New chiral organoantimony(iii) compounds containing intramolecular N → Sb interactions - Solution behaviour and solid state structures

Article abstract of DOI:10.1039/c003318a

Hypervalent organoantimony(iii) compounds of the type [2-(Me ₂NCH₂)C₆H₄]PhSbCl (1), [2-(Me ₂NCH₂)C₆H₄]MesSbBr (7) and [2-(Me₂NCH₂)C₆H₄]_nAr _3-nSb [n = 1, Ar = Ph (4), Mes (9); n = 2, Ar = Ph (5), Mes (10)] were prepared via salt elimination reactions between [2-(Me₂NCH ₂)C₆H₄]Li and MesMgBr and Ph _nSbCl_3-n, [2-(Me₂NCH₂)C ₆H₄]SbBr₂ or [2-(Me₂NCH ₂)C₆H₄]_nSbCl_3-n (n = 1, 2), in appropriate molar ratios. Halogen exchange reactions with aqueous KBr or KI gave [2-(Me₂NCH₂)C₆H₄]ArSbX [Ar = Ph, X = Br (2), I (3); Ar = Mes, X = I (8)]. Metathesis reaction between 1 and MesMgBr affords [2-(Me₂NCH₂)C₆H ₄]PhMesSb (6). Compounds 1-10 were investigated by means of NMR (¹H, ¹³C) in solution and by mass spectrometry. The investigation of the molecular structures of 2-8 by single-crystal X-ray diffraction revealed that the nitrogen atoms of the pendant CH ₂NMe₂ arms are strongly coordinated to the antimony atoms. All compounds exhibit chirality and crystallize as racemic mixtures. The Royal Society of Chemistry.

Full text of DOI:10.1039/c003318a

Dalton
Transactions
An international journal of inorganic chemistry
www.rsc.org/dalton
Volume 39 | Number 28 | 28 July 2010 | Pages 6357–6552
ISSN 1477-9226
PAPER
Silvestru et al.
New chiral organoantimony(III)
compounds containing intramolecular
N → Sb interactions – solution
behaviour and solid state structures
PERSPECTIVE
Łuczkowski, Remelli et al.
Prion proteins and copper ions.
Biological and chemical controversies
1477-9226(2010)39:28;1-1

PAPER
www.rsc.org/dalton | Dalton Transactions
New chiral organoantimony(III) compounds containing intramolecular
N → Sb interactions – solution behaviour and solid state structures†
Dana Copolovici,a Vilma R. Bojan,a Ciprian I. Rat¸,a Anca Silvestru,a Hans J. Breunigb and Cristian Silvestru*a
Received 17th February 2010, Accepted 9th April 2010
First published as an Advance Article on the web 10th May 2010
DOI: 10.1039/c003318a
Hypervalent organoantimony(III) compounds of the type [2-(Me2NCH2)C6H4]PhSbCl (1),
[2-(Me2NCH2)C6H4]MesSbBr (7) and [2-(Me2NCH2)C6H4]nAr3-nSb [n = 1, Ar = Ph (4), Mes (9); n = 2,
Ar = Ph (5), Mes (10)] were prepared via salt elimination reactions between [2-(Me2NCH2)C6H4]Li and
MesMgBr and PhnSbCl3-n, [2-(Me2NCH2)C6H4]SbBr2 or [2-(Me2NCH2)C6H4]nSbCl3-n (n = 1, 2), in
appropriate molar ratios. Halogen exchange reactions with aqueous KBr or KI gave
[2-(Me2NCH2)C6H4]ArSbX [Ar = Ph, X = Br (2), I (3); Ar = Mes, X = I (8)]. Metathesis reaction
between 1 and MesMgBr affords [2-(Me2NCH2)C6H4]PhMesSb (6). Compounds 1–10 were
investigated by means of NMR (1H, 13C) in solution and by mass spectrometry. The investigation of the
molecular structures of 2–8 by single-crystal X-ray diffraction revealed that the nitrogen atoms of the
pendant CH2NMe2 arms are strongly coordinated to the antimony atoms. All compounds exhibit
chirality and crystallize as racemic mixtures.
Introduction
Chiral organostibanes were obtained and their structures in-
vestigated in the last decade because they are of considerable
interest as potential chiral sources for the inductive generation
of optical activity.1-14 One group of chiral organostibanes are
compounds where three different substituents are bonded to
antimony, e.g. compounds of the type RR¢SbX (Ia and Ib in
Fig. 1). These stibanes can be named “Sb-chiral” compounds.
Other types of chirality occur with pendant arm ligands like the 2-
(dimethylaminomethyl)phenyl group, which is able to coordinate
not only through the carbon center but also through the pendant
amino moiety (C,N-ligand). This intramolecular coordination of
the nitrogen atom to antimony induces chirality at the Sb centre
even when the other two substituents are the same (“chelate-
induced-Sb-chiral” compounds, e.g. IIa and IIb in Fig. 1). A
third type of chirality appears when one atom of the resulting
Fig. 1 Chirality in organoantimony(III) compounds.
chelate ring is out of the plane described by the remaining atoms
[compounds with “chiral planarity”, the C(1)–C(6) aromatic
ring and the N(1) atom being the chiral plane and pilot atom,
respectively] (IIIa and IIIb in Fig. 1).15
Known
examples
of
chiral
antimony
derivatives
containing the 2-(dimethylaminomethyl)phenyl group [R] are:
R[(Me3Si)2CH]SbCl, R[(Me3Si)2CH]SbH, R[(Me3Si)2CH]Sb–
aFacultatea de Chimie si Inginerie Chimica, Universitatea Babes-Bolyai,
RO-400028, Cluj-Napoca, Romania. E-mail: cristi@chem.ubbcluj.ro;
Fax: (+40) 264-590818; Tel: (+40) 264-593833
Li·2THF (THF
=
tetrahydrofuran), R[(Me3Si)2CH]Sb–
tetramethylethylenediamine),10
Na·TMEDA (TMEDA
=
R2SbX (X = Cl,2 Br, I11), RSbX2 (X = Cl, Br, I),11 R2SbI·HI,11
cyclo-R4Sb4, RSb[W(CO)5]2, (RSbCl)2E [E = O, S], (RSbI)2O,
(RSbBr)2S, cyclo-(RSbE)n [E = O, n = 3, E = S, n = 2],12 and the
ionic species [R3SbOH]+[I3]-.11
bInstitut fu¨r Anorganische und Physikalische Chemie, Universita¨t Bremen,
D-28334, Bremen, Germany. E-mail: hbreunig@uni-bremen.de; Fax: (+49)
421-21862809; Tel: (+49) 421-21863150
† Electronic supplementary information (ESI) available: X-ray crystallo-
graphic data in CIF format for 2–8; figures representing the molecular
structure and supramolecular architectures in the crystals of compounds
2–8; variable temperature 1H NMR data for compounds 1 (in C6D6,
DMSO-d6) and 7 (in DMSO-d6); 1H and 13C NMR data for compound 9
(in C6D6). CCDC reference numbers 752088 (2), 752089 (3), 752092 (4),
752087 (5), 752091 (6), 752086 (7) and 752090 (8). For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/c003318a
We report here the synthesis and characterisation of [2-
(Me2NCH2)C6H4]ArSbX [Ar = Ph, X = Cl (1), Br (2), I (3);
Ar = Mes, X = Br (7), I (8)], [2-(Me2NCH2)C6H4]nAr3-nSb [n =
1, Ar = Ph (4), Mes (9); n = 2, Ar = Ph (5), Mes (10)] and
[2-(Me2NCH2)C6H4]PhMesSb (6).
