Heteroleptic amidinate complexes of heavy group 15 elements - Synthesis, X-ray crystal structures and theoretical calculations

Article abstract of DOI:10.1002/ejic.200900233

Monosubstituted amidinate complexes [RC(NR)₂]ECl ₂ [E = Sb, R = tBu, R = iPr 1,Cy 2, 2,6-iPr₂C ₆H₃ (Dipp) 3;R = nBu, R' = iPr 4;E = Bi, R = tB u, R' = iPr 5, Dipp 6] were prepared in high yields by sa

Full text of DOI:10.1002/ejic.200900233

FULL PAPER
DOI: 10.1002/ejic.200900233
Heteroleptic Amidinate Complexes of Heavy Group 15 Elements – Synthesis,
X-ray Crystal Structures and Theoretical Calculations
Benjamin Lyhs,[a] Stephan Schulz,*[a] Ulrich Westphal,[a] Dieter Bläser,[a] Roland Boese,[a]
and Michael Bolte[b]
Dedicated to Prof. Dietmar Seyferth on the occasion of his 80th birthday
Keywords: N ligands / Main group elements / Antimony / Bismuth
Monosubstituted amidinate complexes [RC(NRЈ)2]ECl2 [E =
Sb, R = tBu, RЈ = iPr 1, Cy 2, 2,6-iPr2C6H3 (Dipp) 3; R = nBu,
RЈ = iPr 4; E = Bi, R = tBu, RЈ = iPr 5, Dipp 6] were prepared
in high yields by salt elimination reactions of ECl3 with Li
amidinates. 1–6 were characterized by elemental analyses,
NMR and IR spectroscopy and single-crystal X-ray diffrac-
tion. In addition, computational calculations were performed
to clarify the different bonding modes in 1 and 5.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2009)
useful in catalysis, material sciences (i.e. precursors for
CVD) and organic-inorganic hybrids since their steric and
electronic properties can easily be tuned by modification of
the organic substituents R and RЈ.
Introduction
N,NЈ-Chelating organic ligands L such as β-diketiminate
I,[1] guanidinate II[2] and amidinate anions III[3] (Scheme 1)
have attracted growing interest in organometallic chemistry
in the last decade due to their capability to coordinate very
flexible to the metal center as monodentate (η1, a), chelat-
ing (η2, b) or bridging monodentate (µ-η1-η1, c) four-elec-
tron donor (Scheme 2).[4] Moreover, they were found very
In main group element chemistry, research has mainly
focused on the synthesis of group 13 element complexes. In
particular monosubstituted complexes of the type LMX2
(M = Al, Ga, In, X = halide, Me) were found to be suitable
starting reagents in olefin polymerization reactions and for
the synthesis of low-valent group 13 metal complexes of the
type LM (M = Al, Ga, In),[5] in which the metal atom for-
mally adopts the oxidation state +I. The same was found
for group 2 (Mg) and group 14 metal complexes, in particu-
lar LGeX, which were found to be valuable precursors for
the synthesis of the corresponding low-valent organomag-
nesium complexes of the type LMg-MgL {L = ArNC-
(NiPr2)NAr (Priso), [DippNC(Me)]2CH (Dippnacnac)}[6]
as well as GeI complexes.[7]
Scheme 1. Typical N,NЈ-chelating ligands.
Due to our long-term interest in organobismuth and or-
ganoantimony chemistry,[8] we became interested in the syn-
thesis of complexes of the type LECl2 (E = Sb, Bi) contain-
ing N,NЈ-chelating substituents. To our surprise, only a very
few group 15 element complexes of types I–III have been
reported in the literature, in particular those of the heaviest
elements, Sb and Bi.[9] Only very recently, a very few amid-
inate,[10] formamidinate[11] and β-diketiminate[12] complexes
Scheme 2. General coordination modes of amidinate ligands.
[a] Institute of Inorganic Chemistry, University of Duisburg-Essen, have been structurally characterized. Moreover, reduction
45117 Essen, Germany
reaction in a very few cases also yielded low-valent amido-
Fax: +49-201-1833830
diarsene[10] and an unusual β-diiminato arsenic complex.[13]
E-mail: stephan.schulz@uni-due.de
[b] Institute of Inorganic Chemistry, University of Frankfurt,
In an attempt to synthesize potential starting reagents
60438 Frankfurt, Germany
for further reactivity studies, we started to investigate salt
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
elimination reaction between ECl3 (E = Sb, Bi) and Li ami-
Eur. J. Inorg. Chem. 2009, 2247–2253
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B. Lyhs, S. Schulz, U. Westphal, D. Bläser, R. Boese, M. Bolte
FULL PAPER
dinates. Herein, we report on the synthesis of six Sb and Bi
amidinate complexes of the general type LECl2 and their
X-ray crystal structures.
