Novel stannatranes of the type N(CH2CMe2O) 3SnX (X = OR, SR, OC(O)R, SP(S)Ph2, Halogen). Synthesis, molecular structures, and electrochemical properties

Article abstract of DOI:10.1021/ic202179e

The syntheses of the stannatrane derivatives of the type N(CH ₂CMe₂O)₃SnX (1, X = Ot-Bu; 2, X = Oi-Pr; 3, X = 2,6-Me₂C₆H₃O; 4, X = p-t-BuC₆H ₄O; 5, X = p-NO₂

Full text of DOI:10.1021/ic202179e

Article
pubs.acs.org/IC
Novel Stannatranes of the Type N(CH2CMe2O)3SnX (X = OR, SR,
OC(O)R, SP(S)Ph2, Halogen). Synthesis, Molecular Structures, and
Electrochemical Properties
Thomas Zoller,† Christina Dietz,† Ljuba Iovkova-Berends,† Olga Karsten,† Gerrit Bradtmoller,†
̈
̈
Ann-Kristin Wiegand,† Yu Wang,‡ Viatcheslav Jouikov,‡,* and Klaus Jurkschat†,*
†Lehrstuhl fur Anorganische Chemie II der Technischen Universitat Dortmund, D-44221 Dortmund
̈
̈
‡UMR CNRS 6510, Molecular Chemistry and Photonics, University of Rennes, 35042 Rennes, France
S
* Supporting Information
ABSTRACT: The syntheses of the stannatrane derivatives of
the type N(CH2CMe2O)3SnX (1, X = Ot-Bu; 2, X = Oi-Pr; 3,
X = 2,6-Me2C6H3O; 4, X = p-t-BuC6H4O; 5, X = p-NO2C6H4O;
6, X = p-FC6H4O; 7, X = p-PPh2C6H4O; 8, X = p-MeC6H4S;
9, X = o-NH2C6H4O; 10, X = OCPh2CH2NMe2; 11, X =
Ph2P(S)S; 12, X = p-t-BuC6H4C(O)O; 13, X = Cl; 14, X = Br; 15,
X = I; 16, X = p-N(CH2CMe2O)3SnOSiMe2C6H4SiMe2O) are
reported. The compounds are characterized by X-ray
diffraction analyses (3−8, 11−16), multinuclear NMR spectroscopy, 13C CP MAS (14) and 119Sn CP MAS NMR (13, 14)
spectroscopy, mass spectrometry and osmometric molecular weight determination (13). Electrochemical measurements show
that anodic oxidation of the stannatranes 4 and 8 occurs via electrochemically reversible electron transfer resulting in the
corresponding cation radicals. The latter were detected by cyclic voltammetry (CV) and real-time electron paramagnetic
resonance spectroscopy (EPR). DFT calculations were performed to compare the stannatranes 4, 8, and 13 with the cor-
responding cation radicals 4+•, 8+•, and 13+•, respectively.
CH2SiMe2R)6,9,12−14 and stannatrane-like compounds of type
INTRODUCTION
■
N[CH2C(O)O]3SnR4 (R4 = alkyl, Ph, CH2CH2CH2NMe2,
CH2CH2CH2N(O)Me2)9 are also known for a long time but
only four examples have been structurally characterized by
single crystal X-ray diffraction analysis. The methylstannatrane,
[N(CH2CH2O)3SnMe]3·6H2O, (A), is a trimer via intermo-
lecular Sn−O → Sn bridges15 whereas, as result of steric protection
respectively additional intramolecular N(O) → Sn coordina-
tion, the t-butyl-,16 o-anisyl-,12 and dimethylaminooxypropyl-
substituted compounds N(CH2CH2O)3SnR (R = t-Bu, (B);
Metal(IV)-derivatives of triethanolamines are called metal-
latranes.1 These compounds are characterized by their cage
structure, an intramolecular N → M (M = metal) interaction
and chirality of the molecular framework which is described in
terms of right- or left-handed (Δ or Λ) propeller geometry
(Scheme 1).2−4
Scheme 1. Δ and Λ stereochemistry for metallatranes
viewing along the Z−M−N axis (Z is omitted for clarity).
17
o-MeOC6H4, (C)) and N[CH2C(O)O]3Sn(CH2)3N(O)Me2
(D) are monomeric (Scheme 2).
Inorganic stannatranes that lack any tin−carbon bond are
scarce18−21 and to the best of our knowledge only three solid
state structures of derivatives with nitrilotrisethanolato or
nitrilotriacetate ligands have been reported (Scheme 3).22−24
In context with our ongoing studies on alkanol amin deriva-
tives of tin,25−27 the motivation for renewed research on inor-
ganic stannatranes stems from the nontoxicity of these com-
pounds because of the absence of any metal−carbon bond and
the catalytic activity of alkanol amin derivatives of tin in poly-
merization reactions.28
In the last decades the chemistry of metallatranes has been
extensively studied and expanded across the periodic table.5−11
Among the metallatranes especially group 14 element atranes
are the most intensively studied representatives and have been
reviewed in recent years.9−11 Organostannatranes of the type
N(CH2CR1R2O)3SnR3 (R1, R2 = H, Me; R3 = alkyl, aryl,
Received: October 11, 2011
Published: December 23, 2011
© 2011 American Chemical Society
1041
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Scheme 2. Monoorgano-stannatranes and stannatrane-like compounds.
Scheme 3. Stannatranes and stannatrane-like compounds without Sn−C bonding.
[N(CH2CMe2OH)3 + H]+, 583.3 [M − OtBu + N(CH2CMe2OH)3]+,
930.4 [C36H73N3O9Sn2 + H]+.
EXPERIMENTAL SECTION
■
General. All experimental manipulations were carried out under
argon atmosphere using Schlenk technique. All solvents were purified
by distillation under argon from appropriate drying agents according
to standard procedures.29 Tris(2-hydroxy-2-methylpropyl)amine,
N(CH2CMe2OH)3, and 2-(dimethylamino)-1,1-diphenylethanol,
Me2NCH2CPh2OH, were prepared from ammonia, dimethylamine,
and 1,1-dimethyloxirane, respectively.30 Tris(2-hydroxy-2-methylpropyl)-
amine was recrystallized from dry diethyl ether before use. 1,4-Bis-
(hydroxydimethylsilyl)benzene31 and 4-(diphenylphosphino)phenol32
were prepared according to literature methods.
The NMR spectra were recorded on Bruker DRX 500, Bruker DRX
400, and Bruker DPX 300 spectrometers. Chemical shifts δ are given
in ppm and are referenced to the solvent peaks with the usual values
calibrated against tetramethylsilane (1H, 13C, 29Si), 80% H3PO4 (31P),
and tetramethylstannane (119Sn).
1-iso-Propanolato-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-
stannatricyclo[3.3.3.01.5]undecane (2). The procedure is the same as
described for compound 1, but Sn(O-i-Pr)4·HO-i-Pr (1.17 g, 2.82
mmol) was used as starting material. Compound 2 (1.15 g, 2.82 mmol,
1
quantitative) was obtained as colorless amorphous solid. H NMR
(500.13 MHz, C6D6, 298 K): δ 4.78 (complex pattern, 1H, OCH),
2.36 (s, 6H, NCH2), 1.49 (complex pattern, 6H, OCH(CH3)2), 1.17
1
(s, J(1H−13C) = 118.0 Hz, 18H, C(CH3)2). 13C{1H} NMR (100.63
MHz, C6D6, 298 K): δ 70.5 (s, J(13C−117/119Sn) = 46.6 Hz, NCH2),
68.8 (s, J(13C−117/119Sn) = 17.5 Hz, C(CH3)2), 67.7 (s, OCH(CH3)2),
31.5 (s, J(13C−117/119Sn) = 30.4 Hz, C(CH3)2), 28.0 (s, 3J(13C−117/119Sn)
= 27.5 Hz, OCH(CH3)2). 119Sn{1H} NMR (111.89 MHz, CDCl3,
298 K): δ −312 (s, J(119Sn−13C) = 52 Hz, J(119Sn−13C) = 24 Hz). mp
97−98 °C. MS (ESI +): m/z = 162.2 [HN(CH2CMe2OH)2 + H]+,
234.2 [N(CH2CMe2OH)3 + H]+, 511.3 [M − O-iPr + HN-
(CH2CMe2OH)2]+, 583.3 [M − O-iPr + N(CH2CMe2OH)3]+,
930.4 [C36H73N3O9Sn2 + H]+, 1062.3 [N(CH2CMe2O)3SnOSn-
(OCMe2CH2)3N + N(CH2CMe2O)3Sn]+. IR (nujol, ν/cm−1) =
2920, 2856, 1463, 1377, 1289, 1215, 1191, 1073, 977, 947, 788, 726,
649.
The 119Sn CP MAS NMR spectra were recorded with a BrukerAvance
III 400 spectrometer using cross-polarization and high-power proton
decoupling [conditions: 3.7 μs (90°) pulse, contact time 3 ms, 10 s
recycle delay]. Spectra with different spinning rates between 5 and 9 kHz
were recorded to unambiguously determine the isotropic chemical
shifts. Tetracyclohexylstannane was used as secondary reference (δ =
97.35).
Elemental analyses were performed on a LECO CHNS-932 analyzer.
No elemental analyses were performed for compounds 1 and 2
because of their extreme sensitivity toward hydrolysis. For compounds
6, 10, and 16 the experimentally determined values for carbon differ by
1−1.6% from the calculated ones. The electrospray mass spectra were
recorded on a Thermoquest Finnigan instrument using CH3CN or
CH2Cl2 as a mobile phase.
1-(2,6-Dimethylphenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hex-
amethyl-stannatricyclo[3.3.3.01.5]undecane (3). To a stirred solu-
tion of 1 (1.29 g, 3.06 mmol) in dry toluene (200 mL) was added a
toluene solution (50 mL) of 2,6-dimethylphenol (0.37 g, 3.03 mmol).
The mixture was heated at reflux for 1.5 h and then concentrated by
azeotropic distillation of t-BuOH/toluene. Slow cooling to room
temperature provided a colorless amorphous solid. Recrystallization
from toluene and subsequent washing with cold toluene gave colorless
column-like crystals of 3 (1.32 g, 2.80 mmol, 92%). 1H NMR (400.13
3
MHz, C6D6, 298 K): δ 7.07 (d, J(1H−1H) = 7.4 Hz, 2H, m-H), 6.80
1-tert-Butanolato-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-
stannatricyclo-[3.3.3.01.5]undecane (1). To a stirred solution of
tin(IV)-tert-butoxide (4.21 g, 10.24 mmol) in dry toluene (350 mL)
was added within 10 min at room temperature a solution of
N(CH2CMe2OH)3 (2.39 g, 10.24 mmol) in dry toluene (80 mL).
After concentrating the mixture by azeotropic distillation the remain-
ing solvent was removed under reduced pressure. Compound 1 (4.32 g,
10.24 mmol, quantitative) was obtained as colorless microcrystalline
solid. 1H NMR (300.13 MHz, C6D6, 298 K): δ 2.32 (s, J(1H−117/119Sn) =
3
1
(t, J(1H−1H) = 7.4 Hz, 1H, p-H), 2.71 (s, J(1H−13C) = 126.2 Hz,
6H, o-(CH3)), 2.23 (s, J(1H−117/119Sn) = 21.3 Hz, 1J(1H−13C) = 138.1
Hz, 6H, NCH2), 1.09 (s, J(1H−13C) = 125.8 Hz, 18H, C(CH3)2).
1
13C{1H} NMR (100.63 MHz, C6D6, 298 K): δ 157.9 (s, i-C), 129.4(s, o-C),
128.6 (s, m-C), 120.2 (s, p-C), 70.2 (s, J(13C−117/119Sn) = 49.4 Hz,
NCH2), 69.3 (s, J(13C−117/119Sn) = 21.1 Hz, C(CH3)2), 31.2 (s,
J(13C−117/119Sn) = 32.1 Hz, C(CH3)2), 18.0 (s, o-(CH3)). 119Sn{1H}
NMR (111.89 MHz, C6D6, 298 K): δ −333 (s). mp: 209−212 °C.
Anal. Calcd. for C20H33NO4Sn (%): C 51.1, H 7.1, N 3.0. Found: C
51.1, H 7.1, N 2.9. MS (ESI+): m/z = 216.2 [C12H26NO2]+, 234.2
[N(CH2CMe2OH)3 + H]+, 350.1 [M − OC6H3Me2]+, 382.1 [M −
OC6H3Me2 + MeOH]+, 583.3 [M − OC6H3Me2 + N(CH2-
CMe2OH)3]+, 729.2 [N(CH2CMe2O)3SnOMe + N(CH2CMe2O)3Sn]+,
930.5 [C36H73N3O9Sn2 + H]+.