6410 | Dalton Trans., 2010, 39, 6410–6418
This journal is
The Royal Society of Chemistry 2010
©

◦
˚
Table 1 Selected bond distances (A) and angles ( ) for compounds 2, 3,
7 and 8
Results and discussion
Synthesis
2
3
7
8
The preparative pathways leading to compounds 1–10 are shown
in Schemes 1 and 2. The chloride 1 and the heteroleptic stibines
4 and 5 were obtained by reacting stoichiometric amounts of
PhSbCl2 or Ph2SbCl with [2-(Me2NCH2)C6H4]Li. Reaction of
1 with the organolithium reagent gave the stibine 6. Similar
reactions between RSbCl2 or R2SbCl [R = 2-(Me2NCH2)C6H4]
and MesMgBr afforded the related mixed triarylstibines 9 and
10. The bromide 7 was obtained from RSbBr2 and MesMgBr.
Attempts to prepare the corresponding chloride from RSbCl2 and
the Grignard reagent failed and only the same bromide 7 was
isolated as result of in situ halogen scrambling with the inorganic
magnesium salt. The halides 2, 3 and 8 were prepared using
exchange of the halogen in the presence of KBr or KI, according
to similar published procedures.11
Sb(1)–C(1)
Sb(1)–C(10)
Sb(1)–X(1)
Sb(1)–N(1)
2.150(4)
2.146(5)
2.152(4)
2.154(4)
2.149(4)
2.167(4)
2.156(4)
2.166(4)
2.9496(5)
2.456(4)
2.6977(6) 2.9870(4) 2.7016(6)
2.444(4) 2.426(3) 2.468(4)
96.90(17) 97.28(14) 105.55(15) 103.44(17)
93.47(12) 93.00(10) 93.35(12)
90.46(12) 88.67(10) 89.69(10)
75.57(15) 75.15(13) 74.79(15)
88.88(15) 86.75(13) 88.06(14)
C(1)–Sb(1)–C(10)
C(1)–Sb(1)–X(1)
C(10)–Sb(1)–X(1)
N(1)–Sb(1)–C(1)
N(1)–Sb(1)–C(10)
N(1)–Sb(1)–X(1)
C(7)–N(1)–C(8)
C(7)–N(1)–C(9)
C(8)–N(1)–C(9)
Sb(1)–N(1)–C(7)
Sb(1)–N(1)–C(8)
Sb(1)–N(1)–C(9)
93.88(12)
91.70(12)
74.31(14)
87.42(15)
168.85(9) 166.62(8) 166.82(10) 167.57(9)
110.8(5)
112.2(5)
108.5(5)
106.3(3)
102.8(3)
115.8(3)
111.0(3)
111.2(3)
109.1(4)
104.9(2)
105.6(3)
115.0(3)
110.1(4)
111.5(5)
109.6(4)
104.2(3)
105.2(3)
115.9(3)
110.8(4)
110.7(4)
109.5(4)
103.4(3)
106.2(3)
116.1(3)
X = Br for 2 and 7, and I for 3 and 8.
evaporation of a hexane solution (for 7) and CH2Cl2–hexane
(for 8). The molecular structures are shown in Fig. 2–4 (see also
ESI†) and selected interatomic distances and angles are listed in
Table 1.
Scheme 1 Preparation of compounds 1–6
Fig. 2 ORTEP representation at 30% probability and atom numbering
scheme for (SN,CSb)-2 isomer. Hydrogen atoms are omitted.
Scheme 2 Preparation of compounds 7–10
The compounds were obtained as air-stable, colourless and yel-
low (3 and 8) crystalline solids, which melt without decomposition.
They are soluble in common organic solvents, such as chloroform,
methylene chloride or benzene as well as in DMSO. MS and NMR
data of 1–10 as well as elemental analytical data are consistent
with the anticipated formulae. Characteristic ions, including the
molecular ion except for the iodides 3 and 8, are present in the
mass spectra, which contain [RArSb+] (for 1–4, 6–9) and [R2Sb+]
(for 5 and 10) (R = Me2NCH2C6H4; Ar = Ph, Mes) as the base
peak.
Chiral diorganoantimony(III) halides, RR¢SbX
Single crystals of the title halides, suitable for X-ray diffraction
studies were obtained from CHCl3–hexane (for 2 and 3), slow
Fig. 3 ORTEP representation at 30% probability and atom numbering
scheme for (RN,CSb)-7 isomer. Hydrogen atoms are omitted.
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 6410–6418 | 6411
©

A closer check of the crystal packing of the halides 2, 3, 7 and 8
revealed several halogen–hydrogen contacts shorter than the sum
ꢀ
˚
of the corresponding van der Waals radii [cf.
rvdW(Br,H) 3.15 A,
ꢀ
21
˚
r
vdW(I,H) 3.35 A] as well as C–H ◊ ◊ ◊ p (Phcentroid) distances
˚
shorter than 3.10 A which suggest some p interaction between a
hydrogen atom and an aromatic ring. These result in supramolecu-
lar architectures, i.e. layer of alternating chain polymers built from
(SN,CSb)-2 and (RN,ASb)-2 isomers, respectively, with no further
contacts between parallel layers; chain polymer association of
alternating (SN,CSb)-3 and (RN,ASb)-3 isomers with no further
contacts between parallel chains; columnar polymer association of
the (RN,CSb)/(SN,ASb)-7 dimer units, or a 3D structure built from
alternating chain polymers of (RN,CSb)-8 and (SN,ASb)-8 isomers,
respectively (for details, see ESI†).
Fig. 4 ORTEP representation at 30% probability and atom numbering
scheme for (SN,ASb)-8 isomer. Hydrogen atoms are omitted.
The solution behaviour of the halides 1–3, 7 and 8 was
investigated by NMR spectroscopy. The assignment of the signals
1
in H and 13C NMR spectra was based on the 2D NMR spectra
The crystals of the halides 2, 3, 7 and 8 contain discrete
monomers, with no unusual intermolecular distances shorter than
the sum of the van der Waals radii between heavy atoms. In
all these molecules the nitrogen atoms of the pendant arm are
strongly coordinated to the metal trans to the halogen atom [N(1)–
Sb(1)–X(1) 168.85(9), 166.62(8), 166.82(10) and 167.57(9)◦ for
2, 3, 7 and 8, respectively]. The value of Sb(1)–N(1) distance
according to the numbering scheme shown in Scheme 3.
˚
[Sb(1)–N(1) 2.444(4), 2.426(3), 2.468(4) and 2.456(4) A for 2,
3, 7 and 8, respectively] is of the same magnitude as the Sb–
N distances in the trans-N–Sb–X system of the monohalides
˚
[2-(Me2NCH2)C6H4]2SbX [2.423(3) and 2.417(3) A for X = Br
and I, respectively].11
Scheme 3 Numbering scheme for NMR resonance assignments
The Sb–halogen bond distances [Sb(1)–Br(1) 2.6977(6) and
2.7016(6) A for 2 and 7; Sb(1)–I(1) 2.9870(4) and 2.9496(5) A for
3 and 8, respectively] are significantly shorter compared to those
For all compounds the 1H NMR spectra at room temperature
in CDCl3 exhibit two sharp singlet resonances for the NMe2 and
an AB system for the CH2 protons of the pendant arm. This
indicates a similar structure as observed in the solid state by X-ray
diffraction, i.e. the nitrogen atoms are coordinated to antimony
and the configurations at Sb are stable at room temperature in
CDCl3 solution.