Results and Discussion
Reactions of equimolar amounts of ECl3 (E = Sb, Bi)
and Li[RC(NRЈ)2] (R = nBu, tBu; RЈ = iPr, Cy, Dipp) in
Et2O yielded the corresponding monosubstituted amidinate
complexes of the general type [tBuC(NRЈ)2]SbCl2 (RЈ = iPr
1, Cy 2, Dipp 3), [nBuC(NiPr)2]SbCl2 (4), and [tBuC-
(NRЈ)2]BiCl2 (RЈ = iPr 5, Dipp 6), respectively (Scheme 3).
Complexes 1–6 were isolated after standard workup in high
yields.
Figure 2. Molecular structure and atom numbering scheme of a
monomeric unit of [tBuC(NCy)2]SbCl2 (2); displacement ellipsoids
are drawn at the 50% probability level. Hydrogen atoms have been
omitted for clarity.
Scheme 3. Synthesis of monosubstituted amidinate complexes 1–6.
1H and 13C NMR spectra of 1–6 show the expected reso-
nances due to the organic substituents (R, RЈ) of the amid-
inate moiety. The formation of solvent-coordinated (Et2O)
complexes as was previously observed for comparable bis-
muth formamidinates of the type LBiX2 (X = Cl, Br) can
be excluded for 1–6.[11] Single crystals were obtained from
solutions in CHCl3 (1–5) and THF (6) after storage at
–30 °C for 48 h (Figures 1, 2, 3, and 4).
Figure 3. Molecular structure and atom numbering scheme of
[tBuC(NDipp)2]SbCl2 (3); displacement ellipsoids are drawn at the
50% probability level. Hydrogen atoms and CHCl3 molecules have
been omitted for clarity.
Figure 4. Molecular structure and atom numbering scheme of
[nBuC(NiPr)2]SbCl2 (4); displacement ellipsoids are drawn at the
50% probability level. Hydrogen atoms and CHCl3 molecules have
been omitted for clarity.
Figure 1. Molecular structure and atom numbering scheme of a
monomeric unit of [tBuC(NiPr)2]SbCl2 (1); displacement ellipsoids
are drawn at the 50% probability level. Hydrogen atoms have been
omitted for clarity.
amidinate complexes whereas that of 6 shows a larger devi-
ation [55.69(11)° 6]. The N1–C1–N2 angles of 1–6 are al-
most identical and the sum of bond angles at C1 (360.0 1,
The complexes crystallize in the monoclinic space groups 2, 3, 4, 6; 359.8 5), N1 (360.0 1; 359.6 2, 3; 356.8 4; 359.9
P21/c (1) and P21/n (2, 6), in the orthorhombic space group 5; 358.3 6) and N2 (359.2 1; 360.0 2; 355.4 3; 359.9 4, 359.1
Pna21 (3) and in the triclinic space group P1 (4, 5). 3, 4, and 5, 359.5 6) indicate sp2-hybridized carbon and nitrogen
¯
5 contain CHCl3 molecules in the crystal lattice whereas 1 atoms. However, the delocalization of the π-electrons in the
and 2 were obtained as solvent-free complexes. In contrast, amidinate backbone of 1, 2, 3, 4 and 6 is distorted as ex-
the Bi center in 6 is weakly coordinated by a THF donor pressed by the different C1–N1/2 bond lengths. Comparable
and the crystal lattice contains two additional THF mole- findings were previously observed in amidinate and guanid-
cules. The amidinate moieties in 1–6 serve as chelating (η2) inate complexes of the type LECl2 (E = As, Sb).[10,9a] In
four-electron donor ligands. The N1–Sb1–N2 [60.69(6)° 1; contrast, 5 shows identical C–N bond lengths, indicating
60.41(6)° 2; 59.21(8)° 3; 60.99(10)° 4] and N1–Bi1–N2 bite almost perfectly delocalized π-electrons as was reported for
angles [58.43(18)° 5] are close to 60° as is typical for metal [PhC(NMe)2ECl4 (E = As, Sb)[14] and [PhC(NMe)2Sb(Ph)2-
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Heteroleptic Amidinate Complexes of Heavy Group 15 Elements
Cl2.[15] In addition, the E1–N1 and E1–N2 bond lengths of from linearity due to the larger steric demand of the elec-
1–4 and 6 differ significantly, whereas in 5 almost identical tron lone pair.
