Synthesis and characterisation of cyanodithioimidocarbonate [C2N2S2]2- complexes

Article abstract of DOI:10.1039/b314949h

[PPh₄]₂[M(C₂N₂ S₂)₂] (M = Pt, Pd) and [Pt(C₂N₂S₂) (PR₃)₂] (PR₃ = PMe₂Ph, PPh₃) and [Pt(C₂N₂S₂)(PP)] (PP = dppe, dppm, dppf) were all obtained by the reaction of the appropriate metal halide containing complex with potassium cyanodithioimidocarbonate. The dimeric cyanodithioimidocarbonate complexes [{Pt(C₂N₂S₂) (PR₃)}₂] (PR₃ = PMe₂Ph), [M{(C₂N₂ S₂)(η⁵-C₅Me₅)}₂] (M = Rh, Ir) and [{Ru(C₂N₂S₂) (η⁶-p-MeC₆H₄¹Pr)}₂] have been synthesised from the appropriate transition metal dimer starting material. The cyanodithioimidocarbonate ligand is S,S and bidentate in the monomeric complexes with the terminal CN group being approximately coplanar with the CS₂ group and trigonal at nitrogen thus reducing the planar symmetry of the ligand. In the dimeric compound one of the sulfur atoms bridges two metal atoms with the core exhibiting a cubane-like geometry.

Full text of DOI:10.1039/b314949h

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Synthesis and characterisation of cyanodithioimidocarbonate
[C2N2S2]2؊ complexes
Colin J. Burchell, Stephen M. Aucott, Heather L. Milton, Alexandra M. Z. Slawin
and J. Derek Woollins*
School of Chemistry, University of St. Andrews, St. Andrews, Fife, UK KY16 9ST.
E-mail: jdw3@st-andrews.ac.uk
Received 19th November 2003, Accepted 15th December 2003
First published as an Advance Article on the web 12th January 2004
[PPh4]2[M(C2N2S2)2] (M = Pt, Pd) and [Pt(C2N2S2)(PR3)2] (PR3 = PMe2Ph, PPh3) and [Pt(C2N2S2)(PP)] (PP = dppe,
dppm, dppf ) were all obtained by the reaction of the appropriate metal halide containing complex with potassium
cyanodithioimidocarbonate. The dimeric cyanodithioimidocarbonate complexes [{Pt(C2N2S2)(PR3)}2] (PR3 =
i
PMe2Ph), [M{(C2N2S2)(η5-C5Me5)}2] (M = Rh, Ir)and [{Ru(C2N2S2)(η6-p-MeC6H4 Pr)}2] have been synthesised from
the appropriate transition metal dimer starting material. The cyanodithioimidocarbonate ligand is S,S and bidentate
in the monomeric complexes with the terminal CN group being approximately coplanar with the CS2 group and
trigonal at nitrogen thus reducing the planar symmetry of the ligand. In the dimeric compound one of the sulfur
atoms bridges two metal atoms with the core exhibiting a cubane-like geometry.
The coordination of S,S bidentate ligands is an important area.
Complexes with this type of ligand have varied industrial
applications including vulcanisation,1 lubricant additives1,2
and catalysis.1 Furthermore S,S donors can support unusual
magnetic properties1 and may be important in biological
systems.3 There are numerous studies on dithiocarbamate,1
dialkoxydithiophosphate4 and trithiocarbonate5 complexes.
As part of our program studying the properties of sulfur donor
systems6 we have investigated the cyanodithioimidocarbonate,
[C2N2S2]2Ϫ, dianion. The literature contains very few examples
of cyanodithioimidocarbonate complexes of which only
two have been crystallographically characterised [AsPh4]2-
[Ni(C2N2S2)]7 and [Au2(C2N2S2)2].8 The other reported com-
plexes containing the [C2N2S2]2Ϫ anion include organotin
compounds of the type [SnR2(C2N2S2)],9 a vanadium() com-
plex [V(η5-C5H5)2(C2N2S2)] studied by electron spin reson-
ance,10 an oxytechnetium (V) complex [TcO(C2N2S2)2],11 and a
series of salts of the type [X]2[M(S2N2C2)2] (X = (Ph)4As, (Ph)4P
or (nPr)4 N M = Ni, Pt, Pd, Zn or Tl).5d,12 The literature also
reports a series of bridged dinuclear ruthenium complexes for
Reaction of K2MCl4 (M = Pt, Pd) with two equivalents
of potassium cyanodithioimidocarbonate in methanol was
followed by the addition of two equivalents of tetraphenyl
phosphonium chloride. The solvent was removed under
reduced pressure and the residual solid dissolved in dichloro-
methane then filtered through celite (to remove solid KCl). The
solvent was evaporated to give the salts [PPh4]2[M(C2N2S2)2]
(M = Pt, Pd) in excellent yields (Scheme 1). Both the homoleptic
complexes [(PPh4)2Pt(C2N2S2)2] 2 and [(PPh4)2Pd(C2N2S2)2] 3
gave satisfactory microanalyses (Table 2) and were found to be
exceptionally soluble in dichloromethane hence it has been
possible to observe both of the quaternary carbons of the
cyanodithioimidocarbonate ligand in the 13C–{1H} NMR
spectra (Table 3). In the platinum complex 2 the resonance
observed at δ(C) 218.0 ppm has been assigned as S C᎐N and the
᎐
2
᎐
resonance at δ(C) 113.9 ppm as N–C᎐N based on comparisons
᎐
with the dipotassium salt where the S C᎐N resonance was
᎐
2
᎐
noted at δ(C) 228.3 ppm and the N–C᎐N resonance at δ(C)
᎐
122.1 ppm. Similarly in the palladium analogue 3 the two
resonances observed at δ(C) 219.2 and 115.1 ppm correspond to
example
[(η5-C5H5)(PPh3)Ru(C2N2S2)Ru)(PPh3)2[(η5-C5H5)]
S C᎐N and N–C᎐N, respectively. In the IR spectra of 2 and 3
᎐
᎐
᎐
2
Ϫ1
᎐
which bridge via the nitrile nitrogen atom of the cyanodithio-
imidocarbonate ligand as well as being S2 bound.13 Here we
report examples of mononuclear and binuclear complexes
of this ligand.
