1-Naphthyl- and mesityltellurium(IV, II) derivatives of small bite chelating organic ligands: Effect of steric bulk and intramolecular secondary bonding interaction on molecular geometry and supramolecular association

Article abstract of DOI:10.1016/j.jorganchem.2006.09.050

The synthesis and characterization of unsymmetric diorganotellurium compounds containing a sterically demanding 1-naphthyl or mesityl ligand and a small bite chelating organic ligand capable of 1,4-Te?N(O) intramolecular interaction is described. The reaction of ArTeCl₃ (Ar = 1-C₁₀H₇, Np; 2,4,6-Me₃C₆H₂, Mes) with (SB)HgCl [SB = the Schiff base, 2-(4,4′-NO₂C₆H₄CH{double bond, long}NC₆H₃-Me)] or a methyl ketone (RCOCH₃) afforded the corresponding dichlorides (SB)ArTeCl₂ (Ar = Np, 1Aa; Mes, 1Ba) or (RCOCH₂)ArTeCl₂ (Ar = Np; R = Ph (2Aa), Me (3Aa), Np (4Aa); Ar = Mes, R = Ph (2Ba)). Reduction of 1Aa and 1Ba by Na₂S₂O₅ readily gave the tellurides (SB)ArTe (Ar = Np (1A), Mes, (1B)) but that of dichlorides derived from methylketones was complicated due to partial decomposition to tellurium powder and diarylditelluride (Ar₂Te₂), resulting in poor yields of the corresponding tellurides 2A, 2B and 3A. Oxidation of the isolated tellurides with SO₂Cl₂, Br₂ and I₂ yielded the corresponding dihalides. All the synthesized compounds have been characterized with the help of IR, ¹H, ¹³C, and ¹²⁵Te NMR and in the case of 2Aa, and 2Ba by X-ray crystallography. Appearance of only one ¹²⁵Te signal indicated that the unsymmetric derivatives were stable to disproportionation to symmetric species. Intramolecular 1,4-Te?O secondary bonding interactions (SBIs) are exhibited in the crystal structures of both the tellurium(IV) dichlorides, 2Aa, and 2Ba. Steric repulsion of the mesityl group in the latter dominates over lone pair-bond pair repulsion, resulting in significant widening of the equatorial C-Te-C angle. This appears to be responsible for the lack of Te?Cl involved supramolecular associations in the crystal structure of 2Ba.

Full text of DOI:10.1016/j.jorganchem.2006.09.050

Journal of Organometallic Chemistry 691 (2006) 5887–5894
www.elsevier.com/locate/jorganchem
1-Naphthyl- and mesityltellurium(IV,II) derivatives of small bite
chelating organic ligands: Effect of steric bulk and intramolecular
secondary bonding interaction on molecular geometry and
supramolecular association
a,
a
a
a
Ashok K.S. Chauhan *, Anamika , Arun Kumar , Ramesh C. Srivastava ,
b
c
R.J. Butcher , Andrew Duthie
a
Department of Chemistry, University of Lucknow, Lucknow 226 007, India
Department of Chemistry, Howard University, Washington DC 20059, USA
School of Life and Environmental Sciences, Deakin University, Geelong 3217, Australia
b
c
Received 20 June 2006; received in revised form 16 September 2006; accepted 21 September 2006
Available online 30 September 2006
Abstract
The synthesis and characterization of unsymmetric diorganotellurium compounds containing a sterically demanding 1-naphthyl or
mesityl ligand and a small bite chelating organic ligand capable of 1,4-Teꢀ ꢀ ꢀN(O) intramolecular interaction is described. The reaction
of ArTeCl3 (Ar = 1-C10H7, Np; 2,4,6-Me3C6H2, Mes) with (SB)HgCl [SB = the Schiff base, 2-(4,40-NO2C6H4CH@NC6H3-Me)] or a
methyl ketone (RCOCH3) afforded the corresponding dichlorides (SB)ArTeCl2 (Ar = Np, 1Aa; Mes, 1Ba) or (RCOCH2)ArTeCl2
(Ar = Np; R = Ph (2Aa), Me (3Aa), Np (4Aa); Ar = Mes, R = Ph (2Ba)). Reduction of 1Aa and 1Ba by Na2S2O5 readily gave the tellu-
rides (SB)ArTe (Ar = Np (1A), Mes, (1B)) but that of dichlorides derived from methylketones was complicated due to partial decompo-
sition to tellurium powder and diarylditelluride (Ar2Te2), resulting in poor yields of the corresponding tellurides 2A, 2B and 3A. Oxidation
of the isolated tellurides with SO2Cl2, Br2 and I2 yielded the corresponding dihalides. All the synthesized compounds have been charac-
terized with the help of IR, 1H, 13C, and 125Te NMR and in the case of 2Aa, and 2Ba by X-ray crystallography. Appearance of only one
125Te signal indicated that the unsymmetric derivatives were stable to disproportionation to symmetric species. Intramolecular 1,4-Teꢀ ꢀ ꢀO
secondary bonding interactions (SBIs) are exhibited in the crystal structures of both the tellurium(IV) dichlorides, 2Aa, and 2Ba. Steric
repulsion of the mesityl group in the latter dominates over lone pair–bond pair repulsion, resulting in significant widening of the equatorial
C–Te–C angle. This appears to be responsible for the lack of Teꢀ ꢀ ꢀCl involved supramolecular associations in the crystal structure of 2Ba.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Sterically hindered organotelluriums; Supramolecular association; Intramolecular coordination; Secondary bonding interactions
1. Introduction
in the activity of biological macromolecules as well as the
observed electro-optical properties of crystalline molecular
materials. For this reason, theoretical and experimental
structural studies on organotellurium compounds that pos-
sess suitably placed nucleophilic atoms as potential donors
for intra- and/or inter-molecular Teꢀ ꢀ ꢀO/N/X SBI have
gained impetus in the last few years [2] as they allow heuris-
tic conclusions to be drawn for designing model molecules
with desired functionality. Recently, we carried out aryltell-
uration of 4-nitro-40-methylbenzalideneaniline (NMBA)
Secondary bonding interactions (SBIs) among the elec-
tron-rich p-block elements [1] affect the stability and reactiv-
ity of molecules and also influence the ‘chemistry beyond
molecules’. These non-covalent associative forces, besides
the widely recognized hydrogen bonds, play a crucial role
*
Corresponding author.
