Synthesis and characterization of metallatranes with phenyl substituents in atrane cage

Article abstract of DOI:10.1016/j.ica.2006.07.109

A new series of mono- and diphenylsubstituted silatranes and boratranes N(CH₂CH₂O)₂(CHR³CR¹R²O)MZ (M = Si, Z = CH₂Cl, C{triple bond, long}CPh, H, OMenth, R¹, R², R³ = H, Ph; M = B, Z = nothing, R¹, R², R³ = H, Ph) have been synthesized. Both transalkoxylation and stepwise modification of a preformed metallatrane skeleton were used. The chloromethyl derivatives N(CH₂CH₂O)₂(CHRCHRO)SiCH₂Cl (R = H, Ph) react with tert-BuOK under intramolecular cycle expansion to give 1-tert-butoxy-2-carba-3-oxahomosilatranes N(CH₂CH₂O)(CH₂CH₂OCH₂)(CHRCHRO)SiO^tBu (R = H, Ph). The treatment of boratranes N(CH₂CH₂O)₂(CH₂CR¹R²O)B (R¹,R² = H, Ph) with triflic acid and trimethylsilyl triflate results in the products of electrophilic attack at the nitrogen atom. The molecular structures of four silatranes and one boratrane bearing phenyl groups in the atrane skeleton were determined by the X-ray structure analysis.

Full text of DOI:10.1016/j.ica.2006.07.109

Inorganica Chimica Acta 360 (2007) 563–578
www.elsevier.com/locate/ica
Synthesis and characterization of metallatranes with phenyl
substituents in atrane cage
a,
a
a
a
Sergey S. Karlov *, Anastasia A. Selina , Eleonora S. Chernyshova , Yuri F. Oprunenko ,
a
a
b
c
Alexei A. Merkulov , Victor A. Tafeenko , Andrei V. Churakov , Judith A.K. Howard ,
a
Galina S. Zaitseva
a
Chemistry Department, Moscow State University, Leninskie Gory, 119899 Moscow, Russia
Institute of General and Inorganic Chemistry, RAS, Leninskii Pr. 31, Moscow 119991, Russia
b
c
Department of Chemistry, University of Durham, South Road, DH1 3LE Durham, UK
Received 12 May 2006; received in revised form 25 July 2006; accepted 30 July 2006
Available online 18 August 2006
Abstract
A new series of mono- and diphenylsubstituted silatranes and boratranes N(CH2CH2O)2(CHR3CR1R2O)MZ (M = Si, Z = CH2Cl,
C„CPh, H, OMenth, R1, R2, R3 = H, Ph; M = B, Z = nothing, R1, R2, R3 = H, Ph) have been synthesized. Both transalkoxylation and
stepwise modification of a preformed metallatrane skeleton were used. The chloromethyl derivatives N(CH2CH2O)2(CHR-
CHRO)SiCH2Cl (R = H, Ph) react with tert-BuOK under intramolecular cycle expansion to give 1-tert-butoxy-2-carba-3-
oxahomosilatranes N(CH2CH2O)(CH2CH2OCH2)(CHRCHRO)SiOtBu (R = H, Ph). The treatment of boratranes N(CH2CH2O)2-
(CH2CR1R2O)B (R1,R2 = H, Ph) with triflic acid and trimethylsilyl triflate results in the products of electrophilic attack at the nitrogen
atom. The molecular structures of four silatranes and one boratrane bearing phenyl groups in the atrane skeleton were determined by the
X-ray structure analysis.
ꢀ 2006 Elsevier B.V. All rights reserved.
Keywords: Trialkanolamine ligands; Silatranes; Boratranes; NMR spectroscopy; Crystal structure
1. Introduction
of nitrogen atom with the LUMO of MO3Z fragment [2].
Besides an important contribution to the bonding theory,
metallatranes are valuable objects for medicinal chemistry
owing to the broad spectrum of bioactivity [3,4].
The chemistry of the group 14 element metallatranes
(Chart 1) and their analogues has attracted considerable
attention from the theoretical point of view, the nature of
the intramolecular M N interaction being the subject
of interest [1]. Due to the impossibility to describe the for-
mation of the M N coordination bond in the framework
of the classical ‘‘octet’’ rule, several concepts were built up
to explain the phenomenon of the so-called hypervalency.
According to our recent study, the formation of this bond
can be rationalized by an interaction of a lone electron pair
While most of the research on metallatranes was focused
on the variation of the apical substituent Z, the derivatives
bearing different substituents at the carbon atoms of atrane
moiety have been studied to a very limited extent. Among
them the 3,7,10-trimethylsubstituted metallatranes are the
most known [1,5,6]. However, the structural study of such
derivatives seems important as providing new information
concerning the intramolecular bond formation. Further-
more, metallatranes having substituents in the atrane skele-
ton are known to be less toxic than their unsubstituted
analogues and, thus, are more promising as bioactive species.
According to the DFT calculations on nucleophilic sub-
stitution in silatranes, the reactions always proceed via a
*
Corresponding author.
E-mail address: sergej@org.chem.msu.ru (S.S. Karlov).
0020-1693/$ - see front matter ꢀ 2006 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2006.07.109

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S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
trane (26), and 1-hydrosilatrane (19) [25] were synthesized
1
according to the literature procedures. H and 13C NMR
spectra were recorded on a Varian VXR-400 or Bruker
Avance 400 spectrometers, 11B NMR spectra on a Bruker
DRX 500, and 29Si NMR spectra on a Bruker DRX 400
or 500 spectrometers. All chemical shifts are given in
1
ppm (d) relative to Me4Si (for H, 13C, 29Si) or BF3 Æ Et2O
(for 11B). IR spectra were obtained in Nujol on a Zeiss UR-
20. Elemental analyses were carried out by the Microana-
lytical Laboratory of the Chemistry Department, Moscow
State University. Mass spectra (EI-MS, 70 eV) were
recorded on a VARIAN CH-7a device (Philipps-Univer-
sita¨t Marburg, Germany); all assignments were made with
reference to the most abundant isotopes.
Chart 1.
hexacoordinated silicon atom and in some instances
demand a considerable conformational alteration of the
atrane skeleton [7]. The latter might be affected by the pres-
ence of substituents in the side arms of atrane moiety. In
order to clarify whether the presence of such substituents
influences the structure and reactivity of atrane molecules,
a series of works on metallatranes with phenyl substituents
in the atrane cage were commenced in our group.
Recently, we reported the synthesis of germatranes bear-
ing phenyl groups at 3- and/or 4-position of atrane skele-
ton, and the investigation of their structure both in the
solid state and in solution [8,9]. Among the 3-phenylsubsti-
tuted silatranes, only six derivatives have been reported so
far in the literature [10,11]. Characterization of these com-
pounds was limited by the elemental analysis data. Besides
the group 14 metallatranes, boratranes (Chart 1, M = B,
Z = nothing) fell into the scope of our interest due to the
other type of intramolecular M N interaction (classical
coordination bond) in comparison with that in silatranes
and germatranes. To the best of our knowledge, no phe-
nylboratranes as well as 4-phenylsilatranes or silatranes
with two phenyl groups at carbon atoms of atrane cage
have been investigated.
2.1. Synthesis of erythro-2-[bis(2-hydroxyethyl)amino]-1,
2-diphenyl-1-ethanol (3)
A mixture of HN(CH2CH2OH)2 (1.02 g, 9.68 mmol)
and trans-stilbene oxide (1.90 g, 9.68 mmol) was stirred
for 30 h at 120 ꢁC. The resulting material was diluted
with diethyl ether (5 mL), followed by stirring for 2 days
at room temperature. The solidified product was filtered,
washed with ether (7 mL) and hexane (2 · 7 mL), and
dried in vacuo to give 3 (2.02 g, 69%) as a slightly yel-
1
low powder. H NMR (400 MHz, CDCl3):d (ppm): 1.80
(br s, 3H, 3OH), 2.32–2.37 (m, 2H), 2.71–2.78 (m, 2H),
3.36–3.41 (m, 2H), 3.44–3.50 (m, 2H) [(ABXY)2 system
of NCH2CH2O protons], 3.93 (d, J = 9.3 Hz, 1H,
NCH(Ph)), 5.19 (d, J = 9.3 Hz, 1H, OCH(Ph)), 7.32–
7.47 (m, 10H, aromatic protons). 13C NMR (100 MHz,
CDCl3):
d (ppm): 52.68 (2NCH2), 59.56 (2OCH2),
71.32 (NCH(Ph)), 73.65 (OCH(Ph)), 126.87, 127.71,
127.95, 128.19, 128.31, 129.67, 135.87, 142.47
(aromatic carbons). Anal. Calc. for C18H23NO3: C,
71.74; H, 7.69; N, 4.65. Found: C, 72.00; H, 7.58; N,
4.62%.
In continuation of our studies in atrane chemistry [12–
19], we present here the synthesis and characterization of
a series of mono- and diphenylsubstituted metallatranes
(M = Si, Z = CH2Cl, C„CPh, H; M = B, Z = nothing)
and their reactions with nucleophilic and electrophilic
reagents. The structure of compounds 7, 9, 10, 16, 18,
and 21 was determined by the single crystal X-ray analysis.
2.2. Synthesis of threo-2-[bis(2-hydroxyethyl)amino]-1,
2-diphenyl-1-ethanol (4)
The reaction between HN(CH2CH2OH)2 (2.30 g,
21.8 mmol) and cis-stilbene oxide (4.28 g, 21.8 mmol) was
performed as described for 3 to give compound 4 (4.91 g,
2. Experimental
1
All manipulations with silicon- and boron-containing
compounds were carried out under an argon atmosphere
using the standard Schlenk techniques. The solvents were
dried by the standard methods and distilled before use. Tri-
methyl borate and triethoxysilane were purified by distilla-
tion at normal pressure, and diethanolamine was purified
by distillation in vacuo. (Chloromethyl)trimethoxysilane,
potassium tert-butoxide (Aldrich), styrene oxide, trimethyl-
silyl triflate (Merck), and trifluoromethanesulfonic acid
(Fluka) were used as supplied. cis- and trans-stilbene oxides
[20,21], 2,2-diphenyloxirane [22], (phenylethynyl)trichlo-
rosilane [23], (phenylethynyl)trimethoxysilane [24], bora-
75%) as a slightly yellow powder, m.p. 160 ꢁC. H NMR
(400 MHz, CDCl3): d (ppm): 2.47–2.52 (m, 2H), 2.95–
3.02 (m, 2H), 3.63–3.68 (m, 2H), 3.81–3.87 (m, 2H)
[(ABXY)2 system of NCH2CH2O protons], 3.80 (d,
J = 10.3 Hz, 1H, NCH(Ph)), 5.09 (d, J = 10.3 Hz, 1H,
OCH(Ph)), 7.05–7.22 (m, 10H, aromatic protons). 13C
NMR (100 MHz, acetone-d6): d (ppm): 52.77 (2NCH2),
60.31 (2OCH2), 72.31 (NCH(Ph)), 72.96 (OCH(Ph)),
127.75, 128.12, 128.36, 128.54, 128.63, 130.63, 134.17,
143.32 (aromatic carbons). Anal. Calc. for C18H23NO3:
C, 71.74; H, 7.69; N, 4.65. Found: C, 71.69; H, 7.54; N,
4.63%.

