(11), N(1)–Bi(1)–Cl(1) 89.17(8), N(1)–Bi(1)–Cl(2A)
90.21(8), N(1)–Bi(1)–Cl(2) 103.86(8).
ful.
Nonetheless,
carboxyl
group
functionalized
LBi(OOCCF3)2 (3) was prepared in good yield (87%) from
the reaction of 1 with AgOOCCF3 in the absence of light
from –15 °C to room temperature [Equation (3)].
Compounds 1–3 were characterized by spectroscopy and
elemental analysis and confirmed by X-ray crystallography.
The H NMR spectra of 1–3 exhibit the backbone methyl 2.198(10)–2.234(11) Å in 2, and 2.230(6)–2.237(3) Å in 3.
(CMe) and methine (γ-CH) proton resonances as singlets These differences are probably due to the different coordi-
The Bi–N bond lengths are 2.242(3)–2.283(3) Å in 1,
1
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(β-Diketiminato)bismuth(III) Complexes
Ar = 2,6-iPr2C6H3}.[14b] Noteworthy features in 1–3 are the
stereochemically active geometries of the nonbonding lone
pair around the BiIII centers, which are suggested to fit the
10-Bi-4 and 12-Bi-5 systems (n-Bi-l, where n is number of
formal valence-shell electrons about a Bi atom and l is the
number of ligands) predicted by simple valence-shell elec-
tron-pair repulsion theory.[18] Thus, square-pyramidal ge-
ometry was adopted for each five-coordinate Bi center, and
triangular-pyramidal geometry was adopted for each four-
coordinate Bi center, in which some degrees of geometric
distortion were observed from the ideal polyhedra, proba-
bly due to the different ligation groups at the metal centers.
The formation of 1 as a crystalline product from the re-
action of LLi and BiCl3 can be considered as a reaction-to-
crystallization process. Thus, low temperature treatment
(–15 °C) and a long standing time (48 h) were of impor-
tance. The initial reactions from –15 °C to room tempera-
ture gave a product mixture, so we performed the reaction
of LLi and BiCl3 (1:1) with stirring at room temperature
for 48 h. The yellow suspension obtained was allowed to
stand at room temperature for three weeks without fil-
tration to remove the insoluble material, and a new com-
pound [LЈBiCl(μ-Cl)]2 [4; LЈ = N(Ar)=C(Me)CH=C-
(NHAr)CH2], Ar = 2,6-(iPr2C6H3) was isolated as yellow
crystals in 41% yield [Scheme 2, Equation (4)].
Figure 2. Crystal structure of 2 with the thermal ellipsoids at 50%
probability. H atoms are omitted for clarity. Selected bond lengths
[Å] and angles [°]: Bi(1)–N(1) 2.224(11), Bi(1)–N(2) 2.224(12),
Bi(1)–Cl(1) 2.458(4), Bi(1)–Cl(2) 2.984(4), Bi(2)–C(61) 2.194(4),
Bi(2)–Cl(2) 2.688(4), Bi(2)–Cl(3) 2.638(3), Bi(2)–Cl(4) 2.878(4),
Bi(2)–Cl(5) 2.795(4), Bi(3)–C(65) 2.189(15), Bi(3)–Cl(4) 2.959(4),
Bi(3)–Cl(5) 2.844(4), Bi(3)–Cl(6) 2.563(4), Bi(3)–Cl(7) 2.671(4),
Bi(4)–N(3) 2.234(11), Bi(4)–N(4) 2.198(10), Bi(4)–Cl(7) 3.081(4),
Bi(4)–Cl(8) 2.453(4); N(2)–Bi(1)–N(1) 85.7(4), N(2)–Bi(1)–Cl(1)
91.1(3), N(2)–Bi(1)–Cl(2) 94.9(3), C(61)–Bi(2)–Cl(2) 85.4(4),
C(61)–Bi(2)–Cl(3) 88.7(4), C(61)–Bi(2)–Cl(4) 91.7(4), C(61)–Bi(2)–
Cl(5) 89.5(4), C(65)–Bi(3)–Cl(4) 84.5(4), C(65)–Bi(3)–Cl(5) 84.2(4),
C(65)–Bi(3)–Cl(6) 94.6(4), C(65)–Bi(3)–Cl(7) 88.5(4), N(4)–Bi(4)–
N(3) 85.3(4), N(4)–Bi(4)–Cl(7) 96.1(3), N(4)–Bi(4)–Cl(8) 93.7(3).
1
The H NMR spectrum of 4 shows a relatively compli-
cated pattern compared to that of 1. The singlets at δ =
4.09 and 1.55 ppm can be assigned to the γ-CH proton and
CMe, respectively, whereas those at δ = 1.11 and 1.72 ppm
are tentatively assigned to the backbone methylene protons
(CCH2) and the NH proton with satisfactory integrations.
