S,C- and S,S-coupling via dithiolate transfer reactions from tin to nickel complexes

Article abstract of DOI:10.1039/b902569c

Dithiolate tin(iv) complexes [SnMe₂(SS)] (SS = 4,5-dimercapto-1,3-dithiol-2-thione, dmit; 1,2-benzene dithiolate, bdt; and 3,4-toluene dithiolate, tdt) are used as transmetallating agents in the reaction with nickel derivatives [NiBrR′(PR₃

Full text of DOI:10.1039/b902569c

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www.rsc.org/dalton | Dalton Transactions
S,C- and S,S-coupling via dithiolate transfer reactions from tin to nickel
complexes†
Elena Cerrada, Ana Moreno and Mariano Laguna*
Received 6th February 2009, Accepted 2nd June 2009
First published as an Advance Article on the web 15th July 2009
DOI: 10.1039/b902569c
Dithiolate tin(IV) complexes [SnMe2(SS)] (SS = 4,5-dimercapto-1,3-dithiol-2-thione, dmit; 1,2-benzene
dithiolate, bdt; and 3,4-toluene dithiolate, tdt) are used as transmetallating agents in the reaction with
nickel derivatives [NiBrR¢(PR3)2] (R¢ = mesitylene (Mes) and 2,4,6-trisisopropylphenyl (Trip), and
PR3 = PPh3 and PPh2Me). The reaction results in the isolation of different complexes with a great
variety of stoichiometries, including mono-, di- and trinuclear nickel complexes with the general
formulae: [Ni(SS)(PR3)]2, [Ni(Mes)(SS-Mes)(PR3)], [Ni(SS-Mes)2] and [Ni3(bdt)3(PPh2Me)2], and the
organic compounds {dmit(Mes)}2, {dmit(Trip)}2, {dbt(Mes)2} and {tbt(Mes)2} as a consequence of
S,C- and S,S-coupling processes. In the case of [Ni(Mes)(dmitMes)(PPh2Me)], {dmit(Trip)}2, [Ni3(bdt)3-
(PPh2Me)2] and [Ni(bdtMes)2] the X-ray analyses are also presented to confirm the proposed structures.
agents with nickel complexes, the reaction does not proceed in
the expected way of a simple dithiolate ligand transfer. Therefore,
Introduction
we have described in a preliminary communication19 that using
the organometallic nickel(II) derivative, [NiBr(Mes)(PPh2Me)2]
(Mes = mesitylene), in the presence of [SnMe2(dmit)] (dmit = 4,5-
dimercapto-1,3-dithiole-2-thione), a mixture of products are ob-
tained instead of the expected [Ni2(m-dmit)Br2(Mes)2(PPh2Me)4].
Here we extend this reaction to the similar nickel derivatives:
[NiBrR¢(PR3)2] (R¢ = Mes, Trip (2,4,6-tri-isopropylphenyl), PR3 =
PPh3, PPh2Me), using dmit, bdt (1,2-benzenedithiolate) and tdt
(3,4-toluenedithiolate) as dithiolate ligands. This gives rise to
a mixture of products, some of them as a result of S,C- and
S,S-coupling processes.
Tin(IV) complexes are commonly used as transmetallating agents
for a wide variety of anions,1 due to the advantages of solu-
bility in conventional organic solvents and of producing eas-
ily removable (by washing) tin(IV) halide compounds as by-
products. Organometallic tin complexes have been employed
in transmetallation reactions with group 13 metallic salts for
the preparation of group 13 polyfunctional Lewis acids:2–5 with
RLi to prepare organolithium complexes6 for structural and
spectroscopic studies; with transition metal halides to provide a
new route to metallocene derivatives;7–12 with germanium halides13
to give Ge-based reagents for organic synthesis and in the synthesis
of lanthanoid complexes by redox transmetallation reactions.14,15
Organotin(IV) derivatives containing thiolate or selenolate or the
hybrid phosphine–thiolate ligands have been shown to be good
ligand transfer reagents to metals of groups 7–10. Thus, iron(IV)16
and ruthenium(IV),16,17 rhodium(I) and iridium(I),18 nickel(II),
palladium(II) and platinum(II),19–22 gold(I)23–26 and gold(III)27,28
complexes have been prepared in very mild conditions. In addition,
processes involving transmetallation reactions as key steps for a
catalytic process have recently been of considerable interest,29,30
particularly the Stille reaction in the formation of C–C bonds,
which uses organometallic tin complexes as starting materials
and it is believed to proceed via a cycle of oxidative addition–
transmetallation–reductive elimination,31–33 where the transmetal-
lation process is the rate-determining step.31–35 Another interesting
process is the rhodium-catalyzed addition of organometallic
reagents to carbon–heteroatom,36,37 reactions which commonly
involve organorhodium complexes as active species generated by
transmetallation with organometallic reagents such as tin.38–42
In the particular case of dithiolate tin(IV) derivatives we have
shown that in the use of such derivatives as transmetallating
Results and discussion
The reaction of [SnMe2(dmit)] with [NiBr(Mes)(PR3)2] (PR3 =
PPh3 and PPh2Me) (Scheme 1) in 1 : 1 or 1 : 2 molar ratios at
room temperature in acetone gave a mixture of products which
was separated by chromatography and identified spectroscopically.
Since the same complexes are obtained with both stoichiometries
and an excess of the nickel starting material was detected in the 1 : 2
ratio, we performed all the reactions in the 1 : 1 ratio. Apart from
{dmitMes}2, which was previously described by X-ray studies in a
preliminary communication,19 we have obtained [Ni(dmit)(PR3)]2
and [Ni(Mes)(dmitMes)(PR3)] as pure samples.
The [Ni(dmit)(PR3)]2 (PR3 = PPh3, 1; PPh2Me, 2) compounds
1
show a singlet in the 31P{ H} NMR spectra and only the
1
corresponding phosphine signals in the H NMR spectrum. The
elemental analysis indicate the stoichiometry of [Ni(dmit)(PR3)]n.
The lack of ionisation in the liquid secondary ion mass spectrom-
etry (LSIMS) spectra in the case of 1 and the poor solubility
of both of them for a cryoscopic molecular weight measurement
precludes the obtaining of any meaningful information about the
value of n. We can postulate the structure of these compounds
as dimers in comparison with the similar dithiolate (bdt, tdt)
derivatives that will be depicted later on, although a polynuclear
structure is not excluded. Though the structure of the isolated
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales
de Arago´n, Universidad de Zaragoza - CSIC, 50009, Zaragoza, Spain.
E-mail: mlaguna@unizar.es
† CCDC reference numbers 718386–718389. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b902569c
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Scheme 1 Reaction of [SnMe2(dmit)] with [NiBr(Mes)(PR3)2] (PR3 = PPh3 and PPh2Me) with the yields in brackets.
compounds, when comparing the two different phosphines, should
be similar, the order of elution in the chromatographic separation
process was different depending on the PR3 used. So, as is
described in the experimental, compound 1 is obtained first
and 2 is obtained last. [Ni(Mes)(dmitMes)(PR3)] (PR3 = PPh3,
3; PPh2Me, 4) were isolated as mixtures of two isomers in an
When using a bulkier radical, such as 2,4,6-trisisopropylphenyl
(Trip), instead of Mes in the starting nickel complex,
[NiBr(Ar)(PPh3)2], the formation of a product analogous to
{dmit(Mes)}2 ({dmit(Trip)}2, 5) occurs, but as the major prod-
uct of the reaction. Although [Ni(dmit)(PPh3)]2 (1) is ob-
tained as well, the related thiolate thioether derivative (3)
[Ni(Trip)(dmitTrip)(PPh3)] is not, probably as a consequence of
steric factors.
