X-ray diffraction and 2D gradient-assisted 1H-119Sn HMQC NMR studies of structures obtained from nucleophilic substitutions on dimethyltin(IV) salicylaldoximates

Article abstract of DOI:10.1021/om970378e

The reactivity of the trinuclear tin cluster [(Me₂Sn)₂(Me₂SnO)(OCH ₃)(HONZO)(ONZO)] (3a; HONZOH = o-HON=CH-C₆H₄-OH, salicylaldoxime) toward proton-donating nucleophiles is investigated with the purpose of studying the influence of the nature and acidity of the entering nucleophile on the reactivity of 3a and the stability of its cluster network. Reactions of 3a with benzaldoxime, HON=CH-C₆H₅, and phenols HO-C₆H_5-nX_n (pK_a > 8) preserve the cluster network and give rise to smooth substitution of the μ₂-OCH₃ moiety for, respectively, a μ₂-bridging benzaldoximate, generating [(Me₂Sn)₂(Me₂SnO)(ONCHC₆H ₅)-(HONZO)(ONZO)] (4), and μ₂-bridging phenolates, generating [(Me₂Sn)₂(Me₂SnO)-(OC₆H _5-nX_n)(HONZO)(ONZO)] (n = 1, X = 4-Me (5a), 4-Br (5b), 3-Cl (5c), 3-NO₂ (5d); n = 2, 3,5-Me₂ (5e)). More acidic or sterically hindered ortho-disubstituted phenols lead to decomposition of the trinuclear cluster or to mixtures from which no pure trinuclear cluster can be isolated. Reactions of 3a with carboxylic acids, acetic and p-toluic acids, and acetylacetone lead to clean decomposition of the trinuclear cluster, yielding the respective bis[dicarboxylatotetramethyldistannoxanes], 6a and 6b, and dimethyltin bis(acetylacetonate), Me₂Sn(acac)₂, 7. Reaction of 3a with ethylene glycol generates a mixture of trinuclear clusters, from which 1,3-dioxa-2,2-dimethyl-2-stannacyclopentane (8a) precipitates. Crystal structure determinations by X-ray diffraction for 4, 5a, and 5b reveal essentially the same trinuclear clusters as in 3a and related compounds, with a seven-coordinate pentagonalbipyramidal tin atom linked to two five-coordinate trigonal-bipyramidal tin atoms via a network of oxygen atoms. All new trinuclear tin clusters have been characterized in solution by gradient-assisted 2D NMR.

Full text of DOI:10.1021/om970378e

Organometallics 1997, 16, 4377-4385
4377
1
X-r a y Diffr a ction a n d 2D Gr a d ien t-Assisted H-119Sn
HMQC NMR Stu d ies of Str u ctu r es Obta in ed fr om
Nu cleop h ilic Su bstitu tion s on Dim eth yltin (IV)
Sa licyla ld oxim a tes
Rudolph Willem,*,†,‡,§ Abdeslam Bouhdid,§ Abdelkrim Meddour,†,§
Carlos Camacho-Camacho,§,| Fre´de´ric Mercier,†,§ Marcel Gielen,§ and
Monique Biesemans†,§
High Resolution NMR Centre (HNMR) and Laboratory of General and Organic Chemistry of
the Faculty of Applied Sciences (AOSC), Free University of Brussels (VUB), Pleinlaan 2,
B-1050 Brussel, Belgium
Franc¸ois Ribot and Cle´ment Sanchez
Laboratoire de Chimie de la Matie`re Condense´e, URA CNRS 1466, Tour 54, 5e e´tage,
Universite´ Pierre et Marie Curie, 4 Place J ussieu, F-75252 Paris Cedex 05, France
Edward R. T. Tiekink
Department of Chemistry, The University of Adelaide, South Australia 5005, Australia
Received May 7, 1997X
The reactivity of the trinuclear tin cluster [(Me2Sn)2(Me2SnO)(OCH3)(HONZO)(ONZO)]
(3a ; HONZOH ) o-HONdCH-C6H4-OH, salicylaldoxime) toward proton-donating nucleo-
philes is investigated with the purpose of studying the influence of the nature and acidity
of the entering nucleophile on the reactivity of 3a and the stability of its cluster network.
Reactions of 3a with benzaldoxime, HONdCH-C6H5, and phenols HO-C6H5-nXn (pKa > 8)
preserve the cluster network and give rise to smooth substitution of the µ2-OCH3 moiety
for, respectively, a µ2-bridging benzaldoximate, generating [(Me2Sn)2(Me2SnO)(ONCHC6H5)-
(HONZO)(ONZO)] (4), and µ2-bridging phenolates, generating [(Me2Sn)2(Me2SnO)-
(OC6H5-nXn)(HONZO)(ONZO)] (n ) 1, X ) 4-Me (5a ), 4-Br (5b), 3-Cl (5c), 3-NO2 (5d ); n )
2, 3,5-Me2 (5e)). More acidic or sterically hindered ortho-disubstituted phenols lead to
decomposition of the trinuclear cluster or to mixtures from which no pure trinuclear cluster
can be isolated. Reactions of 3a with carboxylic acids, acetic and p-toluic acids, and
acetylacetone lead to clean decomposition of the trinuclear cluster, yielding the respective
bis[dicarboxylatotetramethyldistannoxanes], 6a and 6b, and dimethyltin bis(acetylacetonate),
Me2Sn(acac)2, 7. Reaction of 3a with ethylene glycol generates a mixture of trinuclear
clusters, from which 1,3-dioxa-2,2-dimethyl-2-stannacyclopentane (8a ) precipitates. Crystal
structure determinations by X-ray diffraction for 4, 5a , and 5b reveal essentially the same
trinuclear clusters as in 3a and related compounds, with a seven-coordinate pentagonal-
bipyramidal tin atom linked to two five-coordinate trigonal-bipyramidal tin atoms via a
network of oxygen atoms. All new trinuclear tin clusters have been characterized in solution
by gradient-assisted 2D NMR.
1
1
In tr od u ction
diffraction and gradient-assisted2 2D H-13C and H-
119Sn HMQC3a/HMBC3b,c NMR spectroscopy.4 These
compounds are small clusters displaying two unequiva-
lent salicylaldoximate and three diorganotin moieties
Novel structures resulting from condensation reac-
tions of a diorganotin(IV) oxide, R2SnO (R ) n-Bu,1a
Me1b), with salicylaldoxime, o-HONdCHC6H4-OH, here-
after HONZOH, have recently been elucidated1 by X-ray
(2) (a) Keeler, J .; Clowes, R. T.; Davis, A. L.; Laue, E. D. Methods
Enzymol. 1994, 239, 145. (b) Tyburn, J .-M.; Bereton, I. M.; Doddrell,
D. M. J . Magn. Reson. 1992, 97, 305. (c) Ruiz-Cabello, J .; Vuister, G.
W.; Moonen, C. T. W.; Van Gelderen, P.; Cohen, J . S.; Van Zijl, P. C.
M. J . Magn. Reson. 1992, 100, 282. (d) Vuister, G. W.; Boelens, R.;
Kaptein, R.; Hurd, R. E.; J ohn, B. K.; Van Zijl, P. C. M. J . Am. Chem.
Soc. 1991, 113, 9688.
(3) (a) Bax, A.; Griffey, R. H.; Hawkins, B. L. J . Magn. Reson. 1983,
55, 301. (b) Bax, A.; Summers, M. F. J . Am. Chem. Soc. 1986, 108,
2093. (c) Bax, A.; Summers, M. F. J . Magn. Reson. 1986, 67, 565.
(4) (a) Kayser, F.; Biesemans, M.; Gielen, M.; Willem, R. J . Magn.
Reson. 1993, A102, 249. (b) Martins, J . C.; Verheyden, P.; Kayser, F.;
Gielen, M.; Willem, R.; Biesemans, M. J . Magn. Reson. 1997, 124, 218.
(c) Kayser, F.; Biesemans, M.; Gielen, M.; Willem, R. In Advanced
Applications of NMR to Organometallic Chemistry; Gielen, M., Willem,
R., Wrackmeyer, B., Eds.; Wiley: Chichester, U.K., 1996; Chapter 3,
pp 45-86.
† High Resolution NMR Centre, Free University of Brussels.
‡ E-mail: rwillem@vub.ac.be.
§ Laboratory of General and Organic Chemistry of the Faculty of
Applied Sciences, Free University of Brussels.
| Present address: Universidad Auto´noma Metropolitana-Xochimil-
co, Departamento de Sistemas Biolo´gicos, Calzada del Hueso, 1100 Col.
Villa Quietud, C.P. 04960, Mexico D.F.