1
1
20.9 Hz, J(1H−13C) = 137.1 Hz, 6H, NCH2), 1.72 (s, J(1H−13C) =
124.5 Hz, 9H, C(CH3)3), 1.22 (s, 1J(1H−13C) = 125.6 Hz, 18H,
C(CH3)2). 13C{1H} NMR (100.63 MHz, C6D6, 298 K): δ 70.4 (s,
J(13C−117/119Sn) = 48.4 Hz, NCH2, C(CH3)3), 68.8 (s,
J(13C−117/119Sn) = 21.6 Hz, C(CH3)2), 33.7 (s, J(13C−117/119Sn) =
3
27.5 Hz, C(CH3)3), 31.5 (s, J(13C−117/119Sn) = 30.4 Hz, C(CH3)2).
119Sn{1H} NMR (111.89 MHz, CDCl3, 298 K): δ −319 (s,
J(119Sn−13C) = 49 Hz, J(119Sn−13C) = 30 Hz). mp 111−113 °C. IR
(nujol, ν/cm−1) = 2928, 2855, 1463, 1378, 1288, 1167, 1074, 978, 947,
921, 789, 725, 649. MS (ESI +): m/z = 216.2 [C12H26NO2]+, 234.2
1-(4-tert-Butylphenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hex-
amethyl-stannatricyclo[3.3.3.01.5]undecane (4). The procedure is
the same as described for compound 3, with 1 (2.54 g, 6.02 mmol)
and p-tert-butylphenol (0.90 g, 5.99 mmol) as starting materials.
1042
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Crystals of 4 (2.73 g, 5.48 mmol, 91%) were obtained as colorless
columns. 1H NMR (400.13 MHz, CD2Cl2, 298 K): δ 7.18 (d,
aryl-C), 128.5 (s, aryl-C), 125.6 (d, J(13C−31P) = 7.3 Hz, aryl-C), 119.5
(d, J(13C−31P) = 8.3 Hz, aryl-C), 70.4 (s, J(13C-117/119Sn) = 50.0 Hz,
NCH2), 70.1 (s, J(13C−117/119Sn) = 19.1 Hz, C(CH3)2), 31.2 (s,
J(13C−117/119Sn) = 27.5 Hz, C(CH3)2). 31P{1H} NMR (121.50 MHz,
CD2Cl2, 296 K): δ−6.3 (s, J(31P−13C) = 19.2 Hz). 119Sn{1H} NMR
(111.89 MHz, CD2Cl2, 296 K): δ −311 (s). mp = 217−219 °C. Anal.
Calcd for C29H36NO4PSn (%): C 57.5, H 6.1, N 2.2. Found: C 57.5,
H 6.1, N 1.9. (ESI+): m/z = 216.2 [C12H26NO2]+, 234.3 [N(CH2-
CMe2OH)3 + H]+, 279.1 [Ph2PC6H4OH + H]+, 583.3 [M −
OC6H4NO2 + N(CH2CMe2OH)3]+.
3
3J(1H−1H) = 8.7 Hz, 2H, m-H), 6.85 (d, J(1H−1H) = 8.7 Hz, 2H,
o-H), 2.96 (s, J(1H−117/119Sn) = 23.3 Hz, 1J(1H−13C) = 138.7 Hz, 6H,
1
NCH2), 1.33 (s, J(1H−13C) = 126.0 Hz, 18H, C(CH3)2), 1.28 (s,
1J(1H−13C) = 125.4 Hz, 9H, C(CH3)3). 13C{1H} NMR (100.63 MHz,
CD2Cl2, 298 K): δ 158.0 (s, ipso-C), 142.0 (s, p-C), 126.3 (s, m-C),
118.4 (s, o-C), 70.5 (s, J(13C−117/119Sn) = 49.5 Hz, NCH2), 68.8
(s, J(13C−117/119Sn) = 19.1 Hz, C(CH3)2), 34.1 (s, C(CH3)3), 31.6 (s,
C(CH3)3), 31.2 (s, J(13C−117/119Sn) = 31.1 Hz, C(CH3)2). 119Sn{1H}
NMR (111.89 MHz, C6D6, 298 K): δ −322 (s). Anal. Calcd. for
C22H37NO4Sn (%): C 53.0, H 7.5, N 2.8. Found: C 53.0, H 7.5, N 2.7.
MS (ESI +): m/z = 216.2 [C12H26NO2]+, 234.2 [N(CH2CMe2OH)3 +
H]+, 350.1 [M − OC6H4-tBu]+, 382.1 [M − OC6H4-tBu + MeOH]+,
583.3 [M − OC6H4-tBu + N(CH2CMe2OH)3]+.
1-(4-Methylthiophenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hex-
amethyl-stannatricyclo[3.3.3.01.5]undecane (8). The procedure is
the same as described for compound 3, with 1 (1.79 g, 4.24 mmol)
and p-methylthiophenol (0.53 g, 4.27 mmol) as starting materials.
Crystallization from toluene/hexane and subsequent washing with
1
hexane gave 8 (1.72 g, 3.64 mmol, 86%) as colorless columns. H
1-(4-Nitrophenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexameth-
yl-stannatricyclo[3.3.3.01.5]undecane (5). The procedure is the
same as described for compound 3, with 1 (1.61 g, 3.81 mmol) and
4-nitrophenol (0.53 g, 3.81 mmol) as starting materials. Recrystalliza-
tion from toluene gave compound 5, as its toluene solvate 5·0.25C7H8
3
NMR (400.13 MHz,C6D6, 298 K): δ 7.91 (d, J(1H−1H) = 8.0 Hz,
3
1J(1H−13C) = 160.8 Hz, 2H, o-H), 6.80 (d, J(1H−1H) = 8.0 Hz,
1J(1H−13C) = 158.3 Hz, 2H, m-H), 2.26 (s, J(1H−117/119Sn) = 21.0 Hz,
1
6H, NCH2), 1.93 (s, 3H, C6H4−CH3), 1.12 (s, J(1H−13C) = 125.7
1
Hz, 18H, CCH3). 13C{1H} NMR (100.63 MHz, C6D6, 298 K): δ 136.2
(1,74 g, 3.41 mmol, 90%), as yellowish columns. H NMR (300.13
3
MHz, CD2Cl2, 300 K): δ 8.07 (d, J(1H−1H) = 9.2 Hz, 2H, m-H),
4
(s, p-C), 135.6 (s, i-C), 135.0 (s, J(13C−117/119Sn) = 30.3 Hz, o-C),
7.26−7.12 (m, toluene), 7.01 (d, 3J(1H−1H) = 8.5 Hz, 2H, o-H), 3.00
118.4 (s, 5J(13C−117/119Sn) = 9.5 Hz, m-C), 70.6 (s, J(13C−117/119Sn) =
48.0 Hz, NCH2), 69.5 (s, J(13C−117/119Sn) = 30.6 Hz, C(CH3)2), 31.3
(s, J(13C−117/119Sn) = 27.5 Hz, C(CH3)2), 20.9 (s, C6H4-CH3) .
119Sn{1H} NMR (111.89 MHz, C6D6, 298 K): δ −227 (s,
1
(s, J(1H−117/119Sn) = 23.3 Hz, J(1H−13C) = 139.2 Hz, 6H, NCH2),
1
2.12 (s, toluene), 1.34 (s, J(1H−13C) = 126.0 Hz, 18H, C(CH3)2).
13C{1H} NMR (100.63 MHz, CD2Cl2, 300 K): δ 166.8 (s, ipso-C),
J(119Sn−13C) = 29 Hz, J(119Sn−13C) = 48 Hz). mp: 124−126 °C.
Anal. Calcd for C19H31NO3SSn (%): C 48.3, H 6.6, N 3.0. Found: C
48.3, H 6.5, N 2.8. MS (ESI +): m/z = 216.2 [C12H26NO2]+, 234.2
[N(CH2CMe2OH)3 + H]+, 391.2 [M − SC6H4Me + MeCN]+, 474.1
[M + H]+, 496.1 [M + Na]+.
140.3 (s, p-C), 138.1 (toluene), 129.1 (toluene), 128.4 (toluene),
126.0 (s, m-C), 125.5 (toluene), 119.1 (s, o-C), 70.5 (s, J(13C-117/119Sn) =
18.9 Hz, C(CH3)2), 70.2 (s, J(13C-117/119Sn) = 50.6 Hz, NCH2), 31.1
(s, J(13C-117/119Sn) = 31.8 Hz, C(CH3)2), 21.4 (toluene). 119Sn{1H}
NMR (111.89 MHz, C6D6, 295 K): δ −315 (s). mp = 114−117 °C.
Anal. Calcd for C18H28N2O6Sn·0.25 C7H8 (%): C 46.5, H 5.9, N 5.5.
Found: C 46.3, H 5.9, N 5.2. (ESI+): m/z = 216.3 [C12H26NO2]+,
234.3 [N(CH2CMe2OH)3 + H]+, 350.1 [M − OC6H4NO2]+, 583.3
[M − OC6H4NO2 + N(CH2CMe2OH)3]+, 715.3 [N(CH2CMe2O)3-
SnOSn(OCMe2CH2)3N + H]+, 729.3 [N(CH2CMe2O)3SnOMe +
N(CH2CMe2O)3Sn]+, 930.5 [C36H73N3O9Sn2 + H]+, 1062.4
[N(CH2CMe2O)3SnOSn(OCMe2CH2)3N + N(CH2CMe2O)3Sn]+.
1-(4-Fluorophenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexam-
ethyl-stannatricyclo[3.3.3.01.5]undecane (6). The procedure is the
same as described for compound 3, with 1 (1.56 g, 3.70 mmol) and
4-fluorophenol (0.41 g, 3.66 mmol) as starting materials. Crystals of
compound 6 (1.10 g, 2.39 mmol, 65%) were obtained as colorless
blocks. 1H NMR (300.13 MHz, CD2Cl2): δ 6.94−6.80 (m, 4H,
1-(2-Aminophenolato)-2,8,9-trioxa-5-aza-3,3,7,7,10,10-
hexamethylstannatricyclo[3.3.3.01.5]undecane (9). The procedure is
the same as described for compound 3 with 1 (1.48 g, 3.51 mmol) and
2-aminophenol (0.38 g, 3.48 mmol) as starting materials. Compound 9
1
(1.60 g, 3.48 mmol, 99%) was obtained as colorless solid. H NMR
(300.13 MHz, CD2Cl2): δ 7.08−7.04 (complex pattern, 2H, H4, H6),
3
6.94−6.91 (complex pattern, 1H, H5), 6.62 (dt, J(1H−1H) = 1.4 Hz,
4J(1H−1H) = 7.5 Hz 1H, H3), 3.93 (s, broad, 2H, NH2), 2.87 (s,
1
J(1H−117/119Sn) = 19.3 Hz, 6H, NCH2), 1.27 (s, J(1H−13C) = 125.5
Hz, 18H, C(CH3)2). 13C{1H} NMR (100.63 MHz, CD2Cl2): δ 157.1
(s, C1), 129.2 (s, C2), 128.4 (s, C4), 125.3 (s, C5), 117.6 (s, C6), 117.0
(s, C3), 70.9 (s, J(13C−117/119Sn) = 50.3 Hz, NCH2), 68.5 (s,
J(13C−117/119Sn) = 22.8 Hz, C(CH3)2,), 31.5 (s, J(13C−117/119Sn) =
33.0 Hz, C(CH3)2). 119Sn{1H} NMR (111.89 MHz, CD2Cl2): δ −432
(s). mp: 198−200 °C (decomposition). Anal. Calcd. for C18H30N2O4-
Sn (%): C 47.3, H 6.6, N 6.1. Found: C 47.6, H 6.5, N 5.4. MS (ESI+):
m/z = 216.3 [C12H26NO2]+, 234.3 [N(CH2CMe2OH)3 + H]+, 391.2
[M − OC6H4NH2 + MeCN]+, 459.2 [M + H]+, 583.4 [M −
OC6H4NH2 + N(CH2CMe2OH)3]+, 715.3 [N(CH2CMe2O)3SnOSn-
(OCMe2CH2)3N + H]+, 806.4 [M + C12H24NO3Sn]+.
1
aryl-H), 2.96 (s, J(1H−117/119Sn) = 23.5 Hz, J(1H−13C) = 139.1 Hz,
6H, NCH2), 1.32 (s, 1J(1H−13C) = 126.2 Hz, 18H, C(CH3)2).
1
13C{1H}-NMR (100.63 MHz, CD2Cl2): δ 156.6 (d, J(13C−19F) =
3
234.8 Hz, ipso-C), 156.6 (s, o-C), 119.8 (d, J(13C−19F) = 7.9 Hz,
2
m-C), 115.5 (d, J(13C−19F) = 22.7 Hz, p-C), 70.4 (s, J(13C−119Sn) =
49.4 Hz, NCH2), 70.0 (s, J(13C−119Sn) = 18.7 Hz, C(CH3)2), 31.2 (s,
3J(13C−119Sn) = 31.1 Hz, C(CH3)2). 119Sn{1H} NMR (111.89 MHz,
1-(N,N-Dimethyl-2,2-diphenyl-aminoethanolato)-2,8,9-trioxa-5-
aza-3,3,7,7,10,10-hexamethyl-stannatricyclo[3.3.3.01.5]undecane
(10). The procedure is the same as described for compound 3, with 1
(1.49 g, 3.53 mmol) and 2-(dimethylamino)-1,1-diphenylethanol
(0.85 g, 3.52 mmol) as starting materials. After removing the volatiles
under reduced pressure, compound 10 (1.99 g, 3.37 mmol, 95%) was
obtained as yellowish oil that solidified upon standing. 1H NMR
CD2Cl2): δ −313. mp: 197−198 °C. Anal. Calcd for C18H28FNO4Sn
(%): C 47.0, H 6.1, N 3.0. Found: C 45.8, H 6.1, N 2.8. MS (ESI+):
m/z = 234.3 [N(CH2CMe2OH)3 + H]+, 391.2 [M − OC6H4F +
MeCN]+, 583.3 [M − OC6H4F + N(CH2CMe2OH)3]+, 715.3
[N(CH2CMe2O)3SnOSn(OCMe2CH2)3N + H]+. MS (ESI−):
m/z = 91.0, 137.0.