1
8 : 1 amount (data obtained from 31P{ H} NMR spectra). The
existence of the isomers arises from the relative position of the
phosphine, either trans to the thiolate or trans to the thioether
The same reaction using [NiBr(Mes)(PR3)2] was performed with
two different dithiolates: bdt (1,2-benzenedithiolate) and tdt (3,4-
toluenedithiolate). Using [SnMe2(bdt)] as starting material, the
reaction gave again a mixture of products (Scheme 2), which were
all identified and characterized spectroscopically.
group. Recrystallization of the mixture in the case of PR3
=
PPh3 in dichloromethane, gave an homogeneous sample of yellow
crystals. The X-ray analysis of one of them (vide infra) revealed
the trans position of the triphenylphosphine with respect to the
thioether group. The crystals exist as the major isomer (3a), with
the phosphine molecule trans to the thioether group, as deduced
In this case, in addition to the similar dmit deriva-
tives [Ni(bdt)(PR3)]2 (PR3
[Ni(Mes)(bdtMes)(PR3)] (PR3 = PPh3, 8; PPh2Me, 9), [Ni(bdt)-
(PR3)2] (PR3
PPh3, 10), {bdt(Mes)2} (11), [Ni3(bdt)3-
(PPh2Me)2] (12) and [Ni(bdtMes)2] (13) were isolated. The last
=
PPh3, 6; PPh2Me, 7) and
1
by 31P{ H}NMR, and the minor isomer (3b), with the phosphine
molecule trans to the thiolate group. We assume that the structures
of 3a and 4a should be similar.
=
Scheme 2 Reaction of [NiBr(Mes)(PR3)2] with [Sn(bdt)Me2] with the yields in brackets.
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two derivatives have also been structurally characterised by X-ray
analysis.
corresponding assignment much easier. The LSIMS+ spectrum
displays the molecular peak and the peaks corresponding to the
successive loss of the phosphine molecules. In both reactions
{bdt(Mes)2} (11) can be identified. In this case the homologue
of {dmitR}2 (R = Mes or Trip), as a result of a S,S- and S,C-
coupling, is not obtained; instead only a S,C-coupling is achieved
in 11.
The 1H NMR spectra of [Ni(dbt)(PR3)]2 (PR3 = PPh3, 6;
PPh2Me, 7) show the bdt protons displaced from the phosphine
signals to higher fields, which permits a complete assignment
1
of the resonances by H,1H-COSY experiments. The LSIMS+
(nba as matrix) spectra show that, in both cases, the molecular
peak (considering the compounds as dimers) and the cryoscopic
molecular weight measurement in chloroform (see experimental)
are in agreement with a dinuclear structure. The isolation of such
products is different depending on the phosphine. Complexes
6 and 8 were isolated by precipitation, due to their lower
solubilities. However, for 11, 12 and 13, where PR3 = PPh2Me,
a chromatographic separation of the mixture is obligatory for
their isolation. [Ni(Mes)(bdtMes)(PR3)] (PR3 = PPh3, 8; PPh2Me,
9) were again obtained as a 7 : 1 mixture of isomers (PR3 cis or
trans to the thioether group). We could imagine a similar structure
to that described for 3a for the major isomer. In the case of
complex 8a (the most abundant isomer), the trans disposition of
the phosphine to the thioester group could be determined by a
NOE experiment. The intensities of the signals due to the protons
of PPh3 only changed when the o-Me proton signal, at d 2.06 ppm,
of the mesitylene bonded to the nickel centre was irradiated, and
remained unchanged when the o-methyl protons of the mesitylene
radical bonded to the S atom (d 1.94 ppm) were irradiated. The
1H,1H-NOESY spectrum confirms that the major isomer is the
one with PPh3 trans to the thioether.
The rest of the identified complexes were: [Ni(bdt)(PR3)2]
(only obtained in the case of PR3 = PPh3, 10), [(bdt)(Mes)2]
(11), [Ni3(bdt)3(PPh2Me)2] (12) and [Ni(bdtMes)2] (13). Using
the phosphine PPh2Me, a trinuclear nickel(II) derivative with
the formula [Ni3(bdt)3(PPh2Me)2] (12) is obtained, instead of
the related mononuclear [Ni(bdt)(PR3)2], obtained when using
PPh3. A similar trinuclear derivative with the phosphine PPh3 was
previously obtained as the major product by Kovacs et al.43 in the
reaction of a solution of Na2bdt in THF with [NiCl2(PPh3)2] in a
1 : 1 molar ratio. In the 1H NMR spectrum of [Ni3(bdt)3(PPh2Me)2]
(12), the bdt signals are displaced to higher fields than the
phosphine protons, as seen in the dinuclear derivatives, making the
The yield of the isolated bdt-complexes is different depending
on the reaction conditions, such as if the experiment is performed
at room temperature or refluxed. The dinuclear derivatives are
obtained in slightly higher yields when the reaction is carried out
under reflux.
During the isolation of [Ni(bdt)(PPh2Me)]2 (7), a very small
1
amount of an additional compound could be detected in the H
NMR spectrum. This compound was identified as [Ni(bdtMes)2]
(13), as deduced by NMR and X-ray analysis. Although a better
separation between 7 and 13 by column chromatography was not
possible, a recrystallisation of the sample gave red microcrystals
corresponding to compound 13, accompanied by opaque black
crystals, which were not of diffraction quality.
When using 3,4-toluenedithiolate (tdt) as the dithiolate ligand,
the complexes are obtained in the same order of elution, regardless
of the phosphine used (Scheme 3). Apart from 3,4-toluenedithiole,
{tdt(Mes)2} (14), [Ni(Mes)(tdtMes)(PR3)] (PR3 = PPh3, 15;
PPh2Me, 16), [Ni(tdt)(PR3)]2 (PR3 = PPh3, 17; PPh2Me, 18) and
[Ni(tdtMes)2] (19) were separated by column chromatography.
Compound 14 was identified by 1H NMR, displaying the
presence of two different mesitylene groups, and LSIMS+ (nba
as matrix), with the presence of the molecular peak as the parent
peak.
[Ni(Mes)(tdtMes)(PR3)] (PR3= PPh3, 15; PPh2Me, 16) were
each isolated as a mixture of 4 isomers, which are a consequence
of the relative position of the Me group in the tdt dithiolate ligand
and the cis or trans disposition of the phosphine, with two isomers
being the majority in a relation close to 7 : 1. In this case, we
distinguished the two majority isomers as one with the Me group
in the meta position to the thiolate and the other with the Me meta
to the thioether group (Fig. 1), but we have no evidence regarding
their structure, although we can make propositions, comparing
Scheme 3 Reaction of [NiBr(Mes)(PR3)2] with [Sn(tdt)Me2] with the corresponding yields in brackets.
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nuclearities nor the homologue of the [Ni(SS)(PPh3)2] complex are
observed during the reaction.
X-Ray structures
Structure of [Ni(Mes)(dmitMes)(PPh3)] (3a). The molecule
(Fig. 3) consists of a mononuclear nickel(II) centre with a
triphenylphoshine, a mesitylene group and a mixed dmit ligand
with thiolate and thioether groups, all coordinated to the metallic
centre. The coordination around the nickel can be considered as
a distorted square-planar geometry. The main distortion comes
from the S(1)–Ni(1)–C(13) and S(1)–Ni(1)–P(1) angles which
are 84.73(8)◦ and 170.29(3)◦ respectively. The mesitylene group
bonded directly to the nickel centre is in a nearly perpendicular
disposition with respect to the NiS2CP plane (torsion angle of
about 94◦). It is worth noting that the Ni–S(thioether) distance
Fig. 1 Different isomers for the mononuclear thiolate–thioether nickel
derivative with tdt as the dithiolate ligand.
