Synthesis, characterization, and X-ray structures of diphenyltin(IV) N-(2-hydroxyacetophenone)glycinate, its 1:1 adduct with triphenyltin(IV) chloride, and related systems

Article abstract of DOI:10.1021/om9800290

The compound [Ph₂Sn(2-OC₆H₄C(CH₃)=NCH ₂COO)], 1, shows a distorted trigonal-bipyramidal geometry in the solid state. Reaction of 1 with Ph₃SnCl yields a 1:1 adduct in which the two tin atoms are joined via the carbonyl atom of the ligand in 1 to form a mixed diorgano/triorgano species. NMR data indicate that the 1:1 adduct dissociates in noncoordinating solvent. Similarly, [^tBU₂Sn(2-OC₆H₄C(CH ₃)=NCH₂COO)·^tBu₂SnCl ₂], which has been characterized crystallographically in the solid state, is dissociated in solution. In contrast to the above behavior, monomeric [Vin₂Sn(2-OC₆H₄C(CH₃)=NCH ₂COO)] forms an adduct with a water molecule to yield [Vin₂Sn(2-OC₆H₄C(CH₃)=NCH ₂COO)OH₂] in the solid state.

Full text of DOI:10.1021/om9800290

3058
Organometallics 1998, 17, 3058-3062
Syn th esis, Ch a r a cter iza tion , a n d X-r a y Str u ctu r es of
Dip h en yltin (IV) N-(2-Hyd r oxya cetop h en on e)glycin a te, Its
1:1 Ad d u ct w ith Tr ip h en yltin (IV) Ch lor id e, a n d Rela ted
System s
Dainis Dakternieks*
School of Chemical and Biological Sciences, Deakin University, Geelong,
Victoria 3217, Australia
Tushar S. Basu Baul* and Sushmita Dutta
Chemical Laboratory, Regional Sophisticated Instrumentation, North Eastern Hill University,
Bijni Complex, Bhagyakul, Shillong 793 003, India
Edward R. T. Tiekink*
Department of Chemistry, The University of Adelaide, Australia 5005
Received J anuary 20, 1998
The compound [Ph2Sn(2-OC6H4C(CH3)dNCH2COO)], 1, shows a distorted trigonal-
bipyramidal geometry in the solid state. Reaction of 1 with Ph3SnCl yields a 1:1 adduct in
which the two tin atoms are joined via the carbonyl atom of the ligand in 1 to form a mixed
diorgano/triorgano species. NMR data indicate that the 1:1 adduct dissociates in noncoor-
dinating solvent. Similarly, [tBu2Sn(2-OC6H4C(CH3)dNCH2COO)‚tBu2SnCl2], which has been
characterized crystallographically in the solid state, is dissociated in solution. In contrast
to the above behavior, monomeric [Vin2Sn(2-OC6H4C(CH3)dNCH2COO)] forms an adduct
with a water molecule to yield [Vin2Sn(2-OC6H4C(CH3)dNCH2COO)OH2] in the solid state.
In tr od u ction
are of interest owing to their putative antitumor
activity,9-13 it was observed that the isolated monomeric
complexes contained additional potentially, O-contain-
ing coordination sites. These proved to be sufficiently
basic to coordinate a second Sn-containing species, and
hence, a thorough investigation of the nature of adduct
formation was conducted in noncoordinating solvent
employing 119Sn NMR methods and in the solid state
using X-ray crystallography. Hence, this contribution
reports the preparation of diphenyltin(IV) N-(2-hy-
droxyacetophenone)glycinate and its 1:1 molecular ad-
duct with Ph3SnCl yielding a rare mixed diorganotin/
triorganotin compound that features a nonorgano bridge
as well as related studies containing other diorganotin
entities.
The development of dendritic chemistry is of current
interest owing to the possibility of obtaining compounds
whose structures result in modified and new chemical
properties. These synthetic macromolecules are largely
based on organic residues, however, there is also
considerable interest in transition-metal-mediated den-
drimers, i.e., metallodendrimers.1 Receiving particular
attention are the Ru/polybipyridyl systems owing to
their exciting luminescent and redox properties.2,3 In
contrast, metallodendrimers containing main-group-
element compounds, with the possible exception of those
with Si, are still comparatively unexplored.1 Our inter-
est in this area stems from a program designed to link
smaller Sn-containing entities to form organotin oxo
clusters4,5 in a rational and reliable fashion in order to
control the size, shape, and tin-atom nuclearity. Such
organotin oxo clusters have applications as homoge-
neous catalysts6 and in new materials science.7,8
Exp er im en ta l Section
Ma ter ia ls a n d Sp ectr oscop ic Meth od s. Organotin chlo-
rides (Aldrich) were used after recrystallization from hexane.
(7) Banse, F.; Ribot, F.; Toledano, P.; Maquet, J .; Sanchez, C. Inorg.
