3367
J[ H[ Aupers et al[
"reaction b in Scheme# proceeded readily in Me1CO exchange reactions between R1SnX1 and R?1Sn"dmit#
ð2aŁ[
A limited number of other ðQŁ ðR1SnX"dithiolate#Ł
complexes have been previously reported^ these
include ðNEt3Ł ðPh1SnCl"2\3!toluenedithiolate#Ł\ pre!
pared by addition of NEt3Cl to Ph1Sn"2\3!tol!
solution for most ðQŁ ðR1SnCl"dmit#Ł complexes\ using
NaX or QX "XꢀBr\ I\ NCS or NCSe# in moderate
excess "i[e[ 1 to 3 mole equivalents#] with these
excesses\ halide exchanges were generally complete[
However\ for the NaI:ð0\3!Me1pyridiniumŁ ðPh1SnCl
"dmit#Ł exchange reaction\ a larger excess of NaI was
required to drive the exchange to near completion[
Products with mixed chloride:iodide contents\ ð0\3!
Me1pyridiniumŁ ðPh1SnClnI0−n"dmit#Ł\ could be iso!
lated from incomplete exchanges[ Examples of such
mixed halide products had I]Cl mol ratios of 9[32]
9[46^ 9[47] 9[31 and 9[67] 9[11\ as deduced from X!ray
and elemental analyses\ e[g[ iodine analysis in the three
mixed chloride:iodide complexes were 7[1\ 00[3 and
03[2)\ compared to calculated values of 7[3\ 00[0 and
03[4)\ for ð0\3!Me1pyridiniumŁ ðPh1SnClnI0−n"dmit#Ł
with nꢀ9[32\ 9[46 and 9[67\ respectively[
uenedithiolate#
ð09a\
09bŁ
and
ðPh3AsŁ
ðMe1SnX"mnt#Ł\ from00 Me1SnX1 "XꢀCl\ Br or I#\
Na1"mnt# and ðPh3AsŁNO2 ð00Ł[
Crystal structure determinations
In addition to the previously reported structures of
ðNBu3Ł ðMe1SnCl"dmit#Ł ð2fŁ and ð0\3!Me1pyridiniumŁ
ðPh1Sn"NCS#"dmit#Ł ð2gŁ\ the crystal structures of the
single halide species\ ðNEt3Ł ðPh1SnI"dmit#Ł and ð0\3!
Me1pyridiniumŁ ðPh1SnBr"dmit#Ł have been deter!
mined[
A simple exchange reaction was not obtained
between ðNEt3Ł ðPh1SnCl"dmit#Ł and a large excess of
NH3F "mol ratio 0]11# in MeOH^ the product isolated
analysed for the ~uorine bridged dinuclear species\
ðNEt3Ł ðPh1"dmit#SnFSn"dmit#Ph1Ł[
Unfortunately\ suitable crystals of the bridged ~u!
oride complex\ ðNEt3Ł ð"dmit#Ph1SnFSnPh1"dmit#Ł
could not be obtained for an X!ray di}raction study[
As well as those of the single halide species\ the
structures of the mixed halide species\ ð0\3!Me1
pyridiniumŁ ðPh1SnClnI0−n"dmit#Ł "nꢀ9[46\ 9[31 and
9[11# have been determined[ The structure of ð0\3!
Me1pyridiniumŁ ðPh1SnC9[46I9[32"dmit#Ł was solved
with a R factor of 9[938^ although much less sat!
isfactory R values "ca[ 9[09# were obtained for the
other mixed I:Cl species\ the data is su.cient to allow
useful comparisons to be made with those of the other
compounds[ The mixed halide species can be con!
sidered to be solid solutions\ obtained by crys!
tallisation from solutions containing both halides\
with structures in which an axial site in the trigonal
bipyramidal array is randomly occupied by either of
the di}erent halide ligands[ In the cases of the ð0\3!