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) (a) Kayser, F.; Biesemans, M.; Bouaˆlam, M.; Tiekink, E. R. T.;
El Khloufi, A.; Meunier-Piret, J .; Bouhdid, A.; J urkschat, K.; Gielen,
M.; Willem, R. Organometallics 1994, 13, 1098, 4126. (b) Willem, R.;
Bouhdid, A.; Kayser, F.; Delmotte, A.; Gielen, M.; Martins, J . C.;
Biesemans, M.; Mahieu, B.; Tiekink, E. R. T. Organometallics 1996,
15, 1920.
S0276-7333(97)00378-6 CCC: $14.00 © 1997 American Chemical Society

4378 Organometallics, Vol. 16, No. 20, 1997
Willem et al.
Sch em e 1
1. The reversible reactions linking all these compounds
are nucleophilic substitutions at the cluster site Sn2-
O40-Sn3, where a µ2-bridged T-O group is substituted
for another µ2-bridged W-O one, under proton transfer
from the entering W-OH nucleophile toward the leaving
T-OH one.1 It thus appears that the proton donor
properties of the entering nucleophile as well as the
Sn2-O40-Sn3 bridging functionality entirely deter-
mine the reactivity of such clusters.
Whether all nucleophiles possessing transferable
protons are amenable to such reactions and to which
extent the acidity of the entering nucleophile is a critical
factor remains to be established. The main purpose of
the present paper is to report on the influence of the
nature and acidity of the entering nucleophile on the
reactivity of such compounds, more specifically, on the
stability of their cluster network. It is aimed at defining
the acidity limits within which smooth µ2-bridged nu-
cleophilic substitution with preservation of the cluster
pattern is possible. To do so, we investigated the
reactivity of the most stable of these clusters in solution,
3a ,1b toward a wide panel of proton-donating nucleo-
philes, phenols with various pKa’s, two carboxylic acids,
acetylacetone, ethylene glycol, and benzaldoxime.
A
F igu r e 1. General structure, with atom labeling, of
compounds from several condensation reactions between
di-n-butyl or dimethyltin(IV) oxide and salicylaldoxime,
synthesized previously (1a , 1b1a and 2b, 3a -e1b) or in the
present work (4, 5a -e). HOZN represents the salicylal-
doximate moiety C bound to O40 by its nitrogen atom;
HZN, accordingly represents the benzaldoximate moiety
bound to O40 in the same way.
further motivation to investigating phenols and ben-
zaldoxime is dictated by the noncrystalline 2b in which
tin atoms are bound to both the phenolic and oximic
oxygens of the salicylaldoximate ligands. Since 2b could
not be obtained as a crystalline compound, it was
interesting to investigate whether similar structures
involving only one of these functions can be obtained in
a form amenable to X-ray diffraction analysis.
Resu lts a n d Discu ssion
Syn t h et ic Asp ect s. Compound 3a , [(Me2Sn)2-
(Me2SnO)(OCH3)(HONZO)(ONZO)], is convenient for
investigating nucleophilic substitutions because it is
relatively stable and the leaving nucleophile, methanol,
can easily be eliminated. This feature is important
since attempts at purification of such clusters by
chromatographic methods lead to decomposition.1
Reaction of 3a with benzaldoxime generates a crystal-
line compound amenable to a more precise characteriza-
tion of the oxime binding mode to the Sn2-O40-Sn3
moiety proposed from solution NMR studies for 1b and
2b. Compound 4, represented as [(Me2Sn)2(Me2SnO)-
(ONdCH-C6H5)(HONZO)(ONZO)], was isolated as a
crystalline compound after substitution in benzene of
the µ2-OCH3 group from 3a for a µ2-ONdCH-C6H5 one,
under addition of benzaldoxime (C6H5-CHdNOH) and
elimination of methanol. It was characterized by X-ray
diffraction analysis in the crystalline state and shown
to have the same structure in solution by NMR (see
below). A similar attempt to react 3a with acetal-
doxime, CH3CHdNOH, failed since 3a was recovered
essentially quantitatively. This result emphasizes the
importance of the proton transfer from the entering
toward the leaving nucleophile, as the too low acidity
of acetaldoxime hampers this.
F igu r e 2. Solution structures of 1b and 2b.1b
linked by Sn-O-Sn bridges, with one seven-coordinate
(Sn1) and two five-coordinate (Sn2 and Sn3) tin atoms
(Figure 1).1 The noncrystalline compounds [(R2Sn)2-
(R2SnO)(ONZOH)(HONZO)(ONZO)] (1b, R ) n-Bu; 2b,
R ) Me) (Figure 2) are the key intermediates in the
synthesis of such clusters.1b Cyclohexane, hexane,
acetonitrile, or methanol solutions of 1b give rise to
crystals having structure 1a instead of 1b.1a Compound
2b gives rise to crystalline materials only from low
molecular weight alcohols, T-OH (T ) Me, Et, n-Pr,
i-Pr), providing, respectively, compounds 3a -d instead
of 2b or 2a .1b These structural changes occur during
the crystallizations according to the reaction in Scheme

Substituted Dimethyltin(IV) Salicylaldoximates
Organometallics, Vol. 16, No. 20, 1997 4379
Reacting phenols with 3a is of interest for two
reasons. First, since 3a reacts with salicylaldoxime to
form 2b, with coordination through the oximic rather
than the phenolic oxygen, it should be established
whether a phenolic oxygen is likewise amenable to Sn2-
O40-Sn3 bridging;1 second, the role of the acidity
degree of the entering phenols should be outlined.
Phenols react with 3a in benzene at room tempera-
ture. The anticipated complexes have the general
formula [(Me2Sn)2(Me2SnO)(OAr)(HONZO)(ONZO)]. In
the case of p-cresol (pKa ) 9.82), p-bromophenol (pKa )
9.34), m-chlorophenol (pKa ) 9.08), m-nitrophenol (pKa
) 8.38), and 3,5-dimethylphenol (pKa ) 10.15), novel
compounds 5a -e, respectively (Figure 1), could be
isolated as solids. For the p-cresol and p-bromophenol
derivatives, 5a and 5b, crystals suitable for X-ray
analysis were obtained. Their solid state and solution
structures display essentially the same motifs as do the
solution structures of 5c-e (see NMR data below).
F igu r e 3. Solution state structure of dimeric bis[dicar-
boxylatotetramethyldistannoxanes] obtained from the reac-
tion of 3a with a carboxylic acid R′-COOH (R′ ) CH3, 6a ;
p-CH3-C6H4, 6b).
Sch em e 2
Two further features of the reaction of 3a with
phenols were assessed: steric effects and phenol acidity.
Reaction of 3a with phenols appears sensitive to steric
hindrance, since attempts under similar conditions to
isolate [(Me2Sn)2(Me2SnO)(OAr)(HONZO)(ONZO)] from
2,6-dimethylphenol (pKa ) 10.59) and 2,4,6-trimeth-
ylphenol (pKa ) 10.88) did not provide the desired
compounds in pure form. 119Sn NMR analysis of the
crude reaction mixture reveals that it contains only
small quantities (ca. 10-20%) of the expected aryloxy
complex, together with comparable amounts of 2b and
unreacted 3a , as well as the other usual transients, m2
and m3.1 As steric hindrance of the ortho substituents
of the entering phenols hampers the formation of the
desired aryloxy complex, it is likely that their acidity
facilitates the conversion of 3a to 2b, through protona-
tion of the µ2-alkoxy group.1a
Sch em e 3
and p-toluic acid yielded dimeric bis[dicarboxylatotet-
raorganodistannoxanes], well-known compounds with
a solution structure as shown in Figure 3.5 In view of
the results obtained with phenols, carboxylic acids thus
have sufficient acidity to favor the decomposition of 3a
and the release of the dimethyltin oxide units needed
for the generation of such dimeric bis[dicarboxylatotet-
raorganodistannoxanes], usually synthesized from con-
densation of a diorganotin oxide with a carboxylic acid
in molar ratio 1:1.5 In this picture, the formation of
bis[diacetatotetramethyldistannoxane], 6a, and bis[bis(4-
methylbenzoato)tetramethyldistannoxane], 6b, is readily
explained by the stoichiometry shown in Scheme 2.