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
565
2.3. Synthesis of 2-[bis(2-hydroxyethyl)amino]-1,
1-diphenyl-1-ethanol (5)
2.7. Synthesis of 2-[(2-hydroxy-1,2-diphenylethyl)amino]-
1,2-diphenyl-1-ethanol
A mixture of HN(CH2CH2OH)2 (0.76 g, 7.24 mmol) and
2,2-diphenyloxirane (1.42 g, 7.24 mmol) was stirred for 45 h
at 90 ꢁC. The resulting oily material was diluted with diethyl
ether (3 mL) and kept at ꢀ18 ꢁC for 2 weeks. The colourless
crystals were filtered and dried under reduced pressure to
give 5 (1.11 g, 51%). 1H NMR (400 MHz, CDCl3): d
(ppm): 2.65 (t, J = 5.1 Hz, 4H, 2NCH2), 3.39 (t, J =
5.1 Hz, 4H, 2OCH2), 3.49 (s, 2H, NCH2C(Ph)2), 7.17–
7.21 (m, 2H), 7.27–7.31 (m, 4H), 7.46–7.48 (m, 4H)
(aromatic protons). 13C NMR (100 MHz, CDCl3): d
(ppm): 58.90 (2NCH2), 60.61 (2OCH2), 67.27 (NCH2C-
(Ph)2), 76.54 (OC(Ph)2), 125.93, 126.84, 128.16, 146.49 (aro-
matic carbons). Anal. Calc. for C18H23NO3: C, 71.74; H,
7.69; N, 4.65. Found: C, 71.42; H, 7.80; N, 4.83%.
A vial with a screw cap was charged with a 2.0 M solu-
tion of NH3 in methanol (5.5 mL, 10 mmol) and trans-stil-
bene oxide (5.89 g, 30 mmol). The reaction mixture was
stirred for 12 h at room temperature, followed by heating
for 110 h at 60 ꢁC. The precipitate was filtered, washed
with hexane (3 · 10 mL), and dried in vacuo to give
HN[CH(Ph)CH(Ph)OH]2 (3.43 g, 84%) as a white solid.
1H NMR (400 MHz, CDCl3): d (ppm): 2.54 (br s, 1H,
NH), 3.55 (d, J = 6.8 Hz), 3.77 (d, J = 5.2 Hz) (2H,
2NCH(Ph)), 4.59 (d, J = 6.8 Hz), 4.84 (d, J = 5.2 Hz)
(2H, 2OCH(Ph)), 6.72–7.21 (m, 20H, aromatic protons).
Anal. Calc. for C28H27NO2: C, 82.12; H, 6.65; N, 3.42.
Found: C, 82.40; H, 6.84; N, 3.25%. Two diastereomers.
2.8. Reaction of 2-[(2-hydroxy-1,2-diphenylethyl)amino]-
1,2-diphenyl-1-ethanol with styrene oxide
2.4. Synthesis of erythro-2-[(2-hydroxyethyl)amino]-1,
2-diphenyl-1-ethanol
A mixture of HN[CH(Ph)CH(Ph)OH]2 (0.2 g, 0.5 mmol),
styrene oxide (0.061 g, 0.5 mmol) and toluene (4 mL) was
refluxed for 3 days. After removal of the solvent, the oily res-
idue contained the starting materials along with unidentified
products (1H NMR data).
A mixture of H2NCH2CH2OH (0.93 g, 12 mmol), trans-
stilbene oxide (2.15 g, 11 mmol) and toluene (4 mL) was
refluxed for 24 h. The removal of the solvent in vacuo left
a solid material which was recrystallized from hexane to
give erythro-HN(CH2CH2OH)CH(Ph)CH(Ph)OH (0.73 g,
26%) as a white solid. 1H NMR (400 MHz, CDCl3): d
(ppm): 2.13 (br s, 2H, 2IH), 2.78 (br s, 1H, NH), 2.54–
2.61 (m, 2H, NCH2), 3.50–3.55 (m, 2H, OCH2), 3.85 (d,
J = 6.1 Hz, 1H, NCH(Ph)), 4.80 (d, J = 6.1 Hz, 1H,
OCH(Ph)), 7.12–7.22 (m, 10H, aromatic protons). 13C
NMR (100 MHz, CDCl3): d (ppm): 48.88 (NCH2), 61.09
(OCH2), 68.58 (NCH(Ph)), 76.72 (OCH(Ph)), 126.73,
127.45, 127.55, 127.95, 128.06, 128.28, 139.17, 140.89 (aro-
matic carbons).
2.9. Reaction of 2-[(2-hydroxy-1,2-diphenylethyl)amino]-
1,2-diphenyl-1-ethanol with 2,2-diphenyloxirane
A
mixture of HN[CH(Ph)CH(Ph)OH]2 (0.45 g,
1.2 mmol), 2,2-diphenyloxirane (0.23 g, 1.2 mmol), and tol-
uene (6 mL) was refluxed for 40 h. After removal of the sol-
vent in vacuo, the residue contained only starting materials
(1H NMR data).
2.10. Synthesis of erythro-1-phenylethynyl-3,4-
diphenylsilatrane (6)
2.5. Reaction of erythro-2-[(2-hydroxyethyl)amino]-1,
2-diphenyl-1-ethanol with trans-stilbene oxide
A solution of (MeO)3SiC„CPh (0.74 g, 3.32 mmol) in
methanol (2 mL) was added to a solution of trialkanol-
amine 3 (1.0 g, 3.32 mmol) in methanol (20 mL). Upon stir-
ring of the reaction mixture for 3 days at room temperature,
the formation of a white precipitate was observed. The sol-
vent was partially evaporated, and the solid was filtered,
washed with methanol (2 mL) and pentane (2 · 5 mL),
and dried in vacuo to give 6 (0.76 g, 54%) as a white powder;
m.p. >255 ꢁC. IR: 2175 (C„C) cmꢀ1. 1H NMR (400 MHz,
CDCl3): d (ppm): 2.46–2.51 (m, 1H), 2.79–2.87 (m, 1H),
2.90–2.95 (m, 1H), 3.26–3.34 (m, 1H), 3.82–3.87 (m, 2H),
3.98–4.03 (m, 1H), 4.10–4.17 (m, 1H) [(ABXY)2 system of
NCH2CH2O protons], 4.43 (d, J = 7.1 Hz, 1H, NCH(Ph)),
5.46 (d, J = 7.1 Hz, 1H, OCH(Ph)), 6.98–7.00, 7.15–7.36,
7.54–7.57 (3m, 15H, aromatic protons). 13C NMR
(100 MHz, CDCl3): d (ppm): 50.22, 50.31 (2NCH2), 57.47,
58.19 (2OCH2), 66.94 (NCH(Ph)), 75.27 (OCH(Ph)),
96.15 (SiC„), 96.86 (PhC„), 124.14, 127.33, 127.46,
127.52, 127.57, 127.60, 128.31, 129.24, 131.32, 131.64,
A
mixture of erythro-HN(CH2CH2OH)CH(Ph)CH-
(Ph)OH (0.65 g, 2.5 mmol), trans-stilbene oxide (0.4 g,
2.5 mmol) and xylene (5 mL) was refluxed for 55 h. After
removal of the solvent, the residue contained only starting
materials (1H NMR data). When 1,3,5-triethylbenzene was
used as a solvent, a mixture of unidentified products was
formed after 8 h of reflux (1H NMR data).
2.6. Reaction of erythro-2-[(2-hydroxyethyl)amino]-1,
2-diphenyl-1-ethanol with styrene oxide
A
mixture of erythro-HN(CH2CH2OH)CH(Ph)CH-
(Ph)OH (0.5 g, 1.9 mmol), styrene oxide (0.23 g, 1.9 mmol),
and xylene (4 mL) was refluxed for 35 h. After removal of
the solvent, an oily residue was obtained which contained
both starting materials and products of unidentified struc-
ture (1H NMR data). The catalytic amount of water in the
reaction mixture does not activate the process.