˚
of 2.1997(8) A is shorter than the respective Ni–S(thiolate)
them to the above described for dmit and bdt dithiolates, with the
phosphine trans to the thioether group.
˚
bond length (2.2308(9) A) in [Ni(Et2NS2–H)2] (Et2NS2–
H = N,N-diethyl-2-(2-mercaptothiophenyl)ethylamine),44 [Ni-
A new blend of isomers is identified for [Ni(tdt)(PR3)]2 (PR3 =
PPh3, 17; PPh2Me, 18): two symmetric isomers and one non-
symmetric (Fig. 2). The presence of these three isomers was
(SSR)2] (SSR
=
bsms—4-mercapto-3,3-methyl-1-phenyl-2-
thiabutane45—and 2-ethoxycarbonylsulfanyl-1,2-bis(methylthio)-
1-ethenethiolato)46 and in sulfur rich nickel complexes with
1
1
confirmed by a 31P{ H}-31P{ H} COSY experiment. The sym-
metric species appear as singlets whereas the asymmetric isomer
appears as an AB system. Only in the case of 17 are those signals
detected in a room temperature NMR experiment. However, in
the case of 18 (PR3 = PPh2Me) there is an unique signal at
20 ◦C, which is resolved at -60 ◦C to give the same pattern as
the one observed in 17. We describe these complexes as dimers
of their bdt homologues, on the basis of their mass spectra and
their cryoscopic molecular weight measurement. These dinuclear
complexes are again obtained in slightly higher yields when the
reaction is performed under reflux.
a
bis(2-mercaptophenyl)sulfide ligand.47,48 Ni–S(thioether)
distances in comparable complexes are usually in the range of
49,50
˚
2.17–2.18 A
and Ni–S distances in nickel thioether–thiolate
complexes frequently do not differ at all,51 but in this case, the
presence of the longer Ni–thiolate distance is in accordance
with the higher trans influence of the mesitylene group.52 There
are only two examples in the literature, as confirmed by a
search of dmit–thiolate–thioether nickel complexes described
by X-ray analysis in the Cambridge Crystallographic Data
Base: [Ni(dmit–Me)2(dppe)]53 and [Ni(dmit-o-CH2C6H4CH2-
dmit)(py)2].25 However, in both structures the Ni–S(thioether)
distances are greater than the respective Ni–S(thiolate) bond
lengths, precisely the opposite effect to what we have observed
˚
˚
in 3a. The remaining Ni–P (2.1761(8) A) and Ni–C (1.934(3) A)
bond lengths are similar to those found in related organometallic
phosphino-thiolate derivatives.54–58 The distances in the dmit
ligand [S4–C3 1.637(3), C1–C2 1.334(4), C2–S2 1.743(3) and
Fig. 2 Different isomers for the dinuclear nickel derivative with tdt as the
dithiolate ligand.
As in the reaction with bdt as dithiolate ligand, a similar
derivative to [Ni(bdtMes)2] (13), [Ni(tdtMes)2] (19), is detected
in very small amounts in the isolation of the dimeric compounds.
The H NMR spectrum displays a symmetric disposition of the
Me group in the tdtMes ligand, giving only one signal for both
Me and Mes groups. However, with this dithiolate, neither higher
˚
Fig. 3 Molecular structure of complex 3a. Selected bond lengths [A]
and angles [◦]: Ni(1)–C(13) 1.934(3), Ni(1)–P(1) 2.1761(8), Ni(1)–S(1)
2.1997(8), Ni(1)–S(2) 2.2308(8), S(1)–C(1) 1.759(3); C(13)–Ni(1)–P(1)
90.86(9), C(13)–Ni(1)–S(1) 84.73(8), P(1)–Ni(1)–S(1) 170.29(3),
C(13)–Ni(1)–S(2) 176.70(9), P(1)–Ni(1)–S(2) 92.41(3), S(1)–Ni(1)–S(2)
91.96(3). H omitted for clarity.
1
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˚
C1–S1 1.759(3) A] are similar to those found in metallic complexes
with the dmit ligand acting as a thiolate–thioether ligand.25,53,59,60
Structure of {dmit(Trip)2} (5). Compound 5 gave single
crystals suitable for X-ray structure analysis. The molecular
structure (Fig. 4) confirms the presence of two (dmit)Trip units
˚
interconnected through a S–S bond of 2.082(2) A. As stated above,
a similar structure, previously reported by us,19 with a Mes group,
˚
had a S–S bond length of 2.096(3) A. The main difference between
them consists of the disposition of the two C3S5 (dmit) units. In
compound 5, both rings are orientated on the same side of the
molecule whereas in the other, the dmit subunits have opposite
orientations, probably due to the formation of dimers in the crystal
packing (see below). These dmit units are in a nearly parallel
disposition with a dihedral angle of 5.99◦; however the Trip rings
◦
˚
are both bent, with an angle of about 17.2 . The C–S (1.74 A
˚
=
on average) and the C C (1.345(7) and 1.354(7) A) distances in
the dmit skeleton are similar to those found in dmit derivatives
such as {dmit(Mes)2},19 C3S8,61 C6S10,62 (NMe4)2C6S10,63 C6S12,64–66
C6S14,66 [FeCp(CO)2(C6S10)]67 and (PPh4)2C12S16.63 The stacking of
the molecules along the direction perpendicular to the (100) plane
Fig. 5 Stacking of compound 5 molecules along the direction perpendic-
ular to the (100) plane.
˚
presents intermolecular S ◊ ◊ ◊ S contacts of 3.41 A (shorter than the
˚
sum of the van der Waals radii—3.7 A), giving the formation of
dimers (Fig. 5).
Fig. 6 Molecular structure of complex 12. Selected bond lengths
[A]: Ni(1)–S(2) 2.1731(14), Ni(1)–S(3) 2.1742(15), Ni(1)–S(4) 2.1748(14),
˚
Fig. 4 Molecular structure of complex 5. Selected bond lengths [A]
˚
and angles [◦]: S(1)–C(16) 1.752(6), S(1)–C(1) 1.789(6), S(4)–C(18)
1.750(6), S(4)–S(5) 2.083(2), S(5)–C(19) 1.767(6), C(19)–C(21) 1.354(7),
S(7)–C(20) 1.632(6); C(16)–S(1)–C(1) 99.2(3), C(21)–S(9)–C(22) 100.3(3),
C(2)–C(1)–S(1) 118.7(4), S(3)–C(18)–S(4) 119.6(3), S(6)–C(19)–S(5)
120.1(3), C(19)–C(21)–S(9) 124.3(5). H omitted for clarity.
Ni(1)–S(1) 2.1753(15), Ni(1)–Ni(2) 2.5104(10), Ni(1)–Ni(3) 2.5262(9),
Ni(2)–P(1) 2.2410(14), Ni(2)–S(6) 2.2994(14), Ni(2)–S(5) 2.3443(15),
Ni(2)–S(2) 2.4113(14), Ni(2)–S(3) 2.4692(14), Ni(2)–Ni(3) 2.4729(10),
Ni(3)–P(2) 2.2250(15), Ni(3)–S(5) 2.2917(14), Ni(3)–S(6) 2.3066(14),
Ni(3)–S(4) 2.4411(14), Ni(3)–S(1) 2.4732(14). H omitted for clarity.
Structure of [Ni3(bdt)3(PPh2Me)2] (12). Dark brown crystals
of complex 12 were grown from a dichloromethane solution and
the resulting X-ray crystal structure is shown in Fig. 6. The
structure is similar to the previously described trinuclear cluster
[Ni3(bdt)3(PPh3)2],43 with a cyclic trigonal prismatic Ni3S6 core.