˚
˚
˚
found in [2-(Me2NCH2)C6H4]2SbX [Sb(1)–Br(1) 2.7775(8) A;
11
˚
Sb(1)–I(1) 3.0105(5) A]. However, as expected for a s*-orbital
bonding model,2,10 the Sb–halogen bonds in 2, 3, 7 and 8 are con-
siderably elongated with respect to those observed for the related
16
17
˚
˚
monomeric Ph2SbX [Sb–Br 2.553(1) A; Sb–I 2.771(1) A ].
The antimony centre in all four halides achieves a dis-
torted pseudo-trigonal-bipyramidal environment [SbC(C,N)X
core], with two carbon atoms in the equatorial sites, while the
halogen and the nitrogen atoms are in the axial positions. The
compounds can be described as hypervalent 10-Sb-4 species.18,19
Since three different substituents are attached to the metal
centre these halides belong to the “Sb-chiral” class of compounds
(see Fig. 1). The five-membered SbC3N ring formed through
intramolecular coordination of the nitrogen atom is folded along
the Sb ◊ ◊ ◊ Cmethylene axis, with the nitrogen atom lying out of the
best plane defined by the residual SbC3 fragment. This folding
induces planar chirality (with the aromatic ring and the nitrogen
atom as chiral plane and pilot atom, respectively; isomers given
as SN and RN).15 Taking into account this intramolecular N →
Sb coordination the chirality at the antimony atom in the pseudo-
trigonal bipyramidal environment can be described in term of
CSb and ASb isomers.20 This description was preferred instead of
RSb/SSb isomers for better comparison with the situation observed
for the chiral triarylantimony(III) described in the subsequent
discussion. The title halides crystallize as 1 : 1 mixtures of (RN,ASb)
and (SN,CSb) isomers for 2 and 3, and (RN,CSb) and (SN,ASb)
isomers for 7 and 8.
In order to study dynamic processes variable temperature NMR
study was performed for chloride 1 in various solvents. While
the AB system for the CH2 protons remained unaffected, the
two singlets for the methyl protons of the dimethylamino group
showed coalescence at 65 ◦C in C6D6 solution (calculated DG‡ =
16.6 kcal mol-1).22 This process corresponds to the dissociation–
recoordination between the nitrogen and the antimony atoms, with
inversion at a three-coordinated nitrogen atom and rotation of the
(H2)C–N bond.
The inversion barrier upon the Sb atom was reported to be
1
diminished by nucleophilic solvents.23 The room-temperature H
spectrum of 1 in DMSO-d6 exhibits the same pattern of the
aliphatic region as observed in CDCl3 or in C6D6 solutions,
thus suggesting a similar structure, regardless of the nature of
the solvent. However, by raising the temperature, coalescence of
both systems was observed at different temperatures. Thus, the
two singlet resonances for the NMe2 group showed coalescence at
◦
50 C (calculated DG‡ = 15.7 kcal mol-1), while the coalescence
of the AB system for the CH2 protons was achieved at 78 ◦C
(calculated DG‡ = 17.1 kcal mol-1).
For halides 7 and 8, the NMR data indicate an additional
dynamic process due to replacement of the phenyl group on
6412 | Dalton Trans., 2010, 39, 6410–6418
This journal is
The Royal Society of Chemistry 2010
©

antimony by the bulkier mesityl moiety. The 1H spectra in CDCl3,
at room temperature, exhibit (i) two broad resonances for the
methyl groups from positions 2¢ and 6¢ of the mesityl ligand (ortho-
CH3) in the alkyl region, in addition to the resonances for the
pendant arm protons; (ii) a broad resonance for the protons in
positions 3¢ and 5¢ of the mesityl group in the aromatic region.
This behaviour suggests that the free rotation of the mesityl group
around the Sb–Cmesityl bond is blocked due to the coordination of
the nitrogen atom from the pendant arm to antimony. This process
1
is even better observed in the H spectrum of 7 when recorded
in DMSO-d6. At room temperature there are five well resolved
resonances in the 1 : 1 : 1 : 1 : 1 ratio of intensities for the NMe2
groups and the three Me groups of the mesityl moiety. Moreover,
in the aromatic region two singlet resonances are observed for
the protons of the mesityl group. At 45 ◦C the coalescence of the
resonances for these aromatic protons was achieved (calculated
DG‡ = 15.7 kcal mol-1), while the resonances for the pendant arm
protons remain basically unchanged (see ESI†), thus suggesting
a higher degree of free rotation of the mesityl group around the
Sb–Cmesityl bond.
Fig. 5 ORTEP representation at 30% probability and atom numbering
scheme for (RN,CSb)-4 isomer. Hydrogen atoms are omitted.
to the metal is trans to the ipso carbon of the phenyl group
attached to antimony [N(1)–Sb(1)–C(16) 163.40(12)◦ for 4; N(1)–
Sb(1)–C(19) 161.85(14)◦ for 5a; N(1)–Sb(1)–C(19) 165.6(3)◦ for
6, respectively]. These Sb(1)–N(1) distances [Sb(1)–N(1) 2.848(4),
2.920(3) and 2.923(9) A for 4, 5a and 6, respectively] are, as
expected, longer than in the related monohalides. For compound
Chiral triorganoantimony(III) compounds, RR¢2Sb and RR¢R¢¢Sb
Single crystals suitable for X-ray diffraction studies were obtained
from hot hexane solution (for 4 and 6) or CH2Cl2–hexane (for 5).
Two independent, very similar molecules 5a and 5b are present in
the unit cell of 5 and in the subsequent discussion we will refer only
to molecule 5a. The molecular structures are shown in Fig. 5–7
(see also ESI†) and selected interatomic distances and angles are
listed in Table 2.