1-(4-Diphenylphosphinophenolato)-2,8,9-trioxa-5-aza-
3,3,7,7,10,10-hexamethyl-stannatricyclo[3.3.3.01.5]undecane (7). The
procedure is the same as described for compound 3, with 1 (0.94 g,
2.23 mmol) and 4-(diphenylphosphino)phenol (0.62 g, 2.23 mmol) as
starting materials. Crystallization from toluene and subsequent
washing with cold toluene gave 7 (1.23 g, 1.96 mmol, 88%) as
colorless plates. 1H NMR (300.13 MHz, CD2Cl2, 296 K): δ 7.38−7.24
(m, 10H, aryl-H), 7.20−7.12 (m, 2H, aryl-H), 6.98−6.92 (m, 2H, aryl-
3
(500.13 MHz, C6D6, 303 K): δ 8.18 (d, J(1H−1H) = 7.3 Hz, 4H,
aryl-H), 7.40−7.36 (m, 6H, aryl-H), 3.48 (s, J(1H−117/119Sn) = 25.3
Hz, 2H, Me2NCH2) 2.63 (s, J(1H−117/119Sn) = 16.1 Hz, 6H, NCH2),
2.43 (s, J(1H−117/119Sn) = 12.2 Hz, 6H, N(CH3)2), 1.48 (s, 18H,
C(CH3)2). 13C{1H} NMR (100.63 MHz, CD2Cl2, 298 K): δ 152.0 (s,
3J(13C−117/119Sn) = 27.8 Hz, i-C), 127.9, 126.4, 126.0 (s, aryl-C), 73.3
(s, J(13C−117/119Sn) = 25.5 Hz, CPh2O), 70.6 (s, J(13C−117/119Sn) = 50.1
Hz, NCH2), 68.2 (s, Me2NCH2), 67.9 (s, J(13C−117/119Sn) = 27.6 Hz,
C(CH3)2O), 47.3 (s, N(CH3)2), 32.2 (s, J(13C−117/119Sn) = 32.6 Hz,
C(CH3)2). 119Sn{1H} NMR (111.89 MHz, C6D6, 303 K): δ −462
(J(119Sn−13C) = 29 Hz, J(119Sn−13C) = 50 Hz). mp: 130−132 °C.
Anal. Calcd. for C28H42N2O4Sn (%): C 57.1, H 7.2, N 4.8. Found: C
1
H), 2.97 (s, J(1H−117/119Sn) = 23.4 Hz, J(1H−13C) = 138.8 Hz, 6H,
1
NCH2), 1.33 (s, J(1H−13C) = 126.1 Hz, 18H, C(CH3)2). 13C{1H}
NMR (75.48 MHz, CD2Cl2, 296 K): δ 161.7 (s, aryl-C), 138.8 (d,
J(13C−31P) = 11.3 Hz, aryl-C), 135.9 (d, J(13C−31P) = 21.8 Hz, aryl-C),
133.5 (d, J(13C−31P) = 19.1 Hz, aryl-C), 128.6 (d, J(13C−31P) = 8.9 Hz,
1043
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
55.5, H 6.9, N 4.4. MS (ESI +): m/z = 224.2 [Me2NCH2CPh2]+, 242.2
[Me2NCH2CPh2OH + H]+, 583.4 [M − OCPh2CH2NMe2 + N(CH2-
CMe2OH)3]+, 591.3 [M + H]+, 715.2 [N(CH2CMe2O)3SnOSn-
(OCMe2CH2)3N + H]+, 930.4 [C36H73N3O9Sn2 + H]+, 954.4, 1062.4
[N(CH2CMe2O)3SnOSn(OCMe2CH2)3N + N(CH2CMe2O)3Sn]+,
1256.3.
δ −243 (s). 119Sn{1H} NMR (111.89 MHz, CD2Cl2, 213 K): δ −235
(s) 119Sn CP-MAS NMR (149.22 MHz): δiso −233, −236, −238,
−239. Mp. 198 °C (decomposition). IR (nujol, ν/cm−1) = 2922, 2853,
1461, 1377, 1287, 1190, 1160, 1068, 936, 920, 785, 657. Anal. Calcd.
for C12H24ClNO3Sn (%): C 37.5, H 6.3, N 3.6. Found: C 37.4, H 6.2,
N 3.5. MS (ESI +): m/z = 216.2 [C12H26NO2]+, 234.2 [N(CH2CMe2-
OH)3 + H]+, 350.0 [M − Cl]+, 391.1 [M − Cl + MeCN]+. Molecular
weight (osmometric, CHCl3): Calcd. for C12H24ClNO3Sn: 385.1 g/mol.
Found: 427.6 g/mol.
1-Diphenyldithiophosphinato 2,8,9-trioxa-5-aza-3,3,7,7,10,10-
hexamethyl-stannatricyclo[3.3.3.01.5]undecane (11). To a magneti-
cally stirred solution of 1 (0.58 g, 1.37 mmol) in dry toluene (70 mL)
a solution of diphenylphosphinodithioic acid (0.34 g, 1.36 mmol) in
dry toluene (40 mL) was added dropwise at room temperature. After
stirring for 18 h the volatiles were removed under reduced pressure.
The residue was dissolved in dry toluene (10 mL), heated to reflux and
filtered. Cooling of the filtrate to room temperature and standing for
several days gave 11 (0.70 g, 1.17 mmol, 85%) as colorless crystals. 1H
NMR (400.13 MHz, C6D6, 298 K): δ 8.23 (ddd, 3J(1H−31P) = 14.5 Hz,
3J(1H−1H) = 3.2 Hz, 3J(1H−1H) = 2.5 Hz, 4H, m-H), 7.08 (m, 6H, o-H,
1-Bromido-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-
stannatricyclo[3.3.3.01.5]undecane (14). Trimethylbromidosilane
(0.50 g, 3.27 mmol) was added dropwise to a stirred solution of 1
(1.37 g, 3.25 mmol) in dry toluene (150 mL) at room temperature.
After it was stirred for 48 h at room temperature the mixture was con-
centrated to 80 mL under reduced pressure. The remaining suspension
was heated to reflux, filtered and after slow cooling to room tempe-
rature compound 14 (1.21 g, 2.82 mmol, 87%) was obtained as
1
p-H), 2.55 (s, J(1H−117/119Sn) = 20.7, 6H, NCH2), 1.21 (s, 1J(1H−13C) =
125.2 Hz, 18H, C(CH3)2). 13C{1H} NMR (100.63 MHz, C6D6, 298 K):
colorless crystals. H NMR (400.13 MHz, CD2Cl2, 298 K): δ 2.96 (s,
J(1H−117/119Sn) = 22.2 Hz, 1J(1H−13C) = 138.9 Hz, 6H, NCH2), 1.30
1
(s, J(1H−13C) = 126.1 Hz, 18H, C(CH3)2). 13C{1H} NMR (100.63
δ 139.4 (d, J(13C−31P) = 85.2 Hz, J(13C-117/119Sn) = 16.2 Hz), i-C),
131.7 (d, 2J(13C−31P) = 11.7 Hz, o-C), 130.8 (d, 4J(13C−31P) = 3.0 Hz,
p-C), 128.0 (d, 3J(13C−31P) = 13.0 Hz, m-C), 70.6 (s, J(13C−117/119Sn) =
31.0 Hz, C(CH3)2O), 70.3 (s, J(13C−117/119Sn) = 51.3 Hz, NCH2),
31.5 (s, J(13C−117/119Sn) = 31.7 Hz, C(CH3)2). 31P{1H} NMR (81.02
MHz, C6D6, 298 K): δ 56.5 (s, 2J(31P−119Sn) = 63.0 Hz, 2J(31P−117Sn) =
1
3
MHz, CD2Cl2, 298 K): δ 70.9 (s, J(13C−117/119Sn) = 28.7 Hz,
C(CH3)2), 70.3 (s, J(13C−117/119Sn) = 54.0 Hz, NCH2), 31.2 (s,
J(13C−117/119Sn) = 32.1 Hz, C(CH3)2). 119Sn{1H} NMR (111.89
MHz, CD2Cl2, 298 K): δ −284 (s, Δν1/2 = 15.72 Hz). 13C CP-MAS
NMR (100.63 MHz, 300 K, Supporting Information Figure S7): δiso
73.8 (s, C(CH3)2O, NCH2)), 36.3, 35.4 (CCH3). 119Sn CP-MAS
NMR (149 MHz, 300 K): δiso −260 (s), −271 (s), −282 (s), −290.1
(s). Mp. 180 °C (decomposition). Anal. Calcd. (%) for C12H24-
BrNO3Sn: C 33.6, H 5.6, N 3.3. Found: C 33.7, H 5.8, N 3.1. MS (ESI +):
m/z = 234.2 [N(CH2CMe2OH)3 + H]+, 430.1 [M + H]+, 583.3 [M −
Br + N(CH2CMe2OH)3]+.
1
2
61.0 Hz, J(31P−13C) = 85.2 Hz, J(31P−13C) = 11.9 Hz). 119Sn{1H}
NMR (112 MHz, C6D6, 298 K): δ −246 (d, J(119Sn−31P) = 64 Hz).
2
Mp. 180−182 °C (decomposition). Anal. Calcd. for C24H34NO3PS2Sn
(%): C 48.2, H 5.7, N 2.3. Found: C 48.4, H 5.7, N 2.2. MS (ESI +):
m/z = 234.3 [N(CH2CMe2OH)3 + H]+, 391.1 [M − SP(S)Ph2 +
MeCN]+, 583.3 [M − SP(S)Ph2 + N(CH2CMe2OH)3]+, 600.2
[M + H]+. MS (ESI−): m/z = 248.9 [SP(S)Ph2]−.
1-Iodido-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-
stannatricyclo[3.3.3.01.5]undecane (15). The procedure is the same as
described for compound 14, with 1 (3.06 g, 7.25 mmol) and trimethyl-
iodidosilane (1.45 g, 7.25 mmol) as starting materials. Recrystallization
from toluene gave 15 (3.19 g, 6.70 mmol, 92%) as colorless columns.
1H NMR (400.13 MHz, CD2Cl2, 298 K): δ 2.95 (s, J(1H-117/119Sn) =
1-(4-tert-Butylbenzoato 2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexam-
ethyl-stannatricyclo[3.3.3.01.5]undecane (12). The procedure is the
same as described for compound 11, with 1 (1.66 g, 3.93 mmol) and
4-tert-butylbenzoic acid (0.70 g, 3.93 mmol) as starting materials.
Compound 12 was obtained as colorless amorphous solid (2.07 g,
3.93 mmol, quantitative). Recrystallization from toluene/hexane gave
crystals suitable for single crystal X-ray diffraction analysis. 1H
1
1
22.1 Hz, J(1H−13C) = 138.7 Hz, 6H, NCH2), 1.29 (s, J(1H−13C) =
126.1 Hz, 18H, C(CH3)2). 13C{1H} NMR (100.63 MHz, CD2Cl2, 298
K): δ 71.3 (s, J(13C−117/119Sn) = 33.1 Hz, C(CH3)2), 70.2 (s,
J(13C−117/119Sn) = 53.7 Hz, NCH2), 31.2 (s, J(13C−117/119Sn) = 30.5
Hz, C(CH3)2). 119Sn{1H} NMR (112 MHz, CD2Cl2, 298 K): δ −396
(s). mp: 232 °C. Anal. Calcd. for C12H24INO3Sn (%): C 30.3, H 5.1, N
2.9. Found: C 30.3, H 5.1, N 2.7. MS (ESI +): m/z = 216.2
[C12H26NO2]+, 234.2 [N(CH2CMe2OH)3 + H]+, 306.2 [N-
(CH2CMe2OH)3 + CH2CMe2OH]+, 349.9 [M − I]+, 477.9 [M + H]+.
1,4-Bis[(2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-1-
stannatricyclo[3.3.3.01.5]undecane-1-yloxy)dimethylsilyl]benzene
(16). The procedure is the same as described for compound 3, with 1
(2.30 g, 5.45 mmol) and 1,4-bis(hydroxydimethylsilyl)benzene (0.62 g,
2.74 mmol) as starting materials. The concentrated toluene suspension
was filtered and washed with cold toluene. Crystallization from
dichloromethane/hexane gave 16 (1.96 g, 2.12 mmol, 78%) as
3
NMR (400.13 MHz, C6D6, 298 K): δ 8.14 (d, J(1H−1H) = 8.4 Hz,
2H, o-H), 6.98 (d, 3J(1H−1H) = 8.4 Hz, 2H, m-H), 2.38 (s,
J(1H−117/119Sn) = 18.3 Hz, 6H, NCH2), 1.28 (s, 18H, C(CH3)2), 0.98
(s, 9 H, C(CH3)3). 13C{1H} NMR (100.63 MHz, C6D6, 298 K): δ
156.3 (s, COO), 131.3 (s, aryl-C), 129.3 (s, aryl-C), 128.5 (s, aryl-C),
125.4 (s, aryl-C), 69.6 (s, J(13C−117/119Sn) = 25.7 Hz, NCH2), 70.7 (s,
J(13C−117/119Sn) = 50.5 Hz, 29.9 Hz, C(CH3)2O), 34.8 (s, C(CH3)3),
31.4 (s, J(13C-117/119Sn) = 35.8 Hz, C(CH3)2), 31.0 (s, C(CH3)3).
