Oxidative addition reactions of nicotinamide based organoselenium compounds on [M(PPh3)4] (M = Pd or Pt): An insight study for the formation of several isolable products

Article abstract of DOI:10.1016/j.jorganchem.2012.09.012

Oxidative addition reactions of [2-NC₅H₃(3-COR)Se] ₂ (R = NH₂, NHPh, or NHpym (pym = pyrimidine)) with [M(PPh₃)₄] (M = Pd, Pt) in benzene afforded complexes of the type, [M{η²-SeC₅H₃(3-COR)N}{SeC ₅H₃(3-COR)N}(PPh₃)] (1) (M = Pt, Pd; R = NH₂, NHPh, or NHpym). A similar reaction with [2-NC₅H ₃(3-COOH)Se]₂ gave an insoluble product which after extraction with dichloromethane gave [M(Cl){SeC₅H₃(3-COOH) N}(PPh₃)₂] (2). Compound 2, in methanolic solution is transformed into a dimeric ionic complex, but on prolonged standing in CH ₂Cl₂ or CHCl₃ is converted into [M(Cl){η²-SeC₅H₃(3-COOH)N}(PPh ₃)]. Treatment of [M(PPh₃)₄] with [2-NC ₅H₃(3-CONHPh)SeI] initially yielded the expected oxidative addition product [M(I){SeC₅H₃(3-CONHPh)N}(PPh ₃)₂] (4) which loses a molecule of PPh₃ to give [M(I){η²-SeC₅H₃(3-CONHPh)N}(PPh ₃)] (5). Both 4 and 5 on prolonged standing in dichloromethane gave several products such as [M(I)(Ph)(PPh₃)₂] (6), [2-NC ₅H₃(3-CO)SeNH] (9). All the complexes were characterized by elemental analyses and NMR spectroscopy. The molecular structures of [Pt{η²-SeC₅H₃(3-CONH₂)N} {SeC₅H₃(3-CONH₂)N}(PPh₃)] (1a), [Pd{η²-SeC₅H₃(3-CONHPh)N}{SeC ₅H₃(3-CONHPh)N}(PPh₃)] (1d), [Pt(I)(Ph)(PPh₃)₂] (6) and [Pt(Cl_0.5I _0.5){C₅H₃(3-CONHPh)N}(PPh₃) ₂]·HCl (7) were established by single crystal X-ray diffraction analyses.

Full text of DOI:10.1016/j.jorganchem.2012.09.012

Journal of Organometallic Chemistry 723 (2013) 163e170
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Oxidative addition reactions of nicotinamide based organoselenium compounds
on [M(PPh3)4] (M ¼ Pd or Pt): An insight study for the formation of several
isolable products
Rohit Singh Chauhan a, C. Parashiva Prabhu a, Prasad P. Phadnis a, G. Kedarnath a, James A. Golen b,
,
Arnold L. Rheingold b, Vimal K. Jain a
*
a Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
b Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0358, United States
a r t i c l e i n f o
a b s t r a c t
Article history:
Oxidative addition reactions of [2-NC5H3(3-COR)Se]2 (R ¼ NH2, NHPh, or NHpym (pym ¼ pyrimidine))
with [M(PPh3)4] (M ¼ Pd, Pt) in benzene afforded complexes of the type, [M{
h
2-SeC5H3(3-COR)N}
Received 9 July 2012
Received in revised form
10 September 2012
{SeC5H3(3-COR)N}(PPh3)] (1) (M ¼ Pt, Pd; R ¼ NH2, NHPh, or NHpym). A similar reaction with [2-
NC5H3(3-COOH)Se]2 gave an insoluble product which after extraction with dichloromethane gave
[M(Cl){SeC5H3(3-COOH)N}(PPh3)2] (2). Compound 2, in methanolic solution is transformed into
Accepted 18 September 2012
a dimeric ionic complex, but on prolonged standing in CH2Cl2 or CHCl3 is converted into [M(Cl){h2
-
Keywords:
Palladium
Platinum
Nicotinamide: organoselenium
NMR
SeC5H3(3-COOH)N}(PPh3)]. Treatment of [M(PPh3)4] with [2-NC5H3(3-CONHPh)SeI] initially yielded the
expected oxidative addition product [M(I){SeC5H3(3-CONHPh)N}(PPh3)2] (4) which loses a molecule of
PPh3 to give [M(I){h 4 and 5 on prolonged standing in
2-SeC5H3(3-CONHPh)N}(PPh3)] (5). Both
dichloromethane gave several products such as [M(I)(Ph)(PPh3)2] (6), [2-NC5H3(3-CO)SeNH] (9). All the
complexes were characterized by elemental analyses and NMR spectroscopy. The molecular structures of
X-ray structure
[Pt{
CONHPh)N}(PPh3)] (1d), [Pt(I)(Ph)(PPh3)2] (6) and [Pt(Cl0.5 0.5
were established by single crystal X-ray diffraction analyses.
h h
2-SeC5H3(3-CONH2)N}{SeC5H3(3-CONH2)N}(PPh3)] (1a), [Pd{ 2-SeC5H3(3-CONHPh)N}{SeC5H3(3-
I
){C5H3(3-CONHPh)N}(PPh3)2]$HCl (7)
Ó 2012 Elsevier B.V. All rights reserved.