˚
5 the molecules contain an additional longer intramolecular
˚
Sb(1)–N(2) distance [3.042(3) A for 5a] of the same magnitude
1
˚
as in [2-(Me2NCH2)C6H4]3Sb [av. 3.03 A] [cf. the sum of the
ꢀ
˚
corresponding covalent,
r
cov(Sb,N) 2.11 A, and van der Waals
vdW(Sb,N) 3.74 A, respectively]. The Sb(1)–N(2) vector
lies approximately trans to the C(1) atom of the first pendant
ꢀ
21
˚
The molecules of the triarylstibines 4–6 feature a common struc-
tural aspect, i.e. the nitrogen atom of a pendant arm coordinated
radii,
r
◦
˚
Table 2 Selected bond distances (A) and angles ( ) for compounds 4–6
4
5a
5b
6
Sb(1)–C(1)
Sb(1)–C(10)
Sb(1)–C(16)
Sb(1)–N(1)
2.166(4)
2.152(4)
2.172(4)
2.848(4)
Sb(1)–C(1)
Sb(1)–C(10)
Sb(1)–C(19)
Sb(1)–N(1)
2.177(4)
2.155(4)
2.169(4)
2.920(3)
3.042(3)
96.09(14)
93.76(15)
97.64(16)
68.96(11)
79.46(11)
161.85(14)
161.16(11)
67.10(10)
80.78(14)
113.77(9)
111.2(4)
111.9(4)
111.2(4)
91.4(2)
Sb(2)–C(25)
Sb(2)–C(34)
Sb(2)–C(43)
Sb(2)–N(3)
2.184(4)
2.158(4)
2.157(4)
2.948(3)
3.059(3)
95.99(14)
93.23(15)
98.48(15)
68.85(12)
79.22(11)
161.40(11)
159.60(11)
66.75(10)
79.37(13)
115.70(9)
111.4(4)
112.2(4)
111.4(4)
90.5(2)
Sb(1)–C(1)
Sb(1)–C(10)
Sb(1)–C(19)
Sb(1)–N(1)
2.166(8)
2.149(5)
2.165(8)
2.923(9)
Sb(1)–N(2)
Sb(2)–N(4)
C(1)–Sb(1)–C(10)
C(1)–Sb(1)–C(16)
C(10)–Sb(1)–C(16)
N(1)–Sb(1)–C(1)
N(1)–Sb(1)–C(10)
N(1)–Sb(1)–C(16)
97.62(14)
94.33(14)
96.29(15)
70.04(12)
80.87(12)
163.40(12)
C(1)–Sb(1)–C(10)
C(1)–Sb(1)–C(19)
C(10)–Sb(1)–C(19)
N(1)–Sb(1)–C(1)
N(1)–Sb(1)–C(10)
N(1)–Sb(1)–C(19)
N(2)–Sb(1)–C(1)
N(2)–Sb(1)–C(10)
N(2)–Sb(1)–C(19)
N(1)–Sb(1)–N(2)
C(7)–N(1)–C(8)
C(7)–N(1)–C(9)
C(8)–N(1)–C(9)
Sb(1)–N(1)–C(7)
Sb(1)–N(1)–C(8)
Sb(1)–N(1)–C(9)
C(16)–N(2)–C(17)
C(16)–N(2)–C(18)
C(17)–N(2)–C(18)
Sb(1)–N(2)–C(16)
Sb(1)–N(2)–C(17)
Sb(1)–N(2)–C(18)
C(25)–Sb(2)–C(34)
C(25)–Sb(2)–C(43)
C(34)–Sb(2)–C(43)
N(3)–Sb(2)–C(25)
N(3)–Sb(2)–C(34)
N(3)–Sb(2)–C(43)
N(4)–Sb(2)–C(25)
N(4)–Sb(2)–C(34)
N(4)–Sb(2)–C(43)
N(3)–Sb(2)–N(4)
C(31)–N(3)–C(32)
C(31)–N(3)–C(33)
C(32)–N(3)–C(33)
Sb(2)–N(3)–C(31)
Sb(2)–N(3)–C(32)
Sb(2)–N(3)–C(33)
C(40)–N(4)–C(41)
C(40)–N(4)–C(42)
C(41)–N(4)–C(42)
Sb(2)–N(4)–C(40)
Sb(2)–N(4)–C(41)
Sb(2)–N(4)–C(42)
C(1)–Sb(1)–C(10)
C(1)–Sb(1)–C(19)
C(10)–Sb(1)–C(19)
N(1)–Sb(1)–C(1)
N(1)–Sb(1)–C(10)
N(1)–Sb(1)–C(19)
102.8(3)
98.2(3)
96.5(3)
69.9(3)
78.9(2)
165.6(3)
C(7)–N(1)–C(8)
C(7)–N(1)–C(9)
C(8)–N(1)–C(9)
Sb(1)–N(1)–C(7)
Sb(1)–N(1)–C(8)
Sb(1)–N(1)–C(9)
115.9(5)
110.9(4)
107.0(5)
100.6(3)
120.5(3)
100.9(3)
C(7)–N(1)–C(8)
C(7)–N(1)–C(9)
C(8)–N(1)–C(9)
Sb(1)–N(1)–C(7)
Sb(1)–N(1)–C(8)
Sb(1)–N(1)–C(9)
110.6(9)
113.1(10)
109.0(10)
97.1(7)
100.9(5)
124.8(6)
120.9(3)
108.7(3)
111.1(4)
111.4(4)
110.9(4)
86.1(2)
121.5(3)
108.3(3)
112.1(4)
110.9(4)
110.9(4)
85.4(2)
112.3(3)
122.4(3)
110.9(3)
123.8(3)
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The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 6410–6418 | 6413
©

organic groups attached to the metal become non-equivalent
as a result of the intramolecular N → Sb interactions. Thus,
in 4 one phenyl group is in the equatorial position, while the
other is in the axial position of the pseudo-trigonal-bipyramidal
SbC2(C,N) core, trans to the nitrogen atom. The two organic
ligands bearing the pendant arm are also non-equivalent in the
molecule of 5a: the aryl moiety of one ligand is placed in the
apical position of the square pyramidal SbC(C,N)2 core and
its nitrogen atom is coordinated in the basal plane trans the
Sb–C bond established by the other 2-(Me2NCH2)C6H4 group,
which, subsequently, has both its carbon atom attached to the
metal and its nitrogen atom in the basal plane, coordinated trans
to the Sb–C bond established by the remaining phenyl group.
Indeed, the title stibines crystallize as 1 : 1 mixtures of (RN,CSb)
and (SN,ASb) isomers for 4, (RN1,RN2,ASb1)/(SN1,SN2,CSb1)-5a and
(RN3,RN4,ASb2)/(SN3,SN4,CSb2)-5b isomers [(with respect to the two
chelate rings at a metal centre)] for 5, and (RN,ASb) and (SN,CSb)
isomers for 6.
The crystal packing check for the title triarylstibines
Fig. 6 ORTEP representation at 30% probability and atom numbering
scheme for (RN1,RN2,ASb)-5a isomer. Hydrogen atoms are omitted.
4–6 revealed several C–H ◊ ◊ ◊ p (Phcentroid) distances shorter than
˚
3.10 A which result in supramolecular architectures, i.e. layers
of (RN,CSb)-4 and (SN,ASb)-4 isomers, respectively, with no fur-
ther contacts between parallel layers; chain polymer association
of alternating (RN1,RN2,ASb1)-5a/(SN3,SN4,CSb2)-5b isomers and
(SN1,SN2,CSb1)-5a/(RN3,RN4,ASb2)-5b isomers, respectively, with no
further contacts between parallel chains; double-layer association
between layers of (RN,ASb) and (SN,CSb)-6 isomers, respectively
(for details, see ESI†).
The solution behaviour of the stibines 4–6, 9 and 10 was
investigated by NMR spectroscopy in CDCl3. The assignment of
the signals in 1H and 13C NMR spectra was based on the 2D NMR
spectra according to the numbering scheme shown in Scheme 3.
For all these stibines the 1H NMR spectra at room temperature
in CDCl3 exhibit a sharp singlet resonance for the NMe2 protons.
The spectra of compounds 4 and 9 exhibit a sharp singlet, while
for compounds 5, 6 and 10 an AB system was observed for the
CH2 protons signal of the pendant arm. The spectra exhibit only
1
one set of H or 13C resonances, respectively, for the two organic
groups of the same type (phenyl, mesityl or pendant arm ligand)
attached to antimony in compounds 4, 5, 9 and 10. Variable
temperature 1H spectra (-60 up to 45 ◦C) for compounds 5 and 6
in CDCl3 solutions show no changes in the pattern of the signals.
This suggests that dissociation of the bond between the nitrogen
and antimony atoms is very fast even at this temperature. This
behaviour is also supported by the presence of only one resonance
for the methyl groups from positions 2¢ and 6¢ of the mesityl moiety
(ortho-CH3) in compounds 6, 9 and 10, indicating that free rotation
around the Sb–Cmesityl bond is allowed in these triarylstibines.
No significant changes were observed when the spectra were
recorded in C6D6 for compounds 5 (at r.t. and 45 ◦C) and 9 (at r.t.)
(see ESI†) in comparison with the spectra recorded in CDCl3.