119Sn{1H} NMR (111.89 MHz, C6D6, 298 K): δ −416 (s, Δν1/2 = 387
Hz). Anal. Calcd. for C23H37NO5Sn (%): C 52.5, H 7.1, N 2.7. Found:
C 52.5, H 7.1, N 2.5. MS (ESI +): m/z = 216.3 [C12H26NO2]+, 234.3
[N(CH2CMe2OH)3 + H]+, 528.3 [M + H]+, 583.4 [M −
t
OC(O)C6H4 Bu + N(CH2CMe2OH)3]+.
1-Chlorido-2,8,9-trioxa-5-aza-3,3,7,7,10,10-hexamethyl-
stannatricyclo[3.3.3.01.5]undecane (13). At room temperature, acetyl
chloride (0.31 g, 3.95 mmol) was added dropwise to a stirred solution
of 1 (1.68 g, 3.98 mmol) in dry toluene (100 mL). The mixture was
heated at reflux for 1 h. The reaction mixture was slowly cooled to
room temperature to afford colorless crystals. Recrystallization and
subsequent washing with cold toluene (5 mL) gave 13 (1.10 g, 2.86
1
colorless crystalline solid. H NMR (300.13 MHz, CD2Cl2, 296 K): δ
7.63 (s, J(1H−13C) = 146.0 Hz/148.8 Hz, 4H, aryl-H), 2.88 (s,
J(1H−117/119Sn) = 18.3 Hz, 12H, NCH2), 1.26 (s, 1J(1H−13C) = 125.8
1
2
Hz, 36H, C(CH3)2), 0.35 (s, J(1H−13C) = 118.4 Hz, J(1H−29Si) =
16.3 Hz, 4J(1H−119Sn) = 6.3 Hz, 12H, SiCH3). 13C{1H} NMR (100.63
MHz, CD2Cl2, 296 K): δ 142.5 (s, i-C), 132.5 (s, aryl-C), 70.6 (s,
J(13C−117/119Sn) = 50.2 Hz, NCH2), 69.2 (s, J(13C−117/119Sn) = 18.2
Hz, C(CH3)2O), 31.3 (s, J(13C−117/119Sn) = 31.5 Hz, C(CH3)2), 1.73
1
mmol, 72%) as colorless columns. H NMR (300.13 MHz, CDCl3,
298 K): δ 2.96 (s, J(1H−117/119Sn) = 22.6 Hz, 1J(1H−13C) = 138.8 Hz,
1
3
(s, J(13C−29Si) = 59.6 Hz, J(13C−119Sn) = 7.2 Hz, SiCH3). 29Si{1H}
1
1
6H, NCH2), 1.31 (s, J(1H−13C) = 126.2 Hz, 18H, C(CH3)2). H
NMR (60 MHz, CD2Cl2, 296 K): δ 2.2 (s, J(29Si−13C) = 59.6 Hz,
1
NMR (300.13 MHz, CD2Cl2, 215 K): δ 2.94 (s, Δν1/2 = 39.3 Hz, 6H,
2J(29Si−117/119Sn) = 26.4 Hz). 119Sn{1H} NMR (111.89 MHz, CD2Cl2,
NCH2), 1.24 (s, J(1H−13C) = 126.2 Hz, 18H, C(CH3)2).13C{1H}
1
2
NMR (75.48 MHz, CDCl3, 298 K): δ 70.3 (s, J(13C−117/119Sn) = 25.5
Hz, C(CH3)2), 70.2 (s, J(13C−117/119Sn) = 52.8 Hz, NCH2), 31.1 (s,
J(13C−117/119Sn) = 32.4 Hz, C(CH3)2). 13C{1H} NMR (75.48 MHz,
CD2Cl2, 210 K): δ 70.1 (s, J(13C−117/119Sn) = 23.6 Hz, C(CH3)2), 69.0
(s, J(13C−117/119Sn) = 52.4 Hz, NCH2), 30.5 (s, J(13C−117/119Sn) =
32.4 Hz, C(CH3)2).119Sn{1H} NMR (111.89 MHz, CDCl3, 298 K):
296 K): δ −313 (s, J(119Sn−13C) = 51 Hz, J(119Sn−29Si) = 27 Hz).
mp: 315−316 °C (decomposition). Anal. Calcd for C34H64N2O8-
Si2Sn2 (%): C 44.3, H 7.0, N 3.0. Found: C 43.3, H 6.8, N 2.9. MS
(ESI+): m/z = 216.2 [C12H26NO2]+, 234.2 [N(CH2CMe2OH)3 +
H]+, 583.4 [N(CH2CMe2O)3Sn + N(CH2CMe2OH)3]+, 715.3
[N(CH2CMe2O)3SnOSn(OCMe2CH2)3N + H]+, 773.5, 867.1,
1044
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
932.2, 999.3, 1062.4 [N(CH2CMe2O)3SnOSn(OCMe2CH2)3N +
N(CH2CMe2O)3Sn]+, 1156.8 [M + N(CH2CMe2OH)3 + H]+,
1221.3, 1325.4, 1444.3.
acid, p-t-BuC6H4COOH, gave the stannatranes 3−12,
respectively, in high yields (Scheme 5).
The synthesis of the halogenido-substituted stannatranes
13−15 was achieved by the reaction of compound 1 with acetyl
chloride, CH3C(O)Cl, and trimethylhalogenido silanes, Me3SiX
(X = Br, I), respectively (Scheme 5).
The spacer-bridged dinuclear stannatrane 16 containing a
Sn−O−Si bond sequence was obtained by the reaction of
compound 1 with 1,4-bis(hydroxydimethylsilyl)benzene
C6H4(SiMe2OH)2-1,4 (Scheme 6).
Crystallography. All intensity data were collected with an
Xcalibur2 CCD diffractometer (Oxford Diffraction) using Mo−Kα
radiation at 110 K. The structures were solved with direct methods
using SHELXS-9733 and refinements were carried out against F2 by
using SHELXL-97.33 All non-hydrogen atoms were refined using
anisotropic displacement parameters. The C−H hydrogen atoms were
positioned with idealized geometry and refined using a riding model.
In compound 5·0.25 C7H8 and in compound 15·C7H8 the solvate
molecules were found severely disordered and removed by Squeeze-
(Platon)34 to improve the main part of the structure. CCDC-847238
(3), CCDC-847239 (4), CCDC-847240 (5·0.25 C7H8), CCDC-
847241 (6), CCDC-847242 (7), CCDC-847243 (8), CCDC-847244
(11), CCDC-847245 (12), CCDC-847246 (13), CCDC-847247
(14), CCDC-847248 (15·C7H8), and CCDC-847249 (16) contain
the supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic Data
Centre via www.ccdc.cam.ac.uk/data_request/cif.
Electrochemistry. An EG&G 362 and a PAR-2273 potentiostats
were used for voltammetry and chronoamperometric experiments. The
2 mm in diameter glassy carbon (GC) and a 0.5 mm Pt disk working
electrodes were used. A 2.5 × 50 mm GC rod, separated from the
analyte by a sintered glass diaphragm, was used as counter electrode.
Peak potentials Ep were measured relative to Pt wire electrode
electrochemically covered with polypyrrole and corrected using in situ
reversible system ferrocenium/ferrocene (EF°c+/Fc(DMSO) = 0.31 V vs
SCE35). For EPR-coupled electrochemical experiments, a 1.8 mm
cylindrical three-electrode version of the four-electrode cell36 with Pt
spiral working electrode was used. Cell polarization was starting from
E = 0 V with the increments of 50 mV until the appearance of an EPR
signal.
The stannatranes 3−8 and 11−16 are colorless or yellowish
(5·0.25C7H8) crystalline materials. Notably, on exposure to air
and light the color of the iodido-substituted stannatrane
15·C7H8 changed to yellow. Compound 9 was obtained as
yellow amorphous solid and compound 10 as yellowish oil that
solidified upon standing. All compounds are soluble in benzene,
toluene, dichloromethane and tetrahydrofurane, but at room
temperature the chlorido and bromido derivatives 13 and 14
are only well soluble in dichloromethane or chloroform.
The molecular structures of 3, 4, 5·0.25C7H8, 6−8, 11−14,
15·C7H8, and 16, as determined by single-crystal X-ray
diffraction analysis, are shown in Figures 1−12. Selected
bond distances and bond angles are summarized in Tables 1−3.
The unit cells of compounds 3, 5·0.25C7H8, 11, and 12 each
contain two crystallographic independent molecules a and b the
geometric parameters of which differ only slightly. Con-
sequently, only the molecules 3a, 5a, 11a, and 12a are shown
whereas 3b, 5b, 11b, and 12b are given in the Supporting
Information (Figures S1−S4).
Similar to parent titanatranes N(CH2CMe2O)3TiOR (R = i-Pr;
2,6-di-i−Pr−C6H3)30,39 or 1-tert-butyl-stannatrane N(CH2CH2O)3-
Sn-t-Bu16 and in contrast to the related oxygen bridged tin(II)
As supporting electrolytes, Bu4NPF6 or Bu4NBF4 (as 0.1 M
solution) were used, activated in vacuum at 80 °C for 10 h prior to use.
For conductivity measurements, a conductimeter Jenway 4320 was
used. Multispec 1500 (Schimadzu) UV−vis spectrometer and X-band
Bruker EMX EPR spectrometer (9.46 GHz) coupled to a standard
rectangular cavity were used for spectro-electrochemical experiments.
EPR spectra were simulated using Bruker WINEPR SimFonia software.37
DFT Calculations. Geometry optimization, frequency and NBO
analyses were performed at DFT B3LYP/DGDZVP//HF/6-311G level
using GAUSSIAN 03 package.38
26
alkoxide [HOCMe2CH2N(CH2CMe2O)2Sn]2 or the oxygen
bridged 1-methyl-stannatrane [N(CH2CH2O)3SnMe]3·6H2O,15
the stannatranes 3−8 and 11−16 adopt each a monomeric
structure in the solid state, mainly due to the steric protection
by the methyl groups of the atrane framework. As result of the
intramolecular N→Sn coordination the tin atoms, except for
the benzoate-substituted compound 12, show each a distorted
trigonal bipyramidal configuration with the N(1)/N(2) and the
O(4)/O(104) respectively S(1)/S(2) atoms occupying the
axial positions. The equatorial positions are occupied by the
O(1)−O(3) and O(101)−O(103) atoms, respectively. The tin
atom is displaced from the plane E(Oequatorial) defined by the
oxygen atoms O(1)−O(3) or O(101)−O(103) in direction to
the exocyclic ligand (Table 4). The geometrical goodness
ΔΣ(ϑ)°40 of the trigonal bipyramidal configuration of the tin
atoms in compounds 3−8, 11, and 13−16 falls in the range
between 55.4° (8) and 64.6° (5) and indicates strong distortion
from the ideal geometry (Table 4). The N−Sn distances vary
between 2.295(3) Å (12) and 2.232(2) Å (5b) with the latter
being one of the two shortest Sn−N distance reported for
stannatranes. The shortest such bond so far (2.231(7) Å) was
reported for N[CH2C(O)O]3Sn(CH2)3N(O)Me2.17 The N−
Sn distances in the 1-halogenido-substituted stannatranes 13−
15·C7H8 decreases in the order X = Cl → I (13, X = Cl, d(N−
Sn) = 2.268 (12) Å; 14, X = Br, d(N−Sn) = 2.263(7) Å;
15·C7H8, X = I, d(N−Sn) = 2.279(6) Å). Remarkably, for 1−
halogenido-carbastannatranes N(CH2CH2CH2)3SnX (X = Cl,
d(N−Sn) = 2.37(3)/2.384(4) Å; X = Br, d(N−Sn) = 2.28(2)
Å; X = I, d(N−Sn) = 2.375(6) Å) the strongest donor
interaction was found for X = Br which was explained by
counteractive effects of electronegativity and lone pair interaction
RESULTS AND DISCUSSION
■
The reaction of tin tetra-t-butoxide, Sn(O-t-Bu)4, and tin tetra-
i-propoxide, Sn(O-i-Pr)4, with tris(2-hydroxy-2-methyl-propyl)-
amine, N(CH2CMe2OH)3, gave the novel 1-alkoxy-stanna-
tranes 1 and 2, respectively (Scheme 4).
Scheme 4. Syntheses of 1-alkoxy-stannatranes.
Both compounds are highly sensitive to moisture, well soluble
in dichloromethane, tetrahydrofurane, and diethylether and
show moderate solubility in toluene and benzene. Especially
compound 1 proved to be a rather useful starting material for
the synthesis of a variety of inorganic stannatranes. Thus, in an
acid−base type reaction the treatment of the t-butoxystanna-
trane 1 with phenol, thiophenol and aminoethanol derivatives,
diphenyldithiophosphinic acid, Ph2P(S)SH, and p-t-butyl benzoic
1045
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Scheme 5. Synthesis of the novel stannatranes 3−15.
Scheme 6. Synthesis of compound 16.