E-mail address: akschauhan2003@yahoo.co.in (A.K.S. Chauhan).
0022-328X/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2006.09.050

5888
A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
and examined solid state structures of the resulting diaryltel-
lurides as well as some of their mercury(II) halide complexes
[3] with the view that intramolecular 1,4-Teꢀ ꢀ ꢀN SBI in the
geometrically constrained orthotellurated species or the
metal-assisted C–Hꢀ ꢀ ꢀX interactions could lead to non-cen-
trosymmetric supramolecular structures. Such solids might
possess non-zero second-order susceptibility imparting
thereby linear and non-linear electro-optic properties simi-
lar to those observed for the monoclinic crystal modifica-
tions of the organic substrate, NMBA.
and characterization together with single crystal structural
determination of some unsymmetric diorganotellurium
compounds. Acylmethyl ligands, RCOCH2– (R = Ph, Me,
Np) or the Schiff base, 2-(4,40-NO2C6H4CH@NC6H3-Me),
capable of forming strained four-membered intramolecular
rings via Teꢀ ꢀ ꢀO/N coordination were chosen as one of the
organic ligands attached to tellurium, while 2,4,6-Me3C6H2
(Mes) or 1-C10H7 (Np) were employed as the other ligand
due to their steric and electronic effects as well as their abil-
ity to cause various conformations and cell packings.
Though the influence of intramolecular SBIs on the
molecular and crystal structures of organotellurium com-
pounds has been studied considerably, the role of sterically
demanding groups in this respect have received limited
attention. Whereas the isolation of tellurols RTeH at low
temperatures and that of monomeric volatile metal telluro-
lates M(TeR)2 (M = Zn, Cd, Hg) at room temperature
could be realized by incorporating the bulky 2,4,6-triorgan-
ophenyl [4], sitel [Si(SiMe3)3] [5] or 2-[1-(3,5-dimethyl-
phenyl)-2-naphthyl]-4,5-dihydro-4,4-dimethyloxazole [6]
groups, steric crowding around central tellurium atom has
made the isolation of mesityltellurium triiodide hitherto
impossible [7]. However, simultaneous effects of intramolec-
ular coordination to Te as well as the steric bulk of the
organic ligands on the molecular geometry and crystal
packing of organotelluriums has not been examined, even
though organotelluriums containing a sterically hindered
organic group which is also capable of forming 1,5-Teꢀ ꢀ ꢀN
SBI have been prepared [2n]. We report here the synthesis
2. Results and discussion
Interesting unsymmetric diorganotellurium compounds
containing one sterically demanding group and another
capable of 1,4-intramolecular Teꢀ ꢀ ꢀN/O interaction have
been prepared by the interaction of ArTeCl3 (Ar = Np,
Mes) with (SB)HgCl [SB = 2-(4,40-NO2C6H4CH@NC6H3-
Me)] or an acylmethyl ketone (Scheme 1).
Reduction of the diorganotellurium dichlorides 1Aa and
1Ba with Na2S2O5 affords the tellurides 1A and 1B, which
in turn can be oxidized to 1Ab and 1Bb, 1Ac and 1Bc or
back to 1Aa and 1Ba by Br2, I2, or SO2Cl2, respectively.
Reductions of the acylmethyl derivatives 2Aa, 2Ba and
3Aa are complicated and afford the tellurides, 2A, 2B and
3A in low yields along with the tellurium powder and the
ditellurides, Ar2Te2. Similar decomposition is reported in
the preparation of several other alkylaryl tellurides [8].
Reduction of the dibromides 2Ab, 2Bb and 3Ab (vide infra)
(SB)ArTeX2
X = Br, 1Ab, 1Bb
I, 1Ac, 1Bc
KX
X2
transmetallation
(SB)HgCl
(SB)ArTeCl2
(SB)ArTe
1Aa, 1Ba
1A, 1B
Na2S2O5
SO2Cl2
ArTeCl3
electrophilic
substitution
(RCOCH2)ArTeCl2
(RCOCH2)ArTe
RCOCH3
2Aa, 2Ba,
2A, 2B
3A
R = Ph, 2; Me, 3;
3Aa
,
X2
(RCOCH2)ArTeX2
KX
4
1-C10H7,
4Aa
2Ab 2Bb
X = Br,
,
3Ab
X = I, 2Ac, 2Bc
3Ac
Me
Me
O2N
Ar =
N
Me
SB =
Me
2,4,6-Me3C6H2
1-C10H7
(1)
A
Np (
)
B
Mes ( )
Scheme 1.

A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
5889
interestingly affords better yields of the tellurides on reduc-
tion. Oxidation of these tellurides 2A, 2B and 3A also affor-
ded the corresponding dihalides. The dibromides and
diiodides were also obtained by the metathetical reaction
of KBr and KI with the corresponding dichlorides.
that are significantly shorter than the sum of their van der
Waals radii (3.58 A).
˚
In the crystal packing of the naphthyl derivative, 2Aa,
besides the carbonyl oxygen, the Cl2 atom of a neighboring
molecule also comes sufficiently close to the TeIV atom by
means of intermolecular Teꢀ ꢀ ꢀCl SBI [Teꢀ ꢀ ꢀCl2 = 3.622(1)
The unsymmetric dihalides (SB)ArTeX2 and (RCO-
CH2)ArTeX2 are quite stable to decomposition to the sym-
metric species. All the compounds are crystalline solids
soluble in dichloromethane and chloroform. It is interest-
ing to note that among the dihalides the naphthyl deriva-
tives have comparatively higher melting points than their
mesityl analogues. Greater steric requirement of the mesityl
group probably allows less compact packing of the mole-
cules in the crystal lattice. The IR spectra of the Schiff base
derivatives show m(C@N) at 1590–1645 cmꢁ1 the values for
the tellurides are higher than those for the dihalides. In the
spectra of the acylmethyl derivatives, m(CO) shows a nega-
tive shift with respect to the parent ketone (2–4) which is
indicative of intramolecular Teꢀ ꢀ ꢀOC interaction. In the
1H NMR spectra of the Schiff base derivatives the azome-
thine proton appears downfield, as expected, at ꢂ8.9 ppm
while a singlet for the methylene protons is observed at
ꢂ5.8 ppm in the acylmethyl derivatives. The 2,4,6-substi-
tuted methyl protons in the mesityl derivatives appear as
singlets in the ratio 1(para):2(ortho).