In both cases the intermetallic Ni ◊ ◊ ◊ Ni separations are shorter
respectively, which reinforces the geometrical distortion from
planarity of the Ni(bdt)2 unit. The remaining two nickel atoms,
Ni(2) and Ni(3), show a distorted square pyramidal coordina-
˚
tion lying 0.4438(7) and 0.4440(7) A, respectively, above the
corresponding S4 basal plane. These displacements are smaller
˚
than other Ni-thiolate clusters (distances range from 2.633 to
than those observed (0.579(1) and 0.587 A) in the equivalent
68–74
˚
˚
3.131 A),
ranging from 2.500 to 2.549 A in the case of PPh3
structure with PPh3 ligands. The cis and trans S–Ni–S angles
in the basal plane of the square pyramid range from 73.8(5)
to 98.82(5) and 150.84(5) to 151.32(5)◦, respectively and the
P–Ni–S angles range from 95.73(5) to 109.13(5)◦. The Ni–S bond
lengths in the dianion [Ni(dbt)2]2- (2.1743 A on average) are
˚
shorter than the distances observed with the bridging bdt units
˚
and from 2.5104 to 2.5462 A in complex 12, which are close
75
˚
to the distance of 2.49 A in the metal. Two of the nickel
atoms are five coordinated while the other displays a highly
distorted square-planar coordination to two benzenedithiolate
ligands, with angles S(4)–Ni(1)–S(2) 166.63(6), S(1)–Ni(1)–S(3)
164.91(6), S(1)–Ni(1)–S(2) 92.95(5) and S(2)–Ni(1)–S(3) 84.79(5)◦
and a deviation of the nickel centre from the plane of
˚
˚
(on average: Ni(2)–S 2.381 A and Ni(3)–S 2.3782 A) as in the
cluster with PPh3 ligands. Both Ni(2) and Ni(3) are bonded to one
phosphine molecule (PPh2Me) in the apical position of the pyra-
˚
0.2152(7) A. The dihedral angles between the S(1)–S(2)–S(3)–S(4)
˚
plane and the phenyl rings C(1)–C(2)–C(3)–C(4)–C(5)–C(6)
mid with typical distances Ni–P of 2.2410(14) and 2.2250(15) A,
respectively.
and C(7)–C(8)–C(9)–C(10)–C(11)–C(12) are 7.07 and 12.07◦,
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1
31P{ H}NMR and 119Sn NMR, in order to determine a possible
Structure of [Ni(bdtMes)2] (13). The molecule structure of
complex 13 is shown in Fig. 7. It is an homoleptic nickel(II)
complex with two bdtMes ligands (bdtMes = o-(mesitylenethio)-
thiophenolate-S,S¢) exhibiting crystallographic centrosymmetry
and planar [NiS4] cores. The NiS4 unit, including the phenyl
rings, is highly distorted from planarity. The dihedral angles
between the NiS4 core and the phenyl rings are 64.1 and
mechanism.
In the reactions with dmit as the dithiolate ligand, the first
new product detected is the one resulting from the C,S and
S,S-coupling, {dmitR}2 (R = Mes, Trip, 5), whose signals ap-
pear within the first 5 min of reaction and remain unchanged
throughout the course of the reaction. The signals of the
starting nickel complexes, [NiBr(Mes)(PR3)2] (PR3 = PPh3 and
PPh2Me), decrease at the same time that the ones corresponding
to the new nickel compounds, [Ni(Mes)(dmitMes)(PR3)] and
[Ni(dmit)(PR3)]2, increase.
69.7◦ and the nickel atom is 1.4362(25) A out of the plane.
˚
The two mesitylene radicals are nearly perpendicular to the
Ni(dbt)2 unit, with a torsional angle of 80.9◦. In this molecule
the two Ni–S distances are different, with the Ni–S(thiolate)
In all the reactions, free PR3 is detected in the 31P{ H} NMR
1
˚
˚
(2.1928(19)A) bond longer than the Ni–S(thioether) (2.150(15) A)
bond, as observed in 3. However, similar Ni–thiolate–thioether
homoleptic derivatives display close distances for both units76,77
or longer distances for the Ni–thioether unit.46,78 The discrete
molecules show a stacking along the direction perpendicular
measurements, in addition to some new resonances during the
first minutes of the reaction that then disappear rapidly, which are
probably due to intermediate species. [SnBr2Me2] is also identified
in the 1H NMR and119Sn NMR spectra during the course of
the reaction, in addition to some signals from unidentified tin
complexes.
˚
to the (100) plane, with a Ni ◊ ◊ ◊ Ni separation of 9.966 A
(Fig. 8).
We presume that the formation of {dmitR¢}2 (R¢ = Mes, Trip,
5) and [(S–S)(Mes)2] [S–S = bdt (12), tdt (14)] should go by
different pathways, since {(S–S)(Mes)2} can be detected by heating
[Ni(Mes)(S–SMes)(PR3)] [S–S = bdt (8, 9), tdt (15, 16)] in acetone,
whereas [Ni(Mes)(dmitMes)(PR3)] (3, 4) remain unaltered under
the same conditions.
Although it was neither possible to isolate nor to characterize
any intermediates by NMR, we suggest a possible mechanism
(Scheme 4) based on the obtained complexes. We think that the
formation of a heteronuclear intermediate a should be the first
step. a could then evolve to the intermediates b and/or c as a
consequence of a selective cleavage of the S–Ni or S–Sn bonds,
which, for the formation of b, is accompanied by a mesitylene
group shift from the metal centre to the sulfur atom. Such
intermediates then proceed to the described derivatives according
to Scheme 4
˚
Fig. 7 Molecular structure of complex 13. Selected bond lengths [A] and
angles [◦] (#1: -x, -y, -z): Ni(1)–S(1) 2.150(15), Ni(1)–S(2) 2.1927(19),
S(1)–C(1) 1.778(17), S(1)–Ni(1)–S(1)#1: 180.0, S(1)–Ni(1)–S(2) 90.29(12),
S(1)#1–Ni(1)–S(2) 89.71(12), S(1)–Ni(1)–S(2)#1 89.71(12). H omitted for
clarity.
Experimental
General data
The C, H, N and S analyses were measured on a Perkin-Elmer 2400
microanalyser. The infrared spectra were recorded on a Perkin-
Elmer 883 spectrophotometer, over the range 4000–200 cm-1, using
Nujol mulls between polyethylene sheets. The NMR spectra were
recorded on a Varian UNITY 300, BRUKER ARX 300 or AV400
spectrometer, in CDCl3 or (CD3)2CO at room temperature, if not
1
otherwise mentioned (300 MHz for H and 121,4 MHz for 31P).
Chemical shifts are cited relative to SiMe4 (1H) and 85% H3PO4
(external, 31P). Mass spectra were recorded by liquid secondary
ion mass spectrometry (LSIMS+) on a VG Autospec, using nba
(nitrobenzylalcohol) as matrix and a cesium gun.
Materials
The starting materials, [SnMe2(S-S)],28 [NiBr(Trip)L2] and
[NiBr(Mes)L2],79 were prepared by published procedures. In the
case of [NiBr(Trip)L2] the preparation is similar to that reported
for [NiBr(Mes)L2], but using Mg(Trip)Br instead of Mg(Mes)Br.
All other reagents were commercially available and were used as
supplied.
Fig. 8 Stacking of compound 13 molecules along the direction perpen-
dicular to the (100) plane.
The progress of the transmetallation reactions were monitored
by the use of NMR techniques, in particular by 1H NMR,
6830 | Dalton Trans., 2009, 6825–6835
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Scheme 4 Proposal of the mechanism of the dithiolate transfer reaction.