Figure 2. Molecular structure of compound 4 (ORTEP presentation
at 30% probability of the depicted atoms and atom numbering
scheme).
Figure 1. Molecular structure of compound 3 (molecule 3a, ORTEP
presentation at 30% probability of the depicted atoms and atom
numbering scheme.
Figure 3. Molecular structure of compound 5·0.25C7H8 (molecule 5a,
ORTEP presentation at 30% probability of the depicted atoms and
atom numbering scheme). The solvent molecule was removed by
Platon Squeeze.34
of the halogen substituents.40 As typical for stannatrane-type
compounds, the five membered rings of the atrane framework
adopt uniform envelope conformations and make the molecules
chiral. The combinations of stereoisomers and crystallo-
graphically independent molecules in the unit cell are
summarized in Table 5. Looking along the X−Sn−N axis, the
unit cells of the stannatranes 3, 5·0.25C7H8, and 11 each contain
two crystallographically independent molecules a and b that exist
as pairs of enantiomers (3aΔ, 3bΔ/3aΛ, 3bΛ). The unit cells of
the stannatranes 4, 14, and 15·C7H8 each contain only one cry-
stallographically independent molecule as single enantiomers
1046
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Figure 4. Molecular structure of compound 6 (ORTEP presentation
at 30% probability of the depicted atoms and atom numbering
scheme).
Figure 7. Molecular structure of compound 11 (molecule 11a,
ORTEP presentation at 30% probability of the depicted atoms and
atom numbering scheme).
Figure 5. Molecular structure of compound 7 (ORTEP presentation
at 30% probability of the depicted atoms and atom numbering
scheme).
Figure 8. Molecular structure of compound 12 (molecule 12a,
ORTEP presentation at 30% probability of the depicted atoms and
atom numbering scheme).
Figure 6. Molecular structure of compound 8 (ORTEP presentation
at 30% probability of the depicted atoms and atom numbering
scheme).
with clockwise (4Δ) and anticlockwise (14Λ, 15Λ) orientation
of the propellers whereas the unit cells of compounds 6−8 each
contain one crystallographically independent molecule as well,
but as pair of enantiomers 6Δ/6Λ, 7Δ/7Λ, and 8Δ/8Λ. The unit
cell of the benzoate-substituted stannatrane 12 contains two
crystallographically independent molecules 12aΔ and 12bΛ,
both as single enantiomers. The unit cell of the spacer-bridged
distannatrane 16 contains a single diastereomer in which one
stannatrane moiety shows clockwise and the other one shows
anticlockwise orientation. A special situation is observed for
the chlorido-substituted stannatrane 13. The unit cell contains
Figure 9. Molecular structure of compound 13 (ORTEP presentation
at 30% probability of the depicted atoms and atom numbering
scheme). Only one-half of one atrane propeller is present in the
asymmetric unit. The other half and the two other propellers are
created by symmetry operations (symm. codes (A) −x + 1, x − y + 1,
z; (B) −x + y, −x + 1, z; (C) −y + 1, −x + 1, z; (D) −x + y, y, z; (E) x,
x − y + 1, z).
a single crystallographically independent molecule the atrane
cage of which is, however, completely disordered in such a
1047
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
way that the structure can be interpreted in terms of a super-
position of four pairs of enantiomers of different conformations
(Figure 13).
The same result was obtained from the analysis of X-ray
diffraction data recorded at room temperature. The interpre-
tation is supported by the 119Sn CP MAS spectrum (Supporting
Information, Figure S5) showing four equally intense reson-
ances at δiso −233, −236, −238, and −239. The X-ray powder
diffraction measurement confirms the homogeneity of the bulk
material (Supporting Information, Figure S6). Strange enough,
four equally intense 119Sn resonances are also observed for the
bromido-substituted stannatrane 14 (δiso −260, −270, −282,
−290) (Supporting Information, Figure S7, 13C CP MAS
Figure S8) the molecular structure of which (obtained from
X-ray diffraction data measured at low temperature) shows a
single enantiomer only (see above). The X-ray measurement of
the cell parameters of seven single crystals revealed the same
parameters. Consequently, it is rather unlikely that the bulk
material used for the 119Sn CP MAS spectrum is a mixture com-
posed of single crystals containing different conformers. This is
supported by a X-ray powder diffraction measurement con-
firming this conclusion as the data obtained fit reasonably well
with the simulated data obtained from the single crystal mea-
surement (Supporting Information, Figure S9). Given the fact
that during the 119Sn CP MAS data acquisition the sample heats
up to approximately 60 °C it might be that at this temperature
all four pairs of conformers are formed.
Figure 10. Molecular structure of compound 14 (ORTEP pre-
sentation at 30% probability of the depicted atoms and atom num-
bering scheme). Symmetry codes (A) −x + y, −x + 1, z; (B) −y + 1,
x − y + 1, z.
Compared to the stannatranes 3−8, 11, and 13−16 the tin
atom of the benzoate-substituted stannatrane 12 exhibits an
even more distorted trigonal bipyramidal configuration as result
of the unisobidentate coordination mode of the benzoate sub-
stituent associated with intramolecular O(5) → Sn(1)/O(105)
→ Sn(2) interactions at distances of 2.574(3) (12a) and
2.473(3) Å (12b) that are considerably shorter than the sum of
the van der Waals radii (3.70 Å) of the corresponding atoms.
These interactions are also reflected in a widening of the O(1)−
Sn(1)−O(3)/O(101)−Sn(2)−O(103) angles to 130.0(1)
(12a) and 125.0(1)° (12b). Moreover, a short O→Sn interac-
tion causes a long N→Sn interaction and vice versa.
The 119Sn solution NMR spectra of the 1-alkoxido- and aryloxido-
substituted stannatranes 1−7, and 16, respectively, show single
resonances between δ −311 (7) and δ −333 (3). Surprisingly,
these signals are high- and not, as expected, low-frequency shifted
with respect to tetracoordinated Sn(O-t-Bu)4 (δ −37441,42).
For the latter compound low-frequency shifts at δ −510 and
δ −420 have been reported upon addition of t-butanol and
pyridine, respectively.41 For a reliable interpretation of the
chemical shifts of compounds 1−7 and 16 with respect to the
strength of intramolecular N→Sn coordination, a model
compound such as HC(CH2CMe2O)3SnOR (R = alkyl, aryl)
that lacks such an interaction would be needed which is, however
not easy to be synthesized. The thiophenolato- and diphenyl-
phosphinodithiolato- substituted stannatranes 8 and 11 show
single 119Sn NMR resonances at δ −227 (8) and δ −246 (11),
respectively. The high-frequency shift of the two latter
compounds with respect to the compounds mentioned above
is the result of the introduction of sulfur atoms at the 1-position.
The only slightly high field shift of the resonance observed for 11
compared to the thiophenolato-substituted derivative 8 indicates
pentacoordination of the tin atom in 11 without additional P
S → Sn coordination as already shown for the solid state. The
halogenido-substituted stannatranes 13−15 show single reso-
nances at δ −243 (δ −235 at 213 K, 13), δ −248 (14), and δ
Figure 11. Molecular structure of compound 15·C7H8 (ORTEP
presentation at 30% probability of the depicted atoms and atom
numbering scheme). The solvent molecule was removed by Platon
Squeeze.34
Figure 12. Molecular structure of compound 16 (ORTEP
presentation at 30% probability of the depicted atoms and atom
numbering scheme). Symmetry code (A) −x + 1, −y + 1, −z + 1.
1048
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Table 1. Selected Bond Distances (Å) and Angles (deg) for Compounds 3−8
3 (X = O(4))
4 (X = O(4))
5·0.25C7H8 (X = O(4))
6 (X = O(4))
7 (X = O(4))
8 (X = S(1))
Sn(1)−O(1)
Sn(1)−O(2)
Sn(1)−O(3)
Sn(1)−X
Sn(1)−N(1)
Sn(2)−O(101)
Sn(2)−O(102)
Sn(2)−O(103)
1.965(2)
1.982(2)
1.971(2)
1.960(2)
2.255(2)
1.975(2)
1.980(2)
1.975(2)
1.970(2)
2.253(3)
117.1(1)
115.8(1)
100.4(1)
82.3(1)
1.972(3)
1.974(2)
1.970(3)
1.975(2)
2.258(3)
1.963(2)
1.970(2)
1.975(2)
1.994(2)
2.248(2)
1.972(2)
1.963(2)
1.964(2)
1.987(2)
2.232(2)
119.7(1)
118.1(1)
91.2(1)
1.971(4)
1.969(4)
1.981(4)
1.976(4)
2.254(5)
1.980(2)
1.965(2)
1.969(2)
1.989(2)
2.250(3)
1.987(2)
1.973(2)
1.984(2)
2.411(1)
2.284(3)
Sn(2)−O(104)
Sn(2)−N(2)
O(1)−Sn(1)−O(2)
O(1)−Sn(1)−O(3)
O(1)−Sn(1)−X
O(1)−Sn(1)−N(1)
O(2)−Sn(1)−O(3)
O(2)−Sn(1)−X
O(2)−Sn(1)−N(1)
O(3)−Sn(1)−X
O(3)−Sn(1)−N(1)
N(1)−Sn(1)−X
Sn(1)−X−C(41)
O(101)−Sn(2)−O(102)
O(101)−Sn(2)−O(103)
O(101)−Sn(2)−O(104)
O(101)−Sn(2)−N(2)
O(102)−Sn(2)−O(103)
O(102)−Sn(2)−O(104)
O(102)−Sn(2)−N(2)
O(103)−Sn(2)−O(104)
O(103)−Sn(2)−N(2)
N(2)−Sn(1)−X
115.0(1)
120.1(1)
95.7(1)
82.7(1)
120.0(1)
99.4(1)
82.3(1)
97.3(1)
82.6(1)
178.1(1)
124.8(3)
118.2(2)
116.1(2)
94.9(2)
82.5(2)
120.4(2)
96.5(2)
82.2(2)
101.6(2)
82.3(2)
176.0(2)
124.1(3)
117.1(1)
116.5(1)
104.3(1)
82.7(1)
121.4(1)
90.5(1)
82.5(1)
98.0(1)
82.3(1)
171.8(1)
130.0(2)
117.6(1)
117.7(1)
99.4(1)
80.4(1)
117.4(1)
95.3(1)
81.5(1)
102.6(1)
80.9(1)
176.1(1)
105.2(1)
82.8(1)
121.5(1)
91.9(7)
117.0(1)
101.1(1)
82.0(1)
81.7(1)
101.6(1)
82.3(1)
100.7(1)
82.3(1)
173.6(1)
133.9(2)
117.2(1)
119.9(1)
102.8(1)
82.6(1)
174.0(1)
128.2(1)
115.0(1)
118.8(1)
103.5(1)
83.3(1)
117.7(1)
98.3(1)
121.9(1)
92.9(1)
82.4(1)
82.9(1)
91.9(1)
94.7(1)
82.1(1)
83.0(1)
173.5(1)
133.4(2)
173.1(1)
133.0(2)
Sn(2)−O(104)−C(141)
Table 2. Selected Bond Distances (Å) and Angles (deg) for compounds 11 and 12
11 (X = S, Y = P,
12 (X = O, Y = C, a = 4,
11 (X = S, Y = P,
12 (X = O, Y = C, a = 4,
a, c = 1, b = 3, d = 2) b = 104, c = 40, d = 140)
a, c =1, b = 3, d = 2) b = 104, c = 40, d = 140)
Sn(1)−O(1)
Sn(1)−O(2)
Sn(1)−O(3)
Sn(1)−O(5)
Sn(1)−X(a)
Sn(1)−N(1)
1.979(2)
1.977(2)
1.983(2)
1.981(3)
1.975(3)
1.971(2)
2.574(3)
2.049(2)
2.270(3)
Sn(2)−O(101)
Sn(2)−O(102)
Sn(2)−O(103)
Sn(2)−O(105)
Sn(2)−X(b)
Sn(2)−N(2)
1.984(2)
1.975(2)
1.974(2)
1.989(2)
1.998(3)
1.972(2)
2.473(3)
2.077(3)
2.295(3)
2.428(1)
2.288(2)
2.429(1)
2.276(2)
O(1)−Sn(1)−O(2)
O(1)−Sn(1)−O(3)
O(1)−Sn(1)−O(5)
O(1)−Sn(1)−X(a)
O(1)−Sn(1)−N(1)
O(2)−Sn(1)−O(3)
O(2)−Sn(1)−O(5)
O(2)−Sn(1)−X(a)
O(2)−Sn(1)−N(1)
O(3)−Sn(1)−O(5)
O(3)−Sn(1)−X(a)
O(3)−Sn(1)−N(1)
O(4)−Sn(1)−O(5)
N(1)−Sn(1)−X(a)
N(1)−Sn(1)−O(5)
Sn(1)−X(a)−Y(c)
122.2(1)
108.1(1)
O(101)−Sn(2)−O(102)
O(101)−Sn(2)−O(103)
O(101)−Sn(2)−O(105)
O(101)−Sn(2)−X(b)
O(101)−Sn(2)−N(2)
O(102)−Sn(2)−O(103)
O(102)−Sn(2)−O(105)
O(102)−Sn(2)−X(b)
O(102)−Sn(2)−N(2)
O(103)−Sn(2)−O(105)
O(103)−Sn(2)−X(b)
O(103)−Sn(2)−N(2)
O(104)−Sn(2)−O(105)
N(2)−Sn(2)−X(b)
N(2)−Sn(2)−O(105)
Sn(2)−X(b)−Y(d)
114.5(1)
112.3(1)
118.2(1)
130.0(1)
82.5(1)
102.7(1)
81.2(1)
115.1(1)
146.1(1)
90.5(1)
81.9(1)
75.6(1)
100.8(1)
81.2(1)
55.7(1)
172.2(1)
131.9(1)
102.6(3)
119.7(1)
125.0(1)
84.8(1)
105.4(1)
80.0(1)
114.4(1)
142.1(1)
85.6(1)
80.3(1)
75.9(1)
105.6(1)
80.7(1)
56.7(1)
164.0(1)
137.3(1)
99.7(3)
104.0(1)
80.8(1)
87.8(1)
81.0(1)
111.8(1)
118.7(1)
107.8(1)
80.7(1)
106.0(1)
81.3(1)
84.6(1)
80.5(1)
102.8(1)
80.8(1)
164.8(1)
102.3(1)
168.4(1)
103.9(1)
1049
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Table 3. Selected Bond Distances (Å) and Angles (deg) for Compounds 13−16
13 (X = Cl(1), a = 1a)
14 (X = Br(1), a = 1a))
15·C7H8 (X = I(1), a = 2)
16 (X = O(4), a = 2)
Sn(1)−O(1)
Sn(1)−O(2)
Sn(1)−O(3)
Sn(1)−X
1.974(3)
1.973(3)
1.974(5)
1.969(5)
1.955(5)
2.676(1)
2.279(6)
120.7(3)
117.9(2)
98.6(2)
1.968(2)
1.970(2)
1.972(2)
1.942(1)
2.258(2)
118.4(1)
119.5(1)
97.8(1)
2.338(5)
2.268(12)
118.20(5)
2.473(1)
2.263(7)
Sn(1)−N(1)
O(1)−Sn(1)−O(a)
O(1)−Sn(1)−O(3)
O(1)−Sn(1)−X
O(1)−Sn(1)−N(1)
O(2)−Sn(1)−O(3)
O(2)−Sn(1)−X
O(2)−Sn(1)−N(1)
O(3)−Sn(1)−X
O(3)−Sn(1)−N(1)
N(1)−Sn(1)−X
Sn(1)−O(4)−Si(1)
118.05(4)
97.77(10)
82.23(10)
98.10(8)
81.90(8)
81.2(2)
81.3(1)
115.5(2)
97.1(2)
116.1(1)
96.6(1)
81.8(2)
82.3(1)
98.5(2)
100.2(1)
81.9(1)
82.7(2)
180.000(3)
180.000(2)
178.6(2)
177.8(1)
133.2(1)
The 119Sn and 13C NMR spectra in CD2Cl2 at 213 and 210 K,
respectively, of the chlorido-substituted stannatrane 13 show
the interconversion of conformational isomers (Figure 13) to
be fast on the corresponding NMR time scales. The H NMR
spectrum in CD2Cl2 at 213 K shows a broadening of the NCH2
resonance (Δν1/2 = 39.3 Hz).