An absorption observed at 3294 cm–1 in the IR spectrum of
4 corresponds to ν(N–H).
The single-crystal X-ray structural analysis of 4 unam-
biguously discloses a C,N-chelation bonding mode, which is
completely different to those in 1–3. The same coordination
feature has been found in P and Sb compounds.[7a,7b,8] As
shown in Figure 4, the Bi–N bonds [2.333(6)–2.368(5) Å]
are a little longer than those in 1–3. Bi–Clterminal distances
of 2.544(2)–2.6056(19) Å and Bi–Clbridge distances of
2.7846(19)–2.9310(18) Å were found. The Bi–C bonds are
2.225(6) and 2.228(7) Å long, which is a little longer than
those in 2 [2.189(15) and 2.194(4) Å]. The C–Bi–N bite
angles [78.8(2)–79.8(2)°] are smaller than the N–Bi–N bite
angles in 1–3 [83.40(11)–85.8(3)°]. Compared to the matrix
data of the ligation backbone in 1 [C(1)–C(2) 1.510(6),
C(2)–C(3) 1.398(5), C(3)–C(4) 1.411(5), C(4)–C(5) 1.505(5),
Figure 3. Crystal structure of 3 with the thermal ellipsoids at 50%
probability. H atoms are omitted for clarity. Selected bond lengths
[Å] and angles [°]: Bi(1)–N(1) 2.237(3), Bi(1)–N(2) 2.230(6), Bi(1)–
O(1) 2.460(7), Bi(1)–O(3) 2.353(7), Bi(1)–O(5) 2.753(7); N(1)–
Bi(1)–N(2) 85.8(3), N(1)–Bi(1)–O(1) 82.5(3), N(1)–Bi(1)–O(3)
89.8(3), N(1)–Bi(1)–O(5) 97.7(2).
nation number and the various functional groups at the Bi C(2)–N(1) 1.349(5), C(4)–N(2) 1.335(5) Å], in 4 the C(1)–
center. In C(2), C(2)–C(3), C(3)–C(4), C(4)–C(5), C(2)–N(2), and
a
similar compound, LaBiCl2 {La
=
HC[(CMe)(NCH2CH2NEt2)]2}, Bi–N bond lengths of C(4)–N(1) bond lengths are 1.483(8) [1.455(9) (in another
2.232(2)–2.246(2) Å are observed.[14a] The Bi–Clterminal ligand backbone)], 1.337(8) [1.394(9)], 1.415(8) [1.432(8)],
bonds [2.5901(12) Å in 1, 2.453(4)–2.638(3) Å in 2] are 1.515(8) [1.521(9)], 1.359(7) [1.333(7)], and 1.320(7)
shorter than the Bi–Clbridge bonds [2.8513(12)–2.8720(15) Å [1.271(1)] Å, respectively, which indicates a big change in
in 1, 2.671(4)–3.081(4) Å in 2]. However, these bond lengths the ligand backbone geometry.
are very different to those in LaBiCl2 [Bi–Clterminal 2.675(1)–
Compounds 1 and 4 are isomers that were isolated from
2.736(1) Å]. A similar case is observed for LbBiCl2(μ-Cl)- different conditions. Stirring a THF solution of pure 1 at
BiCl(THF)Lb {Bi–Clterminal 2.5028(13)–2.6827(14) Å; Bi– room temperature for 24 h led to quantitative conversion to
Clbridge 2.7468(14)–2.9822(14) Å; Lb = PhC[(CH)(NAr)]2, 4, which indicates a thermal structural conversion. Simi-
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Y. Li, H. Zhu, G. Tan, T. Zhu, J. Zhang
FULL PAPER
We further investigated the reaction of LLi with 1 equiv.
of BiCl3 in toluene under reflux conditions to see if a new
compound could be generated. LЈЈBi2Cl4 [5; LЈЈ
=
N(Ar)=C(Me)CC(Me)=N(Ar), Ar = 2,6-iPr2C6H3] was
formed as a light brown solid in 45% yield [Scheme 2,
Equation (5)]. Free ligand was found as a byproduct in a
1
nonnegligible amount (5/LH ≈ 1:0.7)[20] by H NMR spec-
tral analysis. Due to the production of a considerable
amount of LH, we tried the reaction with LLi again, in
which the LLi was ensured to have been formed in situ by
1H NMR measurements of the reaction mixture by using
2 equiv. of BiCl3. However, almost the same results were
obtained with the yield of 5 always less than 50%.