Reaction of [SnMe2(dmit)] with [NiBr(Mes)(PPh3)2]
[Ni(Mes)(dmitMes)(PPh2Me)] (4), yellow solid. Yield: 30%
(based on nickel). Anal. calcd for C34H35NiPS5: C, 58.87; H,
5.08; S, 23.11. Found: C, 58.70; H, 5.33; S, 23.51. Mp (◦C): 180.
To a stirred solution of [SnMe2(dmit)] (0.103 g, 0.3 mmol)
in acetone (20 ml) was added [NiBr(Mes)(PPh3)2] (0.235 g,
0.3 mmol). After 5 h of stirring, a brown solid precipitated and was
identified as [Ni(dmit)(PPh3)]2 (1). The solid was filtered off and
after evaporation of the solvent under reduced pressure the residue
was chromatographed on silica gel using dichloromethane–hexane
-1
-1
1
=
IR: n(Mes) 1600, 849 cm ; n(C S) 1064, 1034 cm . H NMR
(CDCl3): d 1.01 (d, 3H, J = 9.9 Hz, PPh2Me), 2.03 (s, 3H, p-Me
(Mes)), 2.06 (s, 3H, p-Me (Mes)), 2.16 (s, 6H, o-Me (Mes)), 2.18
(s, 6H, o-Me (Mes)), 6.28 (s, 2H, m-H (Mes)), 6.69 (s, 2H, m-H
1
(Mes)), 7.37–7.69 (m, 10H, PPh2Me). 31P{ H} NMR (CDCl3): d
19
(1 : 3) as the eluent to give, in order of elution: {dmitMes}2 and
11.6 (s) (isomer a), 14.7 (s) (isomer b). MS (LSIMS+): m/z (%)=
∑
692 (28) [M]+ .
[Ni(Mes)(dmitMes)(PPh3)] (3).
[Ni(dmit)(PPh3)]2 (1), brown solid. Yield: 40% (based on nickel).
[Ni(dmit)(PPh2Me)]2 (2), brown solid. Yield: 40% (based on
nickel) Anal. calcd for C32H26Ni2P2S10: C, 42.21; H, 2.88; S,
35.22. Found: C, 42.44; H, 2.65; S, 35.05. Mp (◦C): 180. IR:
Anal. calcd for C42H30Ni2P2S10: C, 48.76; H, 2.92; S, 30.99. Found:
◦
=
C, 48.50; H, 2.83; S, 31.06. Mp ( C): 173, IR: n(C S) 1056, 1050,
1026 cm-1. 1H NMR (CDCl3): d 7.20–8.00 (m, 30H, PPh3). 31P{ H}
1
-1
1
=
n(C S) 1061, 1028 cm . H NMR (CDCl3): d 2.24 (d, 6H, J =
12.6 Hz, PPh2Me), 7.44–7.46 (m, 12H, PPh2Me), 7.76–7.83 (m,
NMR (CDCl3): d 30.3 (s).
1
8H, PPh2Me). 31P{ H} NMR (CDCl3): d 36.3 (s). MS (LSIMS+):
[Ni(Mes)(dmitMes)(PPh3)] (3), yellow solid. Yield: 27% (based
on nickel). Anal. calcd for C39H37NiPS5: C, 61.98; H, 4.93; S, 21.21.
Found: C, 61.84; H, 4.81; S, 21.48. Mp (◦C): 180. IR: n(Mes) 1600,
m/z (%) = 455 (92) [M - dmit - Ni - PPh2Me]+.
Reaction of [SnMe2(dmit)] with [NiBr(Trip)(PPh3)2]. This reac-
tion was carried out in a similar way to the first reaction, described
with [NiBr(Mes)(PPh3)2], but starting with [NiBr(Trip)(PPh3)]
(0.260 g, 0.3 mmol). A brown solid, identified as [Ni(dmit)(PPh3)]2
(1) precipitated after 5 h of stirring (yield 40%, based on nickel).
The solid was filtered off and, after evaporation of the solvent
under reduced pressure, the residue was chromatographed on
silica gel using dichloromethane–hexane (1 : 3) as the eluent to
give {dmitTrip}2 (5) as the main product.
-1
-1
1
=
848 cm ; n(C S) 1057, 1011 cm . H NMR (CDCl3): d 2.00 (s,
3H, p-Me (Mes)), 2.09 (s, 12H, o-Me (Mes)), 2.18 (s, 3H, p-Me
(Mes)), 6.05 (s, 2H, m-H (Mes)), 7.23 (s, 2H, m-H (Mes)), 7.10–
7.50 (m, 12H, PPh3), 7.60–7.80 (m, 3H, PPh3). 31P{ H} NMR
1
(CDCl3): d 26.9 (s) (isomer a), 21.6 (s) (isomer b). MS (LSIMS+):
m/z (%) = 754 (90) [M]+.
Reaction of [SnMe2(dmit)] with [NiBr(Mes)(PPh2Me)2]. To a
stirred solution of [SnMe2(dmit)] (0.103 g, 0.3 mmol) in acetone
(20 ml) was added [NiBr(Mes)(PPh2Me)2] (0.197 g, 0.3 mmol).
After 5 h of stirring the solvent was evaporated under reduced
pressure and the residue was chromatographed on silica gel using
dichloromethane–hexane (1 : 3) as the eluent to give, in order
of elution: {dmitMes}2,19 [Ni(Mes)(dmitMes)(PPh2Me)] (4) and
[Ni(dmit)(PPh2Me)]2 (2).
{dmitTrip}2 (5), yellow solid. Yield: 50% (based on dmit). Anal.
calcd for C36H46S10: C, ◦54.21; H, 5.80; S, 40.11. Found: C, 54.09;
-1
1
=
H, 5.64; S, 40.38. Mp ( C): 150. IR: n(C S) 1074, 1016 cm . H
NMR (CDCl3): d 1.22 (d, 12H, J = 6.9 Hz, p-CHMe2 (Trip)), 1.24
(d, 24H, J = 6.9 Hz, o-CHMe2 (Trip)), 2.89 (sep, 2H, J = 6.9 Hz,
p-CHMe2 (Trip)), 3.65 (sep, 4H, J = 6.9 Hz, o-CHMe2 (Trip)),
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7.06 (s, 4H, m-H (Trip)). MS (LSIMS+): m/z (%) = 799 (37) [M]+,
603 (13) [M - dmit]+, 399 (100) [M - dmit - Trip]+.
bdt)], [Ni(Mes)(bdtMes)(PPh2Me)] (9), [Ni(bdt)(PPh2Me)]2 (7),
[Ni3(bdt)3(PPh2Me)2] (12) and [Ni(bdtMes)2] (13).