Chem. 1995, 34, 6371.
(8) Petridis, D.; Bakas, T.; Simopoulos, A.; Gangas, N. H. J . Inorg.
Chem. 1989, 28, 2439.
In a related study of synthetic and structural inves-
tigations of organotin(IV)/amino acid compounds, which
(1) Zeng, F.; Zimmerman, S. C. Chem. Rev. 1997, 97, 1681.
(2) Balzani, V.; Campagna, S.; Denti, G.; J uris, A.; Serroni, S.;
Venturi, M. Coord. Chem. Rev. 1994, 132, 1.
(3) Bodige, S.; Torres, A. S.; Maloney, D. J .; Tate, D.; Kinsel, G. R.;
Walker, A. K.; MacDonnell, F. M. J . Am. Chem. Soc. 1997, 119, 10364.
(4) Dakternieks, D.; J urkschat, K.; van Dreumel, S.; Tiekink, E. R.
T. Inorg. Chem. 1997, 36, 2023.
(5) Mehring, M.; Schu¨rmann, M.; Reuter, H.; Dakternieks, D.;
J urkschat, K. Angew. Chem., Int. Ed. Engl. 1997, 36, 1112.
(6) Otera, J . Chem. Rev. 1993, 93, 1449.
(9) Gielen, M. Coord. Chem. Rev. 1996, 151, 41.
(10) Huber, F.; Roge, G.; Carl, L.; Atassi, G.; Spreafico, F.;
Filippeschi, S.; R., Barbieri, A. Silvestri, E. Rivarola, G. Ruisi, F. Di
Bianca and G. Alonzo, J . Chem. Soc., Dalton Trans. 1985, 523.
(11) Huber, F.; Vornefeld, M.; Preut, H.; von Angerer, E.; Ruisi, G.
Appl. Organomet. Chem. 1992, 6, 597.
(12) Huber, F.; Haupt, H. J .; Preut, H.; Barbieri, R.; Lo Giudice, M.
T. Z. Anorg. Allg. Chem. 1977, 432, 51.
(13) Khoo, L. E.; Xu, Y.; Goh, N. K.; Chia, L. S.; Koh, L. L.
Polyhedron 1997, 16, 573.
S0276-7333(98)00029-6 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/13/1998

Diphenyltin(IV) N-(2-hydroxyacetophenone)glycinate
Organometallics, Vol. 17, No. 14, 1998 3059
Found: C, 56.7; H, 4.0; N, 3.0. IR (cm-1): 1682 ν(OCO)asym
Glycine and 2-hydroxyacetophenone (Aldrich) were used as
supplied. Carbon, hydrogen, and nitrogen analyses were
performed with a Perkin-Elmer 2400 Series II. IR spectra
were obtained on a Perkin-Elmer 1720X FT spectrophotometer
,
1602 ν(CdN), 1238 ν(Ph(C-O)). 1H NMR (CDCl3 solution):
δ 7.85-7.89 (m, 4H, Sn-Ph(ortho)), 7.35-7.47 (m, 8H, H-7,9
+ Sn-Ph(meta + para)), 7.15 (d, 9 Hz, 1H, H-6), 6.75 (t, 6 Hz,
1H, H-8), 4.25 (s, 2H, H-2), 2.57 (s, 3H, H-3′) ppm. 13C NMR
(CDCl3 solution): δ 182.1 (C-1), 170.2 (C-3), 166.4 (C-5),, 136.3
(C-7), 130.7 (C-9), 123.7 (C-6), 120.3 (C-4), 117.8 (C-8), 53.5
(C-2), 22.7 (C-3′); Sn-Ph δ 137.6 (ipso), 136.6 (2J (Sn-C) ) 56.0
Hz, ortho), 130.5 (4J (Sn-C) ) 20.6 Hz, para), 128.8 (3J (Sn-
C) ) 86.4 Hz, meta) ppm. 119Sn NMR (CDCl3 solution): δ
-351.7 ppm.
in KBr disks in the range 4000-400 cm-1 1H and 13C NMR
.
spectra were recorded in CDCl3 solution on a Bruker ACF300
spectrometer at 300.13 and 75.47 MHz, respectively, refer-
enced to Me4Si (0.0 ppm) and CDCl3 (77.0 ppm), respectively.
119Sn NMR spectra were recorded, with an inverse-gated pulse
delay of 2 s, using a J EOL GX 270 MHz FT NMR spectrometer
operating at 100.75 MHz.
[P h 2Sn L‚P h 3Sn Cl ] (2): This compound was prepared by
the dropwise addition of an anhydrous benzene solution (30
cm3) of Ph3SnCl (1.0 g, 2.59 mmol) to a hot benzene solution
(50 cm3) containing 1 (1.2 g, 2.59 mmol). The reaction mixture
was refluxed for 2 h, and excess solvent was removed using a
rotary evaporator. The yellow gummy mass thus obtained was
washed several times with hexane and recrystallized from
chloroform solution to give 2 in 65% yield. Mp: 199-200 °C.