Bi–N bond lengths were observed. Moreover, the most
In remarkable contrast to 3, which is a monomeric com-
striking structural difference between 1–4 and 6 on one plex in the solid state, solvent-free complexes 1 and 2 as
hand and 5 on the other hand is reflected by the exocyclic well as 4, which contains a CHCl3 molecule in the crystal
Cl1–E1–Cl2 bond angles, which are significantly smaller in lattice, show weak intermolecular interactions between the
1–4 and 6 compared to the almost linear orientation (Cl1– axial Cl atom (Cl2 1, Cl1 2, Cl1 4) and an adjacent SbЈ
Bi1–Cl2 [175.02(5)°] as observed in 5 (Figures 5 and 6).
atom, resulting in the formation of asymmetric Sb–Cl–SbЈ
bridges. The SbЈ–Cl bond lengths are significantly elon-
gated [3.1171(7) 1, 3.2447(6) 2, 3.1195(9) Å 4] compared to
the Sb–Cl bonds [2.6435(6) 1; 2.6114(6) 2; 2.6735(9) Å 4],
but far below the sum of the van der Waals radii (4.01 Å)
and within the range typically observed for anionic chlor-
2–
4–
5–
idoantimonides Sb2Cl8
,
Sb2Cl10
,
Sb2Cl11
,
and
Sb4Cl16 (Figure 7).[16]
4–
Figure 5. Molecular structure and atom numbering scheme of a
monomeric unit of [tBuC(NiPr)2]BiCl2 (5); displacement ellipsoids
are drawn at the 50% probability level. Hydrogen atoms and
CHCl3 molecules have been omitted for clarity.
Figure 7. Ball-and-stick/polyhedral presentation of 1. Hydrogen
atoms not shown for clarity.
The SbЈ–Cl distances between the second (equatorial) Cl
atom and the adjacent SbЈ atom in 1 and 2 are significantly
longer (4.7343(7) 1, 6.5652(6) Å 2), whereas 4 shows a sec-
ond weak interaction [3.8972(12) Å]. Consequently, 1 and 2
are best described as corner-bridged oligomers, whereas 4
Figure 6. Molecular structure and atom numbering scheme of the
dimer of [tBuC(NDipp)2]BiCl2 (6); displacement ellipsoids are
drawn at the 50% probability level. Hydrogen atoms and additional
THF molecules have been omitted for clarity.
The coordination geometry observed for 1–4 can either forms an edge-bridged oligomer. An even more regular
be described as strongly distorted “saw-horse” or as dis- structure is observed for 5, which shows two almost equal
torted trigonal bipyramidal conformation with the stereo- intermolecular Cl1/2-BiЈ bond lengths [3.1746(17),
chemically active electron lone pair at the Sb atom adopting 3.2102(19) Å]. Even though these bond lengths are elon-
an equatorial position as was previously observed for gated compared to the “regular” Bi–Cl distances
group 15 formamidinate complexes.[11] As a consequence, [2.7399(18), 2.6868(18) Å], 5 is more symmetric than the di-
the axial Sb–Clax [2.6435(6) 1; 2.6114(6) 2; 2.4732(7) 3; meric complex {[2-(6-Mepy)NSiMe3]2BiCl}2 [BiЈ–Cl
2.6735(9) Å 4] and Sb–Nax bond lengths [2.1906(16) 1; 2.629(4), 3.554(6) Å].[17b] As a structural consequence, the
2.2204(17) 2; 2.3059(19) 3; 2.205(3) Å 4] are significantly coordination geometry of Bi atoms in 5 can be described as
elongated compared to the equatorial Sb–ClEqu- distorted octahedral (Figure 8).
ation [(2).4030(6) 1; 2.3982(6) 2; 2.3664(8) 3; 2.4127(9) Å 4]
The distortion most likely results from the small bite an-
and Sb–Neq distances [2.1011(16) 1, 2.1022(16) 2; 2.104(2) gle (N–C–N) of the amidinate moiety, which deviates signif-
3; 2.116(2) Å 4]. The Clax–Sb1–Nax axes [152.46(5)° 1; icantly from the 90° as expected for a regular octahedron.
153.58(5)° 2; 147.81(6)° 3; 152.19(8)° 4] significantly deviate The octahedrons form an edge-shared polymeric structure
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B. Lyhs, S. Schulz, U. Westphal, D. Bläser, R. Boese, M. Bolte
FULL PAPER
experimental values as obtained for 1 and 5 than those of
the monomeric complexes 1a and 5a. In particular the Cl–
Bi–Cl bond angle of the trimer 5b (179°) agrees much better
with the experimentally observed bond angle [175.02(5)°].
The Sb–N and Sb–Cl bond lengths are typically slightly
overestimated whereas the intermolecular BiЈ–Cl bond
length in 5b is slightly shorter than the experimental value
as observed in 5. Surprisingly, the calculated structure of
symmetrically bridged 1c, which was obtained using the ex-
perimental data of 5 as starting point for the structure opti-
mization, is energetically favored by 12 kcal/mol (4 kcal/
mol/monomeric unit) compared to 1b. Moreover, the s-
character of the electron lone pair of the central Sb atom in
1c (93.2%) is higher than that in 1b (87%) and in the mono-
meric complex 1a (87.5%). However, these values are still
below those calculated for the Bi complexes (5a, 94%; 5b,
97%). According to these calculations, the electron lone pair
of the Bi complex is less stereochemically active compared
to that of the Sb complex, which agrees very well with the
different coordination modes as experimentally observed in
the solid-state structures of 1 and 5.