1. Introduction
isolated several serendipitous products, e.g. [Pt(Te){TeeC5H3(R)
N}2(PPh3)] [19]. The reactions of dipyridyl diselenides, in general,
proceed similar to diphenyl diselenide, but dipyrimidyl diselenide
shows different reactivity pattern [17]. In such reactions, besides
expected products [M(SeC5H3N2)2(PXP)] a SeeC bond cleaved
Oxidative addition reactions of diorgano-disulfides or dis-
elenides to palladium(0) and platinum(0) complexes has received
considerable recent attention [1e5] due to its relevance in organic
synthesis [3,6,7] and ease to prepare metal chalcogenolate
complexes which find applications in catalysis [8,9] and materials
science [10,11]. These reactions with platinum(0) precursors afford
mononuclear complexes [12,13] while with palladium(0) species
product, [Pd3(m
-Se)2(PXP)3]2þ could be isolated [17]. This has
prompted us to study the reactivity pattern of N-heterocyclic
selenides with additional functionalities. Thus, the reactions of
nicotinoyl based selenide ligands (I and II), synthesis of which is
described by us recently [22], with [M(PPh3)4] (M ¼ Pd or Pt) have
been investigated. Results of this work are reported here in.
yield binuclear, [Pd2(m
-ER0)2(ER0)2(PR3)2] derivatives as isolable
products [14e16]. However with internally functionalized ligands,
mononuclear palladium complexes are isolated [5,17]. Unlike
disulfides/diselenides, reactions of ditellurides with Pd0/Pt0
CONHPh
COR
complexes often yield
a mixture of products produced by
competitive cleavage of TeeTe and TeeC bonds [18e20].
Recently we have examined reactions of 2-pyridyl dichalcoge-
nides with Pd(0) and Pt(0) phosphine complexes [19e21] and
N
Se )2
SeI
N
(I)
(I)
(II)
* Corresponding author. Tel.: þ91 22 25595095; fax: þ91 22 25505151.
E-mail addresses: arheingold@ucsd.edu (A.L. Rheingold), jainvk@barc.gov.in
(V.K. Jain).
(R = NH2, NHPh, NHpym, OH)
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
http://dx.doi.org/10.1016/j.jorganchem.2012.09.012

164
R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
2. Experimental
squares on F2 for structure 6, while hydrogen atoms were placed in
calculated positions with appropriate riding parameters. For
structure 1d, disorder associated with palladium and selenium
atoms was treated by fixing occupancies of appropriate pairs: that
is, for pair Pd1E, Pd2E (85,15%); Pd1F, Pd2F (95,5%); Se1F, Se3F
(88,12%); Se2E, Se3E (85,15%). Atom parts Pd2E, Pd2F, and Se3F
were refined isotropically. All other non-hydrogen atoms were
refined anisotropically by full matrix least squares on F2 and all
hydrogen atoms were placed in calculated positions with appro-
priate riding parameters. Although numerous residual electron
density peaks and a large weighting factor were noted in the final
refinement, no attempt was made to address these factors. For
structure 7, all non-hydrogen atoms were refined anisotropically by
full matrix least squares on F2. An iodine and chlorine atom were
found to occupy similar positions and were refined with 50%
occupancy with PteI and PteCl distances of PteI 2.66(0.01) and Pte
2.1. Materials and methods
The compounds, [M(PPh3)4] (M ¼ Pt, Pd), [23,24], [2-NC5H3(3-
CONH2)Se]2, [2-NC5H3(3-CONHPh)Se]2, [2-NC5H3(3-CONHC4H3N2)
Se]2, [2-NC5H3(3-COOH)Se]2, and [2-NC5H3(3-CONHPh)SeI] [22]
were prepared according to literature methods. Tertiary phos-
phines were procured from Strem Chemicals. All reactions were
carried out under an argon/nitrogen atmosphere in dry and
distilled analytical grade solvents at room temperature. The 1H, 31
P
{1H}, 77Se{1H}, and 195Pt{1H} NMR spectra were recorded on
a Bruker Avance-II NMR spectrometer operating at 300, 121.49,
57.23 and 64.52 MHz, respectively. Chemical shifts are relative to
internal chloroform peak (
external Ph2Se2 (
d
7.26) for 1H, external 85% H3PO4 for 31P,
d
463 ppm relative to Me2Se) in CDCl3 for 77Se{1H}
and Na2PtCl6 in D2O for 195Pt. Elemental analyses were carried out
on a Thermo Fischer Flash EA1112 CHNS analyzer. The conductivity
measurements were carried out on EUTECH-CON 1500 conduc-
tivity meter.
Cl 2.35(0.001) A. Hydrogen atoms on nitrogen atoms N1 and N2
ꢀ
were found from a Fourier difference map and were refined iso-
ꢀ
tropically with NeH distances of 0.87(0.02) A. All other hydrogen
atoms were placed in calculated positions with appropriate riding
parameters. Disorder associated with the solvent acetonitrile was
treated by using a two part model which resulted in 44.3/55.7
occupancies. Molecular structures were drawn using ORTEP [27].
Crystallographic and structural determination data are listed in
Table 1.