˚
˚
A < 3.83 A, the sum of their van der Waals radii] to be con-
sidered as part of the coordination sphere. The Teꢀ ꢀ ꢀCl2
SBI is cooperated with a metal assisted C–Hꢀ ꢀ ꢀCl interac-
tion (C8B–H8BAꢀ ꢀ ꢀCl2–TeIV) in giving rise to centrosym-
metric dimeric supramolecules. These dimeric units are
oriented in a parallel fashion by means of another
intermolecular metal assisted C–Hꢀ ꢀ ꢀCl interaction (C8A–
H8AAꢀ ꢀ ꢀCl2–TeIV) resulting in a one-dimensional supra-
molecular architecture. It brings all the Te and Cl atoms
in to a plane (r.m.s. deviation of Te and Cl atoms from
˚
the mean plane = 0.0834 A), forming an elegant doubly-
bridged (TeCl2)n polymeric ribbon flanked with organic
ligand on both sides. The antiparallel consecutive Cl1–
Te–Cl2 units in the polymeric chain confer greater stability
to the motif by alternating the local dipole moment. Such
1-D arrays achieved by (A1–Te–A2)n synthons are ubiqui-
tous among organotelluriums containing nucleophilic
atoms one or two bonds from tellurium. The potential of
Teꢀ ꢀ ꢀA recognition pattern to give rise to (A1–Te–A2)n
supramolecular synthons has been recognized in crystal
engineering [2i,2j]. It implies that SBI based synthons are
as effective as those which involve conventional H-bond
or C–Hꢀ ꢀ ꢀA interactions, which are quite common among
organic compounds. In the case of 2Aa, the metal assisted
C–Hꢀ ꢀ ꢀCl interactions appear to be strong enough to bring
all the Te and Cl atoms in the plane of the polymeric rib-
bon, in spite of the involvement of only one of the Cl atoms
in SBI.
The steric repulsion of the mesityl group is quite evident
in the crystal structure of 2Ba and is stronger than lone
pair-bond pair repulsions as it causes angular distorsion,
at least equatorial, of the primary geometry around TeIV.
The observed C1–Te–C9 bond angles in 2Ba [108.0(1)
and 107.9(1) for the two independent molecules] are unusu-
ally large in comparison to the average value of 96(3)ꢁ
found for C–Te–C in the CSD [11] but not uncommon
for aryltelluranes [12] that possess at least one 2,6-disubsti-
tuted aryl ligand attached to TeIV. It may be inferred that
the steric repulsion of ligands in the primary sphere of
Te(IV) affects molecular geometry considerably, albeit, ste-
ric congestion due to the presence of nucleophilic atoms
attached to Te(IV) through SBIs is insignificant as evident
from the C–Te–C angle values in such compounds [9]
which vary over the range 93.1(1)–99.1(1)ꢁ. The crystal
packing of 2Ba differs from that of 2Aa. The bulky mesityl
group inhibits intermolecular Teꢀ ꢀ ꢀCl SBI and 1-D arrays
formed by (ꢀ ꢀ ꢀCl–Te–Clꢀ ꢀ ꢀ)n supramolecular synthon, pres-
ent in 2Aa, is not realized in the crystalline state of 2Ba.
Instead, interplay of C–Hꢀ ꢀ ꢀO and C–Hꢀ ꢀ ꢀCl interactions
(Table 1) in the self assembly of 2Ba results in three-dimen-
sional centrosymmetric supramolecular motif.
The 125Te NMR chemical shifts of some representative
compounds have been measured in solution as well as in
solid state and have been found to be quite sensitive to
the nature of the halogen and the oxidation state of tellu-
rium. Enhanced deshielding is observed in the order
I < Br < Cl and TeII < TeIV for the compounds. The
125Te chemical shifts for the mesityl tellurium(II,IV) deriv-
atives of the Schiff base are nearly 100 ppm downfield to
their corresponding naphthyl analogues but are close to
those for other aryl analogues, (SB)Ar0Te (Ar0 = Ph, 4-
MeOC6H4, 4-MeC6H4) [3] which may be due to the greater
Teꢀ ꢀ ꢀp interaction, even in solution, of the naphthalene
ring compared to the benzene rings.
2.1. Crystal and molecular structure of 2Aa and 2Ba
Compounds 2Aa and 2Ba crystallize in the triclinic crys-
tal system where the primitive lattice in both the com-
pounds bears a center of symmetry. Asymmetric units
consist of only one molecule in 2Aa and two independent
molecules in 2Ba. The TeIV atom in the molecules of these
compounds presents a primary pseudo-trigonal-bipyrami-
dal configuration in complete agreement with the VSEPR
model. The axial Te–Cl bond lengths differ slightly and
the unequal equatorial Te–C distances (Te–Csp3 > Te–
C
sp2) are well within the range commonly observed in other
RFArTeCl2 compounds (RF is an organic ligand suitably
functionalized to bear a nucleophilic atom A, viz. O, N,
S or Cl that involves Te in the intramolecular 1,4-Teꢀ ꢀ ꢀA
SBI) [9,10]. Formation of four-membered rings by means
of Teꢀ ꢀ ꢀO SBIs in 2Aa and 2Ba is evident from interatomic
˚
distances [2.862(4) in 2Aa, 2.890(2) and 2.846(2) A in 2Ba]

5890
A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
Table 1
Hydrogen bond parametersa,b
˚
˚
˚
D–Hꢀ ꢀ ꢀA
d(D–H) (A)
d(Hꢀ ꢀ ꢀA) (A)
d(Dꢀ ꢀ ꢀA) (A)
<(DHA) (ꢁ)
2Aa
2Ba
C8–H8ꢀ ꢀ ꢀCl1i
0.95
0.95
0.95
0.95
3.783(5)
3.765(5)
3.732(6)
3.314(7)
2.854(2)
2.898(1)
2.845(2)
2.604(5)
166.3
152.5
155.7
131.8
C14–H14ꢀ ꢀ ꢀCl2ii
C17–H17ꢀ ꢀ ꢀCl2iii
C11–H11ꢀ ꢀ ꢀOiv
C17A–H17Aꢀ ꢀ ꢀO1Av
C4A–H4AAꢀ ꢀ ꢀCl2Avi
C5A–H5AAꢀ ꢀ ꢀCl2Avii
C11B–H11Bꢀ ꢀ ꢀCl1Aviii
C16B–H16Eꢀ ꢀ ꢀCl1Aix
C13B–H13Bꢀ ꢀ ꢀO1Bx
C1B–H1BAꢀ ꢀ ꢀCl1Bvi
C8B–H8BAꢀ ꢀ ꢀO1Bxi
0.98
0.95
0.95
0.95
0.98
0.95
0.99
0.95
2.699(1)
2.779(1)
2.880(1)
2.864(2)
2.836(1)
2.590(1)
2.741(1)
2.484(1)
3.641(2)
3.586(3)
3.602(3)
3.636(3)
3.469(3)
3.476(3)
3.620(3)
3.370(3)
161.4
143.4
133.7
139.2
123.0
155.4
148.2
155.6
a
Symmetry operations used to generate equivalent atoms: (i) ꢁx, ꢁy, ꢁz; (ii) ꢁx, 1 ꢁ y, ꢁ1 ꢁ z; (iii) ꢁx, ꢁy, ꢁ1 ꢁ z; (iv) x, 1 ꢁ y, z; (v) ꢁ1 + x, y, z; (vi)
ꢁx, 2 ꢁ y, 1 ꢁ z; (vii) ꢁx, 1 ꢁ y, 1 ꢁ z; (viii) x, ꢁ1 + y, z; (ix) 1 ꢁ x, 2 ꢁ y, ꢁz; (x) 1 + x, y, z; (xi) ꢁ1 ꢁ x, 2 ꢁ y, 1 ꢁ z.