Figure 8. Ball-and-stick/polyhedral presentation of 5. Hydrogen
atoms not shown for clarity.
Conclusions
in the solid state. The electron lone pair at the Bi atom is
stereochemically inert, which is in remarkable contrast to
1–4. The structure of 5 significantly differs from thf-coordi-
nated, dimeric 6 [Cl-BiЈ 3.4398(10) Å] and from solvent-co-
ordinated monosubstituted formamidinates of the type
LBiCl2(thf) and [LBiBr2(thf)]2 as recently reported by Jones
et al.,[11] which either form centrosymmetric dimers
([LBiBr2(thf)]2) or adopt a trimeric structure LBiCl2(thf)
with bridging and terminal Cl atoms. The Bi–X–BiЈ bridges
(X = Br, Cl) of these formamidinate complexes are asym-
metrical and the Bi–X distances range from 2.9–3.1 Å (X =
Br) and 2.5–3.7 Å (X = Cl) as was observed for 6.
Six monosubstituted amidinate complexes [RC(NRЈ)2]-
ECl2 of the heaviest group 15 metals (Sb, Bi) have been pre-
pared and structurally characterized. The central metal (Sb,
Bi) as well as the solvent and the steric demand of the amid-
inate substituent, which can be adjusted by use of different
groups R (nBu, tBu) and RЈ (iPr, Cy, Dipp), show a distin-
guished influence to the coordination geometry of the re-
sulting complexes.
Experimental Section
The structural parameters as observed for 1–6 point to a
rather strong influence of both the steric demand of the
amidinate ligand as well as the nature of the solvent. 3,
which contains the sterically most demanding amidinate
substituent, forms a monomeric structure, whereas 4, which
is sterically slightly less hindered than the analogous tBu-
substituted corner-bridged complex 1 forms an edge-
bridged oligomeric structure. Coordination of a donor sol-
vent prevents the formation of oligomeric structures as was
previously observed for comparable formamidinate com-
plexes.[11]
Theoretical calculations were performed in order to elu-
cidate the different structures of 1 and 5, in particular their
different intermolecular interactions and, as a consequence,
their different coordination geometries.[18] Moreover, the
electronic nature of the electron lone pair was investigated
in more detail. Computational calculations starting with the
experimental structural data were performed both with the
monomeric (1a, 5a) and trimeric units (1b, 1c, 5b), which
represents a small cut of the weakly associated oligomeric
complexes. The calculated structural parameters of the tri-
General Procedures: All manipulations were performed under ar-
gon using standard Schlenk techniques or in an inert atmosphere
glove box. Solvents were dried with Na/K (Et2O) and CaH2
1
(CHCl3) and degassed prior to use. H and 13C{1H} NMR spectra
were recorded on a Bruker Avance 500 spectrometer and are refer-
enced to internal CDCl3 (1H: δ = 7.24; 13C: δ = 77.0 ppm). SbCl3
and BiCl3 were commercially available and used after purification
(sublimation). Li amidinates Li[RC(NRЈ)2] were generally prepared
by reaction of a carbodiimide with the corresponding organo-
lithium compound. IR spectra were recorded on a ALPHA-T FT-
IR spectrometer equipped with a single reflection ATR sampling
module. Melting points were measured in sealed capillaries and
were not corrected. Elemental analyses were performed at the Ele-
mentaranalyse-Labor of the University of Essen.
General Preparation of LECl2 (L = Amidinate, E = Sb, Bi): Solid
Li[RC(NRЈ)2] (R = nBu, tBu; RЈ = iPr, Cy, Dipp) was slowly added
within 1 h to a solution of ECl3 in 50 mL of Et2O at –78 °C, stirred
for 1 h and then warmed to ambient temperature over a period of
6 h. The resulting precipitate was filtered and extracted two times
with CHCl3 (40 mL). The solvent was evaporated in vacuo, yielding
grey (E = Sb) and yellowish crystalline solids (E = Bi), respectively.
[tBuC(NiPr)2]SbCl2 (1): tBuC(NiPr)2Li (2.50 g, 13.14 mmol), SbCl3
meric complexes 1b and 5b agree slightly better with the (3.00 g, 13.14 mmol); yield 3.98 g (10.59 mmol, 81%); m.p. 144 °C.
2250 Eur. J. Inorg. Chem. 2009, 2247–2253
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Heteroleptic Amidinate Complexes of Heavy Group 15 Elements
C11H23Cl2N2Sb (375.97 g/mol): found (calcd.): H 6.07 (6.17), C
(75 MHz, CDCl3, 25 °C): δ = 24.1 (CHMe2), 29.4 (CMe3), 40.8
1
35.01 (35.14), N 7.32 (7.45). H NMR (300 MHz, CDCl3, 25 °C): (CMe ), 48.9 (CHMe ), 176.6 (CN ) ppm. IR: ν = 3013, 2964,
˜
3
2
2
3
δ = 1.40 [d, JHH = 6.6 Hz, 12 H CH(CH3)2], 1.45 (s, 9 H, tBu),
2931, 2871, 1493, 1474, 1381, 1362, 1311, 1186, 1115, 1052, 1023,
3
4.61 [sept, JHH = 6.6 Hz, 2 H, CH(CH3)2] ppm. 13C NMR 926, 797, 676, 558, 491, 443, 413 cm–1.