the nitrile (C᎐N) band is observed at approximately 2170 cm ,
᎐
᎐
the imido (C᎐N) band at approximately 1435 cmϪ1 – consider-
ably increased in frequency compared to the uncoordinated
anion indicating the change in delocalisation as a consequence
of coordination. The (M–S) bands are in the range 379–346
cmϪ1. The microanalyses for both species were within the
specified limits. The X-ray crystal structure of 3 has been
obtained (Table 4, Fig. 1). The X-ray analysis shows that the
palladium core lies at the centre of a distorted square planar
coordination sphere with unsymmetrical PdS2C rings. The
whole molecule lies in the plane of the coordination sphere with
Results and discussion
The synthesis of dipotassium cyanodithioimidocarbonate 1
was first reported in the literature by Hantzch and Wolvenkamp
in 190414 and subsequently by other groups.15 The original
synthesis of 1 involved the dropwise addition of potassium
hydroxide in ethanol to cyanamide and carbon disulfide in the
same solvent at 0 ЊC. Our synthesis is essentially the same (eqn.
1) except potassium ethoxide was used in place of potassium
hydroxide to prevent water generation during the reaction:
(1)
After suction filtration the product was isolated as a yellow
powder in good yield (65%). The 13C–{1H} NMR (in dmso-D6)
shows two resonances at δ(C) 228.3 and 122.1 ppm corre-
᎐
sponding to (S C᎐N) and (N–C᎐N), respectively. In the IR
᎐
᎐
2
Ϫ1
᎐
spectrum we observe a strong ν(C᎐N) band at 2146 cm , and a
᎐
strong band at 1315 cmϪ1 assigned as ν(C᎐N). Satisfactory
᎐
Scheme 1 Reaction scheme for preparation of [PPh4]2[M(C2N2S2)2]
{M = Pt (1), Pd (2)}.
microanalytical data were obtained.
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 4
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
369

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Table 1 Details of the X-ray data collections and refinements for compounds 3, 4, 8 and 10
Compound
3
4
8
10
Empirical formula
Crystal system
Space group
C52H40N4P2PdS4
Triclinic
P1
C18H22N2P2PtS2
Monoclinic
C2/c
C36H28FeN2P2PtS2
Triclinic
P1
C26H32Cl6N4Rh2S4
Monoclinic
P2/n
¯
¯
a/Å
b/Å
c/Å
α/Њ
10.861(2)
14.540(3)
15.163(3)
88.894(11)
88.705(10)
83.598(10)
2378.7(8)
2
33.846(10)
11.431(7)
11.030(7)
90
98.17(3)
90
9.3113(13)
9.5996(13)
18.070(2)
999.062(2)
95.808(2)
101.906(2)
1545.7(4)
2
19.181(4)
8.8430(19)
21.576(5)
90
102.771(3)
90
β/Њ
γ/Њ
U/Å3
4262(4)
8
3569.2(13)
4
Z
M
1017.46
0.673
587.53
6.934
865.60
5.259
947.32
1.633
µ/mmϪ1
Measured reflections
Independent reflections (Rint
Final R1, wR2 [I > 2σ(I )]
8060
5365 (0.0239)
0.0338, 0.0715
7744
3264 (0.0352)
0.0345, 0.0676
7914
4411 (0.0293)
0.0316, 0.0655
16908
5062 (0.1637)
0.0458, 0.0672
)
Table 2 Microanalytical data (calculated values in parentheses) and mass spectral data for complexes 2–8
Complex
C
H
N
m/z
2, [(PPh4)2Pt(C2N2S2)2]
3, [(PPh4)2Pd(C2N2S2)2]
4, [Pt(C2N2S2)(PMe2Ph)2]
5, [Pt(C2N2S2)(PPh3)2]
6, [Pt(C2N2S2)(dppe)]
7, [Pt(C2N2S2)(dppm)]
8, [Pt(C2N2S2)(dppf )]
56.82 (56.46)
60.83 (61.38)
36.58 (36.80)
54.25 (54.61)
47.19 (47.39)
46.69 (46.62)
49.75 (50.18)
4.03 (3.65)
4.05 (3.96)
3.59 (3.77)
3.21 (3.62)
3.44 (3.41)
2.97 (3.19)
3.03 (2.81)
4.71 (5.06)
5.31 (5.51)
4.54 (4.77)
3.27 (3.35)
3.74 (3.95)
3.94 (4.03)
3.07 (3.25)
—
169
587
836
710
696
867
Table 3 Selected 13C–{1H} NMR (67.9 MHz) and selected IR data for complexes 2–3a
δ(C) (ppm)
ν/cmϪ1
᎐
᎐
Complex
S2C᎐N
NC᎐N
C᎐N
C᎐N
᎐
M–S
᎐
᎐
᎐
2 [(PPh4)2Pt(C2N2S2)2]
3 [(PPh4)2Pd(C2N2S2)2]
218.0
219.2
113.9
115.1
2171(s)
2172(s)
1436(s)
1436(s)
379(w),360(w)
377(w),346(w)
a Measured in CD2Cl2 at 25 ЊC.
