metal-organic compounds
Experimental
Diethyl dithioxamide was synthesized according to the method of
Hurd et al. (1961). The title complex was prepared according to the
following three-step procedure.
Step 1: cis-[Pt(Me2SO)(PN)Cl2] {1 mmol, prepared in situ by
mixing equimolar quantities of cis-[Pt(Me2SO)2Cl2] and PN}, in a
minimum amount of chloroform (about 10 ml), was reacted with a
stoichiometric amount of H2Et2N2C2S2. The solution turned red and
was allowed to stand at room temperature for 30 min. After this time,
petroleum ether (313±333 K, about 50 ml) was added to the con-
centrated solution. The {[(PN)ClPt(H2Et2N2C2S2)]+ÁCl } salt preci-
pitated immediately as a magenta powder, which was separated from
the colourless supernatant and air dried. Yields were higher than 90%.
Step 2: sodium bicarbonate (200 mg) was added to 1 mmol of the
salt prepared in step 1 dissolved in a minimum amount of chloroform
(about 20 ml). The magenta solution immediately turned orange;
after 30 min of stirring, the sodium bicarbonate was removed by
®ltration and the orange solution was concentrated to a small volume
(about 1 ml). [(PN)ClPt(HEt2N2C2S2)] precipitated as an orange
powder, and was collected and air dried. Yields were higher than 90%.
Step 3: [Pd(ꢀ3-C3H5)(ꢁ-Cl)]2 (1 mmol) was dissolved in a 70:30
(v/v) chloroform±methanol mixture (about 30 ml) and reacted with
half the molar equivalent of the [(PN)ClPt(HEt2N2S2C2)] complex.
The solution, which turned deep red, was allowed to stand for 2 h.
The solvent was removed and the crude products, redissolved in a
minimum amount of chloroform (about 10 ml), were placed on an
alumina column and equilibrated with light petroleum. The desired
product was collected as an orange eluate and concentrated to a small
volume (about 1 ml). On adding petroleum ether (313±333 K, about
30 ml), the title bimetallic complex, (IV), precipitated as an orange
powder. Yields were higher than 80%. The complex was then crys-
tallized from a chloroform solution to obtain samples suitable for
X-ray diffraction studies.
Figure 1
A perspective view of (IV), showing the atomic numbering scheme.
Displacement ellipsoids are drawn at the 30% probability level and H
atoms are shown as small spheres of arbitrary radii. Dashed lines and
atoms represent the alternative arrangement of the disordered allyl
ligand. The disordered solvent chloroform molecule has been omitted for
clarity.
respectively], as is usually observed in similar complexes, e.g.
in our previous work on the related complex [(ꢀ3-allyl)Pd-
(ꢁ-dibenzyl-DTO N,N0-Pd S,S0-Pt)Pt(PN)Cl] [PN is diphenyl-
(2-pyridyl)phosphine; Lanza et al., 2000].
The large size of the diphenyl(2-pyridyl)phosphine ligand
has no signi®cant in¯uence on the PtII geometry because it can
easily be accommodated in the coordination shell, avoiding
signi®cant steric hindrances. The fact that the deformation of
the regular arrangement is only slight in (IV) is evidenced by
the Pt bond angles being very close to the expected value of
90ꢀ and the four Pt bonds being of very similar length [to
1
Spectroscopic analysis: H NMR (300.13 MHz, CDCl3, ꢂ, p.p.m):
8.68 (m, 1H, py-H6), 8.47 (m, 1H, py-H3), 7.80±7.13, (22H, Ar-H and
py-H), 5.39 (m, 1H, allyl CH), 4.81 (dq, 2JHH = 13.8 Hz, 3JHH = 6.8 Hz,
Ê
within 0.077 (3) A]. However, there is a noticeable difference
Ê
[0.059 (3) A] between the two PtÐS distances, due to the
2
2H, N-CH2- cis to P, part AB of ABC3), 3.38 (dq, JHH = 13.8 Hz,
3JHH = 6.8 Hz, 2H, N-CH2- trans to P, part AB of ABC3), 1.15 (t,
3JHH = 6.8 Hz, 3H, N-CH2CH3 trans to P, part C3 of ABC3), 0.95 (t,
3JHH = 6.8 Hz, 3H, N-CH2CH3 cis to P, part C3 of ABC3), 5.42 (m, 1H,
different trans effects of the opposite ligands. This moiety is
almost exactly equivalent to the same fragment we have
previously reported in the related dibenzyl Pd±Pt complex and
in another analogous compound, [(ꢀ6-p-cymene)RuCl{ꢁ-
bis(2-hydroxypropyl)-DTO N,N0-Ru S,S0-Pt}Pt(PN)Cl] (Lanza
et al., 1996).