[Ni(Mes)(bdtMes)(PPh2Me)] (9). Yield: 16% (5 h); 10% (reflux)
(based on nickel) Anal. calcd for C37H39NiPS2: C, 69.71; H, 6.16;
S, 10.06. Found: C, 69.85; H, 6.04; S, 10.38. Mp (◦C): 180. IR:
Reaction of [SnMe2(bdt)] with [NiBr(Mes)(PPh3)2]
-1
-1
1
=
To a stirred solution of [SnMe2(bdt)] (0.087 g, 0.3 mmol) in acetone
(20 ml) was added [NiBr(Mes)(PPh3)2] (0.235 g, 0.3 mmol). After
5 h of stirring at room temperature or 2 h of reflux there
was a red precipitate which was identified as [Ni(bdt)(PPh3)]2
(6). Then the solvent was evaporated under reduced pressure
and a new yellow solid precipitated and was identified as
[Ni(Mes)(bdtMes)(PPh3)] (8). The residue was chromatographed
on silica gel using dichloromethane–hexane (1 : 1) as the eluent
to give in order of elution: [Ni(bdt)(PPh3)2] (10) and {bdt(Mes)2}
(11).
n(Mes): 1602, 851 cm ; n(C C): 1442 cm . H NMR (CDCl3):
d 1.10 (d, 3H, J = 9.5 Hz, PPh2Me), 1.85 (s, 6H, o-Me (Mes)),
2.03 (s, 3H, p-Me (Mes)), 2.11 (s, 6H, o-Me (Mes)), 2.13 (s, 3H,
p-Me (Mes)), 6.23 (s, 2H, m-Mes)), 6.61 (s, 2H, m-Mes)), 6.67 (dd,
1H, J = 7.9, 1.9 Hz, H (bdt)), 6.72 (dt, 1H, J = 7.9, 1.9 Hz, H
(bdt)), 6.92 (dt, 1H, J = 7.9, 1.9 Hz, H (bdt)), 7.12 (dc, 1H, J =
7.9, 1.9 Hz, H (bdt)), 7.40–7.41 (m, 8H, PPh2Me), 7.76–7.77 (m,
2H, PPh2Me). 31P{ H} NMR (CDCl3): d 15.9 (s) (isomer a), 10.01
1
(s) (isomer b). MS (LSIMS+): m/z (%) = 636 (32) [M]+, 517 (22)
[M - Mes]+, 436 (55) [M - PPh2Me]+.
[Ni(bdt)(PPh3)]2, (6). Yield: 45% (5 h); 50% (reflux) (based on
nickel). Anal. calcd for C48H38Ni2P2S4: C, 6◦2.50; H, 4.15; S, 13.90.
[Ni(bdt)(PPh2Me)]2 (7), red solid. Yield: 40% (5 h); 45% (reflux)
(based on nickel) Anal. calcd for C38H34Ni2P2S4: C, 57.17; H, 4.29;
S, 16.04. Found: C, 57.32; H, 4.12; S, 15.98. Mp (◦C): 158. IR:
=
Found: C, 62.38; H, 4.39; S, 13.72. Mp ( C): 220. IR: n(C C)
1420 cm-1. 1H NMR (CDCl3): d 5.68 (d, 2H, J = 8.1 Hz, H1), 6.05
(dt, 2H, J = 8.1, 1.2 Hz, H2), 6.50 (dt, 2H, J = 8.1, 1.2 Hz, H3),
6.67 (dd, 2H, J = 8.1, 1.2 Hz, H4), 7.21–7.58 (m, 24H, PPh3),
n(C C): 1443 cm . H NMR (CDCl3): d 1.42 (d, 6H, J = 9.2 Hz,
PPh2Me), 5.75 (d, 2H, J = 7.8 Hz, H (bdt)), 6.29 (dt, 2H, J = 7.8,
1.0 Hz, H (bdt)), 6.75 (dt, 2H, J = 7.8, 1.0 Hz, H (bdt)), 7.00 (dd,
2H, J = 7.8, 1.0 Hz, H (bdt)), 7.20–7.50 (m, 16H, PPh2Me), 7.80–
-1
1
=
1
7.71–7.78 (m, 6H, PPh3). 31P{ H} NMR (CDCl3): d 33.0 (s).
MS (LSIMS+): m/z (%) = 922 (15) [M]+, 660 (25) [M - PPh3]+.
8.00 (m, 4H, PPh2Me). 31P{ H} NMR (CDCl3): d 15.3 (s). MS
1
Cryoscopic molecular weight: 891.
(LSIMS+): m/z (%) = 796 (35) [M]+, 598 (100) [M - PPh2Me]+,
398 (88) [M - 2PPh2Me]+. Cryoscopic molecular weight:
854.
[Ni(Mes)(bdtMes)(PPh3)]2 (8), yellow solid. Yield: 20% (5 h);
18% (reflux) (based on nickel). Anal. calcd for C42H41NiPS2: C,
72.11; H, 5.91; S, 9.17. Found: C, 72.39; H, 5.74; S, 9.34. Mp (◦C):
[Ni3(bdt)3(PPh2Me)2] (12), green solid. Yield: 10% (5 h); 7%
(reflux) (based on nickel) Anal. calcd for C44H38Ni3P2S6: C, 52.99;
H, 3.84; S, 19.29. Found: C, 53.5; H, 4.15; S, 19.6. Mp (◦C): 118. IR:
-1
-1
1
=
175. IR: n(Mes): 1588, 856 cm ; n(C C): 1420 cm . H NMR
(CDCl3): d 1.94 (s, 6H, o-Me (Mes)), 1.99 (s, 3H, p-Me (Mes)),
2.06 (s, 6H, o-Me (Mes)), 2.15 (s, 3H, p-Me (Mes)), 6.02 (s, 2H,
m-H (Mes)), 6.65 (s, 2H, m-H (Mes)), 6.72 (dt, 1H, J = 7.9, 1.9 Hz,
H (bdt)), 6.75 (dt, 1H, J = 7.9, 1.9 Hz, H (bdt)), 6.95 (dt, 1H, J =
7.9, 1.9 Hz, H (bdt)), 7.05 (dc, 1H, J = 7.9, 1.9 Hz, H (bdt)), 6.96–
-1
1
=
n(C C): 1436 cm . H NMR (CDCl3): d 2.05 (d, 6H, J = 13.2 Hz,
PPh2Me), 6.49 (dd, 2H, J = 5.6, 3.2 Hz, H (bdt)), 7.40–7.50 (m,
14H, PPh2Me, 2H (bdt)), 6.94 (m, 2H, H (bdt)), 7.13–7.21 (m, 8H,
2bdt), 7.72–7.77 (m, 6H, PPh2Me), 7.48–7.57 (m, 10H, PPh2Me),
7.50 (m, 15H, PPh3). 31P{ H} NMR (CDCl3): d 30.3 (s) (isomer
7.30–7.38 (m, 4H, PPh2Me). 31P{ H} NMR (CDCl3): d 30.15 (s).
1
1
a), 23.1 (isomer b). MS (LSIMS+): m/z (%) = 698 (100) [M]+, 597
MS (LSIMS+): m/z (%) = 597 (20) [M - 2PPh2Me]+, 797 (15)
(44) [M - Mes]+, 436 (69) [M - PPh3]+.
[M - PPh2Me]+, 997 (15) [M]+.
1
[Ni(bdt)(PPh3)2] (10), green solid. Yield: 20% (5 h); 17% (reflux)
(based on nickel). Anal. calcd for C42H34NiP2S2: C, 69.73; H, 4.74;
S, 8.86. Found: C, 69.60; H, 4.62; S, 8.64. Mp (◦C): 140. IR:
[Ni(bdtMes)2] (13), red crystals. Minority product. H NMR
(CDCl3): d 2.26 (s, 6H, p-Me (Mes)), 2.29 (s, 12H, o-Me
(Mes)), 6.42–6.43 (m, 4H, H (bdt)), 6.86–6.87 (m, 4H, H (bdt)),
7.08 (s, 4H, m-H (Mes)). MS (LSIMS+): m/z (%) = 457 (62)
[M - Mes]+.
-1
1
=
n(C C): 1441 cm . H NMR (CDCl3): d 7.26–7.47 (m, 20H,
PPh3, 2H (bdt)), 7.56–7.63 (m, 14H, PPh3, 2H (bdt)). 31P{ H}
1
NMR (CDCl3): d 31.0 (s).
{bdt(Mes)2} (11), yellow solid. Yield: 3% (5 h); 3% (reflux)
(based on bdt) Anal. calcd for C24H26S2: C, 76.14; H, 6.92; S, 16.94.