Crystals were mounted on Cryoloops with Paratone-N
oil and data was collected at 100 K with a Bruker APEX II CCD for
[Pt{
[Pt(I)(Ph)(PPh3)2] (6) using Mo Ka radiation and for [Pd{h2
SeC5H3(3-CONHPh)N}{SeC5H3(3-CONHPh)N}(PPh3)] (1d) and [Pt
(Cl0.5 0.5){C5H3(3-CONHPh)N}2(PPh3)2]$HCl (7) data was collected
h
2-SeC5H3(3-CONH2)N}{SeC5H3(3-CONH2)N}(PPh3)] (1a) and
-
I
with a Bruker APEX I CCD using Cu Ka radiation. Data was corrected
for absorption using SADABS and structures were solved by direct
methods [25]. For structure 1a, all non-hydrogen atoms were
refined [26] anisotropically by full matrix least squares on F2.
Hydrogen atoms on nitrogen atoms N2 and N4 were found from
a Fourier difference map and were refined isotropically with NeH
distances of 0.87(0.02) A. All other hydrogen atoms were placed
in calculated positions with appropriate riding parameters. All non-
hydrogen atoms were refined anisotropically by full matrix least
2.2. Synthesis of complexes
2.2.1. [Pt{h
2-SeC5H3(3-CONH2)N}{SeC5H3(3-CONH2)N}(PPh3)] (1a)
To a benzene suspension (10 cm3) of [2-NC5H3(3-CONH2)Se]2
(49 mg, 0.12 mmol), a solution (30 cm3) of [Pt(PPh3)4] (150 mg,
0.12 mmol) in the same solvent was added with stirring which
continued for 4 h at room temperature. The solvent was evaporated
under vacuum and the residue was washed thoroughly with diethyl
ether to remove liberated triphenylphosphine. The residue was
ꢀ
Table 1
Crystallographic and structural determination data for [Pt{SeC5H3(3-CONH2)N}2(PPh3)] (1a), [Pd{SeC5H3(3-CONHPh)N}2(PPh3)] (1d), [Pt(I)(Ph)(PPh3)2] (6), [Pt(Cl0.5 0.5)
I
{C5H3(3-CONHPh)N}(PPh3)2]$HCl (7).
Complex
[Pt{SeC5H3(3-CONH2)N}2
(PPh3)] (1a)
[Pd{SeC5H3(3-CONHPh)N}2
(PPh3)] (1d)
[Pt(I)(Ph)(PPh3)2]
(6)
[Pt(Cl0.5 0.5
(PPh3)2]$HCl (7)
C50H43Cl1.50 0.50N3OP2Pt
1075.53
I
){C5H3(3-CONHPh)N}
Chemical formula
Formula wt.
C30H25N4O2PPtSe2
C42H33N4O2PPdSe2
921.01
C42H35IP2Pt
923.63
I
857.52
Crystal size (mm3)
Radiation used for data collection
Crystal system
0.22 ꢀ 0.20 ꢀ 0.10
0.22 ꢀ 0.10 ꢀ 0.08
0.23 ꢀ 0.20 ꢀ 0.15
0.10 ꢀ 0.05 ꢀ 0.05
Mo-Ka
Cu-Ka
Mo-Ka
Cu-Ka
Triclinic
P1
Orthorhombic
Pbca
Monoclinic
P21/n
Monoclinic
C2/c
Space group
Unit cell dimensions
ꢀ
a (A)
10.3684(15)
20.019(3)
27.418(4)
90
90
90
5690.9(14)
8
2.002
3.56e25.59
7.582/3280
ꢂ11 ꢃ h ꢃ 12
ꢂ24 ꢃ k ꢃ 21
ꢂ33 ꢃ l ꢃ 31
35,034
29.6439(16)
22.5901(13)
33.5733(18)
e
25.420(5)
12.6658(18)
11.476(4)
e
11.8489(2)
14.3967(3)
14.4913(3)
88.5360(10)
68.4110(10)
76.2830(10)
2227.81(8)
2
ꢀ
b (A)
ꢀ
c (A)
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
91.173(2)
e
113.546(14)
e
3
ꢀ
Volume (A )
Z
22,478(2)
24
1.633
2.01e65.08
6.959/10992
ꢂ34 ꢃ h ꢃ 34
ꢂ23 ꢃ k ꢃ 25
ꢂ38 ꢃ l ꢃ 39
11,8174
3387.3(13)
4
1.811
1.75e25.51
5.179/1792
ꢂ30 ꢃ h ꢃ 27
ꢂ12 ꢃ k ꢃ 15
ꢂ13 ꢃ l ꢃ 13
20,338
rcalcd (g cmꢂ3
)
1.603
q
for data collection (ꢁ)
3.17e70.48
10.433/1064
ꢂ11 ꢃ h ꢃ 14
ꢂ16 ꢃ k ꢃ 17
ꢂ17 ꢃ l ꢃ 16
19,008
m
(mmꢂ1)/F(000)
Index range
No of reflections collected
No of independent reflection/no.