γ-CH ligation of L has been reported for P (Scheme 1,
III-2)[7a] and Ge compounds,[11] which have been suggested
to form through elimination of NaCl or LiCl from the reac-
tion of LNa and PCl3 or LLi and GeCl4 followed by dis-
tinct diimine rearrangement within the C5N2 ligand back-
bone. The P compound can be quickly converted into the
III-1-type species in solution by γ-CH proton migration to
one of the imine N-atoms to reestablish the π-electron con-
jugation of the ligand backbone, and is thus considered as
an intermediate.[10c] The stable formation of many III-1
complexes and their derivatives has also been report-
ed.[7b,9,10] Comparably, 5 exhibits γ-C double ligation under
the diimine framework, which may involve further γ-C–H
activation based on coordination similar to that of the Ge
compound.[11] To the best of our knowledge, this is a new
L ligation feature for β-diketiminato complexes.[1–11] Con-
sidering the prior formation of 1 in this reaction system, we
propose that the formation of 5 might undergo an isomer-
ization of partial 1 to A, and A further reacted with another
molecule of BiCl3 by γ-C–H activation to give 5 with the
release of HCl (Scheme 4). C–H activation within the L
backbone has been observed in P,[7–10] As,[10a,10c]
Sb,[7,8,10a,10c] Si,[13] and Ge[13b] complexes, some of which
can occur even in the presence of a relatively active NH
functionality.[7c,10] The HCl generated could acidify the un-
reacted LLi to produce LH. This is in agreement with the
isolation of LH from the reaction. Moreover, the pro-
duction of a considerable amount of LH and less than 50%
yield of 5 suggests the consumption of LLi and BiCl3 in a
degree too larger for further reactions even when changing
the molar ratio of the reactants.
Figure 4. Crystal structure of 4 with the thermal ellipsoids at 50%
probability. H atoms of the aryl groups are omitted for clarity. Se-
lected bond lengths [Å] and angles [°]: Bi(1)–C(1) 2.225(6), Bi(1)–
N(1) 2.368(5), Bi(1)–Cl(1) 2.544(2), Bi(1)–Cl(3) 2.8456(19), Bi(1)–
Cl(4) 2.882(2), Bi(2)–C(31) 2.228(7), Bi(2)–N(3) 2.333(6), Bi(2)–
Cl(2) 2.6056(19), Bi(2)–Cl(3) 2.9310(18), Bi(2)–Cl(4) 2.7846(19),
C(1)–C(2) 1.483(8), C(2)–C(3) 1.337(8), C(3)–C(4) 1.415(8), C(4)–
C(5) 1.515(8), C(2)–N(2) 1.359(7), C(4)–N(1) 1.320(7), C(31)–C(32)
1.455(9), C(32)–C(33) 1.394(9), C(33)–C(34) 1.432(8), C(34)–C(35)
1.521(9), C(32)–N(4) 1.333(7), C(34)–N(3) 1.271(1); C(1)–Bi(1)–
N(1) 78.8(2), C(1)–Bi(1)–Cl(1) 90.68(19), C(1)–Bi(1)–Cl(3)
90.59(18), C(1)–Bi(1)–Cl(4) 80.68(18), C(31)–Bi(2)–N(3) 79.8(2),
C(31)–Bi(2)–Cl(2) 84.66(19), C(31)–Bi(2)–Cl(3) 90.70(18), C(31)–
Bi(2)–Cl(4) 86.89(18).
larly, [LЈSbBr(μ-Br)]2 was thought to undergo intramolecu-
lar C–H activation due to the presence of the active Sb–X
(X = halide).[7c] It is reasonable to deduce that such acti-
vation may be induced from structural isomerization, which
is probably due to the active Bi–N bond (Scheme 3). The
high reactivity of such a bond has been well documented
by Roesky et al. and shows insertion reactions with a series
of carbon-containing unsaturated molecules.[19]
The formulation of 5 was confirmed by spectroscopy and
X-ray crystallography. The 1H NMR spectrum exhibits only
Scheme 3. Isomerization of 1 to 4.
Scheme 4. Plausible mechanism for the formation of 5.
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(β-Diketiminato)bismuth(III) Complexes
one singlet resonance for the CMe protons at δ = 1.96 ppm 1.46(2), C(2)–N(1) 1.301(16), and C(4)–N(2) 1.301(18) Å]
within the ligand backbone. The crystal structure shown in match well with the diimine arrangement.