Anal. Calcd for C40H34ClNO3Sn2: C, 56.6; H, 4.0; N; 1.7.
P r ep a r a tion of Liga n d s. The ligand N-(2-hydroxyaceto-
phenone)glycine (systematic name 2-{[(E)-1-(2-hydroxyphenyl)-
ethylidene]amino}acetic acid, LH2), could not be isolated and,
therefore, was prepared either as its monosodium salt (LHNa)
or monopotassium salt (LHK).
Found: C, 56.5; H, 4.0; N, 1.5. IR (cm-1): 1627 ν(OCO)asym
,
1236 ν(Ph(C-O)). 1H NMR (CDCl3 solution): δ 7.65-7.88 (m,
10H, Sn-Ph(ortho)), 7.38-7.46 (m, 17H, H-7,9 + Sn-Ph(meta
+ para)), 7.14 (d, 9 Hz, 1H, H-6), 6.75 (t, 6 Hz, 1H, H-8), 4.24
(s, 2H, H-2), 2.59 (s, 3H, H-3′] ppm. 13C NMR (CDCl3
solution): δ 182.0 (C-1), 170.2 (C-3), 166.6 (C-5), 136.4 (C-7),
130.8 (C-9), 123.9 (C-6), 120.4 (C-4), 117.9 (C-8), 53.6 (C-2),
22.8 (C-3′); Sn-Ph (a and b represent signals due to Sn-Ph2
and Sn-Ph3, respectively) δ 137.6 (ipso)a, 137.5 (ipso)b, 136.7
(2J (Sn-C) ) 50.4 Hz, ortho)b, 136.1 [2J (Sn-C) ) 55.7 Hz,
ortho)a, 130.7 (4J (Sn-C) ) 21.1 Hz, para)a 130.5 (4J (Sn-C) )
13.2 Hz, para)b, 129.1 (3J (Sn-C) ) 65.0 Hz, meta)b, 128.9
(3J (Sn-C) ) 90.5 Hz, meta)a ppm. 119Sn NMR (CDCl3 solu-
tion): δ: -48.2, -350.3 ppm.
[tBu 2Sn L‚tBu 2Sn Cl2] (3): This compound was isolated from
the reaction of tBu2SnCl2 and LHK (1:1) in methanol solution
employing the procedure described for 1. The yellow product
was obtained upon concentration of a chloroform extract and
recrystallized from chloroform solution to give yellow blocks
in 55% yield. Mp: 132-133 °C. Anal. Calcd for C26H45Cl2-
NO3Sn2: C, 42.9; H, 6.2; N; 1.9. Found: C, 42.8; H, 6.2; N,
1.9. IR (cm-1): 1681 ν(OCO)asym, 1237 ν(Ph(C-O)). 1H NMR
(CDCl3 solution): δ 7.45 (d, 6 Hz, 1H, H-7), 7.34 (t, 6 Hz, 1H,
H-9), 6.87 (d, 9 Hz, 1H, H-6), 6.72 (m, 6 Hz, 1H, H-8), 4.25 (s,
2H, H-2), 2.67 (s, 3H, H-3′), 1.26 (s, 36H, Sn-tBu) ppm. 13C
NMR (CDCl3 solution): δ 181.2 (C-1), 170.9 (C-3), 167.2 (C-
5), 135.6 (C-7), 130.2 (C-9), 123.7 (C-6), 120.8 (C-1), 117.0 (C-
8), 53.9 (C-2), 22.8 (C-3′), 29.8 (Sn-tBu); 40.7 (Sn-tBu) ppm.
119Sn NMR (CDCl3 solution): δ 57.2, -302.4 ppm.
[Vin 2Sn L‚OH2] (4): This compound was prepared from the
reaction of [Vin2SnCl2] and LHNa in methanol solution (1:2
molar proportions) as described for 1. The colorless product
was obtained upon concentration of a chloroform extract and
recrystallized from benzene solution to give colorless blocks
in 58% yield. Mp: 163-164 °C. Anal. Calcd for C14H17NO4-
Sn: C, 44.0; H, 4.5; N; 3.7. Found: C, 43.9; H, 4.2; N, 3.6. IR
(cm-1): 1658 ν(OCO)asym, 1605 ν(CdN), 1240 ν(Ph(C-O)). 1H
NMR (CDCl3 solution): δ 7.50 (d, 9 Hz, 1H, H-7), 7.38 (t, 9
Hz, 1H, H-6), 6.78 (t, 6 Hz, 1H, H-9), 6.28-6.80 (m, 6H, Sn-
Vin), 4.27 (s, 2H, H-2), 2.66 (s, 3H, H-3′) ppm. 13C NMR (CDCl3
solution): δ 182.7 (C-1), 170.3 (C-3), 166.2 (C-5), 136.0 (C-7),
130.5 (C-9), 123.5 (C-6), 120.6 (C-1), 117.9 (C-8), 53.3 (C-2),
22.8 (C-3′), 135.0 (Sn-Vin), 139.5 (Sn-Vin) ppm. 119Sn NMR
(CDCl3 solution): δ -344.6 ppm.