of observed reflections with I > 2
Data/restraints/parameters
5335/4393
36,749/27,026
3137/2672
7566/7293
s
I
5335/4/361
0.0216/0.0479
0.0317/0.0513
1.036
36,749/0/2815
0.0837/0.2272
0.1073/0.2512
1.093
3137/19/210
0.0337/0.0772
0.0455/0.0821
1.061
7566/50/554
0.0282/0.0708
0.0292/0.0716
1.073
Final R1,
R1, R2 (all data)
Goodness of fit on F2
uR2 indices
u

R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
165
2+
on leaving 2b in
CH2Cl2 - C2H5OH
MeOH
CHCl3
2 Cl
(2)
M = Pt (2a), Pd (2b)
(3)
R = OH
insoluble product
extracted from
CH2Cl2
[M(PPh3)4]
)
2
R = NH2, NPh, NHpym
(1)
M
R
1a
1b
Pt
Pd
Pt
NH2
NH2
NHPh 1c
Pd NHPh
1d
1e
Pd NHpym
Scheme 1. Reactions of [M(PPh3)4] (M ¼ Pt, Pd) with [2-NC5H3(3-COR)Se]2.
recrystallized from dichloromethane to afford yellow crystals (yield
66 mg (64%), m.p. 193 ꢁC). Anal. Calcd. for C30H25N4O2PPtSe2: C,
42.02; H, 2.94, N; 6.53%. Found: C, 41.84; H, 2.89; N; 6.56%. IR (KBr,
2.2.4. [Pd{h
2-SeC5H3(3-CONHPh)N}{SeC5H3(3-CONHPh)N}(PPh3)]
(1d)
Prepared similar to 1a using Pd(PPh3)4 (115 mg, 0.10 mmol) and
[2-NC5H3(3-CONHPh)Se]2 (55 mg, 0.10 mmol) and recrystallized
from benzene on refrigeration as dark red crystals (yield 67 mg
(73%), m.p. 174 ꢁC). Anal. Calcd. for C42H33N4O2PPdSe2: C, 54.77; H,
3.61, N; 6.08%. Found: C, 53.94; H, 3.54; N; 6.35%. IR (KBr, cmꢂ1):
cmꢂ1): 3340 (br, nasym(NH2)), 3285 (br, nsym(NH2)), 1670 (
n
(C]O)).
1H NMR (CDCl3)
d: 5.83 (br, NH2), 6.89e6.95 (m, py, CH-5), 7.11e7.73
(m, Ph), 8.07 (d, 6.6 Hz, CH-4), 8.23 (d, 7.8 Hz, CH-4), 8.73 (d, 3.6 Hz,
CH-6), 9.05 (br, CH-6); 31P{1H} NMR (CDCl3)
3806 Hz)].
d
: 6.4 (1J(PteP) ¼
3294(br,
C5H4N), 7.11 (t, 7.5 Hz, Ph), 7.30e7.75 (m, Ph), 8.12(d, 8 Hz), 8.18 (br
d, C5H4N), 9.27 (s, eCONH); 31P{1H} NMR (CDCl3)
: 32.4 ppm.
n(NH)), 1632 (n d: 6.95 (dd, 5.1 Hz,
(C]O)). 1H NMR (CDCl3)
2.2.2. [Pd{
h
2-SeC5H3(3-CONH2)N}{SeC5H3(3-CONH2)N}(PPh3)]
d
(1b)
Prepared similar to 1a using [Pd(PPh3)4] (102 mg, 0.09 mmol) and
[2-NC5H3(3-CONH2)Se]2 (38 mg, 0.095 mmol), and recrystallized
from dichloromethaneehexane mixture as orange crystals (yield
49 mg(72%), m.p.189 ꢁC). Anal. Calcd. forC30H25N4O2PPdSe2:C, 46.86;
H, 3.27, N; 7.28%. Found: C, 45.98; H, 2.99; N; 6.85%. IR (KBr, cmꢂ1):
2.2.5. [Pd{
h
2-SeC5H3(3-CONHpym)N}{SeC5H3(3-CONHpym)
N}(PPh3)] (1e)
Prepared similar to 1a using Pd(PPh3)4 (90 mg, 0.078 mmol) and
[2-NC5H3(3-CONHpym)Se]2 (43 mg, 0.077 mmol) as a red powder
(yield 44 mg (61%), m.p. 174 ꢁC (dec)). Anal. Calcd. for
C38H29N8O2PPdSe2: C, 49.34; H, 3.16, N; 12.11%. Found: C, 50.04; H,
3337 (br, nasym(NH2)), 3150 (br, nsym(NH2)), 1654 (n
(C]O)). 1H NMR
(CDCl3)
d
: 5.81 (br, NH2), 6.88 (t, 6.3 Hz, C5H4N), 7.22e7.72 (m,
3.35; N; 12.03%. IR (KBr, cmꢂ1): 3345 (br,
NMR (CDCl3)
n(NH)), 1654 (
n
(C]O)). 1H
Ph þ C5H4N), 8.07 (d, 6.6 Hz, C5H4N); 31P{1H} NMR (CDCl3)
d:
d: 7.43 (dd, 3.6 Hz, 6.3 Hz, C5H3N2), 7.44e7.50 (m, Ph),
32.6 ppm.
7.68e7.75 (m), 7.90 (t, 6.6 Hz), 8.05 (d, 6.3 Hz, C5H4N), 8.61 (d, 3 Hz,
C5H3N2), 9.15 (br), 9.79 (s, eCONH); 31P{1H}NMR (CDCl3)
d: 32.3 ppm.