Figure 5 illustrates the γ-C double ligation, which presents
Finally, we tested the solvent-free reaction of BiCl3 and
γ-C,N-chelation at each BiIII center. The Bi–N [2.500(13)– LH at 125 °C under vacuum. Extraction with THF fol-
2.539(11) Å] and Bi–C [2.311(16)–2.315(14) Å] bonds are a lowed by crystallization at –20 °C afforded [LH2]+-
little longer than those in 1–4 for the former and in 2 and [BiCl4(THF)]– (6) as colorless crystals in a very low yield
4 for the latter, whereas the Bi–Cl bond lengths [2.504(4)– (9.3%). Most of the residues were insoluble in organic sol-
2.653(4) Å] are comparable to the related terminal dis- vents. [LH2]+Cl– is known as a precursor in the base-neu-
tances. The matrix data for the ligand backbone [C(1)–C(2) tralized formation of LH.[21] The formation of 5 is thought
1.48(2), C(2)–C(3) 1.46(2), C(3)–C(4) 1.544(17), C(4)–C(5) to involve the generation of HCl, which could react with
BiCl3 and LH to give 6. Because of the ionic character, 6 is
insoluble in organic solvents, and its NMR spectrum was
silent. Nonetheless, X-ray crystallography clearly evidences
an ionic pair (Figure 6).
Conclusions
We investigated the reaction of LLi and BiCl3 and, with
careful control of the reaction and isolation conditions, we
prepared a series of bismuth(III) complexes 1, 2, 4, and 5,
the formulations of which were confirmed by structural
characterization, which showed versatile L ligation modes
at the metal atom. This reveals a complexity of the reaction
system and may reasonably explain the unsuccessful isola-
tion of pure compounds previously mentioned due to the
complexity of products.[7c] The temperature-dependent con-
version of 1 to 4 suggests easy isomerization of the β-diketi-
minato ligand, especially in ligating group 15 ele-
ments.[7a,7b,8] On changing the functionality at the BiIII cen-
ter, e.g. the carboxyl group in 3, the N,N-ligation of L ap-
pears to be stable. Multiple coordination sites in the N-
substituents or avoidance of an active group in the back-
bone may have the same function. The former has been
demonstrated by Roesky et al. with the preparation of LaB-
iCl2,[14a] and the latter by Lappert et al. with the synthesis
Figure 5. Crystal structure of 5 with the thermal ellipsoids at 50%
probability. H atoms are omitted for clarity. Selected bond lengths
[Å] and angles [°]: Bi(1)–N(1) 2.500(13), Bi(1)–C(3) 2.315(14),
Bi(1)–Cl(1) 2.519(4), Bi(1)–Cl(2) 2.653(4), Bi(2)–N(2) 2.539(11),
Bi(2)–C(3) 2.311(16), Bi(2)–Cl(3) 2.648(3), Bi(2)–Cl(4) 2.504(4),
C(1)–C(2) 1.48(2), C(2)–C(3) 1.46(2), C(3)–C(4) 1.544(17), C(4)–
C(5) 1.46(2), C(2)–N(1) 1.301(16), C(4)–N(2) 1.301(18); Cl(1)–
Bi(1)–N(1) 99.6(3), Cl(1)–Bi(1)–C(3) 95.6(4), Cl(1)–Bi(1)–Cl(2)
95.69(15), Cl(4)–Bi(2)–N(2) 97.3(3), Cl(4)–Bi(2)–C(3) 92.8(4),
Cl(4)–Bi(2)–Cl(3) 96.05(15).
of Lb Bi2X4 (X = Cl, Br, and I).[14b] With respect to the
2
salt-elimination metathesis, routine operations of removal
of the salt followed by crystallization or recrystallization
seem to be unworkable for obtaining pure 1, 2, and 4. In
contrast, an unusual workup of not separating the LiCl salt
does well. This method will be applied to the isolation of
other Bi complexes.
Experimental Section
General Procedures: All syntheses and manipulations of air- and
moisture-sensitive materials were carried out under nitrogen by
using Schlenk techniques or inside an MBraun Unilab glovebox
filled with argon, in which the calibrated values of O2 and H2O
were strictly controlled below 1.2 ppm. Organic solvents including
toluene, n-hexane, and THF were predried with fine sodium wire
and then heated with sodium/potassium benzophenone under ni-
trogen prior to use. CH2Cl2 and CHCl3 were heated with CaH2 for
at least 3 d before use. Deuterated CDCl3 was degassed, dried with
CaH2, and filtered before use. NMR spectra were recorded with a
Bruker Avance II 500 spectrometer. IR spectra were measured with
a Nicolet 300 spectrometer. Melting points were measured in sealed
glass tubes by using a Büchi-540 instrument. Elemental analysis
Figure 6. Crystal structure of 6 with the thermal ellipsoids at 50%
probability. H atoms are omitted for clarity except NH and γ-CH.