Found: C, 76.30; H, 6.75; S, 16.72. Mp (◦C): 165. IR: n(Mes): 1603,
851 cm ; n(C C): 1435 cm . H NMR (CDCl3): d 2.27 (s, 6H, p-
Me (Mes)), 2.35 (s, 12H, o-Me (Mes)), 6.36–6.39 (m, 2H, H (bdt)),
6.73–6.76 (m, 2H, H (bdt)), 6.97 (s, 4H, m-H (Mes)). LSIMS+:
m/z (%) = 378 (100) [M]+, 259 (37) [M - Mes]+.
Reaction of [SnMe2(tdt)] with [NiBr(Mes)(PPh3)2]
To a stirred solution of [SnMe2(tdt)] (0.091 g, 0.3 mmol) in acetone
(20 ml) was added [NiBr(Mes)(PPh3)2] (0.235 g, 0.3 mmol).
After 5 h of stirring at room temperature or 2 h of reflux the
solvent was evaporated under reduced pressure and the residue
chromatographed on silica gel using dichloromethane–hexane
(1 : 1) as the eluent to give, in order of elution: {tdt(Mes)2}
(14), [Ni(Mes)(tdtMes)(PPh3)] (15), [Ni(tdt)(PPh3)]2 (17) and
[Ni(tdtMes)2] (19).
-1
-1 1
=
Reaction of [SnMe2(bdt)] with [NiBr(Mes)(PPh2Me)2]
To a stirred solution of [SnMe2(bdt)] (0.087 g, 0.3 mmol) in acetone
(20 ml) was added [NiBr(Mes)(PPh2Me)2] (0.197 g, 0.3 mmol).
After 5 h of stirring at room temperature or 2 h of reflux,
the solvent was evaporated under reduced pressure and the
residue chromatographed on silica gel using dichloromethane–
hexane (1 : 1) as the eluent to give, in order of elution:
{bdt(Mes)2} (11) [yield: 17% (5 h); 16% (reflux) (based on
{tdt(Mes)2} (14), yellow solid. Yield: 18% (5 h); 18% (reflux)
(based on tdt). Anal. calcd for C25H28S2: C, 76.48; H, 7.19; S, 16.33.
Found: C, 76.30; H, 7.41; S, 16.10. Mp (◦C): 80. IR: n(Mes): 1583,
849 cm ; n(C C): 1434 cm . H NMR (CDCl3): d 2.06 (s, 3H,
Me (tdt)), 2.31 (s, 3H, p-Me (Mes)), 2.32 (s, 3H, p-Me (Mes)), 2.42
(s, 12H, o-Me (Mes)), 6.21–6.23 (m, 1H, H (tdt)), 6.36 (dd, 1H,
J = 8.0, 1.8 Hz, H (tdt), 6.59–6.60 (m, 1H, H (tdt)), 6.99 (s, 2H,
-1
-1
1
=
6832 | Dalton Trans., 2009, 6825–6835
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©

View Article Online
m-H (Mes)), 7.00 (s, 2H, m-H (Mes)). MS (LSIMS+): m/z (%) =
392 (100) [M]+.
[Ni(Mes)(tdtMes)(PPh3)] (15), yellow solid. Yield: 20% (5 h);
17% (reflux) (based on nickel) Anal. calcd for C43H43NiPS2: C,
72.38; H, 6.07; S, 8.99. Found: C, 72.52; H, 6.20; S, 8.70. Mp (◦C):
Reaction of [SnMe2(tdt)] with [NiBr(Mes)(PPh2Me)2]
To a stirred solution of [SnMe2(tdt)] (0.091 g, 0.3 mmol) in acetone
(20 ml) was added [NiBr(Mes)(PPh2Me)2] (0.197 g, 0.3 mmol).
After 5 h of stirring at room temperature or 2h of reflux the solvent
was evaporated under reduced pressure and the residue chro-
matographed on silica gel using dichloromethane–hexane (1 : 1) as
the eluent to give, in order of elution: {tdt(Mes)2} (14) [yield: 20%
(5 h); 20% (reflux) (based on tdt)], [Ni(Mes)(tdtMes)(PPh2Me)]
(16) and [Ni(tdt)(PPh2Me)2] (18).
-1
-1
1
=
173. IR: n(Mes): 1573, 855 cm , n(C C): 1433 cm . H NMR
(CDCl3): d 1.95 (s, 6H, o-Me (Mes)), 1.99 (s, 3H, p-Me (Mes)),
2.04 (s, 6H, o-Me (Mes)), 2.16 (s, 3H, Me (tdt)), 2.17 (s, 3H, p-Me
(Mes)), 6.01 (s, 2H, m-H (Mes)), 6.64 (s, 2H, m-H (Mes)), 6.52–
6.57 (m, 1H, H (tdt)), 6.50–6.57 (m, 1H, H (tdt)), 7.00–7.06 (m,
1H, H (tdt)), 7.16–7.47 (m, 15H, PPh3). 31P{ H} NMR (CDCl3):
1
[Ni(Mes)(tdtMes)(PPh2Me)] (16). Yield: 17% (5 h); 13% (reflux)
(based on nickel) Anal. calcd for C38H41NiPS2: C, 70.05; H, 6.34; S,
9.84. Found: C, 70.45; H, 6.02; S, 9.76. Mp (◦C): 145. IR: n(Mes):
d 29.9 (s) (isomer a), 30.0 (s) (isomer b), 22.9 (s) (isomer c), 22.8
(s) (isomer d). MS (LSIMS+): m/z (%) = 712 (75) [M]+, 593 (54)
[M - Mes]+, 450 (100) [M - PPh3]+.
-1
-1
1
=
1575, 844 cm ; n(C C): 1434 cm . H NMR (CDCl3): d 1.06 (d,
3H, J = 9.5 Hz, PPh2Me), 1.90 (s, 6H, o-Me (Mes)), 2.07 (s, 6H,
p-Me (Mes)), 2.15 (s, 6H, o-Me (Mes)), 2.17 (s, 3H, Me (tdt)), 6.28
(s, 2H, m-H (Mes)), 6.65 (s, 2H, m-H (Mes)), 6.50–6.68 (m, 1H,
H (tdt)), 6.76–6.82 (m, 1H, H (tdt)), 7.12–7.20 (m, 1H, H (tdt)),
[Ni(tdt)(PPh3)]2 (17), red solid. Yield: 51% (5 h); 58% (reflux)
(based on nickel) Anal. calcd for C50H42Ni2P2S4: C, 63.18; H, 4.45;
S, 13.49. Found: C, 63.36; H, 4.21; S, 13.66. Mp (◦C): 150. IR:
-1
1
=
n(C C): 1442 cm . H NMR (CDCl3): d (isomer a) 1.62 (s, 3H,
Me(1) (tdt)), 1.88 (s, 3H, Me(2) (tdt)), 5.48 (d, 1H, J = 4.1 Hz,
H1), 5.65 (dd, 1H, J = 8.1, 4.1 Hz, H4), 5.87 (d, 1H, J = 8.1 Hz,
H5), 6.33 (d, 1H, J = 8.1 Hz, H2), 6.46 (s, 1H, H6), 6.56 (d, 1H,
J = 8.1 Hz, H3), 7.10–7.30 (m, 18H, PPh3), 7.60–7.80 (m, 12H,
PPh3); d (isomer b) 1.62 (s, 6H, Me (tdt)), 5.48 (s, 2H, H1), 6.33
(d, 2H, J = 8.1 Hz, H2), 6.56 (d, 2H, J = 8.1 Hz, H3), 7.10–7.30
(m, 18H, PPh3), 7.60–7.80 (m, 12H, PPh3); d (isomer c) 1.88 (s,
6H, Me (tdt)), 5.65 (dd, 2H, J = 8.1, 4.1 Hz, H4), 5.87 (d, 2H, J =
8.1 Hz, H5), 6.46 (s, 2H, H6), 7.10–7.30 (m, 18H, PPh3), 7.60–7.80
7.30–7.80 (m, 10H, PPh2Me). 31P{ H} NMR (CDCl3): d 15.8 (s)
1
(isomer a); 15.7 (s) (isomer b); 9.9 (s) (isomer c); 9.8 (s) (isomer d).