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S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
132.41, 139.02 (aromatic carbons). 29Si NMR (99 MHz,
CDCl3): d (ppm): ꢀ94.3. EI-MS: m/z (%) = 427 (17) [M+],
321 (68) [M+ꢀPhCHO], 244 (9) [M+ꢀPhCHOꢀPh]. Anal.
Calc. for C26H25NO3Si: C, 73.04; H, 5.89; N, 3.28. Found:
C, 73.28; H, 6.13; N, 3.09%.
mixture at room temperature for 4 days, the formation of a
white precipitate was observed. When ꢁ1/3 of methanol
volume was removed in vacuo, hexane (4 mL) was added.
The solid was filtered, washed with hexane (2 · 3 mL),
and dried in vacuo to give 9 (0.76 g, 76%) as a white pow-
1
der; m.p. 210 ꢁC. H NMR (400 MHz, CDCl3): d (ppm):
2.11. Synthesis of threo-1-phenylethynyl-3,
4-diphenylsilatrane (7)
2.84 (s, 2H, SiCH2), 2.45–2.50 (m, 1H), 2.78–2.87 (m,
1H), 2.90–2.95 (m, 1H), 3.20–3.27 (m, 1H), 3.70–3.82 (m,
2H), 3.92–3.97 (m, 1H), 4.04–4.10 (m, 1H) [(ABXY)2 sys-
tem of NCH2CH2O protons], 4.40 (d, J = 7.2 Hz, 1H,
NCH(Ph)), 5.38 (d, J = 7.2 Hz, 1H, OCH(Ph)), 6.98–
7.00, 7.11–7.14, 7.18–7.26, 7.31–7.34 (4m, 10H, aromatic
protons). 13C NMR (100 MHz, CDCl3): d (ppm): 31.54
(SiCH2), 50.31, 50.49 (2NCH2), 57.38, 58.00 (2OCH2),
67.11 (NCH(Ph)), 74.74 (OCH(Ph)), 127.33, 127.46,
127.58, 128.31, 129.22, 131.32, 131.80, 139.30 (aromatic
carbons). 29Si NMR (99 MHz, CDCl3): d (ppm): ꢀ79.6.
EI-MS: m/z (%) = 375 (92) [M+], 326 (75) [M+ꢀCH2Cl],
269 (100) [M+ꢀPhCHO], 234 (27) [M+ꢀPhCHOꢀCl],
192 (21) [M+ꢀPhCHOꢀSiCH2Cl], 148 (22) [N(CH2CH2O)-
CHPh+]. Anal. Calc. for C19H22ClNO3Si: C, 60.71; H,
5.90; N, 3.73. Found: C, 60.50; H, 5.88; N, 3.80%.
Analogously to that described for 6, a reaction of trialk-
anolamine 4 (1.0 g, 3.32 mmol) with (MeO)3SiC„CPh
(0.74 g, 3.32 mmol) was performed in methanol (20 mL)
to give silatrane 7 (1.03 g, 73%) as a white powder; m.p.
>250 ꢁC. IR: 2185 (C„C) cmꢀ1 1H NMR (400 MHz,
.
CDCl3): d (ppm): 2.24–2.28 (m, 1H), 2.79–2.86 (m, 1H),
2.93–2.97 (m, 1H), 3.35–3.42 (m, 1H), 3.84–3.90 (m, 1H),
4.00–4.09 (m, 2H), 4.13–4.20 (m, 1H) [(ABXY)2 system
of NCH2CH2O protons], 3.77 (d, J = 10.8 Hz, 1H,
NCH(Ph)), 5.37 (d, J = 10.8 Hz, 1H, OCH(Ph)), 7.14–
7.19, 7.23–7.29, 7.34–7.36, 7.49–7.52 (4m, 15H, aromatic
protons). 13C NMR (100 MHz, CDCl3): d (ppm): 47.47,
47.75 (2NCH2), 57.28 (2OCH2), 69.11 (NCH(Ph)), 72.54
(OCH(Ph)), 96.07 (SiC„), 96.83 (PhC„), 124.20, 126.66,
127.46, 127.61, 127.77, 128.13, 128.95, 129.51, 130.16,
131.36, 132.42, 139.92 (aromatic carbons). 29Si NMR
(99 MHz, CDCl3): d (ppm): ꢀ95.5. EI-MS: m/z (%) = 427
(15) [M+], 321 (100) [M+ꢀPhCHO], 244 (4) [M+ꢀ
PhCHOꢀPh]. Anal. Calc. for C26H25NO3Si: C, 73.04; H,
5.89; N, 3.28. Found: C, 72.82; H, 5.82; N, 3.29%.
2.14. Synthesis of threo-1-chloromethyl-3,4-
diphenylsilatrane (10)
Analogously to that described for 9, a reaction of trialk-
anolamine 4 (0.70 g, 2.32 mmol) with (MeO)3SiCH2Cl
(0.40 g, 2.32 mmol) was performed in methanol (12 mL)
in the presence of KOH (ꢁ0.01 g) to give silatrane 10
1
2.12. Synthesis of 1-phenylethynyl-3,3-diphenylsilatrane (8)
(0.69 g, 79%) as a white powder; m.p. >255 ꢁC. H NMR
(400 MHz, CDCl3): d (ppm): 2.76 (s, 2H, SiCH2), 2.25–
2.28 (m, 1H), 2.76–2.84 (m, 1H), 2.91–2.95 (m, 1H),
3.32–3.40 (m, 1H), 3.80–3.86 (m, 1H), 3.94–4.13 (m, 3H)
[(ABXY)2 system of NCH2CH2O protons], 3.71 (d,
J = 10.5 Hz, 1H, NCH(Ph)), 5.30 (d, J = 10.5 Hz, 1H,
OCH(Ph)), 7.12–7.21, 7.26–7.28, 7.35–7.37 (3m, 10H,
aromatic protons). 13C NMR (100 MHz, CDCl3): d
(ppm): 31.42 (SiCH2), 47.47, 47.76 (2NCH2), 57.05, 57.12
(2OCH2), 69.19 (NCH(Ph)), 71.93 (OCH(Ph)), 126.34,
127.69, 128.15, 128.92, 129.47, 130.12, 131.45, 140.28 (aro-
matic carbons). 29Si NMR (79 MHz, CDCl3): d (ppm):
ꢀ81.0. EI-MS: m/z (%) = 375 (37) [M+], 326 (59)
[M+ꢀCH2Cl], 269 (100) [M+ꢀPhCHO], 234 (9)
[M+ꢀPhCHOꢀCl], 220 (6) [M+ꢀPhCHOꢀCH2Cl], 192
(22) [M+ꢀPhCHOꢀSiCH2Cl], 148 (23) [N(CH2CH2O)-
CHPh+]. Anal. Calc. for C19H22ClNO3Si: C, 60.71; H,
5.90; N, 3.73. Found: C, 60.52; H, 5.76; N, 3.83%.
Analogously to that described for 6, a reaction of trialk-
anolamine 5 (0.60 g, 1.99 mmol) with (MeO)3SiC„CPh
(0.44 g, 1.99 mmol) was performed in methanol (12 mL)
to give silatrane 8 (0.64 g, 75%) as a white powder; m.p.
>250 ꢁC. IR: 2170 (C„C) cmꢀ1 1H NMR (400 MHz,
.
CDCl3): d (ppm): 2.67–2.79 (m, 4H, 2NCH2), 3.65 (s, 2H,
NCH2C(Ph)2), 3.69–3.75 (m, 2H), 3.80–3.86 (m, 2H)
(2OCH2), 7.17–7.32, 7.59–7.60 (2m, 15H, aromatic pro-
tons). 13C NMR (100 MHz, DMSO-d6): d (ppm): 51.83
(2NCH2), 56.86 (2OCH2), 59.86 (NCH2C(Ph)2), 77.01
(OC(Ph)2), 94.26 (SiC„), 100.89 (PhC„), 124.40, 124.95,
126.72, 127.54, 128.23, 128.39, 131.32, 147.16 (aromatic
carbons). 29Si NMR (99 MHz, CDCl3): d (ppm): ꢀ96.5.
EI-MS: m/z (%) = 427 (14) [M+], 280 (100)
[M+ꢀPhCCSiꢀH2O], 245 (61) [M+ꢀPh2CO]. Anal. Calc.
for C26H25NO3Si: C, 73.04; H, 5.89; N, 3.28. Found: C,
72.65; H, 5.92; N, 2.98%.
2.15. Synthesis of 1-chloromethyl-3,3-diphenylsilatrane (11)
2.13. Synthesis of erythro-1-chloromethyl-3,
4-diphenylsilatrane (9)
Analogously to that described for 9, a reaction of trialk-
anolamine 5 (1.53 g, 5.08 mmol) with (MeO)3SiCH2Cl
(0.87 g, 5.08 mmol) was performed in methanol (12 mL)
in the presence of KOH (ꢁ0.01 g) to give 11 (1.59 g,
83%) as a white powder; m.p. >255 ꢁC. 1H NMR
(400 MHz, CDCl3): d (ppm): 2.67–2.78 (m, 4H, 2NCH2),
A
solution comprising trialkanolamine 3 (0.80 g,
2.65 mmol) and a catalytic amount (ꢁ0.01 g) of powdered
KOH in methanol (10 mL) was treated with (MeO)3-
SiCH2Cl (0.45 g, 2.65 mmol). Upon stirring of the reaction