Selected bond lengths [Å] and angles [°]: Bi(1)–O(1) 2.637(3), Bi(1)–
Cl(1) 2.4901(11), Bi(1)–Cl(2) 2.6663(11), Bi(1)–Cl(3) 2.7868(11),
Bi(1)–Cl(4) 2.5166(12), N(1)–C(2) 1.336(4), N(2)–C(4) 1.330(4),
C(2)–C(3) 1.392(4), C(3)–C(4) 1.392(4); Cl(1)–Bi(1)–O(1) 81.96(6),
Cl(1)–Bi(1)–Cl(2) 88.26(3), Cl(1)–Bi(1)–Cl(3) 97.72(3), Cl(1)–Bi(2)–
Cl(4) 93.29(4).
Eur. J. Inorg. Chem. 2011, 5265–5272
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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5269

Y. Li, H. Zhu, G. Tan, T. Zhu, J. Zhang
FULL PAPER
was performed with a Thermo Quest Italia SPA EA 1110 instru-
ment. Commercially available reagents were purchased from Ald-
rich, Acros, Alfa Aesar, and Lvyin Chemical Co. and used as re-
ceived. LH[21] and BiCl3(THF)2[22] were prepared according to pub-
lished procedures.
6 H, C6H3) ppm. 13C NMR (125 MHz, CDCl3, 298 K): δ = 22.65,
24.21, 24.81, 28.58, 28.67, 31.59 (CHMe2, CMe, CF3), 93.25 (γ-
CH), 123.02, 124.64, 125.07, 129.21, 140.74, 142.47, 145.17 (C6H3),
161.19 (OOC), 166.49 (CN) ppm. 19F NMR (470 MHz, CDCl3,
298 K): δ = –77.01 (s) ppm. C37H49BiF6N2O5 (3·THF, 924.77):
calcd. C 48.05, H 5.34, N 3.03; found C 48.43, H 5.56, N 2.87.
The X-ray quality single crystals of 3·1.75THF were obtained by
recrystallization of 3 from a THF/n-hexane (5 mL/5 mL) mixture
at –15 °C.
Preparation of [LBiCl(μ-Cl)]2 (1): Inside the glovebox, nBuLi
(1.04 mL, 2.4 m in n-hexane, 2.50 mmol) was added dropwise to a
precooled (–15 °C) solution of LH (1.05 g, 2.50 mmol) in toluene
(20 mL). The mixture was stirred and warmed to room tempera-
ture. After stirring for 12 h to allow the complete formation of LLi,
the solution was cooled to –15 °C and added to a precooled
(–15 °C) solution of BiCl3(THF)2 (1.15 g, 2.50 mmol) in THF
(20 mL). The mixture was allowed to stand at –15 °C for 48 h. Red
crystals of 1 were formed. After decanting the solution, the residue
Preparation of [LЈBiCl(μ-Cl)]2 [4; LЈ = N(Ar)=C(Me)CH=C-
(NHAr)CH2, Ar = 2,6-(iPr2C6H3)]: LLi (2.5 mmol) in toluene
(30 mL), prepared as described above, was added to a suspension
of BiCl3 (0.79 g, 2.5 mmol) in toluene (10 mL) at room tempera-
ture. The mixture was stirred for 48 h. After workup, the yellow
was extracted with cooled CH2Cl2 (30 mL, –15 °C). The extract suspension was concentrated (ca. 10 mL) and allowed to stand at
was concentrated to dryness under vacuum, and the residue was
room temperature without filtration. After 3 weeks, yellow crystals
of 4 were formed and collected together with the insoluble material.
The solids were extracted with toluene (20 mL), and the extract
washed with n-hexane (5 mL) to give 1 as a red solid. Yield: 1.12 g,
1
64%. M.p. 147 °C (dec.). H NMR (500 MHz, CDCl3, 298 K): δ =
3
3
1.23 (d, JHH = 6.5 Hz, 24 H), 1.36 (d, JHH = 6.5 Hz, 24 H) was dried under vacuum and washed with n-hexane (5 mL) to give
3
(CHMe2), 2.00 (s, 12 H, CMe), 3.37 (sept, JHH = 6.5 Hz, 8 H,
4 as a yellow crystalline solid. Yield: 0.72 g, 41%. M.p. 170 °C
CHMe2), 5.30 (s, 2 H, γ-CH), 7.05–7.33 (m, 12 H, (C6H3) ppm. (dec.). 1H NMR (500 MHz, CDCl3, 298 K): δ = 1.07 (d, JHH
=
=
3
13C NMR (125 MHz, CDCl3, 298 K): δ = 24.60, 25.49, 26.24, 28.49
7.0 Hz, 12 H), 1.13 (d, JHH = 7.0 Hz, 12 H), 1.21 (d, JHH
3
3
3
(CHMe2, CMe), 111.48 (γ-CH), 124.55, 128.21, 128.91, 129.02, 7.0 Hz, 12 H), 1.22 (d, JHH = 7.0 Hz, 12 H) (CHMe2), 1.11 (s, 4
138.75, 145.22 (C6H3), 165.65 (CN) ppm. C58H82Bi2Cl4N4 H, C=CH2), 1.55 (s, 6 H, CMe), 1.72 (s, 2 H, NH), 3.21 (sept, 3JHH
(1395.07): calcd. C 49.93, H 5.92, N 4.02; found C 49.89, H 5.64,
N 3.92.