LHNa . A hot aqueous solution (30 cm3) of NaHCO3 (3.09
g, 36.72 mmol) was added slowly to a hot aqueous solution
(25 cm3) containing glycine (2.75 g, 36.72 mmol) under stirring.
After completion of CO2 evolution, 2-hydroxyacetophenone (5.0
g, 36.72 mmol) in ethanol (50 cm3) was added dropwise. The
reaction mixture was then maintained between 40 and 50 °C
for 2 h, after which the solvent was removed using a rotary
evaporator. A thick yellow mass was precipitated with a
methanol-petroleum ether mixture. This was washed thor-
oughly with petroleum ether and recrystallized from methanol
to yield pure LHNa. Yield: 80%. Mp: 239-240 °C. Anal.
Calcd for C10H10NNaO3: C, 55.8; H, 4.7; N; 6.5. Found: C,
55.7; H, 4.5; N, 6.5. IR (cm-1): 1618 ν(OCO)asym, 1606 ν(Cd
N), 1267 ν(Ph(C-O)).
LHK. A cold aqueous solution (25 cm3) of KOH (2.06 g,
36.72 mmol) was mixed with a cold aqueous solution (25 cm3)
containing glycine (2.77 g, 36.72 mmol) and held at 15-20 °C
in an ice bath, with continuous stirring. An ethanolic solution
(50 cm3) of 2-hydroxyacetophenone (5.0 g, 36.72 mmol) was
added dropwise. A deep-yellow color developed almost im-
mediately, and stirring was continued for 1 h followed by 5 h
at room temperature. The solvent was removed using a rotary
evaporator. The yellow mass was washed with petroleum
ether and precipitated with a methanol-diethyl ether mixture.
The crude product was recrystallized from methanol solution
to yield LHK. Yield: 72%. Mp: 258-260 °C. Anal. Calcd
for C10H10KNO3: C, 51.9; H, 4.4; N; 6.1. Found: C, 51.9; H,
4.3; N, 6.0. IR (cm-1): 1628 ν(OCO)asym, 1606 ν(CdN), 1267
ν(Ph(C-O)).
P r ep a r a tion of Com p ou n d s. P h 2Sn L (1): Ph2SnCl2 (0.79
g, 2.32 mmol) in 30 cm3 of methanol was added dropwise with
continuous stirring to a hot methanol solution (50 cm3)
containing either LHNa or LHK (0.5 or 0.53 g, 2.32 mmol).
The reaction mixture was heated at reflux temperature for 2
h, and then the solvent was removed using a rotary evaporator.
The dry mass was washed thoroughly with hot hexane and
then extracted into chloroform. The yellow product obtained
upon concentration of the chloroform extract was recrystallized
from methanol to yield yellow block crystals of [Ph2Sn(2-
OC6H4C(CH3)dNCH2COO)] (1). Yield: 82%. Mp: 221-222
°C. Anal. Calcd for C22H19NO3Sn: C, 56.9; H, 4.1; N; 3.0.
Cr ysta llogr a p h y. Intensity data were collected at room
temperature on a Rigaku AFC6R diffractometer employing the
ω-2θ scan technique and graphite-monochromated Mo KR
radiation (λ ) 0.710 73 Å). The data sets were corrected
routinely for Lorentz and polarization effects,14 and an empiri-
cal absorption correction15 was applied in each case. The

3060 Organometallics, Vol. 17, No. 14, 1998
Ta ble 1. Cr ysta llogr a p h ic Da ta a n d Refin em en t Deta ils for 1-4
Dakternieks et al.