The X-ray structure of 6a has been described previ-
ously by Lockhart and co-workers.5a Compound 6a ,
synthesized, for comparison, by the usual reaction
involving condensation of the carboxylic acid with
dimethyltin(IV) oxide,5 has physical characteristics
identical to those obtained by scheme 3. Compounds
6a and 6b were characterized by elemental analysis and
solution NMR.10c
With phenols having a pKa slightly lower than 8, no
pure [(Me2Sn)2(Me2SnO)(OAr)(HONZO)(ONZO)] can be
isolated from their reaction with 3a . Thus, for p-
cyanophenol (pKa ) 7.95) and p-nitrophenol (pKa
)
7.16), 119Sn resonance analysis of the reaction mixtures
obtained reveals the desired product together with 2b
and 3a , in the approximate ratios 69:27:4 and 54:42:4,
respectively, in addition to the usual minor species
giving rise to noisy resonances.1b Thus, the threshold
phenol pKa, below which smooth substitution of the
methoxy group of 3a for a substituted phenoxy group
is no longer possible, lies in the range 8.0-8.4. Again,
acidity causes the undesired formation of 2b from 3a
through facilitated proton transfer. That phenol acidity
is determinant is further supported by the reaction of
3a with 2,4-dinitrophenol (pKa ) 4.09), which leads to
destruction of the cluster structure, as revealed by the
collapse of the three 119Sn resonance pattern character-
izing such clusters.1
Reaction of 3a with 2,4-pentanedione (acetylacetone,
acacH) yields bis(2,4-pentanedionato)dimethyltin(IV)
((CH3)2Sn(acac)2, 7). This result shows that the weak-
(5) (a) Lockhart, T. P.; Manders, W. F.; Holt, E. M. J . Am. Chem.
Soc. 1986, 108, 6611. (b) Tiekink E. R. T. Appl. Organomet. Chem.
1991, 5, 1. (c) Tiekink, E. R. T. Trends Organomet. Chem. 1994, 1, 71.
(d) Gielen, M.; Tiekink, E. R. T.; Bouhdid, A.; de Vos, D.; Biesemans,
M.; Verbruggen, I.; Willem, R. Appl. Organomet. Chem. 1995, 9, 639.
(e) Tiekink, E. R. T.; Gielen, M.; Bouhdid, A.; Biesemans, M.; Willem,
R. J . Organomet. Chem. 1995, 494, 247. (f) Gielen, M.; Bouhdid, A.;
Willem, R.; Bregadze, V. I.; Ermanson, L. V.; Tiekink, E. R. T. J .
Organomet. Chem. 1995, 501, 277. (g) Gielen, M.; Biesemans, M.; El
Khloufi, A.; Meunier-Piret, J .; Kayser, F.; Willem, R. J . Fluorine Chem.
1993, 64, 279. (h) Gielen, M.; El Khloufi, A.; Biesemans, M.; Kayser,
F.; Willem, R. Appl. Organomet. Chem. 1993, 7, 201. (i) Gielen, M.; El
Khloufi, A.; Biesemans, M.; Willem, R. Appl. Organomet. Chem. 1993,
7, 119. (j) Yano, T.; Nakashima, K.; Otera, J .; Okawara, R. Organo-
metallics 1985, 4, 1501. (k) Dakternieks, D.; J urkschat, K.; van
Dreumel, S.; Tiekink, E. R. T. Inorg. Chem. 1997, 36, 2023.
The role of the acidity in µ2-nucleophilic substitutions
on the Sn2-O40-Sn3 moiety of 3a was further assessed
by reactions of 3a with carboxylic acids. Thus, the
bidentate nature of carboxylates could a priori favor the
formation of a carboxylate bridging the Sn2 and Sn3
atoms. On the other hand, the higher acidity of car-
boxylic acids, as compared to phenols, is an unfavorable
premice. No cluster with bridging carboxylates of the
type [(Me2Sn)2(Me2SnO)(OOCR′)(HONZO)(ONZO)] was
indeed obtained. Thus, reaction of 3a with acetic acid

4380 Organometallics, Vol. 16, No. 20, 1997
Willem et al.
Sch em e 4
ness of the acid (pKa ca. 9, comparable to phenols)6 is
not a sufficient condition for µ2-nucleophilic substitution
on the Sn2-O40-Sn3 bridge of 3a to be possible.
Instead, the formation of the very stable bis-chelated,
six-coordinate (CH3)2Sn(acac)2 is thermodynamically
favored according to Scheme 3. Compound 7 was easily
characterized from comparison of its NMR spectral and
physical characteristics with literature data.7
Lastly, 3a was allowed to react with ethylene glycol
in order to examine whether a diol is able to chelate
the Sn2-O40-Sn3 unit of 3a . A complex reaction
mixture, from which a solid precipitates, was obtained.
The solid is identified as 2,2-dimethyl-1,3-dioxa-2-stan-
nacyclopentane (8a ), generated as shown in Scheme 4.
Only few data for the very poorly soluble 8a were
provided earlier.8b It was characterized here by solution
1H and 119Sn and solid state 13C and 119Sn NMR, mass
spectrometry, and elemental analysis. Though less
soluble, 8a has properties comparable to those of the
dibutyltin analog.8a,c
The evaporated filtrate of this reaction mixture could
not be worked up to a pure product. It reveals the
presence of approximately 22 ( 4% of 2a , 48 ( 12% of
2b, and 30 ( 8% of a new product, 8b. In situ 2D
gradient-assisted 1H-119Sn HMQC data4 suggest a
solution structure, [(Me2Sn)2(Me2SnO)(OCH2-)(HONZO)-
(ONZO)]2, with an ethane diolate unit of which the two
oxygens “µ2-bridge” each a cluster unit at O40. No
evidence was found for 8b having a structure where a
single ethylene glycol unit bridges the Sn2 and Sn3
atoms of a single cluster with each oxygen bound to a
single tin atom.
X-r a y Diffr a ction Str u ctu r es of 4, 5a , a n d 5b.
The molecular structures of 4 and 5a shown in Figures
4 and 5, respectively, and that of 5b (Figure S1,
Supporting Information) closely resemble those found
for 1a 1a and 3a -d ,1b and hence, a detailed description
is not warranted. Accordingly, the bond lengths and
angles given in Table 1 mainly refer to the bonding
mode of the new ligand around the Sn2-O40-Sn3
bridge, the other data relevant to the remaining part
of the cluster being available in the Supporting Infor-
mation. The structures are isomorphous, and each unit
cell comprises two tin-containing molecules and one
F igu r e 4. Molecular structure and crystallographic num-
bering scheme for [(Me2Sn)2(Me2SnO)(ONZH)(HONZO)-
(ONZO)] (4) (HONZOH ) salicylaldoxime, o-HONdCH-
C6H4-OH; HONZH ) benzaldoxime, HONdCH-C6H5).
Ta ble 1. Selected Geom etr ic P a r a m eter s for 4, 5a ,
a n d 5b
compound
4
5a
5b
Bond Distances (Å)
Sn(1)-O(10)
Sn(1)-O(30)
Sn(2)-O(10)
Sn(2)-O(30)
Sn(2)-O(40)
Sn(2)-C(23)
Sn(2)-C(24)
Sn(3)-O(19)
Sn(3)-O(30)
Sn(3)-O(40)
Sn(3)-C(25)
Sn(3)-C(26)
O(40)-N(4)a
N(4)-C(41)
2.715(4)
2.177(4)
2.153(4)
2.002(4)
2.227(4)
2.120(7)
2.105(7)
2.083(5)
2.020(4)
2.248(5)
2.124(8)
2.116(7)
1.403(7)
1.213(8)
2.695(4)
2.178(3)
2.145(4)
2.016(4)
2.204(4)
2.122(7)
2.122(7)
2.093(5)
2.010(4)
2.255(4)
2.106(7)
2.100(7)
1.365(6)
2.688(4)
2.181(4)
2.140(4)
2.006(4)
2.210(4)
2.097(7)
2.100(7)
2.090(5)
2.008(4)
2.274(4)
2.107(7)
2.096(7)
1.372(6)
Bond Angles (deg)
164.6(3)
80.1(1)
C(21)-Sn(1)-C(22)
O(10)-Sn(2)-O(30)
O(10)-Sn(2)-O(40)
O(30)-Sn(2)-O(40)
C(23)-Sn(2)-C(24)
O(19)-Sn(3)-O(30)
O(19)-Sn(3)-O(40)
O(30)-Sn(3)-O(40)
C(25)-Sn(3)-C(26)
Sn(1)-O(10)-Sn(2)
Sn(3)-O(19)-N(18)
Sn(1)-O(30)-Sn(2)
Sn(1)-O(30)-Sn(3)
Sn(2)-O(30)-Sn(3)
Sn(2)-O(40)-Sn(3)
Sn(2)-O(40)-N(4)a
Sn(3)-O(40)-N(4)a
O(40)-N(4)-C(41)
167.2(3)
80.5(1)
166.3(3)
80.6(2)
154.9(2)
74.4(1)
135.4(3)
87.8(2)
160.5(2)
72.9(2)
153.8(2)
74.1(2)
155.0(1)
74.6(1)
134.3(3)
86.9(2)
136.4(3)
86.7(2)
159.9(2)
73.3(2)
160.0(2)
73.5(1)
135.2(3)
95.1(1)
136.7(3)
95.3(1)
137.8(3)
95.4(2)
121.2(3)
119.5(2)
126.5(2)
114.0(2)
97.8(2)
124.7(3)
118.1(2)
127.9(2)
113.6(2)
98.1(1)
123.6(4)
118.0(2)
127.1(2)
114.7(2)
97.8(1)
120.7(4)
122.3(4)
116.2(7)
129.7(3)
131.9(3)
129.9(4)
131.8(4)
a
For structures 5a and 5b, N(4) is C(41).