Table 1. Crystallographic data for [tBuC(NR)2]SbCl2 (R = iPr 1, Cy 2, Dipp 3), [nBuC(NiPr)2]SbCl2 (4) and [tBuC(NR)2]BiCl2 (R = iPr
5, Dipp 6).
1
2
3
Empirical formula
Molecular mass
Crystal system
Space group
C11H23Cl2N2Sb
375.96
monoclinic
P21/c
C17H31Cl2N2Sb
456.09
monoclinic
P21/n
C29H43Cl2N2Sb·2CHCl3
851.04
orthorhombic
Pna21
a [Å]
b [Å]
c [Å]
α [°]
8.9840(2)
21.4667(6)
8.6151(2)
90
12.2083(5)
8.4120(5)
19.7778(8)
90
27.852(5)
15.962(3)
8.6085(15)
90
β [°]
111.8150(10)
90
1542.50(7)
4
99.946(3)
90
2000.58(17)
4
90
90
γ [°]
V [Å3]
3827.1(12)
4
Z
T [K]
193(2)
0.71073
2.115
1.619
61.0
173(2)
0.71073
1.646
1.514
55.8
173(1)
0.71073
1.303
1.477
58.9
Radiation λ [Å]
µ [mm–1]
Dcalcd. [gcm–3]
2θmax [°]
Crystal dimensions [mm]
Number of reflections
Number of unique reflections
Rmerg
0.26ϫ0.23ϫ0.21
39764
4529
0.31ϫ0.13ϫ0.12
34204
4603
0.36ϫ0.18ϫ0.16
75324
10336
0.0262
0.0708
0.0590
Number of parameters
Restraints
146/0
0.0237
0.0516
1.335
200/0
0.0266
0.0688
1.027
391/1
0.0309
0.0714
0.993
R1[a]
wR2[b]
Goodness of fit[c]
Final max./min. ∆ρ/e·Å–3
0.526/–1.056
0.533/–0.848
0.628/–0.660
4
5
6[d]
Empirical formula
Molecular mass
C11H23Cl2N2Sb·CHCl3
495.33
C22H46Bi2Cl4N4·4CHCl3
1403.86
C29H43Cl2N2Bi·3[C4H8O]
915.85
Crystal system
Space group
triclinic
P1
triclinic
P1
monoclinic
P21/n
¯
¯
a [Å]
b [Å]
c [Å]
α [°]
8.4646(9)
10.2032(11)
13.1082(15)
91.661(6)
96.985(6)
113.195(5)
1029.2(2)
2
8.5021(5)
11.4961(7)
13.2404(9)
102.238(4)
104.223(4)
98.007(3)
1200.68(13)
1
15.0780(3)
21.7447(5)
15.4864(3)
90
111.3847(12)
90
β [°]
γ [°]
V [Å3]
4727.90(17)
4
Z
T [K]
173(2)
0.71073
1.983
1.598
57.1
173(1)
0.71073
8.233
1.942
52.8
173(1)
0.71073
3.875
1.287
55.0
Radiation λ [Å]
µ [mm–1]
Dcalcd. [gcm–3]
2θmax [°]
Crystal dimensions [mm]
Number of reflections
Number of unique reflections
Rmerg
0.34ϫ0.25ϫ0.18
20366
5042
0.17ϫ0.13ϫ0.07
24247
5935
0.27ϫ0.22ϫ0.13
72955
13170
0.0351
0.0658
0.0670
Number of parameters
Restraints
209/0
0.0399
0.893
1.037
1.030/–0.899
218/0
0.0447
0.1138
1.008
514/0
0.0370
0.1012
1.038
R1[a]
wR2[b]
Goodness of fit[c]
Final max./min. ∆ρ/e·Å–3
3.326/–3.863
2.472/–0.763
2
2 2
2
[a] R1 = Σ(||Fo| – |Fc||)/Σ|Fo| [for IϾ2σ(I)]. [b] wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2. [c] Goodness of fit = {Σ[w(|Fo2| |Fc |)2]/(Nobs.
N
/
param.)}1/2. [d] tBu carbon atoms C(27) to C(29) disordered over two sites with SOF 0.5, THF molecules O(60), C(60) to C(63) and
O(70), C(70) to C(73) refined with reduced SOF 0.5 together with the riding hydrogen atoms. In spite of the reduced SOFs of the solvent
molecules, the ADPs still indicate severe disorder which could not be resolved.