Me1pyridiniumŁ ðPh1SnClnI0−n"dmit#Ł "nꢀ9[46 and
9[31#\ the positions of both ligands\ as well as their
occupancy factors\ could be resolved[ However[ only
a single site could be determined for the halides in
ð0\3!Me1pyridiniumŁ ðPh1SnCl9[11I9[67"dmit#Ł[
Organotin!dmit complexes undergo ready dis!
proportionation reactions in solution\ with products
showing suitable losses and gains of organic and dmit
groups[ Tris"dmit#stannate salts\ ðQŁ1ðSn"dmit#2Ł\ are
ubiquitous materials\ appearing as unwanted coprod!
ucts in various tin!dmit preparations and solutions\
e[g[ crystals of ðNEt3Ł1ðSn"dmit#2Ł were deposited\
albeit in a low yield\ from a dilute solution of ana!
lytically pure ðNEt3Ł ðPh1Sn"NCSe#"dmit#Ł in MeOH[
The isolation of a product bearing a greater number
of organic groups than the original organotin com!
pound is a strong indication of a disproportionation
reaction^ such an example is ðNEt3Ł ðPh2Sn"NCS#1Ł\
isolated ð5Ł as a minor product\ from a reaction mix!
ture containing Na1"dmit#\ Ph1Sn"NCS#1 and
ðNEt3ŁBr[ Disproportionations of diorganotin com!
pounds\ R2SnX\ to di! and tetra!organotin species\
are also well!established processes\ especially for com!
pounds with chelating X groups ð6Ł[
Selected bond lengths and angles in these ionic com!
pounds\ including data for the previously published
ðNBu3Ł ðMe1SnCl"dmit#Ł ð2fŁ and ð0\3!Me1pyridiniumŁ
ðPh1Sn"NCS#"dmit#Ł ð2gŁ are listed in Table 2[ Figs 0Ð
provide the atom arrangements in ð0\3!Me1
pyridiniumŁ ðPh1SnBr"dmit#Ł\ ðNEt3Ł ðPh1SnI"dmit#Ł\
ð0\3!Me1pyridiniumŁ ðPh1SnCl9[46I9[32"dmit#Ł and ð0\3!
Me1pyridiniumŁ ðPh1SnCl9[31I9[47"dMit#Ł\ respectively[
The atom numbering system used for ð0\3!Me1
pyridiniumŁ ðPh1SnCl9[11I9[67"dmit#Ł is the same as that
used for ð0\3!Me1pyridiniumŁ ðPh1SnCl9[31I9[47"dmit#Ł
although for the latter only a single halide site was
determined[
Holmes et al[ reported the isolation of ðNEt3Ł1ðSn"o!
SC5H3O#2Ł\ "6#\ from solutions of ðNEt3\ SnF"o!
SC5H3O#1Ł in organic solvents ð7Ł^ rather than dis!
proportionation\ Holmes et al[ suspected hydrolysis
was responsible for the formation of 6 and suggested
the intermediacy of ðNEt3Ł1ðSn"HO#1"o!SC5H3O#1Ł ð7Ł[
Hydrolysis of carbonÐtin bonds was also invoked for
the formation of ðNEt3Ł ðNaŁ ðSn"mnt#2Ł\ from
PhSnCl2\ Na1"mnt# and NEt3Cl in Me1CO solution
"mntꢀ0\1!dicyanoethylene!0\1!dithiolate#Ł ð8Ł and for
the preparation of ðSn"catecholato2Ł1− in the reaction
of ðPhSn"O#OHŁ with catechol in the presence ð7Ł of
NEt2 and Me1C"OMe#1[ However\ our experience with
the dmit complexes suggests that disproportionations
are more probable causes of the unexpected products
than are hydrolyses[ The mobility of dmit group
There are no interactions between the cations and
anions of the ðQŁ ðR1SnX"dmit#Ł species\ however\ in
general there are SÐS contacts between anions just
Ä
within the sum of the van der Waals radii "2[56 A# ð7Ł[
between tin centres has been additionally shown in In all cases\ the structures of the anions are basically