b
The term ‘‘hydrogen bond’’ for such interactions has been discouraged recently (P. Munshi, T.N.G. Row, J. Phys. Chem. A 109 (2005) 659) in favour
of weak van der Waals interactions.
3. Experimental
heated under reflux until a clear solution was obtained. After
cooling and evaporation to ꢂ10 ml, diethyl ether (5 ml) was
added. The solution was decanted off from a sticky mass
which was extracted with ether (3 · 10 ml) and hot chloro-
form (2 · 10 ml). Volatiles were removed from the combined
extract and the residue was dissolved in chloroform (20 ml)
and filtered to remove the solid, if any. Concentration of
the filtrate, addition of pet ether (ꢂ5 ml) and cooling to
0 ꢁC afforded yellow crystalline 1Aa. Yield: (1.27 g, 45%);
mp 200 ꢁC. Anal. Calc. for C24H18N2O2Cl2Te: C, 51.03; H,
3.21; N, 4.96; Cl, 12.55; Te, 22.59. Found: C, 51.22; H,
3.33; N, 5.05; Cl, 12.00; Te, 23.03%. IR (cmꢁ1): 1595.5
(mCH@N). 1H NMR (ppm): d 2.46 (s, Me), 7.26–8.43 (m, aryl),
8.92 (s, CH@N). 125Te NMR: d 802.0. 125Te CP-MAS: d 830.
13C NMR, (dppm): 21.58 (Me), 116.51, 124.27, 124.29,
127.13, 127.25, 127.3, 127.92, 129.51, 130.21, 130.47,
132.73, 133.05, 133.3, 134, 135.53, 145.27, 149.2 (CH@N),
156.57, 140.02, 140.47, 140.85, 140.98.
3.1. General
Preparative work was performed under dry nitrogen.
Melting points were recorded in capillary tubes and are
uncorrected. The starting material [{2-(4-nitrobenzylide-
neamino)-5-methyl}phenyl]mercury chloride was prepared
according to literature method [10]. 1-Naphthyl- and mesi-
tyltellurium trichlorides were prepared by the chlorination
of their corresponding ditellurides. 1-Acetonaphthone was
prepared by the reaction of 1-naphthylmagnesium bromide
with acetyl chloride in THF. Commercial acetophenone and
acetone were used after purification by standard method. 1H
NMR spectra were recorded at 300.13 MHz in CDCl3 on a
Varian DRX 300 Spectrometer using TMS as internal stan-
dard. Solution 13C (100.54 MHz) and 125Te (126.19 MHz)
NMR spectra were recorded in CDCl3on a JEOL Eclipse
Plus 400 NMR spectrometer, using Me4Si and Me2Te as
internal standards. 125Te CP-MAS NMR spectra were
obtained using the same spectrometer equipped with a
6 mm rotor operating at spinning frequencies between 8
and 10 kHz. A 60 s recycle delay was used and typically
1000–5000 transitions were accumulated to obtain adequate
signal-to-noise ratios. The isotropic chemical shifts diso were
determined by comparison of two acquisitions measured at
sufficiently different spinning frequencies and were refer-
enced against Me2Te using solid Te(OH)6 as the secondary
reference (diso 692.2/685.5). IR spectra were recorded as
KBr pellets using a Perkin–Elmer RX1 Spectrometer.
Microanalyses were carried out using a Carlo Erba 1108
make analyzer. Tellurium was estimated volumetrically
and the halogen content gravimetrically as silver halide.
Compound 1Ba was prepared similarly. Yield: (42%);
mp 170 ꢁC. Anal. Calc. for C23H22N2O2Cl2Te: C, 49.60;
H, 3.98; N, 5.03; Cl, 12.73; Te, 22.91. Found: C, 49.21;
H, 3.92; N, 5.22; Cl, 12.22; Te, 23.51%. IR (cmꢁ1):
1590.1 (mCH@N). 1H NMR (ppm): d 2.25–2.73 (s, Me),
7.00–8.05 (m, aryl), 8.88 (s, CH@N).
The yield was comparatively low when these reactions
were carried out in chloroform instead of dioxane.
3.3. Electrophilic substitution reaction: synthesis of
2Aa–4Aa and 2Ba
A mixture of 1-naphthyltellurium trichloride (3.61 g,
10.0 mmol) and acetophenone (2.34 mL, 20.0 mmol) were
stirred slowly at room temperature under the flow of dry
nitrogen for about 15 h until the evolution of HCl ceased.