MS (LSIMS+): m/z (%) = 650 (40) [M]+, 531 (27) [M - Mes]+,
450 (100) [M - PPh2Me]+.
[Ni(tdt)(PPh2Me)]2 (18), red solid. Yield: 45% (5 h); 50% (reflux)
(based on nickel). Anal. calcd. for C40H38Ni2P2S4: C, 58.14; H, 4.63;
S, 15.52. Found: C, 58.02; H, 4.41; S, 15.75. Mp (◦C): 110. IR:
-1
1
=
n(C C): 1440 cm . H NMR (CDCl3): d (isomer a) 1.38 (d, 3H,
J = 8.7 Hz, PPh2Me(2)), 1.46 (d, 3H, J = 8.7 Hz, PPh2Me(1)),
1.79 (s, 3H, Me(1) (tdt)), 2.05 (s, 3H, Me(2) (tdt)), 5.58 (s, 1H, H1),
5.74 (dd, 1H, J = 7.7, 1.8 Hz, H4), 6.10 (d, 1H, J = 7.8 Hz, H5),
6.63 (d, 1H, J = 7.9 Hz, H2), 6.81 (s, 1H, H6), 6.92 (dd, 1H, J =
5.8, 2.3 Hz, H3), 7.26–7.99 (m, 20H, PPh2Me); d (isomer b) 1.46
(d, 6H, J = 8.7 Hz, PPh2Me), 1.79 (s, 6H, Me (tdt)), 5.58 (s, 2H,
H1), 6.63 (d, 2H, J = 7.9 Hz, H2), 6.92 (dd, 2H, J = 5.8, 2.3 Hz,
H3), 7.26–7.99 (m, 20H, PPh2Me); d (isomer c) 1.38 (d, 6H, J =
8.7 Hz, PPh2Me), 2.05 (s, 6H, Me (tdt)), 5.74 (dd, 2H, J = 7.7,
1
(m, 12H, PPh3). 31P{ H} NMR (CDCl3): dA = 33.5, dB = 32.8,
JAB = 6.8 Hz (isomer a); d 33.3 (s) (isomer b); d 32.9 (s) (isomer c).
MS (LSIMS+): m/z (%) = 950 (10) [M]+, 688 (40) [M - PPh3]+.
Cryoscopic molecular weight: 868.
[Ni(tdtMes)2] (19). Minority product. 1H NMR (CDCl3): d 1.55
(s, 6H, Me (tdt)), 1.70 (s, 6H), 2.36 (d, 12H, J = 11.4 Hz), 5.79–
5.80 (m, 4H), 6.80–7.00 (m, 6H). MS (LSIMS+): m/z (%) = 604
(28) [M]+, 485 (42) [M - Mes]+, 333 (44) [M - Mes - tdt]+.
Table 1 Summary of crystallographic data for complexes 3, 5, 12 and 13
3
5
12
13
Empirical formula
Formula weight
Temperature/K
Crystal system
Space group
C39H37Ni PS5
755.67
150(2)
Monoclinic
P21/n
10.329(3)
18.632 (4)
18.775(5)
90
93.717(3)
90
3605.6(16)
4
1.392
C36H46S10
799.33
173(2)
Triclinic
¯
P1
C44H38Ni3P2S6
997.17
100(2)
Monoclinic
P21/c
18.788(4)
11.471(3)
19.393(5)
90
93.476(6)
90
4171.7(17)
4
1.588
C30H30NiS4
577.49
173(2)
Monoclinic
P21/n
9.97(17)
11.228(3)
11.940(3)
90
94.46(3)
90
1332(23)
2
1.440
˚
a/A
12.147(2)
12.389(3)
15.000(3)
74.124(4)
75.996(4)
70.253(4)
2015.3(7)
2
1.317
0.572
0.16 ¥ 0.12 ¥ 0.05
1.43 to 28.3
0.0684
˚
b/A
˚
c/A
a/◦
b/◦
g /◦
3
˚
V/A
Z
Dc/Mg m-3
m/mm-1
0.900
1.750
1.060
Crystal size/mm
q range for data collection/◦
R(int)
0.15 ¥ 0.15 ¥ 0.1
1.54 to 25.04
0.1010
0.0398, 0.1008
0.387, -0.504
0.08 ¥ 0.05 ¥ 0.03
2.06 to 27.00
0.0856
0.0503, 0.0791
0.876, -0.600
0.26 ¥ 0.2 ¥ 0.12
4.01 to 25.03
0.0840
0.0266, 0.0687
0.258, -0.3
R1a, wR2b [I > 2s(I)]
0.0750, 0.2030
0.530, -0.567
-3
˚
Min., max. Dr/e A
ꢀ
ꢀ
ꢀ
ꢀ
2
1/2
a R1 = ꢀFo| - |Fc|/|Fo|. b wR2 = { [w(Fo - Fc2)]/ [w(Fo2)2]}
.
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1.8 Hz, H4), 6.10 (d, 2H, J = 7.8 Hz, H5), 6.81 (s, 2H, H6), 7.26–
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7.99 (m, 20H, PPh2Me). 31P{ H} NMR (-60 ◦C, CDCl3): dA
=
1
16.4, dB = 16.7, JAB = 7.2 Hz (isomer a); d 16.8 (s) (isomer b); d
16.5 (s) (isomer c). MS (LSIMS+): m/z (%) = 824 (45) [M]+, 626
(100) [M - PPh2Me]+. Cryoscopic molecular weight: 776.
Crystallographic studies
Crystals suitable for X-ray diffraction were obtained by slow dif-
fusion of diethyl ether or hexane into dichloromethane solutions.
A summary of the fundamental crystal and refinement data of
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Enraf Nonius Kappa CCD area detector in the case of 3, a
Bruker-Siemens Smart CCD diffractometer for 5 and 12, and in
a Stoe-Siemens four circle diffractometer for 13, using in all cases
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˚
monochromated Mo Ka radiation (l = 0.7107 A), scan type q–2q.
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software package, minimizing w(F0 - Fc )2. Weighted R factors
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R factors (R) are based on F.
2*
2
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In conclusion, we present here dithiolate transfer reactions be-
tween [SnMe2(S–S)] and [NiBrR¢(PR3)2] (S–S = dmit, bdt, tdt;
R¢ = Mes, Trip) in a 1 : 1 ratio. Instead of the reaction being solely
transfer of dithiolate to give the dinuclear [Ni2(m-S–S)R¢2(PR3)4]
derivatives (neither isolated nor detected), the transfer reaction
occurred along with the concatenation of S–C and S–S coupling
reactions, mediated by nickel and tin organometallic complexes,
affording a great variety of organic {S–SR¢}2 or {R¢S–SR¢} and
organometallic [NiR¢(S–SR¢)(PR3)2] compounds. The main point
of this work is that these Ni and Sn mediated organic reactions
can be used for the synthesis of thio or thiolate organic- and
organometallic materials not accessible by other methods.
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Acknowledgements
We thank the Ministerio de Ciencia y Tecnolog´ıa of Spain
for financial support (CTQ2005-08099-C03-01), the Centro de
Excelecencia BRUKER-I.C.M.A and Mike B. Hurtshouse for
supporting the X-ray facilities.
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