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
567
2.91 (s, 2H, SiCH2), 3.64 (s, 2H, NCH2C(Ph)2), 3.64–3.69
(m, 2H), 3.76–3.82 (m, 2H) (2OCH2), 7.15–7.20 (m, 2H),
7.27–7.31 (m, 4H), 7.54–7.57 (m, 4H) (aromatic protons).
13C NMR (100 MHz, CDCl3): d (ppm): 31.70 (SiCH2),
52.65 (2NCH2), 57.38 (2OCH2), 61.34 (NCH2C(Ph)2),
125.08, 127.02, 128.49, 146.76 (aromatic carbons). 29Si
NMR (99 MHz, CDCl3): d (ppm): ꢀ82.2. Anal. Calc. for
C19H22ClNO3Si: C, 60.71; H, 5.90; N, 3.73. Found: C,
60.58; H, 5.86; N, 3.85%.
(OC(Ph)2), 125.54, 126.83, 128.18, 146.17 (aromatic car-
bons). 11B NMR (160 MHz, CDCl3, 60 ꢁC): d (ppm):
15.0. EI-MS: m/z (%) = 309 (2) [M+], 232 (10) [M+ꢀPh],
196 (81) [CH2C(Ph)2O+], 126 (100) [M+ꢀPh2COꢀH].
Anal. Calc. for C18H20BNO3: C, 69.93; H, 6.52; N, 4.53.
Found: C, 69.65; H, 6.53; N, 4.78%.
Method B: Trimethyl borate (0.18 mL, 1.59 mmol) was
added to
a solution of trialkanolamine 5 (0.48 g,
1.59 mmol) in chloroform (12 mL). The reaction mixture
was stirred at room temperature for 24 h, and a large
amount of the precipitate was produced. After a half of
the solvent was removed in vacuo, pentane (10 mL) was
added to the suspension. The precipitate was filtered,
washed with pentane (2 · 5 mL), and dried in vacuo to give
13 (0.44 g, 90%).
2.16. Synthesis of erythro-3,4-diphenylboratrane (12)
Method A: A mixture of trialkanolamine 3 (1.50 g,
4.98 mmol), boric acid (0.31 g, 4.98 mmol), and iso-amyl
alcohol (5 mL) was refluxed with a water collector for
2 h. During this time, a theoretical amount of water
(0.3 mL) was produced. The precipitate was filtered,
washed with hexane (3 · 5 mL) and dried in vacuo to give
boratrane 12 (1.22 g, 79%) as a white solid; m.p. >295 ꢁC.
The product is practically insoluble in the usual organic
solvents. 1H NMR (400 MHz, DMSO-d6, 100 ꢁC): d
(ppm): 2.80–2.83 (m, 2H), 3.43–3.49 (m, 1H), 3.53–3.57
(m, 2H), 3.70–3.75 (m, 1H), 3.84–3.90 (m, 1H), 3.95–
3.99 (m, 1H) [(ABXY)2 system of NCH2CH2O protons],
4.84 (d, J = 5.1 Hz, 1H, NCH(Ph)), 5.69 (d, J = 5.1 Hz,
1H, OCH(Ph)), 7.01–7.05, 7.13–7.18, 7.29–7.32, 7.44–
7.47 (4m, 10H, aromatic protons). 13C NMR (100 MHz,
DMSO-d6, 100 ꢁC): d (ppm): 53.66, 61.27 (2NCH2),
62.11, 63.88 (2OCH2), 75.76 (NCH(Ph)), 77.34
(OCH(Ph)), 123.36, 125.27, 125.34, 126.86, 127.10,
127.95 (aromatic carbons). 11B NMR (160 MHz, CDCl3,
60 ꢁC): d (ppm): 14.9. EI-MS: m/z (%) = 309 (<1) [M+],
203 (100) [M+ꢀPhCHO], 174 (53) [M+ꢀPhCHOꢀ
CH2O+H], 126 (63) [M+ꢀPhCHOꢀPh]. Anal. Calc. for
C18H20BNO3: C, 69.93; H, 6.52; N, 4.53. Found: C,
69.56; H, 6.76; N, 4.35%.
2.18. Synthesis of 3-phenylboratrane (14) and
4-phenylboratrane (15)
Analogously to that described for 12, a reaction of
B(OH)3 (5.0 g, 0.08 mol) with the mixture of trialkanolam-
ines 1 + 2 (18.2 g, 0.08 mol) was performed in iso-amyl alco-
hol (60 mL). Recrystallization of the product from ethanol/
heptane gave 14 (13.3 g, 70%) as a white solid; m.p. 230 ꢁC.
1H NMR (400 MHz, CDCl3): d (ppm): 2.62–2.68 (m, 1H),
2.89–2.97 (m, 1H), 3.04–3.11 (m, 1H), 3.19–3.31 (m, 2H),
3.43–3.47 (m, 1H), 3.90–4.05 (m, 4 H), 5.03 (dd, J =
10.6 Hz, J = 4.0 Hz, 1 H) [(ABXY)2 and ABX systems of
NCH2CH2O and NCH2CH(Ph)O protons], 7.26–7.40 (m,
5 H, aromatic protons). 13C NMR (100 MHz, CDCl3): d
(ppm): 59.44, 59.68 (2NCH2), 61.78, 62.02 (2OCH2), 65.98
(NCH2CH(Ph)), 73.84 (ICH(Ph)), 125.68, 127.80, 128.38,
139.88 (aromatic carbons). 11B NMR (160 MHz, CDCl3,
60 ꢁC): d (ppm): 14.6. EI-MS: m/z (%) = 233 (18) [M+],
126 (100) [M+ꢀPhCHOꢀH], 114 (54) [M+ꢀPhC2H2O].
Anal. Calc. for C12H16BNO3: C, 61.84; H, 6.92; N, 6.01.
Found: C, 61.49; H, 6.68; N, 5.98%.
Method B: Trimethyl borate (0.30 mL, 2.65 mmol) was
added to
a
solution of trialkanolamine
3
(0.80 g,
Upon evaporation of the filtrate, a solid precipitated
which was filtered, washed with hexane, and dried in vacuo
to give 4-phenylboratrane (15) (0.15 g, 8%). 1H NMR
(400 MHz, CDCl3): d (ppm): 2.41–2.44 (m, 1H), 2.75–
2.82 (m, 1H), 2.91–2.98 (m, 1H), 3.04–3.07 (m, 1H),
3.57–3.60 (m, 1H), 3.85–3.89 (m, 2H), 4.05–4.08 (m, 2H),
4.19 (br s, 2H) [(ABXY)2 and ABX systems of NCH2CH2O
and NCH(Ph)CH2O protons], 7.29–7.39 (m, 5H, aromatic
protons). 13C NMR (100 MHz, CDCl3): d (ppm): 53.23,
58.32 (2NCH2), 61.62, 61.93 (2OCH2), 64.36 (OCH2CH-
(Ph)), 68.90 (NCH(Ph)), 127.75, 128.87, 129.22, 131.83
(aromatic carbons).
2.65 mmol) in chloroform (20 mL). Immediately, a large
amount of the precipitate was produced. The reaction
mixture was stirred at room temperature for 24 h, then
the solid was filtered, washed with chloroform (7 mL),
and dried in vacuo to give 12 (0.67 g, 82%) as a white
powder.
2.17. Synthesis of 3,3-diphenylboratrane (13)
Method A: Analogously to that described for 12, a reac-
tion of trialkanolamine 5 (1.19 g, 3.95 mmol) with B(OH)3
(0.24 g, 3.95 mmol) was performed in iso-amyl alcohol
(5 mL) to give boratrane 13 (0.75 g, 60%) as a white pow-
2.19. Synthesis of threo-3,4-diphenylboratrane (16)
1
der; m.p. 277–280 ꢁC (dec.). H NMR (400 MHz, CDCl3):
d (ppm): 2.97–3.00 (m, 4H, 2NCH2), 3.76–3.81 (m, 2H),
3.92–3.97 (m, 2H) (2OCH2), 3.85 (s, 2H, NCH2C(Ph)2),
7.14–7.17, 7.25–7.29, 7.55–7.57 (3m, 10H, aromatic pro-
tons). 13C NMR (100 MHz, CDCl3): d (ppm): 60.22
(2NCH2), 62.24 (2OCH2), 67.76 (NCH2C(Ph)2), 83.24
Analogously to that described for 12, a reaction of tri-
alkanolamine 4 (1.50 g, 4.98 mmol) with boric acid
(0.31 g, 4.98 mmol) was performed in iso-amyl alcohol
(5 mL) to give 16 (1.32 g, 86%) as a white solid; m.p.
1
255–257 ꢁC. H NMR (400 MHz, CDCl3): d (ppm): 2.28–