The resulting white paste was washed with pet-ether
(3 · 10 mL) and triturated with diethyl ether and filtered
to remove excess of acetophenone. Recrystallization from
dichloromethane yielded colourless needles of 2Aa. Yield:
(3.60 g, 81%); mp 188 ꢁC. Anal. Calc. for C18H14OCl2Te:
3.2. Syntheses
3.2.1. Transmetallation reaction: synthesis of 1Aa and 1Ba
A suspension of (SB)HgCl (2.37 g, 5.00 mmol) and
NpTeCl3 (1.80 g, 5.00 mmol) in dry dioxane (40 ml) was

A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
5891
C, 48.60; H, 3.17; Cl, 15.94; Te, 28.69. Found: C, 48.32; H,
130.02, 130.6, 130.67, 130.81, 133.74, 135.41, 138.87,
140.43, 141.41, 154.19 (CH@N), 156.52, 149.69.
Accordingly colourless compounds 2A, 2B and 3A were
obtained by the reduction of their corresponding dibro-
mides (2Ab, 2Bb and 3Ab).
1
3.11; Cl, 16.33; Te, 28.00%. IR (cmꢁ1): 1660 (mC@O). H
NMR (ppm): d 5.71 (s, CH2), 7.43–8.11 (m, aryl). 125Te
NMR: d 761.6. 125Te CP-MAS: d 798. 13C NMR, (d
ppm): 191.9 (CO), 67.1 (CH2).
Compounds 2Ba and 4Aa were prepared similarly.
Compound 2Ba: Yield: (72%); mp 148 ꢁC. Anal. Calc.
for C17H18OCl2Te: C, 46.74; H, 4.15; Cl, 16.23; Te,
29.21. Found: C, 46.51; H, 3.99; Cl, 16.39; Te, 28.64%.
IR (cmꢁ1): 1650 (mC@O). 1H NMR (ppm): d 5.65 (s,
CH2), 2.32–2.81 (s, 3Me), 6.98–8.04 (m, aryl). 125Te
NMR: d 781.2. 125Te CP-MAS: d 814. 13C NMR, (d
ppm): 192.27 (CO), 63.45 (CH2), 20.99, 23.55, 24.17 (3Me).
Compound 4Aa: Yield: (62%); mp 208 ꢁC. Anal. Calc.
for C22H16OCl2Te: C, 53.40; H, 3.26; Cl, 14.33; Te,
25.78. Found: C, 53.12; H, 3.35; Cl, 13.98; Te, 25.22%.
IR (cmꢁ1): 1654 (mC@O). 1H NMR (ppm): d 5.89 (s,
CH2), 7.55–9.00 (m, aryl). 125Te NMR: d 765. 13C NMR,
(d ppm): 194.48 (CO), 69.66 (CH2).
Compound 2A: Dichloromethane solution (25 mL) of
2Ab (1.07 g, 2 mmol) was shaken vigorously in a seperatory
funnel for 10 min with an aqueous solution of (50 mL) of
Na2S2O5 (0.5 g, 2.6 mmol). The yellow organic phase was
separated, washed once with water, and dried for 5 min
over Na2SO4. The solution gradually changed to orange
with slight separation of elemental tellurium. Evaporation
to dryness and fractional crystallization of the residue affor-
ded red coloured bis(1-naphthyl)ditelluride (0.16 g, 30% of
2Ab converted) and 2A: Yield: (0.45 g, 61%); mp 103 ꢁC.
Anal. Calc. for C18H14OTe: C, 57.82; H, 3.77; Te, 34.13.
Found: C, 57.61; H, 3.83; Te, 34.68%. IR (cmꢁ1): 1648
1
(mC@O). H NMR (ppm): d 5.72 (s, CH2), 7.55–8.31 (m,
aryl). 13C NMR, (d ppm): 192.02 (CO), 67.19 (CH2).
Compound 2B: Yield: (53%); mp 98 ꢁC. Anal. Calc. for
C17H18OTe: C, 55.80; H, 4.96; Te, 34.87. Found: C, 55.50;
Compound 3Aa: 1-naphthyltellurium trichloride (1.80 g,
5.00 mmol) was dissolved in an excess of dry acetone
(ꢂ10 mL) and stirred vigorously. White solid of 3Aa sepa-
rated slowly (15 min) which was filtered, washed with cold
ether and recrystallized with chloroform. Yield: (1.62 g,
85%); mp 157 ꢁC. Anal. Calc. for C13H12OCl2Te: C,
40.80; H, 3.16; Cl, 18.53; Te, 33.34. Found: C, 40.56; H,
1
H, 5.05; Te, 35.30%. IR (cmꢁ1): 1650 (mC@O). H NMR
(ppm): d 5.66 (s, CH2), 2.33–2.83 (s, 3 Me), 7.00–8.05 (m,
aryl).
Compound 3A: Yield: (56%); mp 137 ꢁC. Anal. Calc. for
C13H12OTe: C, 50.07; H, 3.88; Te, 40.92. Found: C, 50.24; H,
3.56; Te, 40.52%. IR (cmꢁ1): 1648 (mC@O). 1H NMR (ppm): d
5.29 (s, CH2), 2.53 (s, Me), 7.58–8.15 (m, aryl).
1
3.36; Cl, 18.10; Te, 33.87%. IR (cmꢁ1): 1656 (mC@O). H
NMR (ppm): d 5.12 (s, CH2), 2.5 (s, Me), 7.59–8.16 (m,
aryl). 125Te NMR: d 801.8. 13C NMR, (d ppm): 200.06
(CO), 67.78 (CH2), 29.74 (Me).
3.5. Oxidative addition reaction of 1A–3A, 1B and 2B with
Br2, I2 and SO2Cl2
3.4. Reduction reactions: synthesis of 1A–3A, 1B and 2B
a. Compound 1A (1.00 g, 2.00 mmol) was dissolved in
carbon tetrachloride (25 mL) and a solution of bro-
mine (0.12 mL, 4.40 mmol) in the same solvent was
slowly added with stirring at 0 ꢁC. A light coloured
solid separated which was filtered, dried and recrys-
tallized with CHCl3 to give the corresponding dibro-
mide, 1Ab. Yield: (0.94 g, 72%); mp 190 ꢁC. Anal.