Table 4 Selected bond lengths and angles for compounds 3, 4, 8 and 10a
Compound
3
4
8
10
M(1)–P(1)
M(1)–P(2)
M(1)–S(1)
M(1)–S(2)
—
—
2.2677(18)
2.2670(19)
2.350(2)
2.3566(19)
—
2.2711(17)
2.2833(17)
2.3375(16)
2.3519(17)
—
—
—
2.3293(14) [2.3197(14)]
2.3111(13) [2.3167(13)]
—
2.4008(16) [2.3944(16)]
2.3635(16) [2.3654(16)]
2.4230(15) [2.4284(15)]
1.796(6) [1.786(5)
1.695(6) [1.716(6)]
1.299(7) [1.305(7)]
1.337(8) [1.327(7)]
1.149(8) [1.156(7)]
73.38(5) [73.46(5)]
82.43(5) [81.75(5)]
94.49(5) [94.81(5)]
—
125.7(5) [128.1(5)]
125.0(4) [123.2(4)]
86.9(2) [87.53(19)
90.5(2) [90.13(19)]
107.83(17) [108.99(18)]
—
M(1)–S(1A)
S(1)–C(1)
S(2)–C(1)
C(1)–N(1)
N(1)–C(2)
1.730(4) [1.715(5)]
1.729(5) [1.726(5)]
1.300(5) [1.310(5)]
1.328(7) [1.325(7)]
1.138(6) [1.147(7)]
75.17(5) [75.19(5)]
180.00(7) [180.00(5)]
180.00(5) [180.000(1)]
—
128.2(4) [128.1(4)
121.9(4) [121.4(4)]
87.16(17) [87.21(16)]
87.78(16) [87.11(16)]
—
1.734(7)
1.733(7)
1.300(8)
1.312(11)
1.176(11)
74.62(7)
—
1.747(6)
1.729(6)
1.302(8)
1.320(9)
1.173(9)
74.68(6)
—
C(2)–N(2)
S(1)–M(1)–S(2)
S(1)–M(1)–S(1A)
S(2)–M(1)–S(1A)
P(1)–M(1)–P(2)
S(1)–C(1)–N(1)
S(2)–C(1)–N(1)
M(1)–S(1)–C(1)
M(1)–S(2)–C(1)
M(1A)–S(1)–C(1)
P(1)–M(1)–S(1)
P(2)–M(1)–S(2)
C(1)–N(1)–C(2)
N(1)–C(2)–N(2)
—
—
94.83(7)
127.5(6)
121.7(6)
87.4(2)
87.2(2)
—
94.49(7)
95.96(8)
117.6(7)
173.8(8)
101.04(6)
127.3(5)
122.9(5)
87.7(2)
87.7(2)
—
92.68(6)
91.63(6)
117.6(6)
172.4(8)
—
—
—
120.0(4) [117.2(4)]
172.3(6) [173.3(6)]
119.2(5) [118.8(5)]
174.0(7) [(171.9(7)]
a Square brackets indicate the equivalent value for the second independent molecule.
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
370

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Table 5 31P{1H} NMR (109.4 MHz) and selected IR data for complexes 4–8
Ϫ1
1J(195Pt–31P)/Hz
ν(C᎐N)/cm
ν(C᎐N)/cmϪ1
ν(Pt–S)/cmϪ1
᎐
Complex
δ(P) (ppm)
᎐
᎐
4, [Pt(C2N2S2)(PMe2Ph)2]
5, [Pt(C2N2S2)(PPh3)2]
6, [Pt(C2N2S2)(dppe)]
7, [Pt(C2N2S2)(dppm)]
8, [Pt(C2N2S2)(dppf )]
Ϫ19.0
17.0
42.2
Ϫ53.8
16.0
3071a
3179b
3094a
2634a
3312c
2181
2177
2179
2177
2176
1478
1479
1479
1477
1478
396, 374
397
396, 370
393
399, 350
a Measured in CDCl3 at 25 ЊC. b Measured in CD2Cl2 at 25 ЊC. c Measured in dmso-D6 at 90 ЊC.
Fig. 1 Crystal structure of the dianion in 3.
the largest deviation from planarity being S(1) which lies 0.13
[0.06] Å above the plane. The S(1)–Pd(1)–S(2) angle is 75.17(5)
[75.19(5)Њ in the second independent molecule] showing con-
siderable deviation from idealized 90Њ square planar geometry.
Within the PdS2C ring the Pd–S–C angles are in the range
87.11(16)–87.78(6)Њ and the S(1)–C(1)–S(2) angle is 109.8(3)
[110.5(3)]Њ. The S(1)–S(2) nonbonded distance is 2.83 Å which
is ca. 80% of the van der Waals radii of sulfur and implies that
there is a significant interaction between the two sulfur atoms.
As expected the C᎐N bond length C(1)–N(1) is longer than the
᎐
᎐
C᎐N bond length C(2)–N(2). The nitrile functionality is bent
᎐
with a C(1)–N(1)–C(2) angle of 120.0(4) [117.2(4)]Њ.
The heteroleptic complexes [Pt(C2N2S2)(PR3)2] (PR3
=
Fig. 2 Crystal structure of 4.