(6) Carey, F. A. Organic Chemistry, 3rd ed.; McGraw-Hill: New
York, 1996; p 736.
solvent benzene molecule which is situated about a
crystallographic center of inversion; there are no sig-
nificant interactions between the constituents. The
solvent molecules occupy channels parallel to the c-
direction. The trinuclear cluster of 4 features the usual
seven-coordinate Sn1 atom and two five-coordinate tin
atoms, i.e., Sn2 and Sn3. The geometry about Sn1 is
distorted pentagonal bipyramidal with the methyl sub-
stituents in axial positions. The pentagonal plane
(planar to (0.041 Å) is defined by the phenoxide
oxygens and the oxime nitrogen atoms of the HONZO
(7) (a) Miller, G. A.; Schlemper, E. O. Inorg. Chem. 1973, 12, 677.
(b) McGrady, M. M.; Tobias, R. S. J . Am. Chem. Soc. 1965, 87, 1909.
(c) Howard, W. F., J r.; Crecely, R. W.; Nelson, W. H. Inorg. Chem.1985,
24, 2204. (d) Lockhart, T. P.; Manders, W. F. Inorg. Chem. 1986, 25,
892. (e) Manders, W. F.; Lockhart, T. P. J . Organomet. Chem. 1985,
297, 143. (f) Lockhart, T. P.; Manders, W. F.; Zuckerman, J . J . J . Am.
Chem. Soc. 1985, 107, 4546. (g) Herber, R. H.; Leahy, M. F.; Hazony,
Y. J . Chem. Phys. 1974, 60, 5070.
(8) (a) Davies, A. G.; Price, A. J .; Dawes, H. M.; Hursthouse, M. B.
J . Chem. Soc., Dalton Trans. 1986, 297. (b) Satai, S.; Fujimura, Y.;
Ishii, Y. J . Org. Chem. 1970, 35, 2344. (c) Grindley, T. B.; Wasylishen,
R. E.; Thangarasa, R.; Power, W. P.; Curtis, R. D. Can. J . Chem. 1992,
70, 205.

Substituted Dimethyltin(IV) Salicylaldoximates
Organometallics, Vol. 16, No. 20, 1997 4381
different conjugation abilities of the T substituents. The
Sn-O40 bond lengths are larger in 4 than the corre-
sponding ones in 3a -d , and the expansion in the Me-
Sn2-Me and Me-Sn3-Me angles is also apparent. A
further difference between 4 and the other structures
relates to the geometry about the O40 atom, which is
essentially trigonal planar in 1a , 3a -d , and 5a ,b. In
4, the O40 atom lies 0.461(5) Å out of the plane defined
by the Sn2, Sn3, and N4 atoms, and the sum of the
angles subtended at O40 is 340.8°. This indicates that,
for the benzaldoximate, a significant resonance con-
tributor has the formal negative charge located on the
oxygen atom, while for the phenoxides a significant
contributing resonance structure would have a formal
CdO. Experimental evidence for this is found by the
presence of a very short NdC bond distance [1.213(8)
Å] in 4. Noticeable is also the more symmetrical bridge
in 5a than in 5b.
F igu r e 5. Molecular structure and crystallographic num-
bering scheme for [(Me2Sn)2(Me2SnO)(O-C6H4-CH3)-
(HONZO)(ONZO)] (5a ). An analogous numbering scheme
is used for 5b.
and ONZO anions as well as the O30) atom, which links
Sn1 to the Sn2 and Sn3 atoms; the Sn1 lies 0.0145(4) Å
above the basal plane in the direction of the C22 atom.
The Sn2 and Sn3 atoms each exist in distorted trigonal-
bipyramidal geometries with the Sn2 (Sn3) atom lying
0.0794(4) Å (0.1181(5) Å) out of the C2O30 plane in the
direction of the O10 (O19) atom. A difference map
calculated toward the end of the refinement revealed
the presence of a hydrogen atom on O9, consistent with
the earlier studies,1 and hence the assignment of the
uninegative HONZO and dinegative ONZO anions is
unambiguous. The O-H moiety is involved in an
intramolecular hydrogen bonding contact to the O(20)
atom of 1.77 Å. The C6H5-CHdNO residue is sym-
metrically disposed with respect to the cluster as seen
in the Sn2/O40/N4/C41 and Sn3/O40/N4/C41 torsion
angles of 125.9(6) and -109.9(7)°, respectively, and in
the dihedral angle between the Sn2O2 plane and the
plane through the C6H5-CHdNO atoms of 95.4°.
The structure of compound 4, more specifically the
binding mode of the bridging oximic oxygen atom,
compares well with that proposed from solution NMR
data for 1b and 2b (Figure 2).1b In particular, the
structural arrangement where the salicylaldoximate
ligand C in 1b and 2b and the benzaldoximate ligand
in 4 are perpendicular to the mean plane through the
cluster, comprising the network of Sn-O-Sn bridges
and the ligands A and B, is noticeably common to the
three compounds. The E configuration of the PhCHdNO
moiety of 4 is, however, in contrast with the Z config-
uration in 1b and 2b proposed earlier on the basis of
infrared data.1b Because of this configuration differ-
ence, the structure of 4 cannot be considered as an
indirect support for the existence of a hydrogen bridge
in 1b and 2b. Consequently, it is no longer represented
in Figure 2.
NMR Stu d ies on th e Solu tion Sta te Str u ctu r es
of 4, 5a -e, a n d 8b. An overview of the main NMR data
of 4, 5a -e, 8b in CDCl3 solution is given in Table 2;
the other data are given in the Experimental Section.
The NMR signal assignment, obtained by a combination
1
1
of gradient-assisted2 2D H-119Sn HMQC3a,4 and H-
13C HMBC spectroscopy,3b,c will not be detailed, since
very similar 1H-119Sn HMQC and 1H-13C HMBC
patterns were processed here with the same strategy
for 4, 5a , and 8b as for 1a ,1a 1b,1a,1b 2b,1b and 3a ,b.1b
The J (1H-119Sn) coupling constants determined from
n
2D H-119Sn HMQC correlations are identical in 4, 5a ,
1
and 8b to within 1-2 Hz to the corresponding values
in 1a ,1a 3a ,b, and 2b.1b On the basis of the full
assignment of the SnMe2 groups achieved by H-119Sn
1
HMQC spectroscopy for 5a , the corresponding reso-
nances of 5b-e can be assigned by simple extrapolation.
Likewise, on the basis of 2D 1H-13C HMBC spectra
obtained for 5a , 5c, and 5d , a similar resonance
transposition was achieved to 5b and 5e, except for most
of their aromatic 1H resonances subject to complex
overlapping.
The structures of 4 and 5a are identical in the solution
and solid states. The key data to support this conclusion
as well as to identify the solution structure of 8b in its
crude reaction mixture are the observation of 2D nJ (1H-
119Sn) HMQC correlations between the 119Sn2 and
119Sn3 nuclei and some 1H nuclei of the O40-bound
1
organic moiety. Thus, the 2D H-119Sn HMQC spectra
exhibit a correlation peak between the 119Sn2 and 119Sn3
1
resonances and the H resonance of the ortho protons
of the p-methylphenyl moiety of 5a (4J (1H-o-C46/42-
C41-O40-119Sn2/Sn3) < 2 Hz), of the oximic proton of
the benzaldoxime moiety of 4 (4J (1H41-C41-N4-O40-
119Sn2/Sn3) < 2 Hz), and of the methylene protons of
the ethylene glycol moiety of 8b (3/4J (1H2C-1H2C-O40-
119Sn2/Sn3), a composite correlation). As an example,
Figure 6 shows the cross sections, along the F2, 1H
chemical shift axis, of the 2D gradient-assisted 1H-
119Sn HMQC spectrum obtained for 8b in a mixture with
2a and 2b, at the 119Sn resonance frequencies of the two
five-coordinate tin atoms Sn2 and Sn3. They exhibit
the correlations between the methylene proton reso-
nances and the 119Sn ones of the tin atoms Sn2 and Sn3,
in addition to those from the cluster moiety.
The basic framework and coordination geometries of
4 are retained in both 5a and 5b, the main difference
being the nature of the function bridging the Sn2 and
Sn3 atoms (Figure 5). The substituted phenoxide func-
tions are effectively orthogonal to the Sn2O2 plane as
seen in the Sn2/O40/C41/C42 and Sn3/O40/C41/C42
torsion angles of, respectively, -89.2(6) and 98.3(6)° for
5a and -90.9(7) and 99.0(6)° for 5b. The similarity
between 5a and 5b is not surprising given their very
close pKa’s.