Calc. for C24H18N2O2Br2Te: C, 44.09; H, 2.77; N,
4.28; Br, 24.44; Te, 19.52. Found: C, 44.33; H, 2.56;
N, 4.35; Br, 25.03; Te, 19.22%. IR (cmꢁ1): 1590
A solution of 1Aa (1.13 g, 2 mmol) in dichloromethane
(ꢂ50 ml) was shaken with an aqueous solution of Na2S2O5
(0.57 g, 3 mmol) for 15 min. The organic layer gradually
turned red. It was separated, washed (4 · 50 ml) with water
and dried over anhydrous Na2SO4 overnight. Volatiles
were removed under reduced pressure and the residue crys-
tallized from CHCl3/Et2O to give red needles of 1A. Yield:
(0.63 g, 64%); mp 148 ꢁC. Anal. Calc. for C24H18N2O2Te:
C, 58.35; H, 3.67; N, 5.67; Te, 25.83. Found: C, 58.43; H,
1
1
3.42; N, 5.74; Te, 26.42%. IR (cmꢁ1): 1639.5 (mCH@N). H
(mCH@N). H NMR (ppm): d 2.35 (s, Me), 6.84–7.83
NMR: d 2.18 (s, Me), 6.78–8.54 (m, Aryl), 8.87 (s, CH@N).
125Te NMR: d 471.0. 13C NMR, (d ppm): 20.95 (Me),
115.53, 122.42, 124, 126.04, 126.39, 126.59, 127.22,
127.39, 128.29, 128.82, 129.38, 130.14, 130.39, 133.19,
136.87, 146.72, 149.2 (CH@N), 156.46, 139.13, 140.42,
140.51, 140.91, 141.33, 142.24.
(m, aryl), 8.89 (s, CH@N).
Similarly 2A, 3A, 1B and 2B yielded their correspond-
ing dibromides.
Compound 2Ab: Yield: (74%); mp 159 ꢁC. Anal. Calc.
for C18H14OBr2Te: C, 40.51; H, 2.64; Br, 29.94; Te,
23.91. Found: C, 40.32; H, 2.52; Br, 30.22; Te,
1
Compound 1B was prepared similarly from 1Ba. Yield:
(68%); mp 180 ꢁC. Anal. Calc. for C23H22N2O2Te: C,
56.84; H, 4.56; N, 5.76; Te, 26.25. Found: C, 56.53; H,
24.35%. IR (cmꢁ1): 1655 (mC@O). H NMR (ppm):
d5.72 (s, CH2), 7.54–8.31 (m, aryl). 125Te NMR: d
693.0. 13C NMR, (d ppm): 191.89 (CO), 67.09 (CH2).
Compound 3Ab: Yield: (90%); mp 163 ꢁC. Anal. Calc.
for C13H12OBr2Te: C, 33.11; H, 2.56; Br, 33.88; Te,
27.05. Found: C, 33.54; H, 2.46; Br, 33.72; Te,
1
4.67; N, 5.55; Te, 26.58%. IR (cmꢁ1): 1644.1 (mCH@N). H
NMR (ppm): d 2.31–2.20 (s, Me), 6.81–8.34 (m, aryl),
8.57 (s, CH@N). 125Te NMR: d 575.6. 13C NMR, (d
ppm): 21.05 (Me, NMBA), 21.43 (2, o-Me-Mes), 29.5 (p-
Me-Mes), 115.49, 122.91, 124.16, 126.06, 128.23, 129.38,
27.43%. IR (cmꢁ1): 1650 (mC@O). H NMR (insuffi-
cient solubility).
1

5892
A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
Compound 1Bb: Yield: (76%); mp 178 ꢁC. Anal. Calc.
3.6. Halogen exchange reaction of 1Aa–3Aa, 1Ba and 2Ba
with KBr and KI
for C23H22N2O2Br2Te: C, 42.77; H, 3.43; N, 4.34 Br,
24.74; Te, 19.76. Found: C, 42.58; H, 3.65; N, 4.41;
1
Br, 23.42; Te, 21.02%. IR (cmꢁ1): 1592 (mCH@N). H:
a. A solution of the dichloride in chloroform was stirred
with a two-fold excess of KBr for ꢂ8 h. A colour
change from yellow to red occurred. The mixture
was filtered and the filtrate reduced to approximately
one fifth in vacuo. Addition of petroleum ether 40–
60 ꢁC (10 mL) induced crystallization, providing the
corresponding dibromides (1Ab–3Ab, 1Bb and 2Bb)
in good yields. Their melting points and TLC were
similar to those obtained by the method D(a).
b. Iodides 1Ac and 1Bc were also prepared by using
two-fold excess of KI and the solution of the corre-
sponding dichlorides (1Aa and 1Ba) in dichlorometh-
ane at room temperature.
d 2.51–2.21 (s, Me), 6.87–8.34 (m, aryl), 8.58 (s,
CH@N).
Compound 2Bb: Yield: (70%); mp 121 ꢁC. Anal. Calc.
for C17H18OBr2Te: C, 38.84; H, 3.45; Br, 30.40; Te,
24.27. Found: C, 39.10; H, 3.61; Br, 31.00; Te,
1
24.52%. IR (cmꢁ1): 1657 (mC@O). H NMR (ppm):
d5.76 (s, CH2), 2.34–2.89 (s, 3Me), 7.01–8.10, (m,
aryl).
b. Iodine (0.26 g, 2 mmol) in CCl4 (15 mL) was added
dropwise to the solution of 1A (0.5 g 1 mmol) in the
same solvent at 0 ꢁC. The resulting mixture was con-
centrated till some solid started to precipitate, the
amount increasing on adding pet-ether (40–60 ꢁC).
It was filtered and recrystallized from dichlorometh-
ane to give the corresponding diiodide, 1Ac. Yield:
(0.52 g, 68%); mp 172 ꢁC. Anal. Calc. for
C24H18N2O2I2Te: C, 38.55; H, 2.43; N, 3.75; I,
33.94; Te, 17.06. Found: C, 38.72; H, 2.54; N, 3.43;
In the preparation of 2Ac slow decomposition was
observed and the reaction was not continued for comple-
tion. Immediately it was filtered and the filtrate was con-
centrated to obtain reddish solid. The pure diiodide 2Ac
was obtained by fractional crystallization in ꢂ40% yield.