PMe2Ph, PPh3) and [Pt(C2N2S2)(PP)] (PP = dppe, dppm, dppf )
were all obtained by the reaction of the appropriate [PtCl2-
(PR3)2] or [PtCl2(PP)] complex with one equivalent of
potassium cyanodithioimidocarbonate in tetrahydrofuran. The
solvent was evaporated under reduced pressure and dichloro-
methane added. The mixture was filtered through a Celite
pad to remove precipitated KCl and the filtrate evaporated to
dryness to give the product (eqn. 2).
(2)
All of the compounds gave satisfactory microanalysis and all
showed the anticipated Mϩ in their mass spectra (Table 2). The
᎐
ν(C᎐N) vibrations were observed in the range 2176 to 2181
᎐
cmϪ1 and the ν(C᎐N) vibrations can be seen in the region of
᎐
1476 to 1479 cmϪ1 (Table 5). The ν(Pt–S) all lie within the range
350 to 399 cmϪ1 (Table 5) which is in accord with the values
observed for ν(Pt–S) in trithiocarbonate complexes.5 The plat-
inum(bis-phosphine) cyanodithioimidocarbonate complexes 4
to 7 (Table 5) all showed sharp singlets with platinum satellites
in their 31P{1H} NMR spectra and have similar δ values to
the analogous platinum(bis-phosphino) trithiocarbonate com-
Fig. 3 Crystal structure of 8.
1
plexes.5 The J(195Pt–31P) coupling constants lie in the range
2634–3312 Hz. The 31P{1H} NMR spectra of [Pt(C2N2S2)-
(dppf )], 8, displays fluxional behaviour. It displays two broad
peaks at δ(P) 15.7 and 16.1 ppm with 1J(195Pt–31P) couplings of
3287 and 3331 Hz, respectively, when the 31P{1H} at 30 ЊC.
Upon heating, these two peaks coalesce and finally give one
two conformations. 4 (Table 4, Fig. 2) and 8 (Table 4, Fig. 3)
have been studied by single crystal X-ray diffraction. In both
examples the platinum lies at the centre of a distorted square
planar coordination sphere. The S(1)–Pt(1)–S(2) bite angles in 4
and 8 are 74.62(7) and 74.68(6)Њ, respectively. As expected the
Pt–S bond lengths in 4 and 8 are longer than the corresponding
Pd–S bonds in 3. In the PtS2C ring for 4 the Pt–S–C angles
are 87.2(2) and 87.4(2)Њ. The S(1)–C(1)–S(2) angle is 74.62(7)Њ.
In compound 8 both Pt–S–C angles are identical with a value
of 87.7(2)Њ and the S(1)–C(1)–S(2) angle is 74.68(6)Њ. The non-
bonded sulfur–sulfur distance is 2.85 and 2.84 Å for 4 and 8,
1
distinct peak at δ(P) 16.0 ppm with a J(195Pt–31P) coupling of
3312 Hz at 90 ЊC. We interpret this by postulating that at 30 ЊC
᎐
the nitrile group (C᎐N) is bent away to one side so that it has a
᎐
cis relationship to one phosphine and trans relationship to the
other resulting in two peaks in the 31P{1H} NMR spectrum.
᎐
Upon heating the nitrile group (C᎐N) is able to flip between the
᎐
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
371

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respectively, which both correspond to ca. 80% of the van der
Waals radii of sulfur which implies that in both cases there
is a significant interaction between the two sulfur atoms. As
observed in compound 2 the cyanide group is bent at an angle
of approximately 118Њ in both 4 and 8. In 4 the cyanodithio-
imidocarbonate ligand lies within the coordination plane with
the exception of the nitrile functionality, which is hinged at an
angle of 9Њ above the plane. Similarly in 8 the nitrile function-
ality is hinged at an angle of 2Њ above the plane.
The literature contains numerous reports where tin reagents
have been used as sources of both sulfur–nitrogen fragments
or as dithiooxalate transfer reagents. Examples include [{(n-
Bu)2Sn(S2N2)}2] and [(Me)2Sn(dto)] (dto = dithiooxalate) used
as a metathesis reagents in the preparation of organometallic
iridium sulfur nitrogen complexes16 and platinum and
ruthenium complexes17 containing the dto ligand, respectively.
Complexes 4, 5 and 6 have also been prepared using [Sn(C2-
N2S2)(n-Bu)2] as a cyanodithioimidocarbonate transfer reagent.
[Sn(C2N2S2)(Bu)2] which has been previously reported in the
literature by Seltzer9 was resynthesised by the slow dropwise
addition of a tetrahydrofuran solution of [SnCl2(Bu)2] to di-
potassium cyanodithioimidocarbonate in distilled water. One
equivalent of [Sn(C2N2S2)(Bu)2] was added to a dichloro-
methane solution of [PtCl2(PP)] (PP = (PMe2Ph)2, (PPh3)2,
dppe). The solution was stirred overnight and the solvent
removed under reduced pressure. The remaining solid was
redissolved in the minimum dichloromethane and the product
precipitated by the addition of diethyl ether. The product was
isolated and dried in vacuo. The complexes 4, 5 and 6 prepared
in this manner (Scheme 2) gave identical analytical data to those
prepared by the reaction of the platinum(bis-phosphino)
dichloride with dipotassium cyanodithioimidocarbonate.
Fig. 4 Crystal structure of 10.