= 7.0 Hz, 4 H), 3.41 (br., 4 H) (CHMe2), 4.09 (s, 2 H, γ-CH), 7.12–
7.35 (m, 12 H, C6H3) ppm. 13C NMR (125 MHz, CDCl3, 298 K):
δ = 1.02 (C=CH2), 20.75, 23.22, 23.62, 24.21, 24.35, 24.62, 25.37,
28.09, 28.19, 28.65 (CMe, CHMe2), 99.71 (γ-CH), 123.01, 123.89,
124.50, 125.06, 140.72, 142.46 (C6H3, CNH), 161.19 (CN) ppm. IR
Preparation of [LBiCl(μ-Cl)Bi(nBu)Cl(μ-Cl)]2 (2): The preparation
of 2 was similar to that of 1, and nBuLi (1.25 mL, 2.4 m in n-
hexane, 3.00 mmol), LH (1.26 g, 2. 50 mmol), and BiCl3(THF)2
(1.38 g, 3.00 mmol) were used. The LLi formed in situ, nBuLi, and
BiCl3(THF)2 mixture was allowed to stand at –15 °C for 48 h. Red
crystals of 1 (0.73 g, 42%) were collected. The mother liquor was
concentrated to half its volume under vacuum and then kept at
–15 °C for 72 h to afford orange-red crystals of 2, which were col-
lected by filtration and washed with n-hexane (2 mL). Yield: 0.24 g,
22% (based on quantitative formation of 2 at a 0.25 mmol scale
(KBr plate, Nujol mull):
ν
˜
=
3294 [w, ν(NH)] cm–1.
C71H104Bi2Cl4N4 (4·toluene·n-hexane, 1573.39): calcd. C 54.20, H
6.66, N 3.56; found C 55.09, H 6.68, N 3.30.
Isomerization of 1 to [LЈBiCl(μ-Cl)]2 (4): At room temperature, 1
(0.13 g, 0.20 mmol) was dissolved in THF (6 mL). The solution was
stirred for 24 h, and a yellow solution developed. The solution was
concentrated to dryness under vacuum to give a yellow solid. The
1H NMR spectroscopic analysis confirmed almost quantitative for-
mation of 4.
1
on account of 0.50 mmol excess of nBuLi). M.p. 142 °C (dec.). H
NMR (500 MHz, CDCl3, 298 K): δ = 0.88–0.93 (m, 6 H), 1.26–
1.30 (m,
4 H), 2.50–2.55 (m, 4 H), 3.15–3.22 (m, 4 H)
Preparation of LЈЈBi2Cl4 [5; LЈЈ = N(Ar)=C(Me)CC(Me)=N(Ar),
3
3
(CH2CH2CH2CH3), 1.22 (d, JHH = 6.5 Hz, 24 H), 1.37 (d, JHH
= 6.5 Hz, 24 H) (CHMe2), 2.03 (s, 12 H, CMe), 3.12 (sept, JHH
Ar
= 2,6-iPr2C6H3]: A precooled (–15 °C) solution of LLi
3
=
(1.25 mmol) in toluene (30 mL), prepared as described above, was
added to a precooled (–15 °C) suspension of BiCl3 (0.40 g,
1.25 mmol) in toluene (10 mL). The mixture was heated slowly to
reflux with stirring and kept at this temperature for 12 h. After
workup, the reaction suspension was cooled to room temperature.
After filtration to remove insoluble material, the filtrate was con-
centrated to dryness under vacuum to give a grey-yellow residue,
which was identified as a mixture of 5 and LH in a molar ratio of
6.5 Hz, 8 H, CHMe2), 5.38 (s, 2 H, γ-CH), 7.14–7.29 (m, 12 H,
C6H3) ppm. 13C NMR (125 MHz, CDCl3, 298 K): δ = 14.11, 21.39,
24.67, 25.46, 25.91, 27.47, 28.70, 36.35 (CHMe2, CMe,
CH2CH2CH2CH3), 93.70 (γ-CH), 111.15, 124.79, 125.23, 128.15,
128.96, 129.36, 138.58, 144.37 (C6H3), 165.67 (CN) ppm.
C66H100Bi4Cl8N4 (2069.07): calcd. C 38.31, H 4.87, N 2.71; found
C 38.51, H 5.08, N 2.63.