2.2.3. [Pt{h
2-SeC5H3(3-CONHPh)N}{SeC5H3(3-CONHPh)N}(PPh3)]
(1c)
2.2.6. [Pt(Cl){SeC5H3(3-COOH)N}(PPh3)2] (2a)
Prepared similar to 1a using [Pt(PPh3)4] (125 mg, 0.10 mmol)
and [2-NC5H3(3-CONHPh)Se]2 (56 mg, 0.10 mmol) as a yellow
powder (yield 70 mg (69%), m.p. 179 ꢁC). Anal. Calcd. for
C42H33N4O2PPtSe2: C, 49.96; H, 3.29, N; 5.55%. Found: C, 49.89; H,
To a benzeneemethanol solution (20 cm3) of [2-NC5H3(3-
COOH)Se]2 (59 mg, 0.15 mmol) was added a solution (25 cm3) of
[Pt(PPh3)4] (175 mg, 0.14 mmol) in the same solvent with contin-
uous stirring for 5 h at room temperature. The contents were
concentrated under reduced pressure and diethyl ether (15 ml) was
added to give a yellow precipitate which was filtered and recrys-
tallized from dichloromethaneeethanol mixture as yellow crystals
(yield 104 mg (77%), m.p. 238 ꢁC (dec.)). Anal. Calcd. for
3.41; N; 5.58%. IR (KBr, cmꢂ1): 3295 (br, (C]O)). 1H
n(NH)), 1656 (n
NMR (CDCl3)
d
: 6.71 (br, C5H4N), 7.32e7.47 (m, Ph þ C5H4N), 7.50e
7.67 (m, Ph þ C5H4N); 31P{1H} NMR (CDCl3)
d
: 6.4 (1J(PteP) ¼
3775 Hz)] ppm.

166
R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
[M(PPh3)4)]
(6b)
(9)
M = Pt
M = Pd
M = Pd
(-PPh3)
(4a)
M
Pt (5a)
Pd
(5b)
M = Pt
(5a)
HCl
I/Cl
(6a)
(7)
(8)
(9)
Scheme 2. Oxidative addition of [M(PPh3)4] (M ¼ Pd, Pt) with [2-NC5H3(3-CONHPh)SeI].
C42H34ClNO2P2PtSe: C, 52.76; H, 3.58, N; 1.46%. Found: C, 52.89; H,
3.69; N; 1.58%. Conductivity measurements (
S cm2 molꢂ1): 4.1
(CHCl3), 8.4 (CH3CN), 230.8 (CH3OH). IR (KBr, cmꢂ1): 3346 (br,
(OH)), 1602 ( : 4.56 (br, eCOOH), 6.40
(C]O)). 1H NMR (CDCl3)
2.2.8. trans-[Pt(I){2-SeC5H3(3-CONHPh)N}(PPh3)2] (4a)
m
To a benzene solution (10 cm3) of [2-NC5H3(3-CONHPh)SeI]
(64 mg, 0.16 mmol), a solution (15 cm3) of [Pt(PPh3)4] (198 mg,
0.16 mmol) in the same solvent was added with stirring which
continued for 5 h at room temperature. The contents were concen-
trated under reduced pressure and diethyl ether (15 ml) was added
to yield a yellow precipitate which was filtered out and dried under
vacuum to give a yellow powder (yield 132 mg (74%), m.p. 151 ꢁC).
Anal. Calcd. for C48H39IN2P2OPtSe: C, 51.34; H, 3.50; N, 2.49%. Found:
n
n
d
(br, C5H3N), 6.70 (br, C5H3N), 7.37e7.49 (m, Ph), 8.29 (d, 7.2 Hz,
C5H4N); 31P{1H} NMR (CDCl3)
d
: 14.3 [1J(PteP) ¼ 2750 Hz], 10.3
[1J(PteP) ¼ 3586 Hz].
2.2.7. [Pd(Cl){SeC5H3(3-COOH)N}(PPh3)2] (2b)
Prepared similar to 2a using Pd(PPh3)4 (168 mg, 0.14 mmol) and
[2-NC5H3(3-COOH)Se]2 (60 mg, 0.15 mmol) as an orange powder,
(yield 48 mg (38%), mp 213 ꢁC (dec.)). Anal. Calcd. for
C42H34ClNO2P2PdSe: C, 58.15; H, 3.95, N; 1.61%. Found: C, 57.19; H,
C, 51.72; H, 3.43; N 2.34%. IR (KBr, cmꢂ1): 3051 (br,
n(NH)), 1669
(
n
(C]O)). 1H NMR (CDCl3)
8.92 (s, NH); 31P{1H} NMR (CDCl3)
d: 7.09e7.68 (m), 8.37 (br), 8.57 (br, py),
d
: 13.5 [1J(PteP) ¼ 2925 Hz] ppm.
On leaving a CDCl3 solution of 4a for 3e4 h, a new complex [Pt(I)
4.69; N; 2.50%. Conductivity measurements (
(CHCl3), 4.1 (CH3CN), 198.2 (CH3OH). IR (KBr, cmꢂ1): 3347 (br,
(OH)), 1595 ( : 7.39e7.48 (m, Ph), 7.51e
(C]O)). 1H NMR (CDCl3)
7.57 (m), 7.62e7.70 (m); 31P{1H} NMR (CDCl3)
: 34.7, 15.4 ppm.