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FULL PAPER
3
[tBuC(NCy)2]SbCl2 (2): tBuC(NCy)2Li (2.50 g, 9.25 mmol), SbCl3 25 °C): δ = 1.35 [d, JHH = 6.2 Hz, 12 H, CH(CH3)2], 1.53 (s, 9 H,
3
(2.11 g, 9.25 mmol); yield 3.29 g (7.22 mmol, 78%); m.p. 205 °C
(dec.). C17H31Cl2N2Sb (456.10 g/mol): found (calcd.): H 6.72
(6.85), C 44.57 (44.77), N 6.08 (6.14)%. 1H NMR (500 MHz,
tBu), 6.77 [sept, JHH = 6.2 Hz, 2 H, CH(CH3)2] ppm. 13C NMR
(75 MHz, CDCl3, 25 °C): δ = 25.9 (CHMe2), 29.8 (CMe3), 48.2
(CMe ), 52.8 (CHMe ), 177.8 (CN ) ppm. IR: ν = 2964, 2927,
˜
3
2
2
CDCl3, 25 °C): δ = 1.16–1.87 (m, 20 H, NCy), 1.44 (s, 9 H, tBu), 2880, 1615, 1489, 1452, 1409, 1368, 1311, 1183, 1115, 1046, 925,
4.11 (m, 2 H, NCHC5H10) ppm. 13C NMR (75 MHz, CDCl3, 803, 671, 553, 474 cm–1.
25 °C): δ = 24.9 (C3/C5); 25.8 (C4), 29.4 (CMe3), 34.5 (C2/C6),
41.2 (CMe ), 57.2 (N-C1), 177.8 (CN ) ppm. IR: ν = 2962, 2924,
˜
[tBuC(NDipp)2]BiCl2 (6): tBuC(NDipp)2Li (5.61 g, 13.14 mmol),
BiCl3 (4.15 g, 13.14 mmol); yield 7.25 g (10.36 mmol, 79%); m.p.
183 °C (dec.). C29H43BiCl2N2 (699.56 g/mol): found (calcd.): H
3
2
2847, 1595, 1518, 1452, 1425, 1405, 1377, 1341, 1309, 1299, 1259,
1172, 1015, 889, 865, 795, 712, 660, 629, 484 cm–1.
1
6.13 (6.19), C 49.53 (49.79), N 3.89 (4.00)%. H NMR (300 MHz,
[tBuC(NDipp)2]SbCl2 (3): tBuC(NDipp)2Li (5.61 g, 13.14 mmol),
SbCl3 (3.00 g, 13.14 mmol); yield 5.88 g (9.61 mmol, 73%); m.p.
182 °C. C29H43Cl2N2Sb (612.33 g/mol): found (calcd.): H 7.05
(7.08), C 56.87 (56.89), N 4.51 (4.57)%. 1H NMR (300 MHz,
3
CDCl3, 25 °C): δ = 1.07 (s, 9 H, tBu), 1.32 [d, JHH = 6.9 Hz, 12
3
H, CH(CH3)2], 1.39 [d, JHH = 6.9 Hz, 12 H, CH(CH3)2], 3.47 [m,
4 H, CH(CH3)2], 7.09 (m, 6 H, ArH) ppm. 13C NMR (75 MHz,
CDCl3, 25 °C): δ = 23.2 (CCMe3), 27.9 (CHMe2), 28.5 (CHMe2),
29.7 (CHMe2), 49.5 (CCMe3), 123.1 (C4), 127.6 (C3/C5), 136.7
3
CDCl3, 25 °C): δ = 0.98 (s, 9 H, tBu), 1.30 [d, JHH = 6.6 Hz, 12
3
H, CH(CH3)2], 1.34 [d, JHH = 6.9 Hz, 12 H, CH(CH3)2], 3.30 [m,
(C2/C6), 145.7 (N-C1), 172.8 (CCMe ) ppm. IR: ν = 2959, 2864,
˜
4 H, CH(CH3)2], 7.18 (m, 6 H, ArH) ppm. 13C NMR (75 MHz,
CDCl3, 25 °C): δ = 23.0 (CHMe2), 26.9 (CHMe2), 29.1 (CMe3),
41.9 (CMe3), 123.6 (C4), 127.0 (C3/C5), 136.6 (C2/C6), 144.9 (N-
3
1616, 1433, 1362, 1316, 1258, 1213, 1173, 1091, 1013, 931, 866,
797, 761, 661, 474, 430, 396 cm–1.
C1), 174.8 (CN ) ppm. IR: ν = 2962, 2929, 2868, 1522, 1437, 1382,
˜
2
Single Crystal X-ray Analysis: Crystallographic data of 1–6 are
summarized in Table 1 and bond lengths and angles are given in
Tables 2 and 3. Figures 1, 2, 3, 4, 5, and 6 show ORTEP diagrams
of the solid-state structures of 1–6. Data were collected on a Bruker
AXS SMART APEX CCD (1, 3–6) and a Stoe IPDS-II (2) dif-
fractometer, [Mo-Kα radiation, λ = 0.71073 Å; T = 173(2) K]. The
structures were solved by Direct Methods (SHELXS-97)[19] and re-
fined by full-matrix least-squares on F2 (SHELXL-97, program for
crystal structure refinement).[20] Semi-empirical absorption correc-
tions were applied.