1
2
3
4
formula
fw
C
464.1
22H19NO3Sn
C40H34ClNO3Sn2
849.6
C30H45Cl2NO3Sn2
776.0
C14H17NO4Sn
382.0
cryst size, mm
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
0.19 × 0.32 × 0.48
monoclinic
P21/c
20.280(4)
20.597(5)
9.366(1)
0.02 × 0.12 × 0.15
triclinic
P1h
0.07 × 0.19 × 0.52
triclinic
P1h
0.10 × 0.18 × 0.32
triclinic
P1h
9.323(4)
10.03(1)
8.756(5)
96.61(8)
106.08(5)
104.47(5)
746(1)
13.073(2)
13.961(2)
11.591(2)
92.06(1)
115.39(1)
110.67(1)
1743.6(7)
2
1.618
15.48
0.963-1
3.0-25.0
6467
12.748(2)
16.531(4)
8.117(1)
96.79(2)
96.67(1)
72.45(1)
1613.7(5)
2
1.597
17.43
0.905-1
3.0-27.5
7790
92.06(1)
3909(1)
8
Z
D
2
calcd, g cm-3
1.577
13.28
0.969-1
3.0-27.5
9848
9298
4767
0.042
0.044
0.37
1.699
17.22
0.910-1
3.0-27.5
3661
3452
2890
0.039
0.049
µ, cm-1
transmission factors
θ range, deg
no. of data collcd
no. of unique data
no. of data used
R
6173
3509
0.038
0.037
7457
4018
0.042
0.042
Rw
residual e-/Å3
0.50
0.52
1.31
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 1-4
1a
1b
2a
3b
4c
Sn-O(1)
2.127(4) 2.131(4) 2.167(6) 2.184(4) 2.249(4)
2.064(4) 2.059(4) 2.055(6) 2.057(4) 2.105(4)
2.190(5) 2.178(5) 2.174(6) 2.190(5) 2.254(4)
2.120(6) 2.102(7) 2.127(7) 2.148(8) 2.101(5)
2.138(6) 2.111(6) 2.122(8) 2.152(8) 2.100(5)
1.280(7) 1.276(8) 1.27(1) 1.254(8) 1.263(6)
1.213(7) 1.217(7) 1.24(1) 1.256(7) 1.234(6)
1.330(7) 1.322(7) 1.311(7) 1.335(8) 1.334(6)
1.459(8) 1.470(7) 1.46(1) 1.474(8) 1.467(7)
1.285(7) 1.299(7) 1.293(9) 1.307(8) 1.298(6)
Sn-O(3)
Sn-N(1)
Sn-C(11)
Sn-C(21)
O(1)-C(1)
O(2)-C(1)
O(3)-C(5)
N(1)-C(2)
N(1)-C(3)
O(1)-Sn-O(3)
O(1)-Sn-N(1)
160.3(2) 158.6(2) 160.1(2) 155.0(2) 152.4(1)
77.2(2) 76.2(2) 76.3(2) 74.6(2) 72.8(1)
O(1)-Sn-C(11) 96.0(2) 93.9(2) 93.2(2) 91.6(2) 86.3(2)
O(1)-Sn-C(21) 93.6(2) 94.9(2) 94.0(3) 95.2(2) 90.0(2)
O(3)-Sn-N(1)
83.1(2) 82.6(2) 84.0(2) 81.7(2) 79.6(1)
O(3)-Sn-C(11) 92.3(2) 93.8(2) 92.0(3) 93.4(2) 99.2(2)
O(3)-Sn-C(21) 95.8(2) 96.5(2) 95.2(3) 101.4(3) 91.8(2)
N(1)-Sn-C(11) 113.5(2) 120.2(2) 111.8(3) 120.2(3) 97.7(2)
N(1)-Sn-C(21) 120.5(2) 113.4(2) 110.8(2) 112.8(3) 97.2(2)
C(11)-Sn-C(21) 126.0(2) 126.2(2) 137.4(3) 126.4(3) 162.8(2)
F igu r e 1. Molecular structure and crystallographic num-
bering scheme for molecule a of [Ph2Sn(2-OC6H4C(CH3)d
NCH2COO)] (1).
Sn-O(1)-C(1)
Sn-O(3)-C(5)
Sn-N(1)-C(2)
Sn-N(1)-C(3)
118.8(4) 118.8(4) 117.9(5) 120.5(4) 117.9(3)
126.7(4) 123.1(4) 127.4(6) 125.9(4) 121.6(3)
111.5(4) 111.8(4) 112.7(4) 113.7(4) 112.6(3)
128.2(5) 127.2(4) 127.8(6) 128.4(4) 127.9(4)
structures were solved by direct methods (1, 3;16a 2, 416b) and
each refined by a full-matrix least-squares procedure based
on F.14 Non-hydrogen atoms were refined with anisotropic
displacement parameters and hydrogen atoms included in the
models at their calculated positions (C-H ) 0.97 Å). A σ
weighting scheme was applied, i.e., w ) 1/σ2(F), and the
refinement continued until convergence in each case. Neutral
scattering factors employed were as included in teXsan,14 and
diagrams were drawn with ORTEP17 at the 50% probability
level. Crystallographic data and refinement details are given
in Table 1. Crystallographic information files for all struc-
tures are available upon request from E.R.T.T. (etiekink@
chemistry.adelaide.edu.au).