1
Preparation of LBi(OOCCF3)2 (3): Inside the glovebox, a precooled
solution of AgOOCCF3 (0.09 g, 0.40 mmol) in toluene (5 mL) was
added dropwise to a precooled (–15 °C) solution of 1 (0.14 g,
0.10 mmol) in THF (20 mL) in a dark brown vial. Precipitation of
solid from the solution was immediately observed. This mixture
was allowed to stand at –15 °C for 24 h and then warmed to room
temperature. After stirring for 1.5 h, the mixture was filtered to
remove insoluble material, and the filtrate was dried under vacuum.
The residue was washed with n-hexane (3 mL) to give 3 as an
orange solid, which was analytically pure by 1H NMR spec-
troscopy. Yield: 0.16 g, 87%. M.p. 154 °C (dec.). 1H NMR
ca. 1:0.7 by H NMR spectroscopy. The residue was washed with
a large amount of n-hexane (3ϫ 10 mL) to remove LH, and 5
(0.42 g) was obtained as a light brown solid. The washings were
added to THF (0.5 mL) and allowed to stand at room temperature
for slow concentration; 2 weeks later, light brown crystals of
52·3.7THF (0.15 g) were grown. Total yield: 0.55 g (based on 5),
45%. M.p. 178 °C (dec.). 1H NMR (500 MHz, CDCl3, 298 K): δ =
3
3
1.14 (d, 6 H, JHH = 6.5 Hz), 1.16 (d, 6 H, JHH = 6.5 Hz), 1.24 (d,
3
3
6 H, JHH = 6.5 Hz), 1.28 (d, 6 H, JHH = 6.5 Hz) (CHMe2), 1.96
(s, 6 H, CMe), 3.22 (sept, 2 H, 3JHH = 6.5 Hz), 3.24 (sept, 2 H, 3JHH
= 6.5 Hz) (CHMe2), 7.14–7.42 (m, 6 H, C6H3) ppm. 13C NMR
(125 MHz, CDCl3, 298 K): δ = 1.01 (CBi), 23.37, 24.22, 24.39,
25.98, 27.53, 28.65, 33.28 (CHMe2, CMe), 123.26, 124.31, 127.84,
136.38, 141.82, 142.83 (C6H3), 173.30 (CN) ppm. C29H40Bi2Cl4N2
3
(500 MHz, CDCl3, 298 K): δ = 1.21 (d, JHH = 6.5 Hz, 12 H), 1.45
3
(d, JHH = 6.5 Hz, 12 H, CHMe2), 2.03 (s, 6 H, CMe), 3.23 (sept,
3JHH = 6.5 Hz, 4 H) (CHMe2), 5.34 (s, 1 H, γ-CH), 7.12–7.30 (m,
5270
www.eurjic.org
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 5265–5272

(β-Diketiminato)bismuth(III) Complexes
Table 1. Crystallographic data for 1–6.
1·2toluene
2
3·1.75THF
4·toluene
52·3.7THF
6
Empirical formula
Formula mass
Temperature [K]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
α [°]
β [°]
C72H98Bi2Cl4N4
1579.30
173(2)
C66H100Bi4Cl8N4 C40H55BiF6N2O5.75 C65H90Bi2Cl4N4 C72.8H109.6Bi4Cl8N4O3.7 C33H51BiCl4N4O
2069.02
173(2)
978.84
173(2)
1487.17
173(2)
2219.56
173(2)
842.54
173(2)
triclinic
monoclinic
P2(1)/n
triclinic,
P1
triclinic
P1
monoclinic
P2(1)
monoclinic
P2(1)/c
¯
¯
¯
P1
10.303(2)
13.035(3)
14.361(3)
72.14(3)
73.93(3)
74.32(3)
1727.4(6)
1
1.518
5.284
792
17.666(4)
21.075(4)
22.312(5)
10.583(2)
15.651(3)
16.799(3)
111.84(3)
100.11(3)
101.66(3)
2431.5(8)
2
14.6999(17)
15.9145(18)
17.7187(19)
96.965(9)
114.316(11)
112.658(11)
3287.1(6)
2
14.1084(7)
19.0622(7)
16.2781(8)
10.379(2)
21.808(4)
16.543(3)
111.01(3)
110.393(6)
94.48(3)
γ [°]
V [Å3]
7755(3)
4
4103.4(3)
2
3732.8(13)
4
Z
ρcalcd. [Mg/m3]
μ [mm–1]
F(000)
1.772
1.337
1.503
1.796
1.499
9.363
3.687
5.549
8.857
5.036
3968
984
1484
2144
1688
θ range [°]
Index ranges
3.05–27.46
–13 Յ h Յ 13
–16 Յ k Յ 16
–18 Յ l Յ 18
16928
3.01–27.48
–22 Յ h Յ 22
–27 Յ k Յ 27
–28 Յ l Յ 28
74146
3.01–27.48
–13 Յ h Յ 13
–20 Յ k Յ 20
–21 Յ l Յ 21
23646
2.74–26.00
–17 Յ h Յ 18
–19 Յ k Յ 19
–21 Յ l Յ 21
34507
2.79–26.00
–17 Յ h Յ 17
–23 Յ k Յ 23
–15 Յ l Յ 20
19034
3.04–27.47
–13 Յ h Յ 13
–28 Յ k Յ 28
–21 Յ l Յ 19
35786
No. of reflns. collected
No. of indep. reflns. (Rint
No. of data/restraints/params.