Compared to the 1-alkoxido- and aryloxido-substituted
stannatranes 1−7, the o-aminophenolato- and the aminoetha-
nolato-substituted stannatranes 9 (δ −432) and 10 (δ −462)
show considerable low-frequency shifts indicating additional
intramolecular N→Sn coordination in these compounds. A
single broad resonance (δ (119Sn) = −416 (s, Δν1/2 = 387 Hz))
in the 119Sn NMR spectrum of 12 (C6D6) hints at a fast equili-
brium between penta- and hexacoordinated tin compounds that
is shifted to the latter one.
Table 4. Geometrical Goodness of the Trigonal Bipyramide
ΔΣ(ϑ)° and Distances Δ(E(Oeq)−Sn) for Compounds 3−8
and 11−16 of Type N(CH2CMe2O)3SnX
1
Δ(E(Oeq)−Sn)
compound
X
ΔΣ(ϑ)°/°
/Å
3
O-(1,2-Me2)-C6H3
60.5(Sn1)/ 0.2720(2)/
61.8(Sn2)
0.2636(2)
4
OC6H4-p-tBu
62.57
0.2565(3)
5·0.25C7H8 OC6H4-p-NO2
61.8(Sn1)/ 0.2383(2)/
64.6(Sn2)
0.2621(2)
0.2634(4)
0.2572(2)
0.3134(3)
6
OC6H4-p-F
OC6H4-p-PPh2
SC6H4-p-Me
SP(S)Ph2
61.8
7
62.2
55.4
8
11
55.8(Sn1)/ 0.3213(2)/
56.3(Sn2)
0.3090(2)
t
12
OC(O)C6H4-p- Bu
0.2952(3)/
0.3328(3)
Additional information about the identity of the stannatranes
1
in solution is provided by H and 13C NMR spectroscopy in-
13
Cl
Br
I
61.3
0.2673(17)
0.2779(8)
0.2902(6)
0.2811(1)
cluding 1H−13C hsqc or 13C-dept measurements. As expected, a
high-frequency shift of the NCH2 and CCH3 resonances com-
pared to the free trialkanolamine N(CH2CMe2OH)3 is observed.
14
59.9
58.0
59.4
15·C7H8
16
OSiMe2C6H4SiMe2O−
1
Sn(OCMe2CH2)3N
The H NMR spectra of compounds 1−16 show each one
single resonance for the diastereotopic NCH2 protons of the
atrane framework with J(1H-117/119Sn) coupling in the range of
16.1 Hz (10) to 23.5 Hz (6) (Table 6) and also one single re-
sonance for the diastereotopic CCH3 protons. Thus, com-
pounds 1−16 possess pseudo−C3v symmetry on the NMR time
scale. The 1H NMR spectra of the hexacoordinated tin compounds
9, 10 and 12 (C6D6) show slightly lower J(1H-117/119Sn) couplings
of the atrane NCH2 protons compared to the pentacoordinated
1-alkoxido- and aryloxido-substituted stannatranes 1 and 3−7
(Table 6). For compound 10, the coordination of the dime-
thylamino group is verified by the J(1H-117/119Sn) coupling of
12.2 Hz. In analogy, the 13C NMR spectra show one single re-
sonance for each of the chemically equivalent NCH2, C(CH3)2
and C(CH3)2 carbon atoms. The signals for the NCH2 and
C(CH3)2 carbon atoms show J(13C-117/119Sn) couplings in the
range of 46.6 Hz (2) to 54.0 Hz (14) and 17.5 Hz (2) to 33.1
Hz (15), respectively (Table 6).
Table 5. Stereoisomers of Independent Molecules mx (x = a, b)
with Right- (Δ) and Left-Handed (Λ) Propeller in the Unit Cell
compd.
stereoisomers in the unit cell
3, 5·0.25C7H8, 11
4
mΔa , mΛa , mΔb , mΛb
mΔa
6−8
12
mΔa , mΛa
mΔa , mΛb
13
disordered atrane framework
14, 15·C7H8
16
mΛa
mΔa ,Λ
−396 (15) with the two former shifts being close to the values
observed in their 119Sn CP MAS spectra and indicating the
structures in solution to be rather similar to those found in the
solid state. The dramatic difference between the chemical shifts
of the chlorido- and bromido-substituted stannatranes 13 and
14 on the one hand and the iodido-substituted stannatrane 15
on the other hand is traced to the much higher shielding effect
of iodine and follows the trend observed for the chemical shifts
in CS2 of SnCl4 (δ −150), SnBr4 (δ −638), and SnI4 (δ −1701).43
The ESI-MS data indicate high reactivity of the Sn−X bond
as well as a notable stability of the atrane framework. Thus, for
compounds 1−16 either the mass cluster of the atrane frame-
work (m/z = 350.1 [N(CH2CMe2O)3Sn]+) or mass clusters of
aggregates containing the atrane framework are present in the
1050
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Figure 13. Four pairs of enantiomers of compound 13 by different conformations of the atrane propellers.
Table 6. Selected NMR Data of N(CH2CMe2O)3SnX
J(1H2C−117/119Sn)
J(13CH2−117/119Sn)
J(13CMe2−117/119Sn)
J(13CH3−117/119Sn)
compd.
X
δ
119Sn
/Hz
/Hz
/Hz
/Hz
1
t-BuO
−319
−312
−333
−322
−315
−313
−311
−227
−432
−462
−246
−416
−243
−248
−396
−313
20.9
48.4
46.6
49.4
49.5
50.6
49.4
50.0
48.0
50.3
50.1
51.3
50.5
52.8
54.0
53.7
50.2
21.6
17.5
21.1
19.1
18.9
18.7
19.1
30.6
22.8
27.6
31.0
25.7
25.5
28.7
33.1
18.2
30.4
30.4
32.1
31.2
31.8
31.1
27.5
27.5
33.0
32.6
31.7
35.8
32.4
32.1
30.5
31.5
2
i-PrO
3
2,6-Me2C6H3O
p-t-BuC6H4O
p-NO2C6H4O
p-FC6H4O
p-PPh2C6H4O
p-MeC6H4S
o-NH2C6H4O
Me2NCH2CPh2O
Ph2P(S)S
21.3
23.3
23.3
23.5
23.4
21.0
19.3
16.1
20.7
18.3
22.6
22.2
22.1
18.3
4
5
6
7
8
9
10
11
12
13
14
15
16
p-t-Bu C6H4C(O)O
Cl
Br
I
N(CH2CMe2O)3SnOSiMe2- p-
C6H4SiMe2O
Table 7. Parameters of Electrochemical Oxidation of Stannatranes 4, 8, 13, and 15 at a Platinum Disk Electrode
a
b
c
cmpd
solvent
CH3CN
Ep, V
1.47
Ep − Ep/2, V
ΔEp/Δlg(v), mV
n
α
ΔEp/Δlg(v) mV
IP, eV
5.569
4
0.171
0.115
0.127
0.119
0.098
0.082
40
48
43
25
49
58
0.94
0.94
0.97
1.40
1.18
1.03
0.3
0.4
0.4
0.4
0.5
0.6
23
19
17
22
25
26
4
CH3CN/CH2Cl2
CH2Cl2
1.46
1.33
1.41
4
c
8
CH3CN
5.959
d
8
CH3CN/CH2Cl2
CH2Cl2
1.41 (1.47)
1.40 (1.53)
8
13
15
CH2Cl2
>2.2
7.338
CH2Cl2
>2.3
a
b
c
d
Peak potentials at v = 1 V/s. Formal transfer coefficient, found from (Ep - Ep/2)/1.85 = RT/αF.60 Two peaks merged. Second of two peaks.
ESI-MS spectra showing the dissociation of the axial substituent
under the experimental conditions employed. For none of the
1-alkoxy or 1-aryloxy substituted derivatives 1−7 the molecule
mass cluster [M + H]+ is observed. In contrast to this, the ESI-
MS spectra of 1-(p-methylbenzenethiolate) 8 and of 1-alkoxy
or 1-aryloxy substituted derivatives 9 and 10 containing addi-
tional NR2 (9, R = H; 10, R = Me) donor groups show the
mass clusters [8 + H]+ (90%), [9 + H]+ (70%) and [10 + H]+
(92%), respectively. The ESI mass spectra of 11, 12, 14 and 15
also confirm their identity as well as monomeric structures in
solution by showing mass clusters centered at m/z = 600.2,
528.3, 430.1, or 477.9 which are assigned to [11 + H]+, [12 + H]+,
[14 + H]+, and [15 + H]+, respectively. Furthermore, the
monomeric structure of 13 in solution was verified by osmom-
etric molecular weight determination in chloroform.
Electrochemical Studies. To get an insight into the intra-
molecular electronic interactions in the new stannatranes, the
electrochemical behavior of several compounds was considered.
Depending on their solubility, cyclic voltammetry of com-
pounds 4, 8, 13, 15 was carried out in acetonitrile (AN), CH2Cl2
or in a binary mixture (AN/CH2Cl2, 1:1 v/v) containing
Bu4NPF6 (0.1 M) as supporting salt.
1051
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Figure 14. Cyclic voltammograms for the oxidation of stannatranes. Left: (a) − 4 and (b) − 8 (10−3 mol L−1) in CH3CN/0.1 M Bu4NPF6 at a Pt
disk electrode; v = 5 V/s. Right: I−E curve of 8 (1.1 × 10−3 mol L−1) in CH2Cl2/0.1 M Bu4NPF6 at a Pt disk electrode. (a) normal scan; (b) I−t
1
curve after the hold at Ep . (c) diffusion limiting current of the second oxidation step. v = 0.5 V s−1; T = 22 °C.
Contrary to silatranes44,45 and germatranes,46 the stanna-
tranes 4 and 8 show distinct oxidation signals only at a Pt
electrode. The limiting currents ip of stannatranes 4 and 8 are
both diffusion controlled (ip/v1/2 = const; lg(ip)/lg(v) = 0.45
and 0.46 for 4 and 8, respectively) and, as was shown using
ip/v1/2 ratio along with Cottrell slope from chronoamperometry
at the same electrode,47 the number of electrons transferred at
to oxidize than parent ethers,50 the order of Ep values for
oxygen- and sulfur-containing stannatranyl derivatives is reversed
(Table 7). This is supposedly because of stronger Sn−S versus
Sn−O bonding and a stronger acceptor effect of the stanna-
tranyl moiety on the Ep of 8 compared to the Ep of 4.