The PdII and PtII centres lie on the corresponding mean
plane of the four bonded atoms [respective deviations of
0.034 (1) and 0.038 (1) A], with a dihedral angle of 21.7 (2) .
The two coordination planes form angles of 6.2 (2) and
16.6 (1)ꢀ with the DTO bis-chelating bridge, and the metals
3
allyl central CH), 3.52 (m, JHH = 6.9 Hz, 1H, syn-allyl CH H), 3.50
(m, 3JHH = 6.9 Hz, 1H, syn-allyl CH H), 2.91 (m, 3JHH = 12.7 Hz, 1H,
3
anti-allyl CH H), 2.89 (m, JHH = 12.7 Hz, 1H, anti-allyl CH H);
13C{1H} NMR (75.47 MHz, CDCl3, ꢂ, p.p.m.): 190.8 (d, 3JCP = 11 Hz,
1C, CS trans to P), 190.3 (d, 3JCP = 2 Hz, 1C, CS cis to P), 154.6±124.3
(17C, Ar-C), 52.8 (1C, N-CH2), 52.1 (1C, N-CH2), 13.0 (1C, N-
CH2CH3), 12.7 (1C, N-CH2CH3), 115.5 (1C, allyl central CH), 58.0
(1C, allyl CH2), 57.9 (1C, allyl CH2); 31P{1H} NMR (121.49 MHz,
ꢀ
Ê
1
CDCl3, ꢂ, p.p.m.): 17.3 (PtÐP, JPtP = 3267 Hz). Analysis calculated
for C26H29ClN3PPdPtS2: C 38.33, H 3.59, N 5.16, S 7.83, Cl 4.30%;
found: C 38.61, H 3.71, N 5.25, S 8.05, Cl 4.52%.
Ê
deviate by 0.110 (1) and 0.430 (1) A, respectively, on the
same side. Therefore, (IV) is not perfectly planar. The Pt
moiety is bent by 16.8 (1)ꢀ at the SÁ Á ÁS bite, while the Pd
fragment lies almost on the dithioxamidate plane. This
difference is con®rmed by the puckering analysis (Cremer &
Pople, 1975) of the corresponding ®ve-membered chelate
rings, Pd/N1/C1/C2/N2 and Pt/S1/C1/C2/S2 [' = 53 (12) and
169 (2) , and Q = 0.040 (1) and 0.231 (4) A, respectively],
evidencing the signi®cantly ¯atter coordination of the Pd
centre, while both conformations are intermediate between
half-chair and envelope.
Crystal data
3
[PdPtCl(C3H5)(C6H10N2S2)-
(C17H14NP)]ÁCHCl3
Mr = 934.92
Monoclinic, P21=c
a = 13.423 (3) A
Dx = 1.861 Mg m
Mo Kꢄ radiation
Cell parameters from 50
re¯ections
ꢅ = 6.3±15.0ꢀ
ꢁ = 5.24 mm
T = 298 (2) K
Ê
Ê
ꢀ
1
Ê
b = 13.561 (3) A
Ê
c = 19.156 (4) A
ꢃ = 106.83 (3)ꢀ
Irregular, orange
0.33 Â 0.25 Â 0.15 mm
3
Ê
V = 3337 (1) A
Z = 4
ꢁ
Acta Cryst. (2002). C58, m316±m318
Giuseppe Bruno et al.
[PdPtCl(C3H5)(C6H10N2S2)(C17H14NP)]ÁCHCl3 m317