1362, 1315, 1254, 1228, 1175, 1094, 1007, 798, 784, 761, 714, 663,
435, 401 cm–1.
[nBuC(NiPr)2]SbCl2 (4): nBuC(NiPr)2Li (2.50 g, 13.14 mmol),
SbCl3 (3.00 g, 13.14 mmol); yield 4.10 g (10.91 mmol, 83%); m.p.
82 °C. C11H23Cl2N2Sb (375.97 g/mol): found (calcd.): H 6.12
(6.17), C 35.10 (35.14), N 7.34 (7.45)%. 1H NMR (300 MHz,
CDCl3, 25 °C): δ = 0.95 (t, 3JHH = 7.2 Hz, 3 H, CH2CH2CH2CH3),
3
1.30 [d, JHH = 6.6 Hz, 12 H, CH(CH3)2], 1.42 (m, 2 H,
CH2CH2CH2CH3), 1.53 (m, 2 H, CH2CH2CH2CH3), 2.30 (m, 2 H,
3
CH2CH2CH2CH3), 4.04 [sept, JHH = 6.6 Hz, 2 H, CH(CH3)2]
ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ = 13.7 (CH2-CH2-
CH2-CH3), 22.9 (CH2-CH2-CH2-CH3), 24.1 (CHMe2), 27.1 (CH2-
CH2-CH2-CH3), 29.0 (CH2-CH2-CH2-CH3), 47.8 (CHMe2), 172.6
CCDC-723192 (for 1), -723197 (for 2), -723195 (for 3), -723194
(for 4), -723193 (for 5), -723196 (for 6) contain the supplementary
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.
(CN ) ppm. IR: ν = 2964, 2929, 2870, 1643, 1522, 1464, 1451, 1436,
˜
2
1363, 1336, 1258, 1227, 1203, 1028, 1078, 949, 839, 796, 687, 614,
564, 454, 414 cm–1.
[tBuC(NiPr)2]BiCl2 (5): tBuC(NiPr)2Li (2.50 g, 13.14 mmol), BiCl3 Supporting Information (see also the footnote on the first page of
(4.15 g, 13.14 mmol); yield 4.57 g (9.86 mmol, 75%); m.p. 170 °C
(dec.). C11H23BiCl2N2 (463.20 g/mol): found (calcd.): H 5.12 (5.00),
C 28.47 (28.52), N 5.80 (6.05)%. 1H NMR (300 MHz, CDCl3,
this article): Tables of selected structural parameters, absolute ener-
gies and atomic charges of 1a, 1b, 1c, 5a, and 5b, which were calcu-
lated from NBO population analyses, are given in the supplement.
Table 2. Selected bond lengths [Å] and angles [°] of [tBuC(NR)2]SbCl2 (R = iPr 1, Cy 2, Dipp 3) and [nBuC(NiPr)2]SbCl2 (4) and [tBuC(NR)2]-
BiCl2 (R = iPr 5, Dipp 6).
1
2
3
4
5
6
E1–N1/
E1–N2
E1–Cl1/
E1–Cl2
E1–Cl1/2a
2.1011(16)/
2.1906(17)
2.4030(6)/
2.6435(6)
3.1171(7)/
4.7343(7)
1.352(2)/
1.320(2)
1.536(3)
1.469(2)/
1.470(3)
60.69(6)
108.56(16)
88.02(2)
2.2204(17)/
2.1022(16)
2.6114(6)/
2.3982(6)
3.2447(6)/
6.5652(6)
1.320(3)/
1.366(3)
1.540(3)
1.461(3)/
1.469(3)
60.41(6)
108.29(18)
87.65(2)
2.104(2)/
2.3059(19)
2.3664(8)/
2.4732(7)
Ͼ 8.5
2.205(3)/
2.116(2)
2.6735(9)/
2.4127(9)
3.1195(9)/
3.8972(12)
1.319(4)/
1.346(4)
1.499(5)
1.460(4)/
1.470(4)
60.99(10)
110.8(3)
95.49(7)
152.19(8)/
91.43(7)
2.236(5)/
2.243(5)
2.408(3)/
2.265(3)
2.7399(18)/
2.6868(18)
3.1746(17)/
3.2102(19)
1.336(8)/
1.337(8)
1.554(9)
1.464(7)/
1.466(8)
58.43(18)
109.8(5)
175.02(5)
84.94(15)/
86.46(14)
2.4640(12)/
2.6171(10)
3.4398(10)/
6.4022(12)
1.316(5)/
1.341(5)
1.561(5)
1.422(5)/
1.438(5)
55.69(11)
110.8(3)
89.05(4)
89.90(9)/
97.14(9)
C1–N1/
C1–N2
C1–CR
N1–CRЈ
N2–CRЈ
N1–E1–N2
N1–C1–N2
Cl1–E1–Cl2
Cl1–E1–N1/
Cl1–E1–N2
1.361(3)/
1.323(3)
1.543(3)
1.437(3)/
1.430(3)
59.21(8)
109.0(2)
90.27(3)
98.89(6)/
88.48(6)
/
94.90(5)/
88.02(5)
153.58(5)/
94.53(5)
Cl2–E1–N1/
Cl2–E1–N2
92.55(5)/
152.46(5)
87.41(5)/
97.07(5)
89.29(6)/
147.81(6)
92.30(8)/
93.12(7)
90.60(15)/
89.31(14)
141.99(8)/
86.78(9)
2252
www.eurjic.org
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2009, 2247–2253

Heteroleptic Amidinate Complexes of Heavy Group 15 Elements
Table 3. Selected bond lengths [Å] and angles [°] of the calculated structures of [tBuC(NiPr)2]ECl2 (E = Sb 1, Bi 5).