The geometric parameters in the structure of 4 are
closer to those of 5a ,b than those of 3a -d , reflecting
The 119Sn resonances of 2b generated in solution as
a minor species, as well as the resonances from the other

4382 Organometallics, Vol. 16, No. 20, 1997
Willem et al.
Ta ble 2. 119Sn , 13C a n d 1H NMR Da ta of th e Dim eth yltin Moieties of 4 a n d 5a -e fr om CDCl3 Solu tion s a n d
8b fr om C6D6 Solu tion a
compd
moiety
δ(119Sn)b
nJ (119Sn-119/117Sn)c
δ(13C)d
1J (13C-119/117Sn)e
δ(1H)f
2J (1H-119Sn)
4
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
Me2Sn1
Me2Sn2
Me2Sn3
-452.7
-128.0
-114.4
-452.1
-138.1
-123.6
-451.9
-133.1
-119.5
-451.0
-132.2
-118.6
-450.0
-127.6
-113.9
-452.2
-138.1
-125.0
-461.5
-156.8
-137.6
325h; 46h
100h; 51h
314;h 100h
328h; 60h
90h; 56h
324h; 91h
311h; nrj
90h; 49h
300;h 92h
299h; 46h
85h; 49h
297h; 85h
290h; nrj
89h; 43h
290h; 85h
321/311; 52h
86h; 52h
324/308; 86h
k
15.0
3.6
1.1
14.5
3.7
0.9
14.8
3.9
1.2
14.7
4.1
1.4
14.7
4.2
1.5
15.0
3.5
0.7
l
1102/1056
684/644
649/609
1099/1047
660/630
648/625
1094/1043
664/630
650/625
1090/1040
645/616
650/622
1085/1042
659/628
647/621
1106/1055
664/636
652/623
l
1.15
0.71
0.70
0.92
0.93
0.74
0.90
0.89
0.71
0.91
0.93
0.75
0.93
0.96
0.57
1.10
0.59
0.57
1.18
0.70
0.59
113g
76g
77g
5a (pKa 9.82)
5b (pKa 9.34)
5c (pKa 9.08)
5d (pKa 8.38)
5e (pKa 10.15)
8b
109g
73g
74g
103i
82/78
75/72
109i
73i
73i
108i
73i
74i
112i
74i
74i
114i
79i
102h
l
l
l
l
340h; 103h
77i
Chemical shift data in ppm and coupling constants (in Hz). b 119Sn resonances were referenced to the absolute frequency of Me4Sn
(37.290 665 MHz9); see Experimental Section. c Combined 3J (119Sn1-N18-O19-119/117Sn3) and 2J (119Sn1-O30-119/117Sn3) coupling
pathways, double 2J (119Sn2-O30-119/117Sn3) and 2J (119Sn2-O40-119/117Sn3) coupling pathways, and double 2J (119Sn1-O30-119/117Sn2)
a
d
and 2J (119Sn1-O10-119/117Sn2) coupling pathways. 13C chemical shifts referenced to the solvent (CDCl3) 13C resonance and converted
to the standard Me4Si scale by adding 77.0 (128.0 ppm for C6D6). e Resolved 1J (13C-119Sn) and 1J (13C-117Sn) coupling satellites. f 1H
chemical shifts referenced to the residual solvent (CDCl3) 1H resonance and converted to the standard Me4Si scale by adding 7.24 ppm
g
(7.15 ppm for C6D5H). Pure 2J (1H-119Sn) coupling constants determined from cross sections along the F2 axis (1H nuclei) of 2D 1H-
h
119Sn HMQC spectra at the 119Sn resonance frequency along the F1 axis of the corresponding tin atom. Averaged values from unresolved
i
nJ (119Sn-119Sn) and nJ (119Sn-117Sn) coupling satellites in 119Sn spectra. Averaged values from unresolved 2J (1H-119Sn) and 2J (1H-
j
k
117Sn) coupling satellites in standard 1H spectra. Nonresolved coupling. Not observed. l 13C spectrum not interpretable because 8b
only observed in mixture.
The 119Sn chemical shifts of the tin atoms Sn2 and
Sn3 of 5a -e are markedly high-frequency-shifted with
respect to those of 3a -d (see Table 2 and ref 1b). This
deshielding effect in 5a -e as compared to 3a -d is
attributed to the inductive electronic-withdrawing effect
of the phenoxy group of 5a -e, as compared to the
inductive electronic releasing effect of the alkoxy group
of 3a -d . In addition, the 119Sn chemical shifts of the
substituted phenoxy derivatives 5 display a deshielding
effect in the order 5e < 5a < 5b < 5c < 5d (Table 2).
This deshielding effect parallels the pKa series of the
associated phenols, confirming that the deshielding
trend is associated with the increasing electron-with-
drawing effect of the substituted phenyl group linked
to O40.
The 119Sn chemical shifts of 4 (Sn1, -452.2; Sn2,
-125.6; Sn3, -112.6 ppm) are remarkably close to those
of 2b (Sn1, -451.4; Sn2, -122.9; Sn3, -109.1 ppm),1b
suggesting these values to be characteristic of the
bonding mode of the aromatic oximate ligand to the
F igu r e 6. Data from the 2D gradient-assisted2 1H-119Sn
HMQC spectrum1,3a,4 of the filtrate of the crude reaction
mixture obtained from the reaction of 3a with ethylene
glycol and containing 2a , 2b, and 8b. The figure shows the
cross sections, along the F2 (1H chemical shift axis) at the
119Sn resonance frequencies of the two five-coordinate tin
atoms Sn2 (top) and Sn3 (bottom) of 8b. Each signal
corresponds to a 1H resonance from the proton indicated,
which is coupled to the 119Sn nucleus of the tin atom
Sn2-O40-Sn3 bridge through the oximic oxygen.
NMR Ch a r a cter iza tion of 6a a n d 6b. The solution
1H and 13C NMR data found for 6a (see Experimental
Section) are in good agreement with the data reported
by Lockhart et al.5a The 119Sn NMR spectrum of 6a in
solution reveals two equally intense 119Sn resonances
at -173.8 and -190.2 ppm, with the latter being broad,
an observation also in good agreement with literature
data (-174.4 and -190.0 ppm).5j They are assigned to
the tin atoms of the structure shown in Figure 3, known
to be the most common structure, both in the solid and
the solution states.5b-j,10 The 119Sn chemical shift values
indeed favor five-coordination at both tin atoms rather
than six-coordination.5b-j,9c The assignment of low- and
high-frequency 119Sn resonances to the exo (Sn2) and
1
indicated, all other H resonances being suppressed by the
gradient pulse and phase cycling schemes.1b,4
minor species m2 (ca. -125 and -219 ppm) and m3 (ca.
-283 ppm), are again observed, to variable extents, in
the 119Sn spectra of pure 4 and 5a -e, as in any solution
of such clusters.1

Substituted Dimethyltin(IV) Salicylaldoximates
Organometallics, Vol. 16, No. 20, 1997 4383
Crude, solid 5a and 5b were recrystallized from benzene/
hexane 3:1 (v/v), 5c and 5d from dichloromethane/hexane 4:1
(v/v), and 5e from dichloromethane/hexane 1:2 (v/v) or benzene/
hexane 1:5 (v/v).
endo (Sn1) tin atoms of the structure, conflicting in the
literature,5e,j,10a and given in the Experimental Section,
1
has been achieved by a 2D gradient-assisted H-119Sn
HMQC experiment.10c A similar assignment is proposed
for 6b, the 119Sn chemical shifts (-179.4 and -190.1
ppm) being very similar to those of 6a , and the low-
frequency 119Sn resonance being again broader.
Com p ou n d s 8a a n d 8b. A solution of 1 g (1.3 mmol) of
3a in 30 mL of benzene is added dropwise to 262 mg (4.2 mmol)
of ethylene glycol. After stirring magnetically the mixture for
18 h, the precipitate obtained is filtered off, washed with
benzene, dichloromethane, diethyl ether, and then dried to
yield 530 mg of 8a . The filtrate is evaporated to a mixture
that could not be purified further, either by crystallization (oil)
or by chromatography (decomposition). NMR analysis, as
presented in Results and Discussion, reveals it to consist of a
mixture of 2a , 2b, and the new compound 8b, formally
The high-frequency 119Sn signal around -175 ppm
2
exhibits unresolved J (119Sn-O-119/117Sn) coupling sat-
ellites of 110 Hz for 6a (103 Hz5j) and of 101 Hz for 6b,
which are invisible for the broad low-frequency 119Sn
resonance at -190 ppm. The latter is indicative of some
fluxionality, different from the one previously invoked5e,10b
since it involves only the endo tin atom. Its nature is
1
identified by H-119Sn HMQC spectroscopy.
Com p ou n d 6a . F r om 3a . To a solution of 500 mg (0.65
mmol) of 3a in 50 mL benzene is added dropwise 39 mg of
acetic acid (0.65 mmol) in 20 mL of benzene. After 24 h of
magnetic stirring at room temperature, a white precipitate is
formed. The precipitate is filtered off and recrystallized in
dichloromethane/hexane 3:1 (v/v) to pure 6a .