O(1)-C(1)-O(2) 124.6(7) 125.4(6) 125.5(7) 127.6(6) 125.1(5)
C(2)-N(1)-C(3) 120.2(5) 120.9(5) 119.5(7) 117.9(6) 119.5(4)
a
Sn(2)-Cl(1) 2.446(3), Sn(2)-O(2) 2.453(6), Cl(1)-Sn(2)-O(2)
b
176.5(2). Sn(2)-Cl(1) 2.480(2), Sn(2)-Cl(2) 2.370(2), Sn(2)-O(2)
2.335(2), Sn(2)-C(31) 2.156(8), Sn(2)-C(41) 2.160(8), Cl(1)-
Sn(2)-Cl(2) 86.89(7), Cl(1)-Sn(2)-O(2) 166.5(1), Cl(2)-Sn(2)-
O(2) 79.9(1), C(31)-Sn(2)-C(41) 125.3(3). c Sn-O(4) 2.358(4),
O(1)-Sn-O(4) 128.5(1), O(3)-Sn-O(4) 79.0(1), O(4)-Sn-N(1)
158.7(1), O(4)-Sn-C(11) 85.1(2), O(4)-Sn-C(21) 84.1(2).
Resu lts a n d Discu ssion
Cr ysta l Str u ctu r es. The molecular structure of 1
is shown in Figure 1, and selected interatomic param-
eters are collected in Table 2. The compound crystal-
lizes with two independent molecules in the crystallo-
graphic asymmetric unit, labeled a and b, that do not
differ from each other significantly (see below; the
numbering scheme for molecule b (not illustrated) is as
for molecule a). The structure is molecular with the
closest intermolecular contact involving the non-hydro-
(14) teXsan Structure Analysis Software; Molecular Structure
Corp: The Woodlands, Texas, 1992.
(15) Walker, N.; Stuart, D. Acta Crystallogr., Sect. A 1983, A39, 158.
(16) (a) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W.
P.; Garc´ıa-Granda, S.; Smits, J . M. M.; Smykalla, C. The DIRDIF
program system; Technical Report of the Crystallography Laboratory;
University of Nijmegen: The Netherlands, 1992. (b) Burla, M. C.;
Camalli, M.; Cascarano, G.; Giacovazzo, C.; Polidori, G.; Spagna, R.;
Viterbo, D. J . Appl. Crystallogr. 1989, 22, 389.
(17) J ohnson, C. K. ORTEPII; Report ORNL-5138; Oak Ridge
National Laboratory: Oak Ridge, TN, 1976.

Diphenyltin(IV) N-(2-hydroxyacetophenone)glycinate
Organometallics, Vol. 17, No. 14, 1998 3061
F igu r e 3. Molecular structure and crystallographic num-
bering scheme for [tBu2Sn(2-OC6H4C(CH3)dNCH2COO)‚
tBu2SnCl2] (3).
F igu r e 2. Molecular structure and crystallographic num-
bering scheme for [Ph2Sn(2-OC6H4C(CH3)dNCH2COO)-
SnPh3Cl] (2).
the carboxylate group. This is also manifested in the
apparent lengthening of the C(1)-O(2) bond in 2
compared with the comparable distances in 1, i.e.,
consistent with the IR results (see below). The geometry
about the Sn(2) atom is also distorted trigonal bipyra-
midal with the Cl and O(2) atoms defining the axial
positions. The Sn(2) atom lies 0.2057(5) Å above the
C3 trigonal plane.
The presence of bidentate bridging carboxylate resi-
dues in organotin carboxylate structures is well estab-
lished,18 however, this is the first example of an isolated
ditin structure held together in this fashion, i.e., in
which the two tin atoms are not connected via an organo
link. Further, crystal structures of mixed diorgano/
triorgano tin are also rare, with one example containing
a Sn-Sn bond19 and the other having the tin centers
linked via a central platinum atom.20
gen atoms of 3.382(8) Å occurring between O(2)b and
C(2)bi (symmetry operation i ) x, 0.5 - y, 0.5 + z). The
coordination geometry about the tin atom is defined by
two phenyl groups, an oxygen (O(1), derived from a
unidentate carboxylate group), a phenoxide O(3) atom,
and the imino N(1) atom. The arrangement of the donor
set is distorted trigonal bipyramidal with the two oxygen
atoms defining the axial positions: O-Sn-O 160.3(2)°
for molecule a and 158.6(2)° for molecule b. Distortions
from the ideal geometry may be traced to the restricted
bite angles of the tridentate ligand. Neither of the five-
or six-membered rings formed upon chelation are pla-
nar, as seen in the following torsion angles (value for
molecule b follows in parentheses): Sn/O(1)/C(1)/C(2)
-0.2(8)° (10.5(8)°), Sn/N(1)/C(2)/C(1) -19.7(7)° (-18.9-
(6)°), Sn/O(3)/C(5)/C(4) 37.7(8)° (42.1(7)°), and Sn/N(1)/
C(3)/C(4) 10.9(9)° (-1.6(8)°). Similar features are found
in structures 2-4 described below. The tin atom lies
0.0267(4) Å (0.0457(5) Å) out of the NC2 trigonal plane
in the direction of the more tightly held O(3) atom. In
addition to the differences between molecules a and b
reflected in the above torsion angles, there are several
minor differences in their derived interatomic param-
eters with the most significant of these being the Sn-
O(3)-C(5) angle (Table 2). The geometry found about
the tin atom in 1 is almost identical to that found about
the Sn(1) atom in 2.