E–N
E–Cl
C–N
Cl–E–Cl
N–E–N
1 (XRD)
2.1011(16)/
2.1906(17)
2.4030(6)/2.6435(6)/ 1.352(2)/
88.02(2)
60.69(6)
3.1171(7)/4.7343(7)
2.50/2.60
1.320(2)
1.34/1.39
1.34/1.38
1.36/1.37
1a (SDD) monomer 2.13/2.28
91
90
177
64
61
61
1b (SDD) trimer
2.13/2.23
2.16/2.18
2.52/2.74/3.41/4.56
2.76/2.76/3.16/3.21
1c (SDD) trimer[a]
5 (XRD)
2.236(5)/2.243(5)
2.7399(18)/
2.6868(18)/
3.1746(17)/
3.2102(19)
2.69
1.336(8)/1.337(8)
175.02(5)
58.43(18)
5a (SDD) monomer 2.24
5b (SDD) trimer 2.28/2.30
1.36/1.37
1.36/1.37
165
179
58
58
2.81/2.83/3.03/3.06
[a] Structure optimization using the structural parameter of the Bi complex (monomeric unit).
Konu, M. S. Balakrishna, T. Chivers, T. W. Swaddle, Inorg.
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Allg. Chem. 1986, 533, 55.
Acknowledgments
S. S. thanks Deutsche Forschungsgemeinschaft (DFG) for financial
support.
[10] S. P. Green, C. Jones, G. Jin, A. Stasch, Inorg. Chem. 2007, 46,
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[11] M. Brym, C. M. Forsyth, C. Jones, P. C. Junk, R. P. Rose, A.
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[1] L. Bourget-Merle, M. F. Lappert, J. R. Severn, Chem. Rev.
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[12] a) L. A. Lesikar, A. F. Richards, J. Organomet. Chem. 2006,
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[4] See for further bindings modes: P. C. Junk, M. L. Cole, Chem.
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[13] P. B. Hitchcock, M. F. Lappert, G. Li, A. V. Protchenko, Chem.
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Allg. Chem. 1986, 533, 55.
N. J. Hardman, B. E. Eichler, P. P. Power, Chem. Commun. [15] F. Weller, J. Pebler, K. Dehnicke, K. Hartke, H.-M. Wolff, Z.
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[16] According to a structure search in the Cambridge Structural
Database, as described anions typically show bridging Sb–Cl
bond lengths ranging from 3.00–3.30 Å.
[6] S. P. Green, C. Jones, A. Stasch, Science 2007, 318, 1754.
[7] See the following and references cited therein: a) M. Stender,
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[18] DFT calculations were carried out with the Gaussian03 suite
of programs (M. J. Frisch, et al. Gaussian 03, Revision D.02;
Gaussian Inc., Pittsburgh, PA, 2003, complete reference is
given in the supplement). The molecular structures and ener-
gies of compounds 1a, 1b, 1c, 5a, and 5b were obtained by
performing a complete energy optimization of all geometric
parameters at the b3lyp/sdd level (input keywords “# b3lyp/
sdd opt pop = nboЈЈ), using the atomic coordinate of the crys-
tal structure determination of 1 and 5 (without solvent mole-
cule) as starting point. Population analysis was carried out with
the NBO module as implemented in Gaussian03. The final mo-
lecular structures and list of the final atomic coordinates and
energies, selected bond lengths, and NBO atomic populations
are given in the electronic supplement.
[19] SHELXS-97, Program for Structure Solution: G. M. Sheldrick,
Acta Crystallogr., Sect. A 1990, 46, 467.
[20] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University of Göttingen, Germany, 1997.
Received: March 12, 2009
Published Online: April 21, 2009
Eur. J. Inorg. Chem. 2009, 2247–2253
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2253