3420 Hz. Compound 10 has also been studied by X-ray crystal-
lography (Fig. 4). The X-ray crystal structure clearly shows
that both cyanodithioimidocarbonate ligands bridge the two
rhodium atoms. In each cyanodithioimidocarbonate ligand one
of the sulfur atoms S(1) bridges the two metal centres Rh(1)
and Rh(1A) while the other sulfur S(2) is solely bound to one
of the rhodium atoms Rh(1). Both of the cyanodithioimido-
carbonate ligands are planar with the nitrile functionality bent
away at angle of 119.2(5) [118.8(5)]Њ. The Rh(1)–S(1) bond
length is 2.4008(16) [2.3944(16)] Å and the Rh(1)–S(2) distance
is 2.3635(16) [2.3654(16)] Å. The Rh(1)–S(1A) distance is
2.4230(15) [2.4284(15)] Å. The central core of the molecule
can be described as a distorted cubane type structure. This
distortion from idealized 90Њ geometry can be seen in the S(1)–
C(1)–S(2) angle of 109.2(3) [108.7(3)]Њ. The S(1)–Rh(1)–S(2)
angle of 73.38(5) [73.46(5)]Њ, the S(1)–Rh(1)–S(1A) angle
of 82.43(5) [81.75(5)]Њ and the S(2)–Rh(1)–S(1A) 94.49(5)
[94.81(5)]Њ.
Scheme
2
Reaction scheme for alternate preparation of
[Pt(C2N2S2)(PR3)2] complexes using [Sn(C2N2S2)(Bu)2] as a metathesis
reagent.
Experimental
The dimeric cyanodithioimidocarbonate complexes [{Pt(C2-
N2S2)(PR3)}2] {PR3 = PMe2Ph (9)}, [M{(C2N2S2)(η5-C5Me5)}2]
General
i
{M = Rh (10), Ir (11)} and [{Ru(C2N2S2)(η6-p-MeC6H4 Pr)}2]
Unless otherwise stated, operations were carried out under an
oxygen-free nitrogen atmosphere using predried solvents and
standard Schlenk techniques. All solvents and reagents were
purchased from Aldrich, Alfa Aesar, BDH, Fisons and Strem
and used as received. We are grateful to Johnson Matthey PLC
for the loan of precious metal salts. Diethyl ether and thf (tetra-
hydrofuran) were purified by reflux over sodium-benzophenone
and distillation under nitrogen. Hexane was purified by reflux
over sodium and distillation under an atmosphere of nitrogen.
Dichloromethane was heated to reflux over powdered calcium
hydride and distilled under nitrogen. Chloroform (99 atom%
D), CD2Cl2 (99.6ϩ atom% D) methanol-D4 (99.8 atom% D)
and dmso-D6 (99.5ϩ atom% D) were used as received. The
metal complexes [{PtCl(µ-Cl)(PMe2Ph)}2],18 [{RhCl(µ-Cl)(η5-
C5Me5)}2],19 [{IrCl(µ-Cl)(η5-C5Me5)}2]19 and [{RuCl(µ-Cl)-
(12) have been synthesised and isolated in a similar fashion
to the platinum(bis-phosphine) cyanodithioimidocarbonate
complexes 4–8 by reacting two equivalents of 1 with the
appropriate transition metal dimer starting material (eqn. 3).
(3)
i
(η6-p-MeC6H4 Pr)}2],20 were prepared according to literature
9–12 all gave satisfactory microanalysis and all showed the
procedures. The complexes [PtCl2(PMe2Ph)2], [PtCl2(PPh3)2],
[PtCl2(dppe)] (dppe = bis(diphenylphosphino)ethane), [PtCl2-
anticipated Mϩ in their mass spectra (Table 6). The ν(C᎐N)
᎐
᎐
vibrations were noted in the range 2177 to 2188 cmϪ1 and the
(dppm)] (dppm
=
bis(diphenylphosphino)methane) and
ν(C᎐N) vibrations can be seen in the region of 1424 to 1499
[PtCl2(dppf )] (dppf = bis(diphenylphosphino)ferrocene) were
prepared by the addition of stoichiometric quantities of the
appropriate free phosphine or diphosphine to a dcm solution
of [PtCl2(cod)] (cod = cycloocta-1,5-diene).
᎐
cmϪ1 (Table 6). The bands for ν(M–S) were all observed in the
range 326 to 396 cmϪ1. Compound 9 showed a singlet in its
1
31P{1H} NMR spectra with J(195Pt–31P) coupling constant of
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
372

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Table 6 Microanalytical data (calculated values in parentheses), mass spectral data and selected IR data for complexes 9–12
ν(C᎐N)/cmϪ1
ν(M–S)/cmϪ1
Ϫ1
᎐
Complex
C
H
N
m/z
ν(C᎐N/cm
᎐
᎐
9, [{Pt(C2N2S2)(PMe2Ph)}2]
10, [{Rh(C2N2S2)(η5-C5Me5)}2]
11, [{Ir(C2N2S2)(η5-C5Me5)}2]
26.24 (26.73)
40.21 (38.98)
32.93 (32.49)
40.71 (41.01)
2.22 (2.47)
4.01 (4.08)
3.24 (3.41)
3.76 (4.02)
5.83 (6.23)
7.22 (7.57)
6.16 (6.31)
7.69 (7.97)
—
2188
2177
2179
2181
1433
1485
1499
1473
384, 326
378, 352
367, 349
391, 384
709
889
704
12, [{Ru(C2N2S2)(η6-p-MeC6H4 Pr)}2]
i
Infrared spectra were recorded (IR spectra as KBr discs
unless otherwise stated) on a Perkin-Elmer System 2000 FT/IR/
Raman spectrometer. 31P, 13C and 1H NMR spectra were
recorded using a JEOL DELTA GSX 270 FT NMR spectro-
meter. Microanalysis was performed by the University of
St. Andrews service. Fast atom bombardment (FAB) and
electron ionisation (EI) mass spectra were performed by the
Swansea Mass Spectrometer service.