Compound 2Bc: A solution of 2Ba (1.75 g, 4 mmol) in
CHCl3 (10 mL) was added to a suspension of KI (three-
fold excess) in CHCl3 under stirring at 0 ꢁC. The resulting
greenish-brown solution was stirred for 15 min and filtered
to remove the potassium salts. The solvent was removed
from the filtrate and the residue, upon fractional crystalli-
zation, afforded 2Bc (0.74 g, 30% based on 2Ba) and the
adduct Mes2Te Æ MesTeI (0.4 g, 40% based on 2Ba), mp
88 ꢁC, (lit. 85.9–87.7 [7]). Anal. Calc. for C27H33ITe2: C,
43.84; H, 4.50; I, 17.16; Te, 34.50. Found: C, 43.71; H,
4.37; I, 17.43; Te, 34.11%.
1
I, 34.22; Te, 17.63%. IR (cmꢁ1): 1592 (mCH@N). H
NMR (ppm): d 2.62 (s, Me), 6.95–7.98 (m, aryl),
8.86 (s, CH@N).
Similarly 2A, 3A, 1B and 2B gave their corresponding
diiodides.
Compound 2Ac: Yield: (80%); mp 122 ꢁC. Anal.
Calc. for C18H14OI2Te: C, 34.44; H, 2.25; I, 40.43;
Te, 20.33. Found: C, 34.53; H, 2.32; I, 40.10; Te,
1
20.76%. IR (cmꢁ1): 1649 (mC@O). H NMR (ppm): d
5.91 (s, CH2), 7.31–8.50 (m, aryl). 125Te NMR: d
599.8. 13C NMR, (d ppm): 192.28 (CO), 62.72 (CH2).
Compound 3Ac: Yield: (40%); mp 138 ꢁC. Anal.
Calc. for C13H12OI2Te: C, 27.60; H, 2.14; I, 44.87;
Te, 22.56. Found: C, 27.36; H, 2.36; I, 45.00; Te,
The melting points and IR spectra of the diiodides were
similar to those obtained by oxidative addition of iodine to
the tellurides (method 2.D.b).
1
22.31%. IR (cmꢁ1): 1653 (mC@O). H NMR (ppm):
d5.31 (s, CH2), 2.52 (s, Me), 7.49–8.34 (m, aryl).
Compound 1Bc: Yield: (73%); mp 162 ꢁC. Anal.
Calc. for C23H22N2O2I2Te: C, 37.34; H, 3.00; N,
3.79 I, 34.31; Te, 17.25. Found: C, 37.66; H, 3.20;
N, 3.71; I, 34.04; Te, 17.61%. IR (cmꢁ1): 1597
Table 2
Crystal data and structure refinement
Parameter
2Aa
2Ba
Crystal size (mm3)
Crystal system
Space group
0.52 · 0.22 · 0.20
Triclinic
0.19 · 0.25 · 0.42
Triclinic
1
(mCH@N). H NMR (insufficient solubility).
ꢀ
ꢀ
P1
P1
˚
Compound 2Bc: Yield: (50%); mp 102 ꢁC. Anal.
Calc. for C17H18OI2Te: C, 32.95; H, 2.93; I, 40.95;
Te, 20.59. Found: C, 32.77; H, 3.02; I, 41.31; Te,
a (A)
9.371(2)
9.888(2)
10.962(2)
65.673(3)
78.647(3)
66.141(3)
846.0(3)
2
9.019(2)
14.093(3)
14.723(4)
70.840(4)
78.203(8)
83.120(9)
1727.6(6)
4
1.679
173(2)
1.77–30.17
84.7
0.0293
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
1
20.37%. IR (cmꢁ1): 1658 (mC@O). H NMR (ppm): d
5.57 (s, CH2), 2.23–2.75 (s, 3 Me), 6.2–7.93 (m, aryl).
c. Sulfuryl chloride (0.5 ml) was added dropwise with
stirring to a solution of the telluride (1A–3A, 1B
and 2B) (1 mmol) in dichloromethane at 0 ꢁC. The
reaction mixture was allowed to come to the room
temperature and stirred for 15 min. Concentration
under reduced pressure and addition of pet-ether
afforded the corresponding dichlorides. 1Aa, yield,
82%; 2Aa, yield, 92%; 3Aa, yield, 82%; 1Ba, yield,
80%; 2Ba, yield, 81% (authentic TLC and Mp).
3
˚
V (A )
Z
Dcalcd (Mg mꢁ3
T (K)
)
1.746
93(2)
h Range (ꢁ)
2.04–28.37
91.5
0.0460
0.1275
0.0482
0.1300
Completeness to hmax (%)
R1(F) (I > 2r(I))
wR2(F) (I > 2r(I))
R1 (all data)
0.0719
0.0381
0.0761
wR2 (all data)

A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
5893
a
b
Fig. 1. ORTEP diagram showing 30% probability displacement ellipsoids and the crystallographic numbering scheme with relevant bond parameters for
˚
(a) 2Aa d(A) [Te–C1, 2.125(3); Te–C9, 2.118(4); Te–Cl1, 2.5120(11); Te–Cl2, 2.5174(10)]; <(ꢁ) [C1–Te–C9, 98.38(14); Cl1–Te–Cl2, 173.09(3)] and (b) 2Ba
˚
d(A) [Te–C1, 2.138(3), 2.141(3); Te–C9, 2.127(3), 2.121(3); Te–Cl1, 2.4819(8), 2.4753(8); Te–Cl2, 2.5081(8), 2.5517(9)]; <(ꢁ) [C1–Te–C9, 107.99(10),
107.87(10); Cl1–Te–Cl2, 173.23(3), 170.90(2)].
4. Crystallography
Appendix A. Supplementary material
Single crystals of 2Aa and 2Ba suitable for X-ray
crystallography were obtained by slow evaporation of
their chloroform solutions. Intensity data were collected
on a Bruker PS4 diffractometer with graphite-monochro-
CCDC 608672 and 608671 contain the supplementary
crystallographic data for 2Aa and 2Ba. These data can
be obtained free of charge via htpp://www.ccdc.cam.
ac.uk/conts/retrieving.html, or from the Cambridge Crys-
tallographic Data Centre, 12 Union Road, Cambridge
CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
˚
mated MoKa (0.7107 A) radiation. Data were reduced
and corrected for absorption using the programs SAINT
and SADABS [13]. The structures were solved by direct
methods and difference Fourier synthesis using SHELXS-
97 implemented in the program WINGX 2002 [14].