Com p ou n d 6a . F r om Me2Sn O. To a solution of 364 mg
(6.1 mmol) of acetic acid in 140 mL of toluene/ethanol 3:1 (v/
v) is added 1 g of dimethyltin oxide (6.1 mmol). After 20 min
of refluxing of the heterogeneous reaction mixture, the mixture
became homogeneous and is refluxed for another 6 h. The
ternary followed by the binary azeotrope is distilled off with a
Dean-Stark apparatus until 50% volume reduction. The
remaining solution is evaporated at the Rotavapor, and the
residue obtained is crystallized twice from dichloromethane/
hexane 3:1 (v/v) to pure 6a .
Com p ou n d 6b. To a solution of 500 mg (0.65 mmol) of 3a
in 50 mL of dichloromethane is added dropwise 89 mg of
p-toluic acid (0.65 mmol) in 20 mL of dichloromethane. After
24 h of magnetic stirring at room temperature, a white
precipitate is formed. The precipitate is filtered off and
recrystallized in dichloromethane/hexane 3:1 (v/v) to pure 6b.
Com p ou n d 7. To a solution of 1.528 g (2 mmol) of 3a in
40 mL of benzene is added dropwise a solution of 1.202 g of
acetylacetone (12 mmol) in 10 mL of benzene. After 20 h of
magnetic stirring at room temperature, the solvent is partially
evaporated under vacuum and the residue recrystallized from
benzene to pure 7.
1
discussed elsewhere.10c The H and 13C resonances of
6b have been assigned by 2D 1H-13C HMBC and
HMQC experiments.
NMR Ch a r a cter iza tion of 7 a n d 8a . Compound
1
7, Me2Sn(acac)2, has been characterized readily from H,
13C, and 119Sn NMR data in CDCl3, by comparison with
literature data,7a-d and by elemental analysis. The
119Sn chemical shift of -365.9 ppm (-365 ppm7c) as well
1
as the J (13C-119Sn) coupling constant of 978 Hz (977
2
Hz7c) and the J (1H-119Sn) coupling constant of 96 Hz
(99 Hz7d) are in agreement with the previously de-
scribed7a,b six-coordinate, distorted octahedral structure
with the two methyl groups in a trans configuration,
the bond angle Me-Sn-Me being, nevertheless, only
162.5° in solution.7d 1H and 13C NMR data are found
in the Experimental Section.
Compound 8a , 2,2-dimethyl-1,3-dioxa-2-stannacyclo-
pentane, was characterized by NMR, mass spectrom-
etry, and elemental analysis, in part by comparison with
literature data.8 Its extremely low solubility allowed
1
only the recording of H and 119Sn NMR spectra in a
very diluted CD3OD solution. An unresolved 2J (1H-
119/117Sn) coupling constant of ca. 72 Hz can be recog-
1
nized in its H spectrum. Only a very broad and noisy
119Sn resonance is observed for 8a in its 119Sn spectrum
around -130 ppm, probably as a consequence of ag-
gregation equilibria well established for the better
soluble di-n-butyltin analog.8a,c Further indirect evi-
dence for this interpretation is the observation of a
single 119Sn resonance at -234 ppm in the solid state,
at significantly lower frequency as compared to the
solution state. This indicates a relatively high aggrega-
tion degree for 8a , as already proposed for the di-n-
butyltin analog8a (δ119Sn ) -231).8c
Ch a r a cter iza tion . Mo¨ssbauer parameters (in mm/s): IS,
isomer shift, ref Ca119SnO3; QS, quadrupole splitting; Γ, line
widths. NMR data in CDCl3 (except C6D6 for 8b), chemical
shifts in ppm; coupling constants in hertz. For references, see
footnotes, Table 2. Multiplicity patterns in 1H spectra: br,
broad; d, doublet; dd, doublet of doublets; ddd, doublet of
doublets of doublets; q, quartet; s, singlet; t, triplet; m, complex
pattern; nr, nonresolved. nJ (1H-1H) coupling constants are
2
given in brackets. 1H chemical shifts, J (1H-119Sn) coupling
1
constants, 13C chemical shifts, J (13C-119/117Sn) coupling con-
stants for the tin methyl groups, and the 119Sn chemical shifts
and nJ (119Sn-119/117Sn) coupling constants are given in Table
2 and not repeated here.
Exp er im en ta l Section
Syn th eses. Com p ou n d 4. In a round-bottomed flask
equipped with a condenser and a Dean-Stark apparatus, 2.00
g of 3a (2.6 mmol) and 0.38 g of benzaldoxime (20% molar
excess) are refluxed for 5 h in benzene under distillation of
the azeotrope benzene-methanol. The condenser is equipped
with a CaCl2 tube, in order to avoid moisture in the reaction
mixture. The reaction mixture is magnetically stirred for
another 24 h and subsequently evaporated. The white powder
is recrystallized from a mixture of hexane/benzene 1:1 (v/v).
Com p ou n d s 5a -e. To a solution of 250 mg of 3a (0.33
mmol) in ca. 50 mL of benzene stirred magnetically were added
dropwise 35 mg of p-cresol (for 5a ), 57 mg of p-bromophenol
(for 5b), 45 mg of m-chlorophenol (for 5c), 47 mg of m-
nitrophenol (for 5d ), and 40 mg of 3,5-dimethylphenol (for 5e)
dissolved in 20 mL of benzene. The mixture was stirred for
24 h at room temperature and evaporated under vacuum.
Com p ou n d 4. Yield 73%; mp 139-141 °C. Anal. Found:
C, 40.3; H, 4.3; N, 4.6. Calcd for C27H35O6N3Sn3‚0.5C6H6: C,
40.4; H, 4.3; N, 4.7. Mo¨ssbauer: IS 1.32, 1.11; QS 4.11, 2.89
(Γ 0.85). 1H NMR: H3 6.23, d [8]; H3′ 7.08, nr m; H3′′ 7.01 nr
m; H4 7.01, nr m; H4′ 7.04, nr m; H4′′ 7.09 nr m; H5 6.61, dd
[7,7]; H5′ 6.57, dd [7,7]; H5′′ 7.01 nr m; H6 6.84, d [8]; H6′
6.82, d [8]; H2′′, H6′′ 7.46-7.50, nr m; H7 8.15, s; H17 8.24, s;
H27 7.80, s; OH9 13.86, s. 13C NMR: C1 120.6; C1′ 119.2;
C1′′ 129.9; C2 160.6; C2′ 162.5; C2′′ 126.8; C3 117.8; C3′ 120.9;
C3′′ 128.8; C4 131.1; C4′ 132.7; C4′′ 129.0; C5 117.5; C5′ 117.4;
C5′′ 128.8; C6 135.6; C6′ 132.2; C6′′ 127.0; C7 150.0; C17 155.3;
C27 152.9.
Com p ou n d 5a . Yield 55%; mp 107-109 °C. Anal.
Found: C, 40.8; H, 4.5; N, 3.1. Calcd for
C27H36O6N2-
Sn3‚0.5C6H6: C, 41.2; H, 4.4; N, 3.2. Mo¨ssbauer: IS 1.40, 1.20;
QS 4.11, 2.90 (Γ 0.87). 1H NMR: H3 6.35, d [8]; H3′ 6.84, d

4384 Organometallics, Vol. 16, No. 20, 1997
Willem et al.
[8]; H4 7.15, ddd [8,8,2]; H4′ 7.23, ddd [8,8,2]; H5 6.75, dd [8,8];
H5′ 6.73, dd [8,8]; H6 7.13, dd [8,2]; H6′ 7.06, d [8,2]; H7 8.03,
s; H17 8.17, s; Ho 6.57, d [8], 2H; Hm 7.03, d [8], 2H; CH3
2.28, 3H, s; OH9 13.35, br s. 13C NMR: C1 119.8; C1′ 118.4;
C2 159.9; C2′ 161.7; C3 117.4; C3′ 120.4; C4 131.1; C4′ 132.2;
C5 117.1; C5′ 117.0; C6 135.0; C6′ 131.8; C7 149.6; C17 155.0;
ipso 154.0; ortho 119.7; meta 130.2; para 129.7; CH3 20.4.
Com p ou n d 5b . Yield 68%; mp 129-131 °C. Anal.
4.5 Mo¨ssbauer: IS 1.19; QS 3.28 (Γ1 1.02, Γ2 0.87). 1H NMR:
p-CH3 2.40, 12H; Ho 7.87, d [8], 8H; Hm 7.23, d [8], 8H;
CH3Sn1 0.99, s [2J (1H-119Sn) 92], 12H; CH3Sn2 0.94, s [2J (1H-
119Sn) 90], 12H. 13C NMR: p-CH3 21.7; CO 173.2; ipso 129.0;
ortho 130.4; meta 129.9; para 142.8; CH3Sn1 7.0 [1J (13C-
119/117Sn) ) 770/734]; CH3Sn2 10.0 [1J (13C-119/117Sn) ) 818/783].