568
S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
2.34 (m, 1H), 2.85–2.95 (m, 1H), 3.11–3.21 (m, 1H), 3.52–
3.57 (m, 1H), 3.89–4.06 (m, 2H), 4.14–4.27 (m, 2H)
[(ABXY)2 system of NCH2CH2O protons], 3.99 (d,
J = 10.6 Hz, 1H, NCH(Ph)), 5.40 (d, J = 10.6 Hz, 1H,
OCH(Ph)), 7.15–7.23, 7.36–7.38 (2m, 10H, aromatic pro-
tons). 13C NMR (100 MHz, CDCl3): d (ppm): 53.94,
58.75 (2NCH2), 61.92, 61.99 (2OCH2), 76.17 (NCH(Ph)),
76.37 (OCH(Ph)), 127.00, 127.92, 128.15, 129.04, 129.62,
129.70, 131.47, 138.86 (aromatic carbons). 11B NMR
(160 MHz, CDCl3, 60 ꢁC): d (ppm): 14.0. EI-MS: m/z
(%) = 309 (<1) [M+], 203 (100) [M+ꢀPhCHO], 174 (59)
[M+ꢀPhCHOꢀCH2O+H], 126 (64) [M+ꢀPhCHOꢀPh].
Anal. Calc. for C18H20BNO3: C, 69.93; H, 6.52; N, 4.53.
Found: C, 69.56; H, 6.39; N, 4.55%.
of NCH2CH2O and NCH2CH(Ph)O protons], 4.07 (s,
1H, SiH), 7.25–7.42 (m, 5H, aromatic protons). 13C
NMR (100 MHz, CDCl3): d (ppm): 51.40, 51.97 (2N-
CH2), 57.09, 57.14 (2OCH2), 58.28 (NCH2CH(Ph)), 69.22
(ICH(Ph)), 125.38, 127.81, 128.56, 141.13 (aromatic car-
bons). 29Si NMR (99 MHz, CDCl3): d (ppm): ꢀ83.4.
EI-MS: m/z (%) = 251 (23) [M+], 145 (100) [M+ꢀPhCHO],
101 (6) [M+ꢀCH2CH(Ph)OꢀCH2O], 77 (4) [Ph+]. Anal.
Calc. for C12H17NO3Si: C, 57.34; H, 6.82; N, 5.57. Found:
C, 56.96; H, 6.60; N, 5.67%.
2.22. Synthesis of 1-menthoxysilatrane (21)
A mixture of L-menthol (1.06 g, 6.78 mmol), sodium
(0.03 g, 1.47 mmol), and xylene (8 mL) was refluxed until
the sodium was completely dissolved. The prepared solu-
tion was added dropwise to a refluxing suspension of 1-
hydrosilatrane (19) (0.40 g, 2.26 mmol) in xylene
(10 mL), a vigorous evolution of gas was observed. The
reaction mixture was refluxed for 2 h, then a half of
the solvent was removed in vacuo, and hexane (10 mL)
was added. The precipitated solid was filtered, washed
with hexane (2 · 5 mL), and dried in vacuo to give 21
(0.49 g, 66%) as a white powder. 1H NMR (400 MHz,
CDCl3): d (ppm): 0.74 (d, J = 6.8 Hz), 0.83–0.85 (m),
0.71–0.98 (m), 1.07–1.14 (m), 1.23–1.40 (m), 1.49–1.58
(m), 2.09–2.14 (m), 2.29–2.37 (m), 3.46–3.53 (m) (19H,
protons of menthoxy group), 2.78 (t, J = 6.0 Hz, 6H,
3NCH2), 3.77 (t, J = 6.0 Hz, 6H, 3OCH2). 13C NMR
(100 MHz, CDCl3): d (ppm): 15.71, 21.52, 22.42, 22.86,
24.98, 31.76, 34.91, 44.76, 50.25, 71.44 (carbons of
menthoxy group), 51.54 (3NCH2), 58.04 (3OCH2). EI-
MS: m/z (%) = 329 (12) [M+], 244 (100) [M+ꢀC6H13],
174 (69) [M+ꢀMenthO]. Anal. Calc. for C16H31NO4Si:
C, 58.32; H, 9.48; N, 4.25. Found: C, 57.89; H, 9.47;
N, 3.86%.
2.20. Synthesis of erythro-1-hydro-3,4-diphenylsilatrane
(17)
A suspension comprising erythro-3,4-diphenylboratrane
(12) (0.52 g, 1.68 mmol) and a catalytic amount (ꢁ0.01 g)
of Al(OEt)3 in xylene (25 mL) was treated with HSi(OEt)3
(0.46 mL, 2.52 mmol). After 45 h of reflux, a clear solution
was formed and the reaction mixture was refluxed for an
additional 15 h. Then the solution was evaporated in vacuo
by ꢁ1/3 of the volume. The precipitated solid was filtered,
washed with hexane (2 · 3 mL), and dried in vacuo to give
1
17 (0.41 g, 75%) as a white powder. H NMR (400 MHz,
CDCl3): d (ppm): 2.46–2.50 (m, 1H), 2.78–2.85 (m, 1H),
2.90–2.95 (m, 1H), 3.19–3.26 (m, 1H), 3.64–3.69 (m, 1H),
3.73–3.80 (m, 1H), 3.88–3.94 (m, 1H), 4.02–4.08 (m, 1H)
[(ABXY)2 system of NCH2CH2O protons], 4.24 (s, 1H,
SiH), 4.39 (d, J = 7.1 Hz, 1H, NCH(Ph)), 5.38 (d,
J = 7.1 Hz, 1H, OCH(Ph)), 7.00–7.02, 7.12–7.25, 7.30–
7.33 (3m, 10H, aromatic protons). 13C NMR (100 MHz,
CDCl3): d (ppm): 50.32, 50.73 (2NCH2), 57.09, 57.81
(2OCH2), 67.34 (NCH(Ph)), 74.80 (OCH(Ph)), 127.24,
127.48, 127.55, 128.28, 129.12, 131.35, 132.12, 139.48 (aro-
matic carbons). 29Si NMR (99 MHz, CDCl3): d (ppm):
ꢀ82.9. EI-MS: m/z (%) = 327 (22) [M+], 221 (100)
[M+ꢀPhCHO], 177 (21) [M+ꢀPhCHOꢀCH2CH2O], 130
(6) [M+ꢀCH(Ph)CH(Ph)OꢀH], 77 (7) [Ph+]. Anal. Calc.
for C18H21NO3Si: C, 66.02; H, 6.46; N, 4.28. Found: C,
65.61; H, 6.04; N, 4.04%.
2.23. Synthesis of 1-menthoxy-3-phenylsilatrane (20)
The compound was prepared analogously to that
described for 21 using 1-hydro-3-phenylsilatrane (18)
(0.40 g, 1.59 mmol), L-menthol (0.75 g, 4.77 mmol), and
sodium (0.02 g, 1.04 mmol) in xylene (15 mL). The product
1
(0.17 g, 27%) was isolated as a white powder. H NMR
2.21. Synthesis of 1-hydro-3-phenylsilatrane (18)
(400 MHz, CDCl3): d (ppm): 0.68 (d, J = 7.1 Hz, 3H), 0.85
(d, J = 6.8 Hz, 6H), 0.71–1.02 (m, 3H), 1.12–1.19 (m, 1H),
1.30–1.40 (m, 1H), 1.50–1.59 (m, 2H), 2.17–2.23 (m, 1H),
2.42–2.46 (m, 1H), 3.56–3.62 (m, 1H) (protons of menthoxy
group), 2.42–2.47 (m, 1H), 2.75–2.79 (m, 2H), 2.88–3.00 (m,
2H), 3.05–3.09 (m, 1H), 3.71–3.91 (m, 4H), 4.91 (dd,
J = 10.6 Hz, J = 4.5 Hz, 1H) [(ABXY)2 and ABX systems
of NCH2CH2O and NCH2CH(Ph)O protons], 7.23–7.27,
7.30–7.36 (2m, 5H, aromatic protons). 13C NMR
(100 MHz, CDCl3): d (ppm): 16.02, 21.52, 22.43, 22.98,
24.94, 31.83, 34.97, 44.97, 50.25, 71.68 (carbons of menthoxy
group), 51.87, 52.31 (2NCH2), 58.10 (2OCH2), 58.87
(NCH2CH(Ph)), 69.98 (ICH(Ph)), 125.20, 127.45, 128.32,
A
suspension comprising 3-phenylboratrane (14)
(0.60 g, 2.57 mmol) and a catalytic amount (ꢁ0.01 g) of
Al(OEt)3 in xylene (30 mL) was treated with HSi(OEt)3
(0.71 mL, 3.86 mmol). The reaction mixture was refluxed
for 6 h with the starting boratrane being totally dissolved
in 1 h. On cooling a white solid precipitated, which was fil-
tered, washed with hexane (2 · 5 mL), and dried in vacuo
1
to give 18 (0.52 g, 80%). H NMR (400 MHz, CDCl3): d
(ppm): 2.55–2.60 (m, 1H), 2.79–2.91 (m, 2H), 2.94–2.98
(m, 1H), 3.02–3.13 (m, 2H), 3.76–3.92 (m, 4H), 4.93 (dd,
J = 10.6 Hz, J = 4.6 Hz, 1H) [(ABXY)2 and ABX systems

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
569
141.63 (aromatic carbons). 29Si NMR (80 MHz, CDCl3): d
(ppm): ꢀ94.6. EI-MS: m/z (%) = 405 (45) [M+], 320 (100)
[M+ꢀC6H13], 299 (29) [M+ꢀPhCHO], 250 (98) [M+ꢀMen-
thO], 162 (57) [N(CH2)2CH2CH(Ph)O+]. Anal. Calc. for
C22H35NO4Si: C, 65.15; H, 8.70; N, 3.45. Found: C, 64.89;
H, 8.57; N, 3.56%.
[M+ꢀPhCHO], 250 (40) [M+ꢀPhCHOꢀtert-Bu], 234 (17)
[M+ꢀPhCHOꢀtert-BuO], 222 (76), 204 (9) [M+ꢀPhCHOꢀ
tert-BuOꢀCH2O], 179 (47), 148 (65), 104(41), 91 (78). Anal.
Calc. for C23H31NO4Si: C, 66.79; H, 7.56; N, 3.39. Found: C,
66.43; H, 7.81; N, 3.15%.
2.26. Reaction of 3,3-diphenylboratrane (13) with
CF3SO2OH
2.24. Synthesis of 1-tert-butoxy-2-carba-3-oxahomosilatrane
(24)
Trifluoromethanesulfonic acid (7.1 lL, 0.081 mmol)
was added to a suspension of 3,3-diphenylboratrane
(13) (0.025 g, 0.081 mmol) in CD3CN (0.6 mL). After
shaking the reaction mixture for 5 min, the starting solid
of boratrane was totally dissolved. NMR spectra regis-
tered from the solution within an hour revealed the
selective formation of the N-protonated derivative 27.
1H NMR (400 MHz, CD3CN): d (ppm): 3.25–3.51 (m,
4H, 2NCH2), 3.85–3.94 (m, 2H), 4.21–4.30 (m, 2H)
(2OCH2), 4.24 (s, 2H, NCH2C(Ph)2), 7.33–7.59 (m,
10H, aromatic protons). 13C NMR (100 MHz, CD3CN):
A suspension of 1-chloromethylsilatrane (22) (1.76 g,
7.85 mmol) and tert-BuOK (0.97 g, 8.64 mmol) in dioxane
(50 mL) was refluxed for 12 h. The precipitate was filtered
off, and the filtrate was evaporated in vacuo. The residual
yellow oil was solidified on keeping at room temperature.
The crude product was recrystallized from ether/heptane
to give 24 (1.62 g, 79%) as a white powder. 1H NMR
(400 MHz, C6D6): d (ppm): 1.50 (s, 9H, tert-BuO),
1.92–2.02 (m, 4H), 3.51–3.56 (m, 2H), 3.63–3.68 (m,
2H) [(ABXY)2 system of NCH2CH2O protons], 2.25 (br
t, J = 4.8 Hz, 2H), 3.07 (br t, J = 4.8 Hz, 2H) [(AA0XX0)
system of NCH2CH2OCH2Si protons], 3.92 (s, 2H,
OCH2Si). 13C NMR (100 MHz, C6D6): d (ppm): 32.07
(OC(CH3)3), 53.59 (2NCH2), 58.92 (NCH2CH2OCH2Si),
60.26 (2OCH2), 67.63, 67.70 (NCH2CH2OCH2Si), 71.25
(OC(CH3)3). 29Si NMR (80 MHz, CDCl3): d (ppm):
ꢀ73.6. EI-MS: m/z (%) = 203 (16) [M+ꢀC4H10], 188
(100) [M+ꢀtert-BuO], 147 (38). Anal. Calc. for
C11H23NO4Si: C, 50.54; H, 8.87; N, 5.36. Found: C,
50.12; H, 8.92; N, 5.13%.
d
(ppm): 55.87 (2NCH2), 58.57 (2OCH2), 75.91
(NCH2C(Ph)2), 126.62, 129.42, 130.02, 144.18 (aromatic
carbons).
2.27. Reaction of 3-phenylboratrane (14) with CF3SO2OH
Analogously to that described above, a reaction of 3-phe-
nylboratrane (14) (0.024 g, 0.103 mmol) with triflic acid
(9.1 lL, 0.103 mmol) was performed in CD3CN (0.6 mL).
NMR spectroscopy data revealed the exclusive formation
1
of 28. H NMR (400 MHz, CD3CN): d (ppm): 3.04–3.09
2.25. Synthesis of erythro-1-tert-butoxy-2-carba-3-oxa-7,8-
diphenylhomosilatrane (23)
(m, 1H), 3.34–3.41 (m, 1H), 3.50–3.70 (m, 3H), 3.85–3.90
(m, 1H), 4.21–4.29 (m, 2H), 4.37–4.46 (m, 2H), 5.25 (dd,
J = 10.6 Hz, J = 4.6 Hz, 1H) [(ABXY)2 and ABX systems
of NCH2CH2O and NCH2CH(Ph)O protons], 7.34–7.56
(m, 5H, aromatic protons). 13C NMR (100 MHz, CD3CN):
d (ppm): 58.39, 58.50 (2NCH2), 65.53, 65.58 (2OCH2), 65.29
(NCH2CH(Ph)), 76.85 (OCH(Ph)), 127.05, 129.73, 138.93,
147.82 (aromatic carbons).
Analogously to that described for 24, a reaction of
erythro-1-chloromethyl-3,4-diphenylsilatrane (9) (0.49 g,
1.30 mmol) with tert-BuOK (0.16 g, 1.43 mmol) was per-
formed in dioxane (30 mL). The removal of dioxane left an
oily material which was diluted with hexane (20 mL), fol-
lowed by stirring of the mixture at room temperature for
24 h. A precipitate formed was filtered and dried in vacuo
to give 23 (0.32 g, 59%) as a white powder. 1H NMR
(400 MHz, C6D6): d (ppm): 1.60 (s, 9H, tert-BuO), 1.77–
1.82, 2.38–2.44, 2.61–2.67, 2.92–2.99, 3.17–3.23, 3.28–3.34,
3.54–3.59, 3.67–3.74 (8m, 8H, (ABXY)2 system of NCH2-
CH2O protons), 3.97–4.16 (m, 2H, AB system of OCH2Si
protons), 4.26 (d, J = 6.4 Hz, 1H, NCH(Ph)), 5.69 (d,
J = 6.4 Hz, 1H, OCH(Ph)), 6.91–6.95, 7.03–7.06, 7.26–7.29
(3m, 10H, aromatic protons). 13C NMR (100 MHz, C6D6):
d (ppm): 32.34 (OC(CH3)3), 52.88 (NCH2CH2O), 59.66
(NCH2CH2OCH2Si), 62.29 (NCH2CH2O), 67.37 (OCH2Si),
68.47 (NCH2CH2OCH2Si), 70.64 (NCH(Ph)), 71.67
(OC(CH3)3), 77.75 (OCH(Ph)), 126.77, 127.24, 127.72,
127.80, 128.03, 131.29, 136.13, 141.59 (aromatic carbons).
29Si NMR (80 MHz, C6D6): d (ppm): ꢀ73.1. EI-MS: m/z
(%) = 413 (5) [M+], 383 (8) [M+ꢀCH2O], 355 (31)
[M+ꢀC4H10], 340 (100) [M+ꢀtert-BuO], 307 (16)
2.28. Reaction of 3,3-diphenylboratrane (13) with
CF3SO2OSiMe3
Analogously to that described above, a reaction of 3,3-
diphenylboratrane (13) (0.028 g, 0.091 mmol) with trim-
ethylsilyl triflate (16.4 lL, 0.091 mmol) was performed in
CD3CN (0.6 mL). According to the NMR spectroscopy
data, in a mixture of products, compound 29 was the
major component. 1H NMR (400 MHz, CD3CN): d
(ppm): 0.43 (s, 9H, SiMe3), 3.25–3.31 (m, 2H), 3.39–3.46
(m, 2H) (2NCH2), 3.95–4.01 (m, 2H), 4.25–4.30 (m, 2H)
(2OCH2), 4.23 (s, 2H, NCH2C(Ph)2), 7.33–7.55 (m, 10H,
aromatic protons). 13C NMR (100 MHz, CD3CN): d
(ppm): 59.38 (2NCH2), 65.33 (2OCH2), 68.05
(NCH2C(Ph)2), 126.14, 127.13, 129.51, 144.24 (aromatic
carbons).