The stannatranes 13 and 15 did not show any distinct oxi-
dation peaks up to the media limits. As was pointed out by
Broka et al.,45 the chlorido-substituted silatrane N(CH2CH2O)3-
SiCl cannot be oxidized. No such data exist for the chlorido-
substituted germatrane N(CH2CH2O)3GeCl but one can
expect even higher Ep since germatranes are more difficult to
oxidize than silatranes.46,51 From a simple correlation of Ep with
calculated IPs of the stannatranes 4, 8, and 13, the oxidation
potential of the chlorido-substituted derivative 13 should be
above 2.3 V which corroborates the results of its voltammetry.
On the contrary, compound 13 shows a well-shaped reduc-
tion peak at Ep = −1.5 V; the reduction process results in
elimination of Cl− anions whose oxidation peak at ∼1 V is
detected by voltammetry during the second cycle. The peak at
−1.5 V falls into the range of reduction potentials of known
chloridostannanes52 and might have arisen from the dissociative
reduction of Sn−Cl bond in 13. Similarly, the oxidation peak of
the iodide anion I− appears after the reduction of 15. This is in
agreement with the conductivity measurements of 13 in CH3CN/
CH2Cl2 (50:50 v/v), which have only shown residual solvent
conductance and no contribution from any ionic conductivity
due to the possible Sn−Cl dissociation prior to the reduction.
A practically identical conductivity curve was observed for the
phenolato-substituted stannatrane 4. Therefore the chlorido-
substituted stannatrane 13, just as 4, remains a covalent com-
pound in solution, at least in this media.
EPR-Spectroelectrochemistry. Since the oxidation of the
phenolato-substituted stannatrane 4 shows partial reversibility
(Figure 14), it was studied by real-time EPR-coupled electro-
chemistry. The solution of 4 (10−3 mol L−1) in AN/0.1 M
Bu4NPF6, initially ERP-silent, has shown the signal of para-
magnetic species when the potential 1.23 V was applied (Figure 15).
The visible end-to-end span of the observed spectrum (Δ =
23−24 G) corresponds to the coupling constants from 2 sets of
equivalent protons and to some contribution from 117/119Sn
nuclei. The g-factor (g = 2.0036) is slightly increased relative to
that of pure organic radicals because of the interaction with
1
this step is n = 1 (Table 7). Temperature dependence of lg(ip )
of 8 provides Ea = 2.46 kJ/mol (2.85 kJ/mol for second peak),
corresponding to the activation energy of the diffusion flow
of solvent. The peak half-widths Ep − Ep/2 of 4 and 8 are too
large for simple one-electron reversible processes, supposedly
because of the adsorption interactions or substantial structural
reorganization accompanying electron transfer.
In a less polar solvent such as CH2Cl2, the oxidation of 8
proceeds via two steps (Figure 14), with the second one being
reversible already at v = 0.5 V s−1. With the vertex potential set
before the onset of the second oxidation peak (Ev = 1.45 V),
the first peak also starts showing cathodic counterpart (at v >
50 V/s). Thus, both oxidation signals arise from electro-
chemically reversible processes. The i−t curve with the hold at
Ep1 (Figure 14) allowed to subtract the diffusion limited current
48
1
of the first peak ip (the baseline for the second peak and to
2
quantify the current of the second oxidation step, ip . The latter
was shown to have an electron stoichiometry of n = 0.4, caused
by self-reactions involving cation radicals, as it was observed in
the case of oxidation of Ar2S or ArSM49 with the HOMO
localized on the ArS fragment. Thus, the similarity in the oxi-
dation pattern of 8 and aryl sulfides suggests that the p-CH3C6H4S
fragment in 8 is most probably the reaction site that accounts
for the first oxidation peak. The Ep of compound 8 is about
150−200 mV higher than those of diaryl or arylalkyl sulfides,50
due to the electron acceptor effect of the stannatranyl sub-
stituent. The possibility of oxidation of the stannatranyl moiety
2
at Ep should obviously be ruled out because not only the
HOMO but also the lower lying HOMO−1 in 8 is mostly built
of sulfur atom orbitals. Moreover, considering orbital energies
(as IP = −εHOMO in Koopman’s approach, by B3LYP/LANL2DZ)
of HOMO−1 in 8 (6.655 eV) and of SOMO in 8+• (6.094 eV),
it is more probable that a second electron withdrawal affects the
cation radical, like in the case of aryl sulfides. In contrast to the
trend in Epox of diaryl and arylalkyl thioethers, which are easier
1052
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
DFT Calculations. The geometry of the stannatranes 4, 8,
and 13 and of their cation radicals was optimized using a com-
bined treatment: primary adjustment was done at HF/6-311G
level, and then the structure was optimized at DFT B3LYP/
DGDZVP level, better accounting for long-term and
delocalizing electronic interactions. The same level was used
for NBO analysis and to check the optimized structures for the
absence of imaginary vibrations.
The N−Sn distance is very little affected by electron with-
drawal. It becomes slightly longer in 4+•, slightly shorter in 8+•
and remains practically unchanged in 13+• (Table 8). Meanwhile,
other geometrical parameters of these stannatranes show re-
markable configurational change when forming the cation radical.
Thus, for the neutral stannatrane 4, the dihedral angle φ
(∠Co‑Ar−Ci‑Ar−O−Sn) is 93.63°, while it becomes 3.81° in the
cation radical (Figure 16) showing that the atrane moiety twists
Figure 15. EPR spectrum from the oxidation of stannatrane 4 in AN/
0.1 M Bu4NPF6 at a Pt microspiral electrode. Upper, experimental;
lower, simulated using the parameters in the text. T = 233 K, E = 1.23 V.
oxygen and tin and falls into the range of the values for known
phenoxyl radicals.53,54 The triplet of triplets pattern with 1:2:1
intensities is rather straightforward and fits well with two pairs
of practically equivalent protons (o,o′- and m,m′-) in the sup-
posed phenoxyl species. Though the ends of the spectrum are
not well enough resolved to allow extracting exact Sn119/117
coupling constants, its symmetry permits to suppose two values
aSn119 = 6.7 G and aSn117 = 7.4 G.
The set of 2H with the hfc constant of aHo = 6.22 G can be
substituted with two large proton hfc constants (aHo‑ = 6.27 G
Figure 16. B3LYP/DGDZVP optimized geometry of stannatrane 4
and its cation radical (see text).
and aHo′ = 6.03 G), assigned to two slightly different ortho-
‑
protons of the phenyl ring (see Figure 14). This substitution
provides a better fitting but in any case, this difference is at the
level of the (possible) contribution from the protons of the
t-Bu group. Two m-protons account for a smaller constant,
aHm = 1.85 G (2H). It appears as there is no coupling with the
atrane cage nitrogen atom or, if any, its contribution is very
small. In general, the presence of d-metals often results in
strong spin−orbital interactions55 broadening the spectral lines
and making it difficult to observe well resolved hyperfine structure.
Thus the cation radical, hereafter referred to as CR, of stannatrane
4 has the spin distribution as an O-substituted t-Bu-phenoxy
radical and not as a proper metallatrane, similarly to the cation
radicals of germatranes in which the 1-substituent has lower own
ionization potential than the atrane nitrogen atom.51
around the O−Sn bond by the right angle (55° for the couple
8/8+•). The driving force of this remarkable twist is the interaction
of pz-orbitals of the O and S atoms with the π-systems of the
aromatic fragments, destabilizing the HOMO in the neutral
molecules and stabilizing the corresponding CRs. The
stabilization of the phenoxy system in 4+• is stronger than of
the arylthio fragment in 8+•: while the couple 4/4+• clearly
switches between two most stable − orthogonal and planar −
forms (both corresponding to global minima on the energy
surface), the bulkiness of the S atom and the poorer match in
the size of overlapping orbitals in 8+• force the latter to adopt a
compromise half-eclipsed configuration. It implies that the
nuclear frames of 4 and 8, following the redistribution of the
Table 8. Selected Geometrical Parameters (Distances in Å, Angles in Degrees), Fermi Contact Terms (FCT, MHz), and NBO
Charges for Stannatranes 4, 8, 13, and Their Cation Radicals from DFT B3LYP/DGDZVP Calculations
N
Sn
a
b
b
compd
l(Sn−N)
l(Sn−X)
∠N−Sn−X
∠X−Sn−O
∠O−Sn−O
FCT
q(NBO)
FCT
q(NBO)
4
2.240
2.265
2.402
2.273
2.374
2.376
2.030
2.121
2.442
2.582
2.373
2.332
171.66
177.84
175.94
173.82
179.97
164.89
102.46 (89.07)
96.32 (98.93)
101.72
126.77 (101.43)
118.73
−0.348
−0.342
−0.326
−0.342
−0.327
−0.327
1.296
1.307
1.171
1.196
1.195
1.163
4+•
0.0000
0.0003
0.7022
−0.3056
−2.6584
104.5738
8
116.02
8+•
13
13+•
99.99 (91.72)
100.60
118.46
116.69
105.72 (90.45)
b
th126.34 (111.03)
a
X is first atom of the 1-substituent, as in Scheme 4. for two Sn-symmetrical Oeq atoms, the value given in the parentheses is for the remaining
nonsymmetrical Oeq.
1053
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
Figure 17. Unpaired electron density (SOMO) delocalization on the phenoxy fragment in the cation radical 4+• by B3LYP/DGDZVP (a), and
doubly populated (SOMO−1) orbital (b) with small contribution of 3c−4e N−Sn−O bonding.
Figure 18. Geometry and FMOs for 13/13+• from B3LYP/DGDZVP optimization: (a) neutral, (b) cation radical, (c) HOMO of 13 and (d)
SOMO of 13+•. The contribution of intramolecular N−Sn−O (3c-4e) bonding is clearly seen, though with moderate orbital coefficients.
electron density upon oxidation (electrochemical electron
transfer is adiabatic by its nature), exist in two fixed geometries:
those of neutral and of the oxidized forms (4 vs 4+• and 8 vs 8+•).
This fact precludes the formation of pure Nernstian reversible
redox systems for these compounds which accounts for small
apparent transfer coefficient α for 4 and 8 (Table 7). There is
no contribution of the nitrogen atom to the spin−orbital
interactions in 4+• since the 3c-4e system has lower energy than
SOMO (Figure 17) and is doubly populated. The 4+• is thus a
phenoxyl radical; it agrees very well with its EPR spectrum that
has no characteristic pattern of a nitrogen-centered radical.
Fermi contact couplings at the nitrogen and tin atoms (Table 8),
and at the atoms of the phenoxy fragment, obtained from
B3LYP/DGDZVP calculations, agree well with this feature.
Contrary to CRs of germatranes, showing no unpaired spin
density on the germanium atom and no coupling with it,56 the
spectrum of the iodido-substituted stannatrane 15 shows the
117/119Sn satellites which is also consistent with the nonzero
FCT on the Sn atom (Table 8).
Upon oxidation of the chlorido-substituted stannatrane 13,
the tin atom also undergoes substantial reorganization: instead
of a trigonal bipyramid it adopts the configuration of the
pyramid with a rhombic base, when one oxygen atom is at the
apical position and the long diagonal of the base is formed by
nitrogen and chlorine atoms (Figure 18); in general it re-
sembles to Berry pseudorotation transition state. The calculated
Sn−Oeq bond length is 1.994 Å in average, whereas the third
Sn−Oeq distance (for which ∠Cl−Sn−Oeq = 90°) is 2.244 Å.
The N−Sn−Cl angle being 180° in the neutral molecule is
smaller by about 15°, bringing closer the nitrogen and chlorine
atoms (Table 8).
suggesting that upon electron withdrawal, the whole orbital
system involved must be very perturbed with no possibility of
delocalizing stabilization of the cation radical. The spin-bearing
orbital in 13+• is mainly localized on the tin atom (sf. Table 8),
and is neither sterically shielded nor involved into conjugation
as in germatranes.46,56 On this reason it is probably much more
difficult to observe this species in solution, since it is closer to
R4Sn or R5Sn radicals58 than to known CRs of sila- or germa-
tranes with N-centered spin-carrying orbitals.46,56,57 The im-
portance of surrounding Sn Oeq-atoms in the HOMO suggests
a strongly perturbed Sn environment upon electron removal
leaving few chances for observing such CR under conventional
conditions. It is then rather questionable whether it is possible
to observe these species in solution, above the freezing point of
common electrochemical solvents. Also, 13 has high value of
the ionization potential (Table 7) which, using the approximate
Ep − IP correlation, leads to the Ep of about 2.4−2.6 V, mean-
ing that the oxidation of this stannatrane could not be observed
under the conditions employed. However, these estimations are
based on the gas phase data and bonds polarization in the
solution might lower the actual oxidation potential, so a broad
shoulder observed at ∼2.2−2.3 V for 13 and 15 in CH2Cl2
might actually stem from this oxidation. In any case, high
oxidation potential of 13 and 15 excludes the use of spin traps
because many of them undergo oxidation much before these
potentials.59
CONCLUSION
■
In this manuscript we have demonstrated the high potential of
the t-butoxido-substituted stannatrane N(CH2CMe2O)3SnO-t-
Bu (1) for the synthesis, in mostly acid−base-type reactions, of
a great variety of novel inorganic stannatranes of the type
N(CH2CMe2O)3SnX (X = OR, SR, OSiMe2C6H4SiMe2OSn-
(OCMe2CH2)3N, OC(O)R, SP(S)Ph2, halogen). In fact, com-
pound 1 is a tin tetraalkoxide the cage-type structure including
intramolecular N→Sn interaction of which induces high reactivity
of the axial Sn−O bond only. Consequently, compound 1 might
The structure of the HOMO of the chlorido-substituted
stannatrane 13 is rather complex (Figure 18). Contrary to the
HOMO’s of lighter metallatranes (M = Si, Ge) the 3c-4e
bonding system of which involves the easiest to ionize orbital
(n-electrons of N),46,56,57 the HOMO of 13 only contains it to
a small extent (at least, at the B3LYP/DGDZVP theory level)
1054
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
(22) E. F. Rickard, C.; R. Roper, W.; J. Woodman, T.; James Wright,
L. Chem. Commun. 1999, 837−838.
be an ideal candidate for the controlled functionalization of
acidic surfaces. In this sense, an even higher reactivity is to be
expected for amino-substituted stannatranes of the type
N(CH2CMe2O)3SnNR2 (R = H, alkyl, aryl) the synthesis of
which is envisaged. Electrochemical measurements show that
anodic oxidation of the stannatranes 4 and 8 occurs via
electrochemically reversible electron transfer resulting in corre-
sponding cation radicals (CRs) detected by CV and real-time
EPR spectroelectrochemistry. The own oxidation potential of
the X-Ar substituent in these compounds is lower than that of
the stannatranyl moiety, so 4 and 8 follow the oxidation pattern
and form the CRs of the corresponding aromatic derivatives
substituted with a stannatranyl group.