Fig. 7 ORTEP representation at 30% probability and atom numbering
scheme for (RN,ASb)-6 isomer. Hydrogen atoms are omitted.
arm ligand. A difference which should be noted is the significant
increaseof theC–Sb–Cbond angles inthe trigonalpyramidal SbC3
skeleton when a bulky mesityl group is attached to antimony, i.e.
in the chiral stibine 6 (see Table 2)
As in the title chiral halides, the antimony centre in 4 and
6 achieves a distorted pseudo-trigonal-bipyramidal environment
[SbC2(C,N) core, hypervalent 10-Sb-4 species18,19], with two car-
bon atoms in the equatorial sites, and a carbon and nitrogen
atom in the axial ones. In 5a, if both intramolecular N →
Sb interactions are taken into account, the overall coordination
geometry around antimony can be described as distorted square
pyramidal [SbC(C,N)2 core; hypervalent 12-Sb-5 species18,19], with
a carbon atom in the apical position and the nitrogen atoms in cis
positions of the base.
Conclusions
New chiral diorganoantimony(III) halides and triorganoanti-
mony(III) compounds were prepared and characterized both in
solid state and in solution. In solid state the intramolecular N →
Sb interaction induces chirality at the metal centre in compounds
containing two organic groups of the same type attached to
The conformation of the five-membered SbC3N rings in the
triarylstibines 4–6 induces planar chirality,15 as observed for the
halides 2, 3, 7 and 8. Moreover, chirality at the antimony centre of
4 and 5 is also induced, at least in solid state, since the same
6414 | Dalton Trans., 2010, 39, 6410–6418
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The Royal Society of Chemistry 2010
©

antimony. All compounds crystallize as racemates. NMR studies
provided evidence for the presence of the intramolecular N → Sb
interaction in the chiral halides, in solution, at room temperature.
This resulted in hindered rotation around the Sb–C bond in the
mesityl-containing derivatives due to steric impediments. Variable-
temperature experiments revealed several dynamic processes
which include the intramolecular coordination–decoordination of
the nitrogen atom, configuration inversion at the metal centre and
free rotation around the Sb–C bond. For the triorganostibines
the NMR data suggest that dissociation of the bond between the
nitrogen and antimony atoms is very fast at room temperature.
Synthesis of [2-(Me2NCH2)C6H4]PhSbBr (2). A solution of
KBr (1.07 g, 9 mmol) in distilled water (15 mL) was added to a
clear, colorless solution of 1 (1.11 g, 3 mmol) in CH2Cl2 (25 mL).
The mixture was stirred vigorously for 3 days at room temperature,
then the organic layer was separated. The aqueous phase was
washed with CH2Cl2 (4 ¥ 10 mL) and the unified organic phases
were dried over anhydrous CaCl2. After filtration and removal of
the solvent under reduced pressure, compound 2 was obtained
as a white solid (1.12 g, 90%), mp 140 ◦C. Anal. Calcd. for
C15H17BrNSb (412.96): C, 43.63; H, 4.15; N, 3.39. Found: C,
43.25; H, 4.06; N, 3.12%. H NMR (300 MHz, 20 ◦C, CDCl3):
1
d 2.11 [3 H, s, N(CH3)2 (A)], 2.42 [3 H, s, N(CH3)2 (B)], AB spin
system with A at 3.55 and B at 3.62 ppm (2 H, CH2, 2JHH 14.2 Hz),
3
7.22 (1 H, d, H-3, C6H4, JHH 6.9 Hz), 7.30 (3 H, m, H-meta +
Experimental
3
4
para, C6H5), 7.42 (1 H, ddd, H-4, C6H4, JHH 7.4, JHH 1.5 Hz),
3
4
General procedures
7.47 (1 H, ddd, H-5, C6H4, JHH 7.1, JHH 1.4 Hz), 7.51 (2 H, m,
H-ortho, C6H5), 8.59 (1 H, dd, H-6, C6H4, 3JHH 7.1, 4JHH 1.6 Hz).
13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 45.30 [s, N(CH3)2 (B)],
45.57 [s, N(CH3)2 (A)], 65.55 (s, CH2), 126.34 (s, C-3), 128.57 (s, C-
4), 128.94 (s, C-meta), 129.36 (s, C-5 or C-para), 129.38 (s, C-para
or C-5), 134.63 (s, C-ortho), 138.57 (s, C-6), 142.02 (s, C-2), 142.83
(s, C-1), 142.93 (s, C-ipso). MS (EI, 70 eV, 200 ◦C), m/z (%): 412 (2)
[M+], 332 (100) [M+ - Br], 134 (24) [R+] [R = 2-(Me2NCH2)C6H4].
NMR spectra were recorded in dried solvents on BRUKER DPX
200, BRUKER Avance 300 or BRUKER AVANCE DRX 400
1
instruments. H and 13C chemical shifts are reported in d units
1
(ppm) relative to the residual peak of solvent (ref. CHCl3: H
7.26, 13C 77.0 ppm; C6H6: 1H 7.16, 13C 128.06 ppm; DMSO-
1
d6: H 2.50, 13C 39.43 ppm). Mass spectra were recorded with
FINNIGAN MAT 8200 and microOTOF-Q-Bruker spectrome-
ters. Melting points were measured on an Electrothermal 9200
apparatus and are not corrected. Elemental analyses were per-
formed by Facultatea de Farmacie, Universitatea de Medicina
si Farmacie “Iuliu Hatieganu”, Cluj-Napoca (Romania). All
manipulations were carried out under an inert atmosphere of
argon using Schlenk techniques. Solvents were dried and freshly
distilled under argon prior to use. N,N-Dimethylbenzylamine,
mesityl bromide and butyllithium (15% in hexane) were com-
mercially available. [2-(Me2NCH2)C6H4]Li,24 PhSbCl2, Ph2SbCl,25
[2-(Me2NCH2)C6H4]SbBr2 and [2-(Me2NCH2)C6H4]2SbCl,11 were
prepared according to published methods.
Synthesis of [2-(Me2NCH2)C6H4]PhSbI (3). A mixture of KI
(1.07 g, 9 mmol) and 1 (0.72 g, 1.95 mmol) in acetone (60 mL) was
stirred vigorously for 12 h, at room temperature. The reaction
mixture was filtered off and the solvent was removed under
vacuum. The title compound was obtained as a yellow solid
(0.87 g, 97%), mp 149 ◦C. Anal. Calcd. for C15H17INSb (459.96):
C, 39.17; H, 3.73; N, 3.05. Found: C, 39.42; H, 3.92; N, 2.97%.
1H NMR (300 MHz, 20 ◦C, CDCl3): d 2.14 [3 H, s, N(CH3)2
(A)], 2.42 [3 H, s, N(CH3)2 (B)], AB spin system with A at 3.53
and B at 3.61 ppm (2 H, CH2, 2JHH 14.2 Hz), 7.20 (1 H, m, H-3,
C6H4), 7.29 (3 H, m, H-meta + para, C6H5), 7.44 (2 H, m, H-4,5,
C6H4), 7.52 (2 H, m, H-ortho, C6H5), 8.69 (1 H, m, H-6, C6H4).
13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 45.22 [s, N(CH3)2 (B)],
45.73 [s, N(CH3)2 (A)], 65.43 (s, CH2), 126.38 (s, C-3), 128.72
(s, C-4), 128.90 (s, C-meta), 129.35 (s, C-5 or C-para), 129.46 (s,
C-para or C-5), 134.88 (s, C-ortho), 138.20 (s, C-2), 139.89 (s, C-
ipso), 141.60 (s, C-6), 142.89 (s, C-1). MS (EI, 70 eV, 200 ◦C), m/z
(%): 382 (3) [M+ - Ph], 332 (100) [M+ - I], 134 (17) [R+] [R =
2-(Me2NCH2)C6H4].