However, further recrystallization of 2b in dichloromethanee
m
S cm2 molꢂ1): 1.2
{h
2-SeC5H3(3-CONHPh)N}(PPh3)] (5a) with the liberation of free
phosphineconverted inphosphineoxide, wasformedasevidentfrom
NMR spectra.1H NMR (CDCl3)
: 7.15 (t, 7.2 Hz, C5H4N), 7.34 (t, 7.5 Hz,
n
n
d
d
d
Ph), 7.46e7.73 (m, Ph), 8.21 (d, 7.8 Hz, C5H4N), 8.32(br, C5H4N), 8.94(s,
CONH); 31P{1H} NMR (CDCl3)
d
: 4.0 [1J(PteP) ¼ 3668 Hz)] ppm, 29.4
ethanol mixture gave
a
brown powder, [Pd(Cl){2-Se-C5H3(3-
(OPPh3);77Se{1H} NMR (CDCl3)
d
:201 [1J(PteSe) ¼ 166 Hz)], 195Pt{1H}
COOH)N}(PPh3)] (3) (yield 46 mg (41%), m.p. 201 ꢁC (dec.)). Anal.
NMR (CDCl3)
d
: ꢂ4397 [d, 1J(PteP) ¼ 3686 Hz] ppm.
Calcd. for C24H19ClNO2PPdSe: C, 47.63; H, 3.16, N; 2.31%. Found: C,
When 4a was left in CH2Cl2 for recrystallization for more than 2
days, yellow crystals of [Pt(I)(Ph)(PPh3)2] (6a) (yield 34 mg, m.p.
182 ꢁC (dec.)) were formed which were manually separated. Anal.
Calcd. for C42H35IP2Pt: C, 54.61; H, 3.82%. Found: C, 55.32; H, 3.33%.
47.69; H, 3.49; N; 3.95%. IR (KBr, cmꢂ1): 3056 (
n
(OH)), 1590 (
: 6.89e7.15 (m), 7.43e7.48 (m), 7.71e7.76 (q,
6.6 Hz), 8.46 (d, 6.3 Hz); 31P{1H} NMR (CDCl3)
: 31.8 ppm.
n(C]
O)). 1H NMR (CDCl3)
d
d

R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
167
O
NHPh
PPh3
I
N
Se
M
Ph3P
(4)
-PPh3
-PPh3
O
O
PhHN
N
NH
Se
N
I
Se
M
M
Ph3P
Ph3P
I
(5)
O
NH
N
Se
PPh3
I
Ph
PPh3
PPh3
(9)
M
M
Ph3P
Ph
I
(6)
Scheme 3. A possible path way involved in the formation of [Pt(I)(Ph)(PPh3)2] (6) and [2-NC5H3(3-CO)SeNH] (9).
1H NMR (CDCl3)
31P{1H} NMR (CDCl3)
d
: 7.36e7.48 (m, Ph), 7.64e7.73 (m), 7.74e7.76 (m);
(7) (16 mg, m.p.168 ꢁC). Anal. Calcd. for C48H39Cl0.5 0.5
I
N2OP2Pt$HCl:
d
: 21.7 [1J(PteP) ¼ 3092 Hz)] ppm. The yellow-
C, 55.73; H, 3.90; N, 2.71%. Found: C, 55.72; H, 3.89; N 2.64%. IR (KBr,
orange insoluble part, sticking to the flask, was separated and the
filtrate (A) was collected. The insoluble part was dissolved in
acetonitrile and filtered, from which an orange insoluble part was
filtered out and identified as [PtI2(PPh3)2] (8) (yield 17 mg,
m.p. > 270 ꢁC). Anal. Calcd. for C36H30I2P2Pt: C, 44.41; H, 3.10%.
Found: C, 44.12; H, 2.98%. The acetonitrile filtrateon recrystallization
cmꢂ1): 3054 (br, (C]O)). 1H NMR (CDCl3)
n
(NH)), 1681 ( : 6.65 (t,
n
d
8 Hz, py), 6.78 (t, 7.5 Hz), 7.16e7.69(m, Ph), 8.04 (d), 8.19 (d, 7.8 Hz,
py), 8.50 (s, NH); 31P{1H} NMR (CDCl3)
ppm.
d
: 9.4 [1J(PteP) ¼ 3564 Hz]
The filtrate A on drying under vacuum yielded a brown powder
which was thoroughly washed with diethyl ether and characterized
as [2-NC5H3(3-CO)SeNH] (9) (10 mg, m.p. 252 ꢁC). Anal. Calcd. for
C6H4N2OSe: C, 36.20; H, 2.03; N, 14.06%. Found: C, 35.22; H, 2.08; N,
gave cream crystals of [Pt(Cl0.5 0.5){C5H3(3-CONHPh)N}(PPh3)2]$HCl
I
13.87%. IR (KBr, cmꢂ1): 3089 (br,
n
(NH)), 1654 (
n
(C]O)). 1H NMR
(DMSO-d6)
(DMSO-d6)
d
: 7.78 (s), 8.11 (d, 7.2 Hz), 8.29 (s), 8.44 (s); 13C{1H} NMR
d
: 119.8, 128.1, 135.6, 151.6, 160.5, 168.3 (C]O); 77Se{1H}
NMR (DMSO-d6)
d
: 951 ppm. Mass (m/z) ¼ 199 (Mþ); 141, 122
(SeCONH).