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S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
2.29. Reaction of 3-phenylboratrane (14) with
CF3SO2OSiMe3
CH(Ph)OH (3), threo-N(CH2CH2OH)2CH(Ph)CH(Ph)OH
(4) and N(CH2CH2OH)2CH2CPh2OH (5). When a mixture
of diethanolamine and appropriate oxirane was kept at 90–
120 ꢁC for 30–45 h, the desired ligands 3–5 were isolated in
moderate to good yields (Eq. (1)).
Analogously to that described above, a reaction of
3-phenylboratrane (14) (0.030 g, 0.129 mmol) with trimeth-
ylsilyl triflate (23.4 lL, 0.129 mmol) was performed in
CD3CN (0.6 mL). According to the NMR spectroscopy
data, in a mixture of products, compound 30 was the major
R1
R2
R3
H
N(CH2CH2OH)2
CHR3CR1R2OH
HN(CH2CH2OH)2
1
component. H NMR (400 MHz, CD3CN): d (ppm): 0.51
O
3–5
(s, 9H, SiMe3), 3.02–3.08 (m, 1H), 3.39–3.46 (m, 1H),
3.53–3.73 (m, 3H), 3.86–3.91 (m, 1H), 4.23–4.32 (m, 2H),
4.39–4.44 (m, 2H), 5.20 (dd, J = 10.6 Hz, J = 4.5 Hz, 1H)
[(ABXY)2 and ABX systems of NCH2CH2O and
NCH2CH(Ph)O protons], 7.35–7.44 (m, 5H, aromatic pro-
tons). 13C NMR (100 MHz, CD3CN): d (ppm): ꢀ0.39
(SiMe3), 57.81, 57.92 (2NCH2), 66.50, 66.86 (2OCH2),
65.50 (NCH2CH(Ph)), 76.56 (OCH(Ph)), 126.98, 129.53,
129.61, 139.16 (aromatic carbons).
3: R1 = H; R2 = R3 = Ph (erythro-)
4: R1 = R3 = Ph; R2 = H (threo-)
5: R1 = R2 = Ph; R3 = H
ð1Þ
In contrast to the reaction with styrene oxide [9], in the
case of 2,2-diphenyloxirane trialkanolamine was
5
obtained as the sole product. No other products were
detected in the reaction mixture by NMR spectroscopy.
We attempted to extend this method to the preparation
of trialkanolamines containing two or more phenyl groups
in different arms. Thus, erythro-HN(CH2CH2OH)CH(Ph)-
CH(Ph)OH and HN[CH(Ph)CH(Ph)OH]2 were tested in
several reactions with phenylsubstituted oxiranes; however,
neither of them was found successful (see Section 2).
2.30. Reaction of boratrane (26) with CF3SO2OSiMe3
Analogously to that described above, a reaction of
boratrane (26) (0.030 g, 0.191 mmol) with trimethylsilyl
triflate (34.7 lL, 0.191 mmol) was performed in CD3CN
(0.6 mL). According to the NMR spectroscopy data, in a
mixture of products, compound 31 was the main compo-
nent. 1H NMR (400 MHz, CD3CN): d (ppm): 0.49 (s,
9H, SiMe3), 3.48 (t, J = 6.1 Hz, 6H, 3NCH2), 4.19 (t,
J = 6.1 Hz, 6H, 3OCH2). 13C NMR (100 MHz, CD3CN):
3.2. Synthesis and reactivity of phenylsubstituted
metallatranes
d
(ppm): ꢀ0.51 (SiMe3), 58.32 (3NCH2), 66.06
In the present study, silatranes and boratranes with phe-
nyl substituents in the atrane skeleton were synthesized
using two different methods. The first one implies the for-
mation of the metallatrane cage directly in the course of
the reaction. Thus, compounds 6–13 were obtained by
the treatment of trialkanolamine with the corresponding
trialkoxysilane or -borane (Eq. (2)). The transesterification
of (phenylethynyl)trimethoxysilane, as well as trimethylb-
orate, with trialkanolamines 3–5 proceeds without a cata-
lyst, while (chloromethyl)trimethoxysilane reacts only in
the presence of a catalytic amount of KOH. The reaction
rate of phenylsubstituted trialkanolamines 3–5 is apprecia-
bly lower in comparison with the parent N(CH2CH2OH)3
[28,29]. So, a prolonged reaction time is required to provide
good yields of the products (54–90%).
(3OCH2).
2.31. X-ray crystallography
The crystal data, data collection, structure solution and
refinement parameters for compounds 7, 9, 10, 16, 18, and
21 are listed in Table 1. All structures were solved by direct
methods [26] and refined by full-matrix least-squares on F2
[27] with anisotropic thermal parameters for all non-hydro-
gen atoms except disordered solvent CHCl3 molecule in
structure 21. In structures 7, 9, 10, 16 and 18, all hydrogen
atoms were found from different Fourier synthesis and
refined with isotropic thermal parameters. In 21, all hydro-
gen atoms were placed in calculated positions and refined
using a riding model.
Boratranes 12–16 were also prepared upon treatment of
boric acid with the corresponding trialkanolamine (Eq.
(3)). This reaction may be considered as a modification of
the first method [1,6]. The reaction of B(OH)3 with the mix-
ture 1 + 2 (9:1) (see [9] for detail) afforded compounds 14
and 15 as a mixture of the same ratio, which proved possi-
ble to separate via recrystallization. It should be noted that
both approaches to boratranes (cf. Eqs. (2) and (3)) give
the products with similar high yields. However, the reac-
tion with trimethyl borate proceeds in milder conditions
and is more convenient as far as the synthetic aspect is
concerned.
3. Results and discussion
3.1. Synthesis of trialkanolamine ligands
Previously, we reported that the reaction of
diethanolamine with styrene oxide leads to the mixture of
monophenylsubstituted aminoalcohols N(CH2CH2OH)2-
CH2CH(Ph)OH (1) and N(CH2CH2OH)2CH(Ph)CH2OH
(2) in a 9:1 ratio [9]. In this study, a similar approach
was developed for the synthesis of novel diphenylsubsti-
tuted trialkanolamines erythro-N(CH2CH2OH)2CH(Ph)-