Synthesis of [2-(Me2NCH2)C6H4]PhSbCl (1). [2-(Me2NCH2)-
C6H4]Li (3.36 g, 24 mmol) in hexane (90 mL) was added to a cold
solution (-78 ◦C) of PhSbCl2 (6.44 g, 24 mmol) in hexane (250 mL).
The reaction mixture was stirred at -78 ◦C for 2 h, then allowed to
warm to room temperature and stirred for a further 72 h. The
solvent was removed in vacuum and the remaining solid was
extracted with benzene. The yellowish solution was filtered and
removal of the solvent gave 6.47 g (74%) of the title compound as
a white solid, mp 115 ◦C. Anal. Calcd. for C15H17ClNSb (368.51):
C, 48.89; H, 4.65; N, 3.80. Found: C, 48.54; H, 4.25; N, 3.72%.
1H NMR (400 MHz, 20 ◦C, CDCl3): d 2.07 [3 H, s, N(CH3)2 (A)],
2.42 [3 H, s, N(CH3)2 (B)], AB spin system with A at 3.56 and B
Synthesis of [2-(Me2NCH2)C6H4]Ph2Sb (4). [2-(Me2NCH2)-
C6H4]Li (3.4 g, 24 mmol) in hexane (80 mL) was added to a
cold solution (-78 ◦C) of Ph2SbCl (7.51 g, 24 mmol) in hexane
(200 mL). The reaction mixture was stirred at -78 ◦C for 2 h, then
allowed to warm to room temperature and stirred for further 72 h.
The solvent was removed in vacuum and the remaining solid was
extracted with benzene. The yellowish solution was filtered and
removal of the solvent gave 8.0 g (81%) of the title compound as
a white solid, mp 89 ◦C. Anal. Calcd. for C21H22NSb (410.16): C,
2
at 3.61 ppm (2 H, CH2, JHH 14.4 Hz), 7.22 (1 H, d, H-3, C6H4,
3JHH 7.4 Hz), 7.31 (3 H, m, H-meta + para, C6H5), 7.41 (1 H, ddd,
H-4, C6H4, 3JHH 7.4, 4JHH 1.4 Hz), 7.48 (1 H, ddd, H-5, C6H4, 3JHH
4
7.4, JHH 1.1 Hz), 7.52 (2 H, m, H-ortho, C6H5), 8.50 (1 H, dd,
H-6, C6H4, 3JHH 7.5, 4JHH 1.0 Hz). 13C-NMR (100.6 MHz, 20 ◦C,
CDCl3): d 45.32 [s, N(CH3)2 (B)], 45.47 [s, N(CH3)2 (A)], 65.60 (s,
CH2), 126.37 (s, C-3), 128.51 (s, C-4), 128.95 (s, C-meta), 129.28
(s, C-5 or C-para), 129.37 (s, C-para or C-5), 134.57 (s, C-ortho),
137.06 (s, C-6), 143.00 (s, C-2), 144.34 (s, C-1), 144.61 (s, C-ipso).
MS (CI, NH3), m/z (%), neg.: 404 (100) [M- + Cl], 369 (11) [M-];
pos.: 370 (2) [M+ + H], 332 (100) [M+ - Cl], 292 (10) [M+ - Ph].
61.50; H, 5.41; N, 3.4◦1. Found: C, 61.24; H, 5.77; N, 3.54%. H
1
NMR (400 MHz, 20 C, CDCl3): d 1.89 [6 H, s, N(CH3)2], 3.46
(2 H, s, CH2), 7.14 (2 H, m, H-3,4, C6H4), 7.26 (8 H, m, H-5,6,
C6H4, and H-meta + para, C6H5), 7.46 (4 H, m, H-ortho, C6H5).
13C-NMR (100.6 MHz, 20 ◦C, CDCl3): d 43.81 [s, N(CH3)2], 65.26
(s, CH2), 127.54 (s, C-3), 127.67 (s, C-para), 128.04 (s, C-4), 128.22
(s, C-5), 128.32 (s, C-meta), 136.17 (s, C-ortho), 137.15 (s, C-6),
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 6410–6418 | 6415
©

140.55 (s, C-2), 142.19 (s, C-ipso), 144.62 (s, C-1). MS (CI, NH3),
m/z (%), pos.: 410 (28) [M+ + H], 332 (100) [M+ - Ph], 136 (45)
[R+ + 2H] [R = 2-(Me2NCH2)C6H4].
when a white solid formed and was filtered off. Recrystallization
from acetone gave 2.9 g (47%) of the title compound as colourless
◦
crystals, mp 170 C. Anal. Calcd. for C18H23BrNSb (455.04): C,
1
47.51; H, 5.09; N, 3.0◦8. Found: C, 47.24; H, 4.83; N, 3.25%. H
Synthesis of [2-(Me2NCH2)C6H4]2PhSb (5). [2-(Me2NCH2)-
C6H4]Li (2.35 g, 16.7 mmol) in hexane (80 mL) was added to
a cold solution (-78 ◦C) of Ph2SbCl (2.25 g, 8.3 mmol) in hexane
(80 mL). The reaction mixture was stirred at -78 ◦C for 2 h, then
allowed to warm to room temperature. The yellowish solution
was filtered and the solvent was removed in vacuum to yield 3.51 g
NMR (300 MHz, 20 C, CDCl3): d 1.93 (3 H, s,br, ortho-CH3),
2.14 [3 H, s, N(CH3)2 (A)], 2.23 (3 H, s, para-CH3), 2.36 [3 H, s,
N(CH3)2 (B)], 2.74 (3 H, s,br, ortho-CH3), AB spin system with A
2
at 3.43 and B at 3.73 ppm (2 H, CH2, JHH 13.9 Hz), 6.82 (2 H,
3
s,br, H-3¢,5¢, C6H2), 7.16 (1 H, d, H-3, C6H4, JHH 7.1 Hz), 7.34
(1 H, ddd, H-4, C6H4, 3JHH 7.4, 4JHH 1.4 Hz), 7.40 (1 H, ddd, H-5,
C6H4, 3JHH 7.3, 4JHH 0.7 Hz), 8.58 (1 H, dd, H-6, C6H4, 3JHH 7.3,
4JHH 1.4 Hz). 13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 20.96 (s,
para-CH3), 25.08 (s,br, ortho-CH3), 45.45 [s, N(CH3)2], 66.27 (s,
CH2), 125.99 (s, C-3), 128.66 (s, C-5), 128.89 (s, C-4), 129.08 (s,br,
C-3¢,5¢), 137.72 (s, C-6), 139.05 (s, C-4¢), 139.85 (s, C-1¢), 142.46
(s, C-1 and C-2¢,6¢), 143.40 (s, C-2). MS (CI, NH3), m/z (%), neg.:
534 (63) [M- + Br], 374 (58) [M- - Br-], 79 (100) [Br-] [R = 2-
(Me2NCH2)C6H4]; pos.: 456 (3) [M+ + H], 374 (100) [M+ - Br],
336 (9) [M+ - Mes].
◦
(90%) of the title compound as a white solid, mp 100 C. Anal.
Calcd. for C24H29N2Sb (467.26): C, 61.69; H, 6.26; N, 6.00. Found:
C, 61.34; H, 5.98; N, 5.84%. 1H NMR (300 MHz, 20 ◦C, CDCl3):
d 1.88 [12 H, s, N(CH3)2], AB spin system with A at 3.35 and B at
3.59 ppm (4 H, CH2, 2JHH 12.9 Hz), 7.09 (2 H, m, H-4, C6H4), 7.21
(9 H, m, H-3,5,6, C6H4, and H-meta + para, C6H5), 7.45 (2 H, m,
H-ortho, C6H5). 13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 44.00 [s,
N(CH3)2], 65.74 (s, CH2), 126.93 (s, C-para), 127.02 (s, C-4), 127.24
(s, C-5), 127.82 (s, C-3), 128.10 (s, C-meta), 136.28 (s, C-ortho),
137.21 (s, C-6), 143.76 (s, C-2), 144.52 (s, C-1), 145.23 (s, C-ipso).