(30 cm3). The filtrate was evaporated to dryness in vacuo to give
a white powder. The product was recrystallised by vapour
diffusion from chloroform/hexane. Yield 0.068 g (63%). 1H
NMR (CDCl3): δ 7.50–7.30 (m, 10 H, aromatic) and 1.60 (d, 12
H, 3J(195Pt–1H) 28 Hz, 2J(31P–1H) 10 Hz, PMe).
Method b. [PtCl2(PMe2Ph)2] (0.070 g, 0.129 mmoles) was
dissolved in dcm (20 cm3) and [Sn(C2N2S2)(Bu)2], 13, (0.045 g,
0.129 mmoles) was added as a solid in one portion. The result-
ing colourless solution was stirred for 24 h. The solvent was
evaporated in vacuo and the remaining solid was dissolved in
the minimum volume of dcm (5 cm3) and the product was
precipitated with diethyl ether (30 cm3) to give a white powder.
Yield 0.064 g (84%). The analytic and spectroscopic data for
[Pt(C2N2S2)(Me2PPh)2], 4, synthesised by method b were identi-
cal to those found in material produced by method a.
[K2C2N2S2], 1. Carbon disulfide (15.876 g, 0.2085 mol) was
added to a stirred solution of cyanamide (8.765 g, 0.2085 mol)
in absolute ethanol (20 cm3). The temperature of the solution
was maintained below 0 ЊC while a solution of potassium
ethoxide, (35.131 g, 0.417 mol) in absolute ethanol (160 cm3),
was added over a period of 30 min. The resulting mixture
was stirred for a further hour. The resulting precipitate was
collected by filtration and dried in vacuo to give the product as
a yellow powder. Yield 26.40 g (65%). Found (Calc. for
[Pt(C2N2S2)(PPh3)2], 5. Method a. This was prepared in the
same way as platinum complex 4 via method a using [PtCl2-
(PPh3)2] (0.100 g, 0.127 mmoles and potassium cyanodithio-
imidocarbonate (0.040 g, 0.206 mmoles) to give a white powder.
Yield 0.088 g (83%). 1H NMR (CD2Cl2): δ 7.43–7.21 (m, 30 H,
aromatic).
C2N2S2K2): C 12.48 (12.36), N 14.60 (14.41)%. 13C–{1H} NMR
᎐
(dmso-D ): δ(C) 228.3 (S C᎐N), 122.1 (N–C᎐N). Selected IR
᎐
2
᎐
6
᎐
data (KBr): 2146s ν(C᎐N), 1315br,s ν(C᎐N).
᎐
᎐
Method b. This was prepared in the same way as platinum
complex 4 via method b using [PtCl2(PPh3)2] (0.060 g, 0.076
mmoles) and [Sn(C2N2S2)(Bu)2], 13, (0.026 g, 0.076 mmoles) to
give a white powder. Yield 0.028 g (44%). The analytic and
spectroscopic data for [Pt(C2N2S2)(PPh3)2],5, synthesised by
method b were identical to those found in material produced by
method a.
[(PPh4)2Pt(C2N2S2)2], 2. K2PtCl4 (0.200 g, 0.482 mmol) was
dissolved in methanol (20 cm3) and potassium cyanodithioimi-
docarbonate (0.187 g, 0.964 mmol) was added as a solid in one
portion and the mixture was stirred for 2 days. The mixture was
filtered to remove a small amount of solid material and washed
through with a further portion of methanol (20 cm3). Tetra-
phenylphosphonium chloride (0.361 g, 0.964 mmol) was added
to the stirred solution and the mixture was stirred for a further
hour. The solvent was evaporated in vacuo and the remaining
solid was extracted with dcm (20 cm3). The mixture was filtered
through a celite pad to remove precipitated KCl and washed
through with more dcm (30 cm3). The filtrate was evaporated to
dryness in vacuo to give a yellow powder. The product was
recrystallised by vapour diffusion from dcm/ether. Yield 0.426 g
[Pt(C2N2S2)(dppe)], 6. Method a. This was prepared in the
same way as platinum complex 4 via method a using [PtCl2-
(dppe)] (0.100 g, 0.151 mmol) and potassium cyanodithio-
imidocarbonate (0.040 g, 0.206 mmol) to give a white powder.
Yield 0.046 g (43.9%). 1H NMR (CDCl3): δ 7.72–7.47 (m, 20 H,
aromatic), 2.58–2.37 (m, 4H, PCH2CH2P).
Method b. This was prepared in the same way as platinum
complex 4 via method b using [PtCl2(dppe)] (0.100 g, 0.151
mmoles) and [Sn(C2N2S2)(Bu)2], 13, (0.053 g, 0.151 mmoles) to
give a white powder. Yield 0.092 g (86%). The analytic and
spectroscopic data for [Pt(C2N2S2)(dppe)], 6, synthesised by
method b were identical to those found in material produced by
method a.
(80%). 13C–{1H} NMR (CD Cl ): δ(C) 218.0 (S C᎐N), 135.7 (d,
᎐
2
2
2
4J(31P–13C) 3 Hz, p-phenyl), 134.6 (d, 2J(31P–13C) 9 Hz,
o-phenyl), 130.7 (d, J(31P–13C) 13 Hz, m-phenyl), 117.7 (d,
J( P– C) 89 Hz, i-phenyl), 113.9 ppm (N–C᎐N). H NMR
3
1
31
13
1
᎐
᎐
(CD2Cl2): δ 7.94–7.60 (m, 40 H, aromatic).