(23) Clark, A. M.; Rickard, C. E. F.; Roper, W. R.; Woodman, T. J.;
Wright, L. J. Organometallics 2000, 19, 1766−1774.
(24) Ilyukhin, A. B.; Davidovich, R. L.; Logvinova, V. B. Russ. J. Inorg.
Chem. 1999, 44, 1833−1836.
(25) Zoller, T.; Iovkova-Berends, L.; Berends, T.; Dietz, C.;
̈
Bradtmoller, G.; Jurkschat, K. Inorg. Chem. 2011, 50, 8645−8653.
̈
(26) Zoller, T.; Iovkova-Berends, L.; Dietz, C.; Berends, T.;
̈
Jurkschat, K. Chem.Eur. J. 2011, 17, 2361−2364.
(27) Berends, T.; Iovkova, L.; Bradtmoller, G.; Oppel, I.; Schurmann,
̈
̈
M.; Jurkschat, K. Z. Anorg. Allg. Chem. 2009, 635, 369−374.
(28) Krause, J.; Richter, S.; Lindner, S.; Schmidt, A.; Jurkschat, K.;
Schurmann, M.; Bradtmoller, G.; DE 10 2008 021 980 A1: 2009.
̈
̈
(29) Amarego, W. L. F.; Chai, C. L. L. Purification of Laboratory
Chemicals, 5th ed.; Butterworth-Heinemann: Oxford, U.K., 2003.
(30) Mun, S.-d.; Lee, J.; Kim, S. H.; Hong, Y.; Ko, Y.-h.; Shin, Y. K.;
Lim, J. H.; Hong, C. S.; Do, Y.; Kim, Y. J. Organomet. Chem. 2007, 692,
3519−3525.
ASSOCIATED CONTENT
■
S
* Supporting Information
CIF file, figures showing molecular structures, 119Sn CP MAS
NMR, powder X-ray diffraction, and 13C CP MAS NMR, and
tables showing crystal data and structure refinement. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(31) Merker, R. L.; Scott, M. J. J. Polym. Sci., Part A 1964, 2, 15−29.
(32) Sieber, F.; W., P. Jr.; Toker, J. D.; Wentworth, A. D.; Metz,
W. A.; Reed, N. N.; Janda, K. D. J. Org. Chem. 1999, 64, 5188−5192.
(33) Sheldrick, G. M. Acta Crystallogr. A 2008, 64, 112.
(34) Spek, A. L. Acta Crystallogr. 2009, D65, 148.
(35) Mann, C. K.; Barnes, K. K. Electrochemical Reactions in
Nonaqueous Systems; Marcel Dekker Inc.: New York, 1970.
(36) Zeitouny, J.; Jouikov, V. Phys. Chem. Chem. Phys. 2009, 11,
7161−7170.
AUTHOR INFORMATION
■
Corresponding Author
*klaus.jurkschat@tu-dortmund.de.
(37) WINEPR SimFonia, version 1.25; Bruker Analytische
Messtechnik GmbH, Karlsruhe, 1994−1996.
REFERENCES
(38) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, E.; Robb,
M. A.; Cheeseman, J. R.; Montgomery Jr., J. A.; Vreven, T.; Kudin, K.
N.; Burant, J. C.; Millam, J. M.; Iyengar, S. S.; Tomasi, J.; Barone, V.;
Mennucci, B.; Cossi, M.; Scalmani, G.; Rega, N.; Petersson, G. A.;
Nakatsuji, H.; Hada, M.; Ehara, M.; Toyota, K.; Fukuda, R.; Hasegawa,
J.; Ishida, M.; Nakajima, T.; Honda, Y.; Kitao, O.; Nakai, H.; Klene,
M.; Li, X.; Knox, J. E.; Hratchian, H. P.; Cross, J. B.; Adamo, C.;
Jaramillo, J.; Gomperts, R.; Stratmann, R. E.; Yazyev, O.; Austin, A. J.;
Cammi, R.; Pomelli, C.; Ochterski, J. W.; Ayala, P. Y.; Morokuma, K.;
Voth, G. A.; Salvador, P.; Dannenberg, J. J.; Zakrzewski, V. G.;
Dapprich, S.; Daniels, A. D.; Strain, M. C.; Farkas, O.; Malick, D. K.;
Rabuck, A. D.; Raghavachari, K.; Foresman, J. B.; Ortiz, J. V.; Cui, Q.;
Baboul, A. G.; Clifford, S.; Cioslowski, J.; Stefanov, B. B.; Liu, G.;
Liashenko, A.; Piskorz, P.; Komaromi, I.; Martin, R. L.; Fox, D. J.;
Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara, A.;
Challacombe, M.; Gill, P. M. W.; Johnson, B.; Chen, W.; Wong,
M. W.; Gonzalez, C.; Pople, J. A. Gaussian 03, revision B. 01; Gaussian,
Inc.: Pittsburgh, PA, 2003.
■
(1) Baltkais, N. J.; Voronkov, M. G.; Zelchan, G. I. Izv. AN Latv. SSR,
ser. khim. 1964, 2, 102.
(2) Martinez, A.; Robert, V.; Gornitzka, H.; Dutasta, J.-P. Chem.Eur.
J. 2010, 16, 520−527.
(3) Evgeniou, E. M.; Pergantis, S. A.; Leontidis, E.; Keramidas, A. D.
Inorg. Chem. 2005, 44, 7511−7522.
(4) Tasaka, M.; Hirotsu, M.; Kojima, M.; Utsuno, S.; Yoshikawa, Y.
Inorg. Chem. 1996, 35, 6981−6986.
(5) Singh, A.; Mehrotra, R. C. Coord. Chem. Rev. 2004, 248,
101−118.
(6) Karlov, S. S.; Tyurin, D. A.; Zabalov, M. V.; Churakov, A. V.;
Zaitseva, G. S. J. Mol. Struct. (THEOCHEM) 2005, 724, 31−37.
(7) Phukan, A. K.; Guha, A. K. Inorg. Chem. 2010, 49, 9884−9890.
(8) Phukan, A. K.; Guha, A. K. Inorg. Chem. 2011, 50, 1361−1367.
(9) Verkade, J. G. Coord. Chem. Rev. 1994, 137, 233−295.
(10) Karlov, S. S.; Zaitseva, G. S. Chem. Het. Comp. 2001, 37, 1325−
1357.
(39) Mun, S.-d.; Kim, S. H.; Lee, J.; Kim, H.-J.; Do, Y.; Kim, Y.
(11) Puri, J. K.; Singh, R.; Chahal, V. K. Chem. Soc. Rev. 2011, 40,
1791−1840.
Polyhedron 2010, 29, 379−383.
(40) Kolb, U.; Draeger, M.; Dargatz, M.; Jurkschat, K.
Organometallics 1995, 14, 2827−2834.
(41) Caruso, J.; Alam, T. M.; Hampden-Smith, M. J.; Rheingold, A.
L.; Yap, G. A. P. J. Chem. Soc., Dalton Trans. 1996, 2659−2664.
(42) Hampden-Smith, M. J.; Wark, T. A.; Rheingold, A.; Huffman, J.
C. Can. J. Chem. 1991, 69, 121−129.
(43) Burke, J. J.; Lauterbur, P. C. J. Am. Chem. Soc. 1961, 83, 326−
331.
(12) Ovchinnikov, Y.; Struchkov, Y.; Baryshok, V.; Voronkov, M.
J. Struct. Chem. 1994, 35, 750−753.
(13) Tzschach, A.; Ponicke, K. Z. Anorg. Allg. Chem. 1975, 413,
̈
136−142.
(14) Jurkschat, K.; Mugge, C.; Tzschach, A.; Zschunke, A.;
Engelhardt, G.; Lippmaa, E.; Magi, M.; Larin, M. F.; Pestunovich,
̈
̈
V. A.; Voronkov, M. G. J. Organomet. Chem. 1979, 171, 301−308.
(15) Swisher, R. G.; Day, R. O.; Holmes, R. R. Inorg. Chem. 1983, 22,
3692−3695.
(44) Broka, K. G., V.; Stradins, J.; Zelcans, G. Zhurn. Obsch. Khim.
1991, 61, 1374−1378.
(16) Tzschach, A.; Jurkschat, K. Comm. Inorg. Chem. 1983, 3, 35−50.
(17) Dakternieks, D.; Dyson, G.; Jurkschat, K.; Tozer, R.; Tiekink,
E. R. T. J. Organomet. Chem. 1993, 458, 29−38.
(45) Broka, K.; Stradins, J.; Glezer, V.; Zelcans, G.; Lukevics, E.
J. Electroanal. Chem. 1993, 351, 199−206.
(46) Soualmi, S.; Ignatovich, L.; Lukevics, E.; Ourari, A.; Jouikov, V.
J. Organomet. Chem. 2008, 693, 1346−1352.
(18) Li, J.; Liao, R.-A.; Xie, Q.-L. Prog. Nat. Sci. 1994, 4, 68−72.
(19) Ravenscroft, M. D.; Roberts, R. M. G. J. Organomet. Chem. 1986,
312, 45−52.
(47) Malachesky, P. A. Anal. Chem. 1969, 41, 1493−1494.
(48) Bard, A. J.; Faulkner, L. R. Electrochemical Methods: Fundamental
and Applications, 2nd ed.; John Wiley & Sons: New York, 2001.
(49) Wendt, H.; Hoffelner, H. Electrochim. Acta 1983, 28, 1465−
1472.
(20) Li, J.; Tang, Y.-J.; Liu, H.; Dong, S.-P.; Xie, Q.-L. Gaodeng
Xuexiao Huaxue Xuebao 1998, 19, 1074−1077.
(21) Kolosova, N. D. Z., N. N.; Shriro, V. S.; Kocheskov, K. A.;
Barminova, N. P. Patent SU 643508 A1 19790125, 1979.
1055
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056

Inorganic Chemistry
Article
(50) Jouikov, V.; Simonet, J. In Encyclopedia of Electrochemistry; Bard,
A., Stratman, M., Shaefer, H., Eds.; Wiley-VCH: New York, 2004;
Vol. 8, pp 235−276.
(51) Soualmi, S.; Ignatovich, L.; Lukevics, E.; Ourari, A.; Jouikov, V.
ECS Trans. 2008, 13, 63−69.
(52) Markusova, K.; Kladekova, D.; Zezula, I. Chemicke Zvesti 1980,
34, 726−39.
(53) Weiner, S. A. J. Am. Chem. Soc. 1972, 94, 581−584.
(54) Pokhodenko, V. D.; Kalibabchuk, N. N. Teor. i Eksperim. Khim.
1970, 6, 124−128.
(55) Gerson, W. H. Electron Spin Resonance Spectroscopy of Organic
Radicals; Wiley-VCH: Weinheim, Germany, 2003.
(56) Soualmi, S.; Ignatovich, L.; Jouikov, V. Appl. Organometal. Chem.
2010, 24, 865−861.
(57) Jouikov, V. ECS Trans. 2010, 28, 5−16.
(58) Iley, J. In The Chemistry of Organic Germanium, Tin and Lead
Compounds; Patai, S., Ed.; John Wiley & Sons: New York, 1995,
p 267−290.
(59) McIntire, G. L.; Blount, H. N.; Stronks, H. J.; Shetty, R. V.;
Janzen, E. G. J. Phys. Chem. 1980, 84, 916−921.
(60) Andrieux, C. P.; Saveant, J. M. In Investigations of Rates and
Mechanisms of Reactions; Bernasconi, C. F., Ed.; Wiley-VCH:
New York, 1986.
1056
dx.doi.org/10.1021/ic202179e | Inorg. Chem. 2012, 51, 1041−1056