◦
MS (EI, 70 eV, 200 C): m/z (%): 466 (1) [M+], 389 (100) [M+ -
Synthesis of [2-(Me2NCH2)C6H4]MesSbI (8). A mixture of
KI (0.28 g, 1.69 mmol) and 7 (0.53 g, 1.16 mmol) in acetone
(60 mL) was stirred vigorously for 12 h, at room temperature.
The reaction mixture was filtered off and the solvent was removed
under vacuum. The solid residue was recrystallized from CH2Cl2
to afford the title compound as yellow crystals (0.40 g, 69%), mp
180 ◦C. Anal. Calcd. for C18H23INSb (502.04): C, 43.06; H, 4.62;
N, 2.79. Found: C, 42.82; H, 4.33; N, 2.64%. 1H NMR (300 MHz,
20 ◦C, CDCl3): d 1.92 (3 H, s,br, ortho-CH3), 2.15 [3 H, s, N(CH3)2
(A)], 2.23 (3 H, s, para-CH3), 2.35 [3 H, s, N(CH3)2 (B)], 2.71
(3 H, s,br, ortho-CH3), AB spin system with A at 3.42 and B at
3.71 ppm (2 H, CH2, 2JHH 13.9 Hz), 6.82 (2 H, s,br, H-3¢,5¢, C6H2),
7.14 (1 H, m, H-3, C6H4), 7.36 (2 H, m, H-4,5, C6H4), 8.68 (1 H,
m, H-6, C6H4). 13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 20.93 (s,
para-CH3), 24.99 (s,br, ortho-CH3), 45.29 [s, N(CH3)2 (B)], 45.55
[s, N(CH3)2 (A)], 66.09 (s, CH2), 126.08 (s, C-3), 128.75 (s, C-4),
128.89 (s,br, C-3¢,5¢–partially overlapped by the resonance of C-5
carbon), 128.99 (s, C-5), 137.24 (s, C-1¢), 139.01 (s, C-4¢), 139.59
(s, C-2), 140.22 (s, C-6), 142.51 (s, C-1 and C-2¢,6¢). MS (EI, 70
eV, 200 ◦C), m/z (%): 374 (100) [M+ - I], 255 (10) [RSb+], 240 (15)
[MesSb+], 134 (30) [R+] [R = 2-(Me2NCH2)C6H4].
Ph], 332 (76) [M+ - R], 134 (23) [R+] [R = 2-(Me2NCH2)C6H4].
Synthesis of [2-(Me2NCH2)C6H4]PhMesSb (6). MesBr (1.32 g,
1.0 mL, r 1.301 g cm-3, 6.6 mmol) in THF (20 mL) was added
dropwise, under stirring, to the Mg filings (0.159 g, 6.6 mmol). The
mixture starts to warm up and results in a yellow solution after
2 h. Solid 1 (2.44 g, 6.6 mmol) was added to the resulted solution
of MesMgBr and the reaction mixture was left to stirr over night
at ambient temperature. The solvent was removed under vacuum
and the white oily residue was extracted with hexane. The hexane
solution was filtered off and removal of the solvent gave 1.83 g
(61%) of the title compound as a white, crystalline solid, mp 94–
95 ◦C. Anal. Calcd. for C24H28NSb (452.24): C, 63.74; H, 6.24; N,
1
3.10. Found: C, 63.71; H, 5.93; N, 3.23%. H NMR (300 MHz,
20 ◦C, CDCl3): d 2.00 [6 H, s, N(CH3)2], 2.38 (3 H, s, para-CH3),
2.41 (6 H, s, ortho-CH3), AB spin system with A at 3.44 and B at
2
3.57 ppm (2 H, CH2, JHH 13.2 Hz), 6.97 (2 H, s, H-3¢,5¢, C6H2),
7.20 (2 H, m, H-3,5, C6H4), 7.30 (1 H, ddd, H-4, C6H4, 3JHH 7.2,
4JHH 1.4 Hz), 7.40 (3 H, m, H-meta + para, C6H5), 7.63 (2 H, m,
H-ortho, C6H5), 7.73 (1 H, dd, H-6, C6H4, 3JHH 7.2, 4JHH 1.7 Hz).
13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 21.02 (s, para-CH3), 26.39
(s,br, ortho-CH3), 44.01 [s, N(CH3)2], 65.30 (s, CH2), 127.33 (s, C-
para), 127.42 (s, C-3), 127.65 (s, C-4), 128.18 (s, C-5), 128.31 (s,
C-meta or C-3¢,5¢), 128.32 (s, C-3¢,5¢ or C-meta), 136.01 (s, C-6),
136.56 (s, C-ortho), 136.95 (s, C-1¢), 137.62 (s, C-4¢), 139.88 (s, C-
1), 142.35 (s, C-ipso), 144.16 (s, C-2), 145.00 (s, C-2¢,6¢). MS (ES),
m/z (%), pos.: 453 (25) [M+ + H], 332 (100) [M+ - Mes] [R =
2-(Me2NCH2)C6H4].
Synthesis of [2-(Me2NCH2)C6H4]Mes2Sb (9). A solution of
MesMgBr [prepared from MesBr (0.84 g, 0.65 mL, r 1.301 g cm-3,
4.2 mmol) and magnesium filings (0.10 g, 4.2 mmol) in anhydrous
THF (20 mL)] was added dropwise to a stirred solution of [2-
(Me2NCH2)C6H4]SbCl2 (0.69 g, 2.1 mmol) in THF (20 mL) cooled
to 0 ◦C. The reaction mixture was allowed to warm to room
temperature and then stirred over night. The solvent was removed
under vacuum and the remaining residue was extracted with
hexane. The clear hexane solution was evaporated to dryness to
give 0.86 g (83%) of the title compound as a white crystalline solid,
mp 102 ◦C. Anal. Calcd. for C27H34NSb (494.31): C, 65.60; H, 6.93;
N, 2.83. Found: C, 64.93; H, 7.37; N, 2.92%. 1H NMR (300 MHz,
20 ◦C, CDCl3): d 1.92 [6 H, s, N(CH3)2], 2.27 (12 H, s, ortho-
CH3), 2.28 (6 H, s, para-CH3), 3.48 (2 H, s, CH2), 6.83 (4 H, s,
H-3¢,5¢, C6H2), 7.07 (1 H, ddd, H-5, C6H4, 3JHH 7.3, 4JHH 1.9 Hz),
7.18 (1 H, dd, H-3, C6H4, 3JHH 7.4, 4JHH 1.7 Hz), 7.23 (1 H, ddd,
Synthesis of [2-(Me2NCH2)C6H4]MesSbBr (7). MesMgBr was
prepared from MesBr (2.73 g, 2.1 mL, d 1.301 g cm-3, 13.7 mmol)
and magnesium filings (0.33 g, 13.7 mmol) in anhydrous di-
ethyl ether (60 mL). The solution of the Grignard reagent was
added dropwise to a stirred solution of [2-(Me2NCH2)C6H4]SbBr2
(5.72 g, 13.7 mmol) in THF (60 mL) cooled to 0 ◦C. The reaction
mixture was allowed to warm to room temperature and then
stirred for 48 h. The solvents were removed under vacuum and the
remaining grey residue was extracted with toluene (3 ¥ 50 mL).