2.2.9. [Pd(I){h
2-SeC5H3(3-CONHPh)N}(PPh3)] (5b)
To a benzene solution (10 cm3) of [2-NC5H3(3-CONHPh)SeI]
(57 mg, 0.14 mmol), a solution (15 cm3) of [Pd(PPh3)4] (160 mg,
0.14 mmol) in the same solvent was added with stirring which
continued for 6 h at room temperature, whereupon a brown
powder formed. The powder was filtered out and dried under
vacuum to give the title complex, [Pd(I){h
2-SeC5H3(3-CONHPh)
N}(PPh3)] (5b) (yield 28 mg (52%), m.p. 138 ꢁC). Anal. Calcd. for
C30H24IN2OPPdSe: C, 46.69; H, 3.13, N; 3.63%. Found: C, 46.32; H,
3.15; N; 3.67%. IR (KBr, cmꢂ1): 3344 (br,
n
(NH)), 1654 (
: 7.04 (m, Ph), 7.15 (t, 7.5 Hz, C5H4N), 7.34 (t,
7.5 Hz, Ph), 7.53 (br, Ph), 7.74 (m, Ph), 8.22 (d, 8.1 Hz, C5H4N),
8.80 (d, 5.1 Hz, C5H4N); 31P{1H} NMR (CDCl3)
: 31.7 ppm. The
n(C]O)).
1H NMR (CDCl3)
d
d
supernatant was concentrated to 2 ml and on addition of diethyl
ether (15 cm3) a red powder, [Pd(I)(Ph)(PPh3)2] (6b) (yield 16 mg,
28%, m.p.198e201 ꢁC) was precipitated which was separated by
filtering through a G-3 filtering unit and dried in vacuo. Anal.
Fig. 1. ORTEP diagram of [Pt{SeC5H3(3-CONH2)N}2(PPh3)] (1a) with atomic number
scheme. The ellipsoids were drawn at the 50% probability.

168
R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
Fig. 2. ORTEP diagram of [Pd{SeC5H3(3-CONHPh)N}2(PPh3)] (1d) with atomic number scheme. The ellipsoids were drawn at the 50% probability.
Calcd. for C42H35IP2Pd: C, 60.41; H, 4.22%. Found: C, 59.97; H,
4.39%. 1H NMR (CDCl3)
: 6.91 (t, 6 Hz, C5H4N), 7.04 (m, Ph),
7.14e7.36 (m, Ph), 7.49 (br, Ph), 7.59 (t, 7.8 Hz), 7.75 (m, Ph); 31P
{1H} NMR (CDCl3)
: 20.0 ppm. The filtrate was dried in vacuum
to give a brown powder which was identified as [2-NC5H3(3-CO)
SeNH] (9). Anal. Calcd. for C6H4N2OSe: C, 36.20; H, 2.03; N,
14.06%. Found: C, 36.30; H, 2.22; N, 13.61%; 77Se{1H} NMR
resonance indicating the existence of a single species in solution.
The resonances for platinum complexes appeared at 6.4 ppm while
the signals for the palladium complexes were considerably
d
d
deshielded (d w32.5 ppm). The resonances for platinum complexes
were flanked by 195Pt satellites with 1J(PteP) values of w3800 Hz
suggesting disposition of PPh3 ligand trans to the nitrogen atom
[19]. The complexes tend to decompose when left in CDCl3 solution
for several hours at room temperature.
(DMSO-d6) d: 951 ppm.
Reaction of M(PPh3)4 with {2-NC5H3(COOH-3)Se}2 in benzene
methanol mixture gave an insoluble solid which after extraction
with CHCl3/CH2Cl2 afforded complexes of composition [M(Cl)
{SeC5H3(COOH-3)N}(PPh3)2] (2) (M ¼ Pt (2a) or Pd (2b)).
Compounds 2 are non-conducting in acetonitrile or chloroform
solution but exhibit conducting (diionic) behavior in methanol. This
suggests that a dimeric diionic species containing bridging sele-
nolate ligand is formed in methanol (Scheme 1). The 31P NMR
spectra of 2 displayed two resonances, as expected and can be
attributed to the phosphine ligands trans to chloride and selenolate
3. Results and discussion
Treatment of [M(PPh3)4] (M ¼ Pd or Pt) with nicotinamide based
diselenides, {2-NC5H3(3-COR)Se}2 (R ¼ NH2, NHPh, NHpym;
pym ¼ pyrimidyl), in benzene at room temperature afforded
complexes of composition [M{h
2-SeC5H3(3-COR)N}{SeC5H3(3-
COR)N}(PPh3)] (1) in 61e73% yield as yellow to orange/red crys-
talline solids (Scheme 1). The 31P NMR spectra exhibited a single
Fig. 3. ORTEP diagram of [Pt(I)(Ph)(PPh3)2] (6) with atomic number scheme. The
ellipsoids were drawn at the 50% probability. Interatomic parameters: bond lengths
ꢀ
(A): Pt(1)eC(19), 2.015(9); Pt(1)eI(1), 2.6979(9); Pt(1)eP(1), 2.2903(16); bond angles
(ꢁ): P(1)#ePt(1)eP(1), 178.27(9); C(19)ePt(1)eP1, 90.86(4); P(1)ePt(1)eI(1), 89.14(4);
C(19)ePt(1)eI(1), 180.00(1).
Fig. 4. ORTEP diagram of [Pt(Cl0.5 0.5
number scheme. The ellipsoids were drawn at the 50% probability.