2
119Sn NMR: Sn1 -190.1 (br; J (119Sn-119/117Sn) unresolved);
Sn2 -179.4 [2J (119Sn-119/117Sn) ) 101].
Found: C, 36.6; H, 4.0; N, 2.9. Calcd for
C26H33O6-
Com p ou n d 7. Yield 56%; mp >300 °C (lit.7b mp >300 °C.
Anal. Found: C, 41.6; H, 6.0. Calcd for C12H20O4Sn: C, 41.5;
H, 5.8. Mo¨ssbauer: IS 1.17; QS 3.94 (Γ1 0.97, Γ2 0.93) (lit.7g
IS 1.20; QS 3.94 (T ) 110 K)). 1H NMR: CH3C 1.67, s, 12H;
dCH 5.02, s, 2H; CH3Sn 0.90, s [2J (1H-119/117Sn) ) 96/92], 6H
(lit.7d [2J (1H-119Sn) ) 99]). 13C NMR: CH3C 28.1; CO 190.8;
dCH 100.2; CH3Sn 7.8 [1J (13C-119/117Sn) ) 978/936] (lit.7c
[1J (13C-119Sn) ) 977]). 119Sn NMR: -365.9; (lit.7c -365.
N2Sn3Br‚0.5C6H6: C, 36.9; H, 3.8; N, 3.0. Mo¨ssbauer: IS 1.33,
1.14; QS 4.19, 2.98 (Γ 0.80). 1H NMR: H3 6.31, d [8]; H3′ 6.81,
d [8], H4, H4′, H6, H6′ 7.07-7.24, nr m, 4H; H5 6.73, dd [7,7];
H5′ 6.76, dd [7,7]; H7 8.01, s; H17 8.15, s; Ho 6.51, d [9], 2H;
Hm 7.29, d [9], 2H, OH9 13.31, br s. 13C NMR: C1 120.6; C1′
119.9; C2 159.9; C2′ 161.7; C3 118.6; C3′ 121.8; C4 131.3; C4′
132.5; C5 117.4; C5′ 117.3; C6 135.3; C6′ 132.0; C7 149.9; C17
155.4; ipso 156.0; ortho 117.5; meta 132.8; para 112.5.
Com p ou n d 5c. Yield 71%; mp 160-162 °C. Anal. Found:
C, 36.2; H, 3.9; N, 3.2. Calcd for C26H33O6N2Sn3Cl: C, 36.3;
H, 3.9; N, 3.3. Mo¨ssbauer: IS 1.29, 1.17; QS 4.12, 2.91 (Γ 0.96).
1H NMR: H3 6.38, d [8]; H3′ 6.87, d [8], H4 7.19 nr m; H4′
7.27, dd [8,8]; H5 6.81, dd [8,8]; H5′ 6.78, dd [8,8]; H6 7.20 nr
m; H6′ 7.13, br d [8]; H7 8.03, s; H17 8.17, s; Ho 6.66, s; Ho′
6.56, d [8]; Hm′ 7.17, nr m; Hp 6.91, d [8]; OH9 13.26, br s.
13C NMR: C1 120.0; C1′ 118.6; C2 159.9; C2′ 161.8; C3 117.5;
C3′ 120.5; C4 131.3; C4′ 132.4; C5 117.5; C5′ 117.2; C6 135.2;
C6′ 132.0; C7 149.8; C17 155.4; ipso 158.0; ortho 120.2; ortho′
118.2; meta 135.1; meta′ 130.6; para 120.5.
Com p ou n d 5d . Yield 67%; mp 185-188 °C. Anal.
Found: C, 35.8; H, 4.0; N, 4.7. Calcd for C26H33O8N3Sn3: C,
35.8; H, 3.8; N, 4.8. Mo¨ssbauer: IS 1.29, 1.12; QS 3.96, 2.93
(Γ 0.81). 1H NMR: H3 6.34, d [8]; H3′ 6.83, d [8]; H4, H6 7.15-
7.18, nr m, 2H; H4′ 7.22-7.24, m; H5 6.78, dd [8,8]; H5′ 6.74,
dd [8,8]; H6′ 7.10, br d [8]; H7 8.03, s; H17 8.17, s; Ho 7.43, br
s; Ho′ 7.72, br d [8]; Hm′ 7.34, dd [8,8]; Hp 6.92, br d [8]; OH9
13.23, br s. 13C NMR: C1 119.9; C1′ 118.5; C2 159.6; C2′ 161.7;
C3 117.5; C3′ 120.5; C4 131.4; C4′ 132.6; C5 117.7; C5′ 117.4;
C6 135.3; C6′ 132.0; C7 149.8; C17 155.6; ipso 149.6; ortho
114.1; ortho′ 114.8; meta 158.3; meta′ 130.3; para 126.0.
Com p ou n d 5e. Yield 91%; mp 100-103 °C. Anal. Found:
C, 39.5; H, 4.6; N, 3.3. Calcd for C28H38O6N2Sn3: C, 39.4; H,
4.5; N, 3.3. Mo¨ssbauer: IS 1.33; 1.08; QS 3.99, 2.73 (Γ 0.96).
1H NMR: H3 6.11, d [8]; H3′, H4, H4′, H6, H6′ 6.79-7.09 nr
m, 5H; H5, H5′ 6.59-6.62 nr m, 2H; H7 8.12, s; H17 8.17, s;
Ho 6.31, s, 2H; Hp 6.53, s; CH3 2.16, s, 6H; OH9 13.80, br s.
13C NMR: C1 120.6; C1′ 119.2; C2 160.5; C2′ 162.5; C3 117.8;
C3′ 120.9; C4 131.1; C4′ 132.6; C5 117.5; C5′ 117.4; C6 135.5;
C6′ 132.2; C7 150.0; C17 155.2; ipso 157.0; ortho 118.6; meta
139.5; para 122.9; CH3 21.5.
Com p ou n d 8a . Yield 65%; mp >300 °C. Anal. Found:
C, 23.3; H, 5.1. Calcd for C4H10O2Sn: C, 23.0; H, 4.8.
Mo¨ssbauer: IS 1.09; QS 3.01 (Γ1 1.08, Γ2 1.07). MS: M + 1,
211. 1H NMR: CH2 3.60, s, 4H; CH3Sn 0.60, s, 6H [2J (1H-
119/117Sn) ) 72 unresolved]. 119Sn NMR: ca. -130 (very br).
119Sn CP MAS NMR: -234. 13C CP MAS NMR: CH2 62.0;
CH3Sn 7.2 [1J (13C-119Sn) ) 808] 5.5 [1J (13C-119Sn) ) 845].
Com p ou n d 8b. NMR characterization in reaction mixture
1
containing also 2a and 2b by H-119Sn HMQC NMR: 119Sn1
-461.5, correlated with 1H, H7 8.20, s; H17 8.30, s; OH(9)
14.03, s; CH3 1.18, s. 119Sn2 -156.8, correlated with 1H, H17
8.30, s; H3 6.44, d [7]; CH3 0.70, s; CH3-Sn1 1.18, s; OCH2 3.14,
s. 119Sn3 -137.6, correlated with 1H, H17 8.30, s; CH3 0.59,
s; CH3-Sn1 1.18, s; OCH2 3.14, s.
Cr ysta llogr a p h y. Intensity data for the colorless crystals
of 4, 5a , and 5b, each isolated as a hemi-benzene solvate, were
measured at room temperature (20 °C) on a Rigaku AFC6R
diffractometer fitted with graphite-monochromatized Mo KR
radiation, λ ) 0.710 73 Å. The ω: 2θ scan technique was
employed to measure data up to a maximum Bragg angle of
27.5°; the data sets were corrected for Lorentz and polarization
effects11 and an empirical absorption correction was applied
in each case.12 In the case of 4, significant decomposition (ca.
20%) of the crystal occurred during the data collection, and
hence, a correction was applied to the data set by assuming a
linear decay. Relevant crystal data are given in Table 3. The
structures were solved by direct-methods employing
DIRDIF92,13a SIR88,13b and SHELXS8613c for 4, 5a , and 5b,
respectively, and each refined by a full-matrix least-squares
procedure based on F.11 Non-H atoms were refined with
anisotropic displacement parameters, and H atoms were
included in the models in their calculated positions (C-H 0.97
Å); the OH hydrogen atom was located in the refinement of
both 4 and 5b but not for 5a . The refinements were continued
until convergence by employing σ weights (i.e., w ) 1/σ2(F))
and the analysis of variance showed no special features,
indicating that an appropriate weighting scheme had been
applied in each case. Final refinement details are collected
in Table 3. The numbering schemes employed are shown in
Figures 5, 6 and S(1), which were drawn with ORTEP14 at 30%
probability ellipsoids. The teXsan11 package, installed on an
Iris Indigo workstation, was employed for all calculations.