The clear toluene solution was concentrated and stored at -28 ◦C
3
4
H-4, C6H4, JHH 7.5, JHH 1.3 Hz), 7.61 (1 H, dd, H-6, C6H4,
3JHH 7.5, JHH 1.0 Hz). 13C-NMR (75.4 MHz, 20 ◦C, CDCl3):
4
6416 | Dalton Trans., 2010, 39, 6410–6418
This journal is
The Royal Society of Chemistry 2010
©

Table 3 Crystallographic data for compounds 2–8
2
3
4
5
6
7
8
Empirical formula
M
T
C15H17BrNSb
412.96
297(2)
Monoclinic
C2/c
25.7685(17)
7.9478(5)
15.3568(10)
90
103.259(1)
90
3061.3(3)
8
11 854
C15H17INSb
459.95
297(2)
Monoclinic
P21/c
13.2997(9)
12.2869(8)
10.4529(7)
90
111.129(1)
90
1593.29(18)
4
12 446
C21H22NSb
410.15
297(2)
Monoclinic
P21/c
8.452(3)
35.081(12)
6.335(2)
90
95.200(6)
90
1870.7(11)
4
14 969
C24H29N2Sb
467.24
297(2)
Triclinic
¯
P1
8.7366(6)
16.1565(11)
16.1689(11)
88.276(1)
89.618(1)
82.723(1)
2262.9(3)
4
C24H28NSb
452.22
297(2)
Monoclinic
P21/c
8.4829(17)
37.717(8)
6.7885(14)
90
98.986(3)
90
2145.3(8)
4
15 307
C18H23BrNSb C18H23INSb
557.28
297(2)
Monoclinic
502.02
297(2)
Monoclinic
Crystal system
Space group
P21/n
P21/c
˚
a/A
8.8931(5)
9.5876(6)
21.2914(13)
90
99.265(1)
90
9.8671(6)
15.2192(9)
13.3666(8)
90
104.159(1)
90
˚
b/A
˚
c/A
a/◦
b/◦
g /◦
V/A
Z
3
˚
1791.70(19)
4
13 934
1946.3(2)
4
15 379
No. of reflections collected
22 113
No. of independent reflections 3115
3248
3817
7962
3758
3656
3976
(Rint = 0.0303) (Rint = 0.0295) (Rint = 0.0298) (Rint = 0.0463) (Rint = 0.0510) (Rint = 0.0280) (Rint = 0.0369)
Absorption correction
m(Mo-Ka)/mm-1
R1 [I > 2s(I)]
wR2
Multi-Scan26
4.396
Multi-Scan26
3.653
0.0327
0.0638
1.213
Multi-Scan26
1.474
0.0421
0.0914
1.157
Multi-Scan26
1.229
0.0442
0.0838
1.085
Multi-Scan26
1.293
0.0871
0.1500
1.376
Multi-Scan26
3.764
0.0367
0.0872
1.154
Multi-Scan26
2.999
0.0392
0.0818
1.113
0.0395
0.0886
1.177
GOF on F2
d 20.90 (s, para-CH3), 25.82 (s, ortho-CH3), 44.36 [s, N(CH3)2],
65.87 (s, CH2), 127.05 (s, C-5), 127.69 (s, C-4), 128.38 (s, C-3),
128.54 (s, C-3¢,5¢), 137.25 (s, C-1¢), 137.68 (s, C-6), 138.89 (s, C-
4¢), 139.42 (s, C-1), 144.76 (s, C-2¢,6¢), 144.81 (s, C-2). MS (CI,
NH3), m/z (%), neg.: 492 (7) [M- - H], 374 (68) [M- - Mes], 359
(17) [M- - R], 134 (8) [R-] [R = 2-(Me2NCH2)C6H4]; pos.: 494 (5)
[M+ + H], 374 (100) [M+ - Mes], 256 (9) [RSb+ + H], 134 (9) [R+].
attached with epoxy glue on cryoloops. Data were collected
at room temperature (297 K) on a Bruker SMART APEX
diffractometer, using graphite-monochromated Mo-Ka radiation
˚
(l = 0.71073 A). Scan type w and f. Absorption corrections:
multi-scan.26 The structures were refined with anisotropic thermal
parameters. The hydrogen atoms were refined with a riding model
and a mutual isotropic thermal parameter. For structure solving
and refinement the software package SHELX-97 was used.27 The
drawings were created with the Diamond program.28
Synthesis of [2-(Me2NCH2)C6H4]2MesSb (10). A solution of
MesMgBr [prepared from MesBr (0.33 g, 0.25 mL, r 1.301 g cm-3,
1.7 mmol) and magnesium filings (0.04 g, 1.7 mmol) in anhydrous
THF (20 mL)] was added dropwise to a stirred solution of [2-
(Me2NCH2)C6H4]2SbCl (0.72 g, 1.7 mmol) in THF (20 mL) cooled
to 0 ◦C. The reaction mixture was allowed to warm to room
temperature and then stirred over night. The solvent was removed
under vacuum and the remaining yellowish oily residue was
extracted with hexane. The clear hexane solution was evaporated
to dryness to give 0.47 g (54%) of the title compound as a white
crystalline solid, mp 83–85 ◦C. Anal. Calcd. for C27H35N2Sb
(509.34): C, 63.67; H, 6.93; N, 5.50. Found: C, 63.23; H, 6.77;
Acknowledgements
Financial support from National University Research Council
(CNCSIS, Romania; Research Project Nos. TD-93/2006 and
A-709/2006) and the Ministry of Education and Research of
Romania (Excellency Research Program, project CEx-05-D11-
16/2005 and Research Project PNII-ID 2052/2009) is greatly
appreciated. We thank Universita¨t Bremen for providing research
facilities and DAAD for financial support during short-term
research stays. We also thank the NATIONAL CENTER FOR
X-RAY DIFFRACTION and Dr Richard Varga (“Babes-Bolyai”
University, Cluj-Napoca, Romania) for the support in the solid
state structure determinations.
◦
1
N, 5.34%. H NMR (300 MHz, 20 C, CDCl3): d 1.92 [12 H, s,
N(CH3)2], 2.26 (3 H, s, para-CH3), 2.28 (6 H, s, ortho-CH3), AB
2
spin system with A at 3.33 and B at 3.65 ppm (4 H, CH2, JHH
13.2 Hz), 6.80 (2 H, s, H-3¢,5¢, C6H2), 7.05 (2 H, m, H-5, C6H4),
7.21 (4 H, m, H-3,4, C6H4), 7.45 (2 H, d, H-6, C6H4, 3JHH 7.2 Hz).
13C-NMR (75.4 MHz, 20 ◦C, CDCl3): d 20.98 (s, para-CH3), 26.32
(s, ortho-CH3), 44.33 [s, N(CH3)2], 65.62 (s, CH2), 126.86 (s, C-5),
127.32 (s, C-3), 128.18 (s, C-4, and C-3¢,5¢), 136.88 (s, C-1¢), 137.63
(s, C-6), 140.73 (s, C-1), 142.12 (s, C-4¢), 144.77 (s, C-2¢,6¢), 145.05
(s, C-2). MS (EI, 70 eV, 200 ◦C), m/z (%): 508 (2) [M+], 389 (100)
[M+ - Mes], 374 (15) [M+ - R], 240 (8) [M+ - 2R], 134 (21) [R+]
(R = Me2NCH2C6H4).
Notes and references
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The details of the crystal structure determination and refinement
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6418 | Dalton Trans., 2010, 39, 6410–6418
This journal is
The Royal Society of Chemistry 2010
©