Table 1
Crystal data, data collection and refinement parameters for 7, 9, 10, 16, 18, and 21
Compound
7
9
10
16
18
21
Empirical formula
Formula weight
Crystal system
Space group
Unit cell dimensions
C
427.56
triclinic
26H25NO3Si
C19H22ClNO3Si
375.92
monoclinic
P21/c
C19H22ClNO3Si
375.92
monoclinic
C2/c
C18H20BNO3
309.16
monoclinic
P21/n
C12H17NO3Si
251.36
monoclinic
P21/c
C17H32Cl3NO4Si
448.88
orthorhombic
P212121
ꢀ
P1
˚
a (A)
10.169(7)
11.051(6)
11.148(3)
98.11(3)
94.74(4)
114.29(5)
1117(1)
2
12.286(2)
7.020(2)
20.807(2)
13.1203(3)
12.6304(3)
21.6576(4)
14.657(3)
14.784(5)
14.694(4)
9.549(3)
9.900(3)
13.085(5)
10.634(3)
10.681(3)
19.977(11)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
95.78(2)
92.650(1)
101.86(2)
99.36(3)
3
˚
V (A )
1758.3(6)
4
1.399
0.300
3585.1(1)
8
1.393
0.298
1584
3116(2)
8
1.318
0.088
1220.5(7)
4
1.368
0.189
536
2269(2)
4
1.314
0.478
952
Z
Dcalc (g cmꢀ3
Absorption coefficient (mmꢀ1
F(000)
)
1.272
0.133
452
)
792
1312
Diffractometer
Temperature (K)
Graphite-monochromated
Mo Ka radiation (k/A)
Enraf-Nonius CAD4
293(2)
0.71073
Enraf-Nonius CAD4
293(2)
0.71073
Bruker SMART
120.0(2)
0.71073
Enraf-Nonius CAD4
293(2)
0.71073
Enraf-Nonius CAD4 Enraf-Nonius CAD4
293(2)
293(2)
0.71073
0.71073
˚
h Range (ꢁ)
2.06–25.47
1.67–24.97
1.88–28.00
2.20–24.97
2.16–24.98
2.04–24.99
ꢀ12 6 h 6 2,
ꢀ12 6 k 6 2,
ꢀ23 6 l 6 4
4146
Index ranges
ꢀ12 6 h 6 10, ꢀ13 6 k 6 13, ꢀ14 6 h 6 14, 0 6 k 6 8, ꢀ17 6 h 6 14,
ꢀ17 6 h 6 17, ꢀ3 6 k 6 17, ꢀ11 6 h 6 11,
0 6 l 6 13
0 6 l 6 24
ꢀ16 6 k 6 14,
ꢀ28 6 l 6 25
12452
ꢀ3 6 l 6 17
ꢀ11 6 k 6 11,
ꢀ3 6 l 6 15
5524
Reflections collected
4283
3134
8825
Independent reflections (Rint
Data/restraints/parameters
Goodness-of-fit on F2
)
4077 (0.0790)
4077/0/376
0.893
3134 (0.0000)
3134/0/315
0.933
4306 (0.0206)
4306/0/314
1.077
5475 (0.0437)
5475/0/576
0.868
2147 (0.0327)
2147/0/223
1.099
3318 (0.0196)
3318/0/247
0.961
Final R indices [I > 2r(I)]
R1 = 0.0578, wR2 = 0.1555
R1 = 0.0643,
wR2 = 0.1318
R1 = 0.1355,
wR2 = 0.1587
R1 = 0.0331, wR2 = 0.0890 R1 = 0.0390, wR2 = 0.0785
R1 = 0.0399,
wR2 = 0.1019
R1 = 0.0605,
wR2 = 0.1077
R1 = 0.0337,
wR2 = 0.0831
R1 = 0.1150,
wR2 = 0.0946
0.02(9)
R indices (all data)
R1 = 0.3055, wR2 = 0.2031
0.270 and ꢀ0.293
R1 = 0.0399, wR2 = 0.0926 R1 = 0.1616, wR2 = 0.0984
Flack parameter [39]
Largest difference in
peak and hole (e A
0.281 and ꢀ0.338
0.412 and ꢀ0.411
0.227 and ꢀ0.172
0.257 and ꢀ0.226
0.216 and ꢀ0.187
ꢀ3
˚
)

572
S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
3
R
H
N
N
N
2
R
R
N(CH2CH2OH)2
R
1
CHR3CR1R2OH
R
MenthOH / MenthONa
- H2
O
O
Si
O
3–5
Si
H
O
O
M
O
(MeO)3M
X
O
O
– 3 MeOH
O
X
OMenth
20: R=Ph; 21: R=H
6–13
18: R=Ph; 19: R=H
1
3
2
1
2
3
CPh, R =R =Ph, R = H; 7: threo, M = Si, X = C CPh, R =H; R =R = Ph;
6: erythro, M = Si, X = C
ð5Þ
1
2
3
1
3
2
8: M = Si, X = C CPh, R =R =Ph, R =H; 9: erythro, M = Si, X = CH2Cl, R =R =Ph, R =H;
1
2
3
1
2
3
10: threo, M = Si, X = CH2Cl, R =H, R =R =Ph; 11: M = Si, X = CH2Cl, R =R =Ph, R =H;
1
3
2
1
2
3
Remarkably, compound 20, according to the NMR
spectroscopy data, was isolated as one diastereomer and,
therefore, presented pure enantiomeric form. The crystalli-
zation of only one of two diastereomers in solution
accounts for the low yield of the product (27%). Our
attempts at growing a single crystal of 20 in order to estab-
lish the absolute configuration around C3 atom in the
atrane skeleton failed. To our knowledge, this is the first
example of a chemical resolution for racemic mixture of
metallatranes.
12: erythro, MX = B, R =R =Ph, R =H; 13: MX = B, R =R =Ph, R =H
ð2Þ
ð3Þ
3
R
H
2
R
N
N(CH2CH2OH)2
CHR3CR R2OH
1+2, 3–5
1
1
R
O
B
B(OH)3
O
– 3 H2O
O
12–16
Modification of a metallatrane structure may also be
achieved by reactions in which the atoms of side arms of
trialkanolamine moiety are involved. In this study, such
transformations were of particular interest since the differ-
ent nature of phenylsubstituted and unsubstituted arms of
the atrane cage could govern the reaction course and,
hence, might help in the clarification of the Ph-groups
influence on metallatrane reactivity.
12: erythro, R1=R3=Ph, R2=H; 13: R1=R2=Ph, R3=H;
14: R1=Ph, R2=R3=H; 15: R1=R2=H, R3=Ph;
1
2
3
16: threo, R =H, R =R =Ph
The second method consists of successive modifica-
tion of a preformed metallatrane skeleton. This can
be achieved either by a reaction proceeding directly
at the element atom or by a transmetallation reaction
[1,6]. Such conversions essentially reflect the reactivity
of metallatranes. Thus, transmetallation of boratranes
12 and 14 with triethoxysilane in the presence of trie-
thoxyaluminium as a catalyst afforded phenylsubstituted
silatranes 17 and 18 (Eq. (4)). The yields amount to
75% and 80%, respectively, and are somewhat lower
than previously found for unsubstituted analogue 19
[25].
A specific reaction of intramolecular cycle expansion
was found for 1-chloromethylsilatrane (22): the treatment
with various sodium alkoxides led to the formation of
1-alkoxy-2-carba-3-oxahomosilatranes [30]. To determine
the cycle expansion of whether arm (phenylsubstituted
or non-substituted) is more preferable, we subjected ery-
thro-3,4-diphenyl derivative 9 to the reaction with potas-
sium tert-butoxide. The behaviour of silatrane 22 in
similar conditions was studied as well (Eq. (6)). In case
of 9, the formation of the sole product was observed with
the ring expansion taking place exclusively in an unsubsti-
tuted arm of atrane moiety. The product was assigned the
structure of 23 on the basis of the 13C NMR spectroscopy
data. The comparison of the 13C chemical shifts of
2-homosilatranes 23 and 24 with each other and with
the starting 9 and 22 as well as with the previously
described N(CH2CH2O)2(CH2CH2OCH2)SiOEt (25) [30]
(Table 2) revealed the following. In the products 23–25,
the 13C NMR resonances of the unchanged five-mem-
bered rings carbons are downfield shifted by 2–4 ppm,
as compared with those of the corresponding 1-chloro-
methylsilatrane, while the carbons of the expanded five-
membered ring show considerably more pronounced
downfield shifts of 7–11 ppm. The unambiguous assign-
ment of the signals of 23 was made using 13C APT and
13C proton-coupled NMR spectra. The character of sig-
nals splitting in the latter is in full agreement with the
supposed structure. To our opinion, the preferable cycle
expansion of the unsubstituted arm of atrane moiety in
23 is caused by the comparative steric undifficulty and
3
3
R
R
H
H
N
2
N
B
2
R
R
1
1
R
R
(EtO)3SiH / (EtO)6Al2
O
Si
H
O
O
O
– (EtO)3B
O
O
12: erythro, R1=R3=Ph, R2=H
14: R1=Ph, R2=R3=H;
17: erythro, R1=R3=Ph, R2=H
18: R1=Ph, R2=R3=H;
ð4Þ
The Si–H function in silatrane 19 can be converted
into an Si–OR function by the reaction of 19 with alco-
hols in the presence of the corresponding sodium alkox-
ide [6]. We have found that hydride 18 and its
unsubstituted analogue 19 react with L-(ꢀ)-menthol in
the presence of sodium to give 1-menthoxysilatranes 20
and 21, respectively, the yield of 21 being higher (Eq.
(5)).

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
573
Table 2
13C NMR chemical shifts of atrane cage carbons for 9 and 22–25
R
7
5
12
N
4
8
R
11
O
O
Si
O
2
OR'
22
R0 = Et; R = H (25)a
R0 = t-Bu; R = H (24)
R0 = t-Bu; R = Ph (23)
9
C2
C4
C5
C7
C8
C11
C12
a
65.40
66.35
58.05
53.0
59.6
59.6
67.63
67.70
58.92
53.59
60.26
60.26
53.59
67.37
68.47
59.66
52.88
62.29
77.75
70.64
57.3
51.1
51.1
57.3
57.3
51.1
57.38
50.49
50.31
58.00
74.74
67.11
53.0
Values taken from [30].
H
N
greater flexibility of the NCH2CH2O fragment together
with the greater negative charge on the oxygen atom in
NCH2CH2O group.
TfO
2
R
1
R
R
R
CF3SO2OH
O
O
CD3CN
N
B
N
O
R
1
2
R
27: R =R =Ph;
2
N
B
R
t
1
2
BuOK
- KCl
28: R =Ph, R =H
O
1
O
Si
O
O
Si
R
O
O
O
O
t
O Bu
SiMe3
CH2Cl
9: erythro, R=Ph; 22: R=H
O
TfO
23: erythro, R=Ph; 24: R=H
1
2
N
B
13: R =R =Ph;
1
2
2
ð6Þ
14: R =Ph, R =H;
R
1
2
1
26: R =R =H
R
According to the literature, electrophilic reagents such
as HOTf, MeOTf, or Me3SiOTf may react with the
atrane-type compounds through an attack at the apical
nitrogen atom, at apical substituent or at equatorial atoms
[31–33]; the reaction pathway is determined by the nature
of these groups and reagent as well as by the strength of
the transannular M N interaction. We have tested the
phenylsubstituted boratranes 13 and 14, and their unsubsti-
tuted analogue 26 in reactions with triflic acid and Me3Si-
triflate (Eq. (7)). The treatment of boratranes 13 and 14
with HOTf resulted in the exclusive formation of N attack
derivatives 27 and 28. The attack at the N atom also pre-
vailed in the reactions of boratranes 13, 14 and 26 with
Me3SiOTf. In this case, however, the formation of minor
products was observed. The corresponding signals in the
1H and 13C NMR spectra could be assigned with caution
to the products of attack at the O atom ([Me3SiO-
CH2CH2N(CH2CH2O)2B]+OTfꢀ in the case of 26, for 13
and 14 regiochemistry of minor products cannot be estab-
lished due to the small concentration). The formation of
minor products might be explained by the greater thermo-
dynamic preference of Si–O bond formation, as compared
with Si–N bond.
CF3SO2OSiMe3
CD3CN
O
O
O
2
1
29: R =R =Ph;
1
2
major products
30: R =Ph, R =H;
1
2
31: R =R =H
ð7Þ
1
The identity of compounds 27–31 was confirmed by H
and 13C NMR spectroscopy. The signals of all atrane
cage protons of products 27–31 are downfield shifted by
0.3–0.5 ppm in comparison with those of the starting
boratranes. At the same time, the general appearance of
the spectra and the signals multiplicity remain unchanged.
The latter suggests that products 27–31 retain the symmetry
of the starting boratrane molecules, and only the bridge-
head N and B atoms undergo transformations in the course
of an electrophilic attack.
It should be noted that the reactions of the unsubsti-
tuted boratrane 26 with triflic acid and methyl triflate were
previously reported by Alder and Jin [34]. The similar
process of N-protonation was found upon treatment of
26 with HOTf. In contrast, the reaction with MeOTf affor-