[(PPh4)2Pd(C2N2S2)2], 3. This was prepared in the same way
as platinum complex 2 using K2PdCl4 (0.200 g, 0.613 mmol),
potassium cyanodithioimidocarbonate (0.238 g, 1.225 mmol)
and tetraphenylphosphonium chloride (0.459 g, 1.225 mmol) to
give a yellow/brown powder. Yield 0.567 g (91%). 13C–{1H}
[Pt(C2N2S2)(dppm)], 7. This was prepared in the same way as
platinum complex 4 via method a using [PtCl2(dppm)] (0.100 g,
0.154 mmoles) and potassium cyanodithioimidocarbonate
(0.040 g, 0.206 mmoles) to give a white powder. Yield 0.093 g
(87%). 1H NMR (CDCl3): δ 7.74–7.43 (m, 20 H, aromatic), 4.70
(t, 2H, 2J(31P–1H) 21.5 Hz, PCH2P).
NMR (CD Cl ): δ(C) 219.2 (S C᎐N), 135.7 (d, 4J(31P–13C) 3 Hz,
᎐
2
2
2
p-phenyl), 134.6 (d, 2J(31P–13C) 10 Hz, o-phenyl), 130.7 (d,
3J(31P–13C) 13 Hz, m-phenyl), 117.7 (d, 1J(31P–13C) 89 Hz,
1
᎐
i-phenyl), 115.1 ppm (N–C᎐N). H NMR (CD Cl ): δ 7.93–7.60
᎐
2
2
(m, 40 H, aromatic).
[Pt(C2N2S2)(dppf )], 8. This was prepared in the same way as
platinum complex 4 via method a using [PtCl2(dppf )] (0.100 g,
0.122 mmol) and potassium cyanodithioimidocarbonate (0.030
g, 0.154 mmol) to give a yellow powder. Yield 0.043 g (41%). 1H
NMR (dmso-D6, 30 ЊC): δ 7.66–7.53 (m, 20 H, aromatic), 4.61
(br, m, 4H, α-CH (C5H4)), 4.43 (br, m, 4H, β-CH (C5H4)).
[Pt(C2N2S2)(PMe2Ph)2], 4. Method a. [PtCl2(PMe2Ph)2]
(0.100 g, 0.184 mmoles) was dissolved in thf (20 cm3) and
potassium cyanodithioimidocarbonate (0.050 g, 0.257 mmoles)
was added as a solid in one portion. The resulting colourless
solution was stirred for 24 h. The solvent was evaporated in
vacuo and the remaining solid was extracted with dcm (20 cm3).
The mixture was filtered through a celite pad to remove
precipitated KCl and washed through with additional dcm
[{Pt(C2N2S2)(PMe2Ph)}2], 9. This was prepared in the same
way as platinum complex 4 via method a using [{PtCl(µ-Cl)-
(PMe2Ph)}2] (0.100 g, 0.124 mmoles) and potassium cyano-
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
373

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dithioimidocarbonate (0.048 g, 0.247 mmoles) to give a yellow
CCDC reference numbers 224724–224727. See http://
www.rsc.org/suppdata/dt/b3/b314949h/ for crystallographic
data in CIF or other electronic format.
powder. Yield 0.083 g (75%). 31P–{1H} NMR (CD2Cl2): δ(P)
1
1
Ϫ17.9 ppm. J(195Pt–31P) 3420 Hz. H NMR (CDCl3): δ 7.50–
7.30 (m, 10 H, aromatic) and 1.60 (d, 12 H, 3J(195Pt–1H) 28 Hz,
2J(31P–1H) 10 Hz, PMe).
References
1 (a) A. M. Bond and R. L. Martin, Coord. Chem. Rev., 1984, 54, 23;
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of Sulfur Compounds, ed. S. Mitchell, Taylor and Francis, London,
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[{Rh(C2N2S2)(ꢀ5-C5Me5)}2], 10. This was prepared in the
same way as platinum complex 4 via method a using [{RhCl-
(µ-Cl)(η5-C5Me5)}2] (0.100 g, 0.162 mmoles) and potassium
cyanodithioimidocarbonate (0.063 g, 0.324 mmoles) to give a
red powder. Yield 0.056 g (49%). 1H NMR (CDCl3): δ 1.83–1.69
(m, 30H, η5-C5Me5).
[{Ir(C2N2S2)(ꢀ5-C5Me5)}2], 11. This was prepared in the same
way as platinum complex 4 via method a using [{IrCl(µ-Cl)-
(η5-C5Me5)}2] (0.100 g, 0.126 mmoles) and potassium cyano-
dithioimidocarbonate (0.049 g, 0.251 mmoles) to give an
orange powder. Yield 0.071 g (64%). 1H NMR (CDCl3): δ 1.92–
1.63 (m, 30H, η5-C5Me5).
4 (a) I. P. Gray, H. L. Milton, A. M. Z. Slawin and J. D. Woollins,
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and U. W. Suter, Inorg. Chim. Acta, 2000, 299, 199; (c) S. Menzer,
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D. B. Sowerby and S. F. Lu, Polyhedron, 1995, 14, 3389.