Full-matrix least-squares refinements on F2, using all
data, were carried out with anisotropic displacement
parameters applied to all non-hydrogen atoms. Hydrogen
atoms were included in geometrically calculated positions
using a riding model and were refined isotropically.
Crystallographic parameters and details of the data
collection and refinement are given in Table 2. ORTEP
diagrams for compounds 2Aa and 2Ba are presented in
Fig. 1.
125Te NMR spectra and figures depicting supramolec-
ular architectures in the crystal packings of compounds
2Aa and 2Ba are provided as Supplementary material.
Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/
j.jorganchem.2006.09.050.
References
[1] (a) N.W. Alcock, Adv. Inorg. Chem. Radiochem. 15 (1972) 1;
(b) P. Pyykko¨, Chem. Rev. 97 (1997) 597.
[2] (a) W.R. McWhinnie, Phosphorus Sulfur Silicon 67 (1992) 107;
(b) I.D. Sadekov, A.A. Maksimenko, A.G. Maslakov, V.I. Minkin,
J. Organomet. Chem. 391 (1990) 179;
Acknowledgement
(c) V.I. Minkin, I.D. Sadekov, A.A. Maksimenko, O.E. Kompan,
Yu.T. Struchkov, J. Organomet. Chem. 402 (1991) 331;
(d) W.R. McWhinnie, I.D. Sadekov, V.I. Minkin, Sulfur Rep. 18
(1995) 295;
Financial assistance by the Department of Science and
Technology, Government of India, New Delhi, is gratefully
acknowledged.

5894
A.K.S. Chauhan et al. / Journal of Organometallic Chemistry 691 (2006) 5887–5894
(e) V.I. Minkin, I.D. Sadekov, B.B. Rivkin, A.V. Zakharov, V.L.
Nivorozhkin, O.E. Kompan, Yu.T. Struchkov, J. Organomet. Chem.
536–537 (1997) 233;
[3] A.K.S. Chauhan, Anamika, A. Kumar, P. Singh, R.C. Srivastava,
R.J. Butcher, J. Beckmann, A. Duthie, J. Organomet. Chem. 691
(2006) 1954.
(f) R.M. Minyaev, V.I. Minkin, Can. J. Chem. 76 (1998) 776;
(g) I.D. Sadekov, V.I. Minkin, A.V. Zakharov, A.G. Starikov, G.S.
Borodkin, S.M. Aldoshin, V.V. Tkachev, G.V. Shilov, F.J. Berry, J.
Organomet. Chem. 690 (2005) 103;
(h) I. Vargas-Baca, T. Chivers, Phosphorus Sulfur Silicon 264 (2000)
207;
(i) A.F. Cozzolino, I. Vargas-Baca, S. Mansour, A.H. Mahmoudkh-
ani, J. Am. Chem. Soc. 127 (2005) 3184;
(j) A.F. Cozzolino, J.F. Britten, I. Vargas-Baca, Crystal Growth Des.
6 (2006) 181;
(k) N. Sudha, H.B. Singh, Coord. Chem. Rev. 135/136 (1994) 469;
(l) S.D. Apte, H.B. Singh, R.J. Butcher, J. Chem. Res. (S) (2000)
160;
(m) G. Mugesh, A. Panda, S. Kumar, S.D. Apte, H.B. Singh,
R.J. Butcher, Organometallics 21 (2002) 884;
(n) K. Kandasamy, S. Kumar, H.B. Singh, G. Wolmershauser,
Organometallics 22 (2003) 5069;
(o) S. Kumar, H.B. Singh, G. Wolmershauser, J. Organomet.
Chem. 690 (2005) 3149;
(p) I. Haiduc, R.B. King, M.G. Newton, Chem. Rev. 94 (1994)
301;
[4] (a) M. Bochmann, K.J. Webb, J. Chem. Soc., Dalton Trans. (1991)
2325;
(b) M. Bochmann, A.P. Coleman, K.J. Webb, M.B. Husthouse, M.
Mazid, Angew. Chem., Int. Ed. Engl. 31 (1991) 973.
[5] P.J. Bonasia, J. Arnold, Inorg. Chem. 31 (1992) 2508.
[6] K. Kandasamy, H.B. Singh, G. Wolmershauser, Inorg. Chim. Acta
358 (2005) 207.
[7] G.N. Ledesma, E.S. Lang, E.M. Vazquez-Lopez, U. Abram, Inorg.
Chem. Commun. 7 (2004) 478.
[8] N. Petragnani, Tetrahedron 12 (1961) 219.
[9] J. Zukerman-Schpector, I. Haiduc, Phosphorus Sulfur Silicon 17
(2001) 73, and references therein.
[10] A.K.S. Chauhan, Anamika, A. Kumar, R.C. Srivastava, R.J.
Butcher, J. Beckmann, A. Duthie, J. Organomet. Chem. 690 (2005)
1350.
[11] F.H. Allen, O. Kannard, Chem. Des. Automat. News 8 (1993) 1.
[12] (a) D. Naumann, L. Ehmanns, K.F. Tebbe, W. Crump, Z. Anorg.
Allg. Chem. 619 (1993) 1269;
(b) Y. Takaguchi, H. Fujihara, N. Furukawa, J. Organomet. Chem.
498 (1995) 49;
(c) M. Asahara, M. Tanaka, T. Eradi, M. Wada, J. Chem. Soc.,
Dalton Trans. (2000) 3493;
(d) D. Dakternieks, J. O’Connell, E.R.T. Tiekink, J. Organomet.
Chem. 598 (2000) 49;
(e) T.M. Klapotke, B. Krumm, P. Mayer, K. Polborn, O.P. Ruscitti,
Inorg. Chem. 40 (2001) 5169.
(q) I. Haiduc, J. Zukerman-Schpector, Phosphorus Sulfur Silicon
171 (2001) 171;
(r) J. Zukerman-Schpector, I. Haiduc, Cryst. Eng. Commun. 4
(2002) 178;
(s) G.D. Markham, C.L. Bock, M. Trachtman, C.W. Bock, J.
Mol. Struct. (Theochem.) 459 (1999) 187;
(t) O. Niyomura, S. Kato, S. Inagaki, J. Am. Chem. Soc. 122
(2000) 2132.
[13] SMART, SAINT and SADABS, Siemens Analytical X-ray Instruments Inc.,
Madison, Wisconsin USA, 1999.
[14] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837.