574
S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
ded the product of O-methylation, [MeOCH2CH2N(CH2-
CH2O)2B]+OTfꢀ.
and N(CH2CHMeO)3B (14.2 ppm) and correspond to the
tetracoordination of boron atoms [1]. The 29Si NMR spec-
tra of the studied silatranes show single resonances in the
range ꢀ79.6 to ꢀ96.5 ppm. These values testify to the pen-
tacoordinated nature of Si atom in solution [6].
The novel compounds 3–21, 23, 24, 27–31 were charac-
1
terized by elemental analyses, IR, H, 13C, 11B, 29Si NMR
spectroscopy and mass spectrometry.
3.3. NMR spectra
3.4. Crystal structures
The 1H NMR spectra of unsubstituted metallatranes
comprising two broad triplets of (AA0XX0)3 system for
N(CH2CH2O)3M protons are well known. The presence
of one or two phenyl groups in one arm of the atrane cage
complicates the spectra entailing non-equivalence of all
To the best of our knowledge, compounds 7, 9, 10, 16
and 18 are the first structurally characterized silatrane
and boratrane derivatives bearing Ph substituents in the
atrane cage. The molecular structures of 7, 9, 10, 16 (one
independent molecule), 18, and 21 are shown in Figs. 1–
6, the selected bond lengths and angles are listed in Table 3.
The coordination polyhedron of the silicon atom in
studied silatranes 7, 9, 10, 18, and 21 represents a distorted
trigonal bipyramid with N atom and C atom (for com-
pounds 7, 9, 10), H atom (for compound 18) or O atom
(for compound 21) in the axial positions and three oxygen
atoms occupying the equatorial sites. The N–Si–C(H,O)ax
fragment is almost linear (173.81(5)–179.0(3)ꢁ) in all these
compounds. According to the Cambridge Structural Data-
base (ver. 5.27, January 2006) [35], the values of Si N
distance in 7, 9, 10, 18, and 21 lie within the typical range
1
skeleton protons [9]. A typical H NMR spectrum of phe-
nylsubstituted metallatrane shows a set of multiplets of
(ABXY)2 system for N(CH2CH2O)2M protons as well as
(a) multiplets of ABX system for NCH2CHPhO protons,
or (b) two doublets of AX system for NCHPhCHPhO pro-
tons, or (c) a broad singlet or multiplet of AB system for
NCH2CPh2O protons.
Due to the complex pattern of 1H NMR spectra for Ph-
substituted metallatranes, the 13C NMR spectra proved
very useful to analyse crude reaction mixtures. The 13C
NMR spectra of 3-Ph-substituted and 3,4-Ph2-substituted
derivatives display six signals of atrane skeleton carbons,
whereas the spectra of 3,3-Ph2-substituted compounds
show four signals, two higher field ones arising from the
carbon atoms of unsubstituted N(CH2CH2O)2M rings.
The 11B chemical shifts for the prepared boratranes
range between 14.0 and 15.0 ppm. These values are close
to those of the previously studied N(CH2CH2O)3B (26)
˚
for silatranes (1.964–2.420 A) and clearly verify the exis-
tence of Si–N transannular bond. The silicon atom is dis-
˚
placed by 0.17–0.18 A (DSi) towards the apical
substituent from the equatorial plane defined by three oxy-
gen atoms. It should be noted that the Si N distances in
˚
˚
˚
7 (2.132(5) A), 9 (2.136(4) A), and 10 (2.124(1) A) are close
to those previously found in the unsubstituted analogues:
Fig. 1. Molecular structure of 7.

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
575
Fig. 2. Molecular structure of 9.
Fig. 3. Molecular structure of 10.
˚
N(CH2CH2O)3SiC„CPh (2.094(2) A) [12], N(CH2CH2O)3-
far not been reported in the literature, some data concerning
the X-ray investigation of N(CH2CHMeO)3SiH are avail-
able in a review by Hencsei [37]. The value of Si N
˚
SiCH2Cl (2.120(8) A) [36]. While the structural data for
N(CH2CH2O)3SiH, unsubstituted analogue of 18, have so

576
S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
Fig. 4. Molecular structure of 16. One independent molecule is shown.
˚
distance in 18 (2.135(2) A) is close to that in N(CH2CH-
˚
MeO)3SiH (2.146 A) as well. Previously we have shown that
the M N distance alterations in germatranes bearing the
same apical substituents and different substituents at carbon
atoms of the atrane skeleton are caused mainly by the steric
requirements and crystal packing effects [8,9].
The Si–Oeq distances in Ph-substituted arms of atrane
moiety are slightly longer than the Si–Oeq distances in the
unsubstituted arms within the same molecule (see Table
3). All five-membered rings of silatrane skeleton in 7, 9,
10, 18, and 21 adopt an ‘‘envelope’’-like conformation,
the carbon atoms in a-positions to the N atom occupy
the ‘‘flap’’ sites. In the substituted five-membered rings of
compounds 7, 9, 18, and 21, the phenyl groups occupy
the equatorial positions. In silatrane 10, the Ph-group that
is bound to the carbon atom in a-position to the N atom
occupies the axial position.
The structure of boratrane 16 essentially differs from
that of silatranes. The coordination polyhedron of the B
atom in 16 represents a distorted tetrahedron with the
˚
boron being displaced by 0.31, 0.32 A (DB) towards the
nitrogen atom from the equatorial plane defined by three
oxygen atoms. The N-B-O angles vary within the range
102.1(2)–103.2(2)ꢁ, while the O–B–O angles vary within
the range 113.3(2)–116.3(2)ꢁ. All five-membered rings of
the boratrane skeleton adopt an ‘‘envelope’’-like conforma-
tion. The carbon atoms lying in b-positions to the N atom
Fig. 5. Molecular structure of 18.

S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
577
Fig. 6. Molecular structure of 21.
Table 3
The main geometrical parameters for 7, 9, 10, 16, 18, and 21
˚
˚
˚
˚
˚
Compound
d(Mꢂ ꢂ ꢂN) (A)
d(M–X) (A)
DM (A)
DN (A)
d(M–O) (A)
\N–M–X (ꢁ)
Unsubstituted arm
Substituted arm
1.666(4)
7
2.132(5)
2.136(4)
2.124(1)
1.684(3)
1.687(3)
2.135(2)
2.130(3)
1.856(7)
1.874(6)
1.894(2)
0.17
0.17
0.17
0.32
0.31
0.18
0.18
0.35
0.35
0.38
0.32
0.34
0.38
0.38
1.648(5)
1.652(5)
1.643(3)
1.659(3)
1.662(1)
1.665(1)
1.425(3)
1.436(3)
1.423(3)
1.429(3)
1.659(2)
1.654(2)
1.654(2)
1.651(2)
1.657(3)
179.0(3)
177.4(2)
173.81(5)
9
1.659(3)
1.666(1)
1.446(3)
1.437(4)
1.660(2)
10
16a
18
21
1.50(2)
176.6(8)
176.4(1)
1.657(2)
a
Two independent molecules.
occupy the ‘‘flap’’ sites. The B N distances in 16
decreases the product yields in comparison with those
found for the unsubstituted analogues. We have shown
that in the reaction of erythro-1-chloromethyl-3,4-diphe-
nylsilatrane with tert-BuOK, the unsubstituted NCH2-
CH2O arm exclusively undergoes the intramolecular cycle
expansion. The chemical behaviour of the prepared boratr-
anes was examined in the reactions with triflic acid and
Me3Si-triflate. Irrespective of boratrane structure, the elec-
trophilic attack takes place mainly at the bridgehead nitro-
˚
˚
(1.684(3) A, 1.687(3) A, two independent molecules) are
slightly longer than that in the parent boratrane N(CH2-
˚
CH2O)3B (1.6764(3) A) [38].
Summarizing the results, a series of silatranes and
boratranes based on the C-phenylsubstituted trialkanolam-
ines have been prepared using two different approaches.
The presence of phenyl groups in the ligands reduces the
rate of atrane skeleton formation and in most cases

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S.S. Karlov et al. / Inorganica Chimica Acta 360 (2007) 563–578
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cage of the studied metallatranes results in only a slight
elongation of the M N coordination bond in the solid
state, as compared with the corresponding unsubstituted
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[8,9], such M N distance alteration should be referred to
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Acknowledgements
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J. Organomet. Chem. 627 (2001) 1.
The authors thank RFBR for the financial support (06-
03-33032a). A.V.C. is grateful for a grant to the Russian
Science Support Foundation.
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Appendix A. Supplementary data
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1128.
The crystallographic data (excluding structure factors)
for the structures reported in this paper have been depos-
ited with the Cambridge Crystallographic Data Centre as
supplementary publications Nos. CCDC 247418 for 7,
247419 for 9, 247416 for 10, 247417 for 16, 247414 for 18
and 247419 for 21. Copies of the data can be obtained free
of charge on application to CCDC, 12 Union Road, Cam-
bridge CB2 1EZ, UK [fax: (int. code) + 44 1223 336 033;
e-mail: deposit@ccdc.cam.ac.uk]. Supplementary data asso-
ciated with this article can be found, in the online version,
at doi:10.1016/j.ica.2006.07.109.
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