Com p ou n d 6a . Yield 77% from 3a and 74% from
(CH3)2SnO; mp 238-241 °C, respectively, 240-242 °C (lit.5a
mp 240 °C). Anal. Found: C, 22.5; H, 4.3. Calcd for
C
16H36O10Sn4: C, 22.3; H, 4.2. Mo¨ssbauer: IS 1.20; QS 3.57
(Γ1 1.01, Γ2 0.91). 1H NMR: CH3C 1.92, 12H; CH3Sn1 0.81, s
[2J (1H-119/117Sn) ) 91/87], 12H; CH3Sn2 0.79, s [2J (1H-
119/117Sn) ) 87/83], 12H; (lit.5a CH3Sn1 and CH3Sn2 0.79
[2J (1H-119Sn) ) 89.0] and 0.77 [2J (1H-119Sn) ) 86.8]. 13C
NMR: CH3C 22.9; CO 177.6; CH3Sn1 and CH3Sn2 8.7 [1J (13C-
119/117Sn) ) 802/768] and 5.9 [1J (13C-119/117Sn) ) 752/713]; (lit.5a
CH3Sn1 and CH3Sn2 5.9 [1J (13C-119Sn) ) 748] and 8.7
[1J (13C-119Sn) ) 800]. 119Sn NMR: Sn1 -190.2 (br; 2J (119Sn-
119/117Sn) unresolved); Sn2 -173.8 [2J (119Sn-119/117Sn) ) 110].
Com p ou n d 6b . Yield 44%; mp 208-210 °C. Anal.
Found: C, 41.3; H, 4.7. Calcd for C40H52O10Sn4: C, 41.1; H,
(11) teXsan: Structure Analysis Software. Molecular Structure
Corp., The Woodlands, TX.
(12) Walker, N.; Stuart, D. Acta Crystallogr., Sect. A 1983, 39, 158.
(13) (a) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W.
P.; Garcia-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. (c) Sheldrick, G. M.
SHELXS86, Program for the Automatic Solution of Crystal Structure,
University of Go¨ttingen, Germany, 1986.
(9) (a) Mason, J . Multinuclear NMR; Plenum Press: New York,
1987; pp 625-629. (b) Davies, A. G.; Harrison, P. G.; Kennedy, J . D.;
Puddephatt, R. J .; Mitchell, T. N.; McFarlane, W. J . Chem. Soc. A 1969,
1136. (c) Wrackmeyer, B. Annu. Rep. NMR Spectrosc. 1985, 16, 73.
(10) (a) Vatsa, C.; J ain, V. K.; Kesavadas, T.; Tiekink, E. R. T. J .
Organomet. Chem. 1991, 408, 157. (b) Gross, D. C. Inorg. Chem. 1989,
28, 2355. (c) Ribot, F.; Sanchez, C.; Meddour, A.; Gielen, M.; Tiekink,
E. R. T.; Biesemans, M.; Willem, R. J . Organomet. Chem., submitted
for publication.
(14) J ohnson, C. K. ORTEP. Report ORNL-5138, Oak Ridge Na-
tional Laboratory, TN, 1976.

Substituted Dimethyltin(IV) Salicylaldoximates
Organometallics, Vol. 16, No. 20, 1997 4385
Ta ble 3. Cr ysta llogr a p h ic Da ta a n d Refin em en t Deta ils for 4, 5a , a n d 5b
4
5a
5b
formula
fw
C30H38N3O6Sn3
892.7
C30H39N2O6Sn3
879.7
C29H36BrN2O6Sn3
944.6
cryst size, mm
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
0.08 × 0.32 × 0.32
triclinic
P1h
0.13 × 0.29 × 0.29
triclinic
P1h
0.16 × 0.16 × 0.24
triclinic
P1h
12.334(5)
14.624(7)
10.101(3)
103.00(3)
102.90(2)
86.63(4)
1730(1)
2
11.744(5)
15.768(5)
10.200(4)
105.10(3)
112.88(3)
87.30(3)
1677(1)
2
11.765(9)
15.76(1)
10.205(8)
105.09(7)
113.43(6)
87.26(7)
1673(2)
2
Z
D
calcd, g cm-3
1.713
1.742
1.875
F(000)
874
21.90
0.898-1
8339
7972
4821
862
22.58
0.939-1
8117
7742
5471
914
34.60
0.909-1
8098
7724
4611
µ, cm-1
transmission factors
no. of data collcd
no. of unique data
no. of unique data
with I g 3.0σ(I)
R
0.039
0.039
0.67
0.037
0.044
0.84
0.038
0.034
0.66
Rw
residual electron density
NMR Exp er im en ts. The samples were prepared by dis-
solving ca. 40 mg of product in 0.5 mL of CDCl3. All spectra
were recorded at 303 K on a Bruker AMX500 spectrometer
equipped with a digital lock and operating at 500.13, 125.77,
and 186.50 MHz for 1H, 13C, and 119Sn nuclei, respectively.
Chemical shifts were referenced to the residual solvent peak
(CDCl3) and converted to the standard TMS scale by adding
7.23 and 77.0 ppm for 1H and 13C nuclei, respectively. The
119Sn reference frequency was calculated from the absolute
frequency of Me4Sn, which is 37.290 665 MHz9 at the B0 field
pretations are to be expected when 117Sn and 119Sn chemical
shift data are compared, since 117Sn/119Sn isotopic effects on
tin chemical shifts are known to be negligible.15,17 Accordingly,
for reasons of presentation convenience, all tin NMR data are
presented as 119Sn chemical shifts.
Mo1ssba u er Da ta . Mo¨ssbauer data were acquired and
processed as previously described.1a
Ack n ow led gm en t. The financial support of the
Belgian Flemish Science Foundation (FKFO, Grant
2.0094.94) and of the Belgian “Nationale Loterij” (Grant
9.0006.93) is gratefully acknowledged (R.W., M.B.). The
authors are indebted to the European Union Program
“Human Capital & Mobility” (R.W., C.S.) for financial
support (Contract ERBCHRX-CT-94-0610). Research
grants from the Australian Research Council (E.R.T.T.)
are gratefully acknowledged. We thank Mrs. I. Ver-
bruggen for recording routine NMR spectra and Dr. B.
Mahieu, Universite´ Catholique de Louvain, Louvain-
la-Neuve (B), for recording the Mo¨ssbauer data. Post-
doctoral grants of the Flemish “Fonds voor Wetenschap-
pelijk Onderzoek Vlaanderen” (A.M.) and of the Mexican
“Consejo Nacional de Ciencia y Tecnologia” (C.C.C) are
gratefully acknowledged.
1
corresponding to 100.000 000 MHz for the H nuclei in TMS.
Broad-band 1H-decoupled 13C and 119Sn spectra as well as
13C DEPT spectra were recorded using the Bruker pulse
sequences with standard delays. All heteronuclear correlation
spectroscopy consisted of gradient-enhanced2 versions of the
standard HMQC3a and HMBC3b,c pulse sequences, all pro-
cessed in the magnitude mode. In particular, the gradient-
enhanced2 1H-119Sn HMQC4 and the 1H-13C HMBC3b,c ex-
periments were implemented in exactly the same way as
presented recently.1b
The 13C and 119Sn solid state NMR spectra were obtained
as described previously.15
Routine NMR 1H, 13C, and 117Sn NMR spectra were recorded
on a Bruker AC250 instrument tuned at 250.13, 67.93, and
89.15 MHz, respectively. On this instrument, 117Sn spectra
were recorded instead of the more common 119Sn ones to
overcome a local radio interference problem.16 No misinter-
Su p p or tin g In for m a tion Ava ila ble: Further details of
the structure determination including atomic coordinates, bond
distances and angles, and thermal parameters for 4, 5a , and
5b (19 pages). Ordering information is given on any current
masthead page.
(15) (a) Biesemans, M.; Willem, R.; Damoun, S.; Geerlings, P.;
Lahcini, M.; J aumier, P.; J ousseaume, B. Organometallics 1996, 15,
2237. (b) Dumartin, G.; Kharboutli, J .; Delmond, B.; Pereyre, M.;
Biesemans, M.; Gielen, M.; Willem, R. Organometallics 1996, 15, 19.
(16) (a) Koch, B. R.; Fazakerley, G. V.; Dijkstra, E. Inorg. Chim.
Acta 1980, 45, L51. (b) Harrison, P. G. In Chemistry of Tin; Harrison,
P. G., Ed.; Blackie & Son Ltd.: Glasgow, 1989; Chapter 3, p 113.
OM970378E
(17) McFarlane, H. C. E.; McFarlane, W.; Turner, C. J . Mol. Phys.
1979, 37, 1639.