The molecular structure of 2 is illustrated in Figure
2, and further details are given in Table 2. The closest
non-hydrogen intermolecular contact in the lattice of
3.455(9) Å occurs between C(11) and C(16)i (symmetry
operation i ) - x, 1 - y, 1 - z). The compound is
dinuclear and may be considered as an adduct formed
between 1 and Ph3SnCl. A comparison of chemically
equivalent geometric parameters for 1 with those about
the Sn(1) atom in 2 shows a remarkable consistency;
the Sn(1) atom lies 0.0376(5) Å out of the trigonal plane
in the direction of the O(3) atom. The only significant
difference in the coordination geometries is found in the
C-Sn-C angle, which has expanded to 137.4(3)° in 2
compared with 126.0(2)° and 126.2(2)° for molecules a
and b, respectively, in 1. The other major difference
between the geometries may be related to the formation
of the O(2)fSn(2) interaction. Thus, the Sn(1)-O(1)
bond is longer in 2 owing to the withdrawal of electron
density from O(2) and donation to the Sn(2) atom via
A similar structure to 2 is found for 3 (Figure 3), and
selected parameters are collected in Table 2. In this
case, the adduct involves two diorganotin centers. A
distorted trigonal-bipyramidal geometry is found about
the Sn(1) atom in which the Sn atom lies 0.0930(5) Å
out of the NC2 plane in the direction of the O(3) atom.
With the exception of the elongation of the Sn(1)-C
bonds in 3, the geometry is essentially as found in 2;
however, it is noted that the disparity in the C-O(1),
O(2) distances is not as pronounced in 3 owing to the
shorter Sn(2)-O(2) interaction of 2.335(2) Å, a result
that may be correlated with the enhanced Lewis acidity
t
of Bu2SnCl2 compared with Ph3SnCl. The strength of
the Sn(2)-O(2) contact is responsible for the elongation
of the Sn(2)-Cl(2) bond; O(2)-Sn(2)-Cl(2) is 166.5(1)°.
The final structure is that of 4, which was shown to
be five-coordinate in solution (see below) but six-
coordinate in the solid-state owing to the coordination
of a water molecule; see Figure 4 and Table 2 for details.
The geometry is distorted octahedral with the two vinyl
groups occupying trans positions (C-Sn-C 162.8(2)°)
above and below a NO3 equatorial plane. Similar
coordination geometries to those seen in 4 have been
found in some related 2,6-pyridinedicarboxylate21,22 and
N-methyliminidiacetate22 structures, however, in these
(18) Tiekink, E. R. T. Appl. Organomet. Chem. 1991, 5, 1; Trends
Organomet. Chem. 1994, 1, 71.
(19) Cowley, A. H.; Hall, S. W.; Nunn, C. M.; Power, J . M. Angew.
Chem., Int. Ed. Engl. 1988, 27, 838.
(20) Almeida, J . F.; Dixon, K. R.; Eaborn, C.; Hitchcock, P. B.;
Pidcock, A.; Vinaixa, J . J . Chem. Soc., Chem. Commun. 1982, 1315.

3062 Organometallics, Vol. 17, No. 14, 1998
Dakternieks et al.
A similar spectrum was obtained when equimolar
amounts of 1 and Ph3SnCl were mixed in the same
solvent, which indicates that compound 2 completely
dissociates into 1 and Ph3SnCl under these conditions.
Cooling the solution of 2 to -10 °C causes only a minor
shift of the low-frequency 119Sn resonance (δ -350.9)
but a more substantive shift of the higher frequency
resonance (δ -83.5 ppm). At -95 °C, the two 119Sn
resonances occur at -223.0 and -347.4 ppm, which
indicates that the equilibrium between Ph3SnCl and 1
has moved substantively toward formation of 2. The
119Sn shift of the adducted Ph3SnCl is comparable to
that found for other similar five-coordinate species:25
-
(Ph3SnClO2 δ -251 at -95 °C in CH2Cl2; Ph3SnCl‚
pyridine δ -219 in pyridine at room temperature).
The 119Sn NMR spectrum at room temperature of a
CH2Cl2 solution of 1 to which an equimolar amount of
Ph2SnCl2 was added shows resonances at -114.0 (cf
-33 ppm for Ph2SnCl2 at room temperature25) and
-348.0 ppm, indicating substantial adduct formation.
On cooling, the resonance at -114.0 moves progressively
to lower frequency, and at -95 °C, the 119Sn NMR
spectrum contains two resonances at -236.8 and -342.7
ppm. Clearly, the magnitude of the interaction between
1 and an additional tin moiety is dependent on the
Lewis acidity of the latter.