5 (a) S. M. Aucott, A. M. Z. Slawin and J. D. Woollins, Polyhedron,
2000, 19, 499–502; (b) A. Muller, P. Christopliemk, I. Tossidis
and C. K. Jorgensen, Z. anorg. allg. Chem., 1973, 401, 274; (c) J. M.
Burke and J. P. Fackler, Jr., Inorg. Chem., 1972, 11, 2744; (d ) J. P.
Fackler, Jr. and D. Coucouvanis, J. Am. Chem. Soc., 1966, 88, 3913.
6 (a) M. C. Aragoni, M. Arca, C. Denotti, F. A. Devillanova,
E. Grigiotti, F. Isaia, F. Laschi, V. Lippolis, L. Pala, A. M. Z. Slawin,
P. Zanello and J. D. Woollins, Eur J. Inorg. Chem., 2003, 1291;
(b) S. M. Aucott, P. Bhattacharyya, H. L. Milton, A. M. Z. Slawin
and J. D. Woollins, New J. Chem., 2003, 27, 1466; (c) M. J. Manos,
J. D. Woollins, A. D. Keramidas, A. M. Z. Slawin and
T. A. Kabanos, Angew. Chem., Int. Ed., 2002, 41, 2801;
(d ) P. Bhattacharyya, J. Novosad, J. Phillips, A. M. Z. Slawin,
D. J. Williams and J. D. Woollins, J. Chem. Soc., Dalton Trans., 1995,
1607; (e) V. C. Ginn, P. F. Kelly, A. M. Z. Slawin, C. Papadimitriou,
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Dalton Trans., 1992, 2129.
i
[{Ru(C2N2S2)(ꢀ6-p-MeC6H4 Pr)}2], 12. This was prepared in
the same way as platinum complex 4 via method a using
i
[{RuCl(µ-Cl)(η6-p-MeC6H4 Pr)}2] (0.100 g, 0.163 mmoles) and
potassium cyanodithioimidocarbonate (0.063 g, 0.327 mmoles)
1
to give a dark orange powder. Yield 0.080 g (75%). H NMR
3
(CDCl3): δ 5.49 and 5.35 (AB system, J(1H–1H) 5.5 Hz, 4H,
aromatic) 2.61 (m, 1H, CHMe2) 2.06 (s, 3H, CH3) and 1.15 (d,
(CH3)2CH, 6H).
[Sn(C2N2S2)(Bu)2], 13. To a stirred solution of dipotassium
cyanodithioimidocarbonate (3.127 g, 0.0103 moles) in distilled
water (10 cm3), [SnCl2(nBu)2] (2.00 g, 0.0103 moles) in thf
(10 cm3), was added dropwise over half an hour. The reaction
mixture was stirred for a further 2.5 h and then poured
onto crushed ice. The resulting white solid was filtered and
washed with distilled water (20 cm3) and dried in vacuo to give
a white powder. Yield 3.56 g (99%). The product was
then recrystallised from methanol. Found (Calc. for
C10H18N2S2Sn): C 34.78 (34.40), H 5.49 (5.20), N 7.81 (8.02)%.
1H NMR (CD3OD): δ 1.81–1.70 (m, 4H, α-CH2) 1.56–1.44
7 F. A. Cotton and C. B. Harris, Inorg. Chem., 1968, 7, 2140.
8 Z. Assefa, R. J. Staples and J. P. Fackler, Jr., Acta Crystallogr., Sect.
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10 A. T. Casey and J. B. Raynor, J. Chem. Soc., Dalton Trans., 1983,
2057.
(m, 8H, βCH2 and γCH2) and 1.02–0.97 (t, 6H, δ-CH3).
᎐
Selected IR data (KBr): 2190s ν(C᎐N), 1368br,s ν(C᎐N), 382w
᎐
᎐
cmϪ1 ν(Sn–S).
11 H. Spies and B. Johannsen, Inorg. Chim. Acta, 1981, 48, 255.
12 F. A. Cotton and J. A. McCleverty, Inorg. Chem., 1967, 6, 229.
13 R. S. Prasad and U. C. Agarwala, Polyhedron, 1992, 11, 1117.
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331, 265.
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(b) H. Hlawatschek, M. Drager and G. Gattow, Z. Anorg. Allg.
Chem., 1982, 491, 145.
X-Ray crystallography
Tables 1 and 4 list details of data collections and refinements.
For 3 and 4 data were collected at room temperature using
Mo–Kα radiation with a Rigaku Mercury system, and for 8 and
10 at 125 K using a Bruker SMART system. Several crystals of
10 were examined, solvation appears to be causing problems
with the crystal quality; the reported data are from the best data
set we were able to obtain. Intensities were corrected for
Lorentz-polarisation and for absorption. The structures
were solved by the heavy atom method or by direct methods.
The positions of the hydrogen atoms were idealised. Refine-
ments were by full-matrix least squares based on F 2 using
SHELXTL.21
16 S. M. Aucott, A. M. Z. Slawin and J. D. Woollins, Can. J. Chem.,
2002, 80, 1481.
17 C. J. Adams, J. Chem. Soc., Dalton Trans., 2002, 1545.
18 W. Baratta and P. S. Pregosin, Inorg. Chim. Acta, 1993, 209, 85.
19 C. White, A. Yates and P. M. Maitlis, Inorg. Synth., 1992, 29, 228.
20 M. A. Bennett, T. N. Huang, T. W. Matheson and A. R. Smith,
Inorg. Synth., 1982, 21, 74.
21 SHELXTL, Bruker AXS, Madison, WI, 1999.
D a l t o n T r a n s . , 2 0 0 4 , 3 6 9 – 3 7 4
374