Completeness to θ
)
7827 (0.0446)
7827/0/381
98.8%
17678 (0.2286)
17678/0/754
99.5%
10932 (0.0931)
10932/123/513
97.9%
12904 (0.0874)
12904/0/661
99.9%
13820 (0.075)
13820/1443/719
99.8%
8507 (0.0679)
8507/0/380
99.3%
GOF/F2
1.010
0.966
1.089
0.710
0.972
1.102
R1,[a] wR2[b] [IϾ2σ(I)]
R1,[a] wR2[b] (all data)
Largest diff. peak/hole [e/Å3]
0.0344, 0.0902
0.0362, 0.0916
2.464/–3.310
0.0813, 0.1251
0.1965, 0.1593
1.538/–1.785
0.0744, 0.1702
0.1135, 0.2137
2.485/–2.471
0.0427, 0.0584
0.1026, 0.0640
1.449/–1.301
0.0634, 0.0940
0.0852, 0.1031
1.938/–1.322
0.0303, 0.0450
0.0540, 0.0547
1.391/–1.433
2
2 2
[a] R1 = Σ||Fo| – |Fc||/Σ|Fo|. [b] wR2 = [Σw(Fo – Fc ) /Σw(Fo2)]1/2
.
(976.41): calcd. C 35.67, H 4.13, N 2.87; found C 35.23, H 4.65, N
2.60.
crystallographic data for this paper. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
Preparation of [LH2]+[BiCl4(THF)]– (6): LH (0.70 g, 1.68 mmol)
and BiCl3(THF)2 (0.89 g, 1.68 mmol) were placed into a 50 mL
Schlenk flask and subjected to evacuation. The mixture was heated
slowly to 125 °C and kept at this temperature for 5 h. After cooling
to room temperature, the resultant solid was extracted with THF
(15 mL). The extract was concentrated (ca. 5 mL) and then layered
with n-hexane (0.5 mL). After keeping at –20 °C for 72 h, colorless
crystals of 6 were obtained from the solution. Yield: 0.13 g, 9.3%.
M.p. 143 °C. Due to the poor solubility of 6, the resonance signals
in the NMR spectra (1H and 13C) were hard to assign. IR (KBr
Acknowledgments
This work was supported by the National Nature Science Founda-
tion of China (NNSFC) (No. 20972129 and 91027014), the Re-
search Fund for New Teacher of Higher Education (No.
200803841012), and the National Fund for Fostering Talents of
Basic Science (NFFTBS) (No. J1030415).
plate, Nujol mull): ν = 3248 [w, ν(NH)] cm–1. C H BiCl N O
˜
33 51
4
2
(842.56): calcd. C 47.04, H 6.10, N 3.32; found C 46.10, H 5.01, N
3.33.
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X-ray Structure Determination and Refinement: The crystallo-
graphic data for 1–6 were collected with a Rigaku R-Axis Spider
IP system (1–3 and 6) or an Oxford Gemini S Ultra (4 and 5). In
all cases graphite-monochromated Mo-Kα radiation (λ
=
0.71073 Å) was used. Absorption corrections were applied by using
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were solved by direct methods (SHELXS-96)[23] and refined against
F2 using SHELXL-97.[24] In general, the non-hydrogen atoms were
located by difference Fourier synthesis and refined anisotropically,
and hydrogen atoms were included by using the riding model with
Uiso tied to the Uiso of the parent atoms unless otherwise specified.
The carbon atoms of the THF solvent molecules in 3 and 5 and of
the toluene molecule in 4 were isotropically refined. A summary of
cell parameters, data collection, and structure solution and refine-
ment is given in Table 1. CCDC-837123 (for 1·2toluene), -837124
(for 2), -837125 (for 3·1.75THF), -837126 (for 4·toluene), -837127
(for 52·3.7 THF), and -837128 (for 6) contain the supplementary
Eur. J. Inorg. Chem. 2011, 5265–5272
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
5271

Y. Li, H. Zhu, G. Tan, T. Zhu, J. Zhang
FULL PAPER
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Received: August 3, 2011
Published Online: October 25, 2011
5272
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Eur. J. Inorg. Chem. 2011, 5265–5272