F igu r e 4. Molecular structure and crystallographic num-
bering scheme for [Vin2Sn(2-OC6H4C(CH3)dNCH2COO)-
OH2] (4).
structures, association (2.5-2.8 Å) via one of the car-
boxylate oxygen atoms leads to the formation cen-
trosymmetric dimers featuring central Sn2O2 cores. In
4, the closest Sn‚‚‚O(1)i intermolecular contact is 3.319-
(4) Å (symmetry operation i ) 1 - x, 1 - y, 1 - z).
The solid-state IR spectrum of 1 displays a band at
1682 cm-1, which may be assigned to a ν(OCO)asym
The 119Sn NMR spectrum at room temperature of a
CH2Cl2 solution of 3 shows resonances at 57.2 (cf 56.0
t
for Bu2SnCl2 in CH2Cl2) and -302.4 ppm, indicating
negligible interaction between these two species in
solution. The magnitude of the interaction is not
changed much on cooling the solution to -95 °C (δ 47.8
and -297.8 ppm).
vibration, and in 2, this vibration appears at 1627 cm-1
.
The shift of the ν(OCO)asym band at ca. 55 cm-1 to lower
wavenumbers in 2 confirms the interaction of Ph3SnCl
with the carbonyl oxygen atom of complex 1. In these
compounds, the v(CdN) band appears23 as a single
sharp band at the same frequency and is assigned as
being due to CdNfSn coordination in the solid state.
The band at ca. 1270 cm-1 of the Na/K salts moves
toward lower frequency by 30 cm-1 in the complexes,
owing to the coordination of phenolic oxygen to tin
atom.24 Thus, the IR results provide strong evidence
for the complexation of the potentially multidentate
ligand.
The 119Sn NMR spectrum of [Vin2SnL‚OH2] (4) in
CHCl3 shows a single resonance at -344.6 ppm indica-
tive of five-coordinate tin (by comparison to other
compounds described above), indicating that water is
not coordinated in solution contrary to the X-ray study
(see above).
The 1H and 13C NMR spectra of 1-4 show the
expected resonances and integration (see Experimental
Section).
Con clu sion
Given the availability of a series of crystal structures,
it was thought of interest to probe the solution-state
structures in order to ascertain whether the observed
association in the solid-state persisted in solution.
Solu tion Str u ctu r es. Compound 1 (room temper-
ature in CH2Cl2 solution) shows one 119Sn resonance at
δ -351.7 ppm; a similar value was found for the in situ
reaction of 1:1 mol equiv of LHNa with Ph2SnCl2 in the
same solvent. Compound 2 gives two 119Sn resonances
of equal intensity (δ -49.9 and -351.4 ppm) in CH2Cl2
solution. The signal at δ -351.4 ppm is assigned to the
five-coordinate tin center in the Ph2SnL core and the
resonance at δ -49.9 ppm is assigned to the Ph3SnCl
moiety (cf δ -47.0 ppm for Ph3SnCl in CH2Cl2 solution).
Compounds of the form R2Sn(2-OC6H4C(CH3)dNCH2-
COO) have been shown to form adducts with R3SnCl
and R2SnCl2 in the solid state as shown by X-ray
crystallography. 119Sn NMR shows extensive adduct
formation at low temperature but extensive dissociation
at room temperature.
Ack n ow led gm en t. The Department of Science and
Technology (India) for the award of a BOYSCAST
Fellowship, the Department of Industry, Science, and
Technology (Australia), and North-Eastern Hill Uni-
versity are thanked for enabling T.S.B.B. to work in
Australia. The support of the Australian Research
Council and the Council of Scientific and Industrial
Research, New Dehli, are gratefully acknowledged.
(21) Gielen, M.; Acheddad, M.; Tiekink, E. R. T. Main Group Met.
Chem. 1993, 16, 367 and references therein.
(22) Aizawa, S.; Natsume, T.; Hatano, K.; Funahashi, S. Inorg.
Chim. Acta 1996, 248, 215.
(23) Calligaris, M.; Randaccio, L. Comprehensive Coordination,
Chemistry; Wilkinson, G., Guard, R. D., McCleverty, J ., Eds.; Pergamon
Press: New York, 1987; Vol. 2, p 715.
Su p p or tin g In for m a tion Ava ila ble: Tables of the struc-
ture determinations for 1-4, including atomic coordinates,
bond distances and angles, and thermal parameters (25 pages).
Ordering information is given on any current masthead page.
OM9800290
(24) Biradar, N. S.; Roddabasanagoudar, V. L.; Aminabhavi, T. M.
Polyhedron 1984, 3, 575.
(25) Colton, R.; Dakternieks, D. Inorg. Chim. Acta 1988, 148, 31.