I
){C5H3(3-CONHPh)N}(PPh3)2]$HCl (7) with atomic

R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
169
Table 2
Selected bond lengths (A) and angles ( ) of [Pt{SeC5H3(3-CONH2)N}2(PPh3)] (1a).
Table 4
ꢁ
Selected bond lengths (A) and angles (ꢁ) of [Pt(Cl0.5 0.5
I
){C5H3(3-CONHPh)
ꢀ
ꢀ
N}(PPh3)2]$HCl (7)
Pt(1)eP(1)
Pt(1)eSe(1)
Se(1)eC(5)
P(1)ePt(1)eN(1)
P(1)ePt(1)eSe(2)
Se(1)ePt(1)eSe(2)
N(1)eC(5)eSe(1)
Pt(1)eSe(1)eC(5)
2.2016(9)
2.4437(4)
1.902(3)
171.24(8)
90.13(3)
166.119(13)
105.8(2)
78.33(11)
Pt(1)eN(1)
Pt(1)eSe(2)
Se(2)eC(7)
P(1)ePt(1)eSe(1)
Se(1)ePt(1)eN(1)
N(1)ePt(1)eSe(2)
Pt(1)eSe(2)eC(7)
Pt(1)eN(1)eC(5)
2.086(3)
2.4231(4)
1.907(3)
103.58(3)
69.99(8)
96.14(8)
95.71(11)
105.9(2)
Pt(1)eC(1)
Pt(1)eCl(3)
Pt(1)eP(2)
N(2)eC(6)
1.997(3)
2.390(3)
2.3057(7)
1.361(4)
1.348(4)
171.51(3)
88.36(3)
90.34(8)
88.70(11)
175.01(16)
Pt(1)eI(1)
Pt(1)eP(1)
O(1)eC(6)
N(2)eC(7)
2.6672(6)
2.3221(7)
1.226(4)
1.413(4)
1.350(4)
91.24(8)
90.63(13)
90.68(3)
175.79(9)
2.31(15)
N(1)eC(1)
N(1)eC(2)
P(2)ePt(1)eP(1)
P(1)ePt(1)eI(1)
C(1)ePt(1)eP(2)
P(2)ePt(1)eCl(3)
C(1)ePt(1)eCl(3)
C(1)ePt(1)eP(1)
P(1)ePt(1)eCl(3)
P(2)ePt(1)eI(1)
C(1)ePt(1)eI(1)
Cl(3)ePt(1)eI(1)
ligands. The 1J(PteP) values (2750 (trans to selenolate) and 3586 Hz
(trans to Cl)) for 2a are also in accordance with this configuration.
The complex 2b when left in CH2Cl2eEtOH solution for several
hours at room temperature, gave a brown powder of composition
several hours, at least two compounds, [PdI(Ph)(PPh3)2] (6b) and
[2-NC5H3(3-CO)SeNH] (9), were separated. Singh et al. have isolated
complexes similar to 5b in the reaction of [Pd(Ph3)4] with {2-(4,4-
dimethyl-2-oxazolinyl)phenyl}seleneyl halides (halide ¼ Cl, Br, I)
or {2-(N,N-dimethylaminomethyl)phenyl}selenyl halide (hal-
ide ¼ Br or I) [5].
[Pd(Cl){
a single 31P NMR resonance at 31.8 ppm. Recently Singh and co-
workers [5] have reported a similar complex, [Pd(Cl){
2-SeC6H4-
h
2-SeC5H3(COOH-3)N}(PPh3)] (3). The latter showed only
h
C(O)CH2CMe2N}(PPh3)] which was isolated from the reaction of
[Pd(PPh3)4] with bis{2-(4,4-dimethyl-2-oxazolinyl)phenyl}dis-
elenide in dichloromethane.
The formation of 6 and 9 from 4/5 is rather intriguing and
a plausible route for their formation is depicted in Scheme 3. During
the oxidative addition reaction between [M(PPh3)4] and seleneyl
iodide the expected oxidative product of composition 4 is formed
and is isolated in case of platinum. This product loses a molecule of
phosphine, rapidly in case of palladium to give isolable 5b, and
slowly (over a period of few hours) in case of platinum to afford 5a,
which contain bidentate chelating four-membered selenolate
(SeXN) ligand. Alternatively, the selenolate can also function as
a six-membered SeXN chelating ligand via amide nitrogen atom
coordination (Scheme 3). This species may have resonance inter-
The reaction of [M(PPh3)4] with 2-NC5H3(3-CONHPh)SeI in
benzene at room temperature is quite complex giving several
products formed by dissociation and/or decomposition of initially
produced oxidative addition complex, [M(I){SeC5H3(3-CONHPh)
N}(PPh3)2] (4) (M ¼ Pt (4a), Pd (4b)) (Scheme 2). In the case of
platinum, 4a could be isolated in 74% yield as a yellow powder. The
magnitude of 1J(PteP) suggests that the phosphine ligands are
mutually trans. Compound 4a slowly loses triphenylphosphine in
CDCl3 solution to yield a new selenolate complex, [Pt(I){h2
-
SeC5H3(3-CONHPh)N}(PPh3)] (5a). The 31P and 195Pt NMR data for
5a are consistent with the phosphine ligand trans to the nitrogen
atom of the chelating (SeXN) selenolate ligand [17]. When 4a was
left in CH2Cl2 solution for more than 2 days, at least four
action between filled metal d
p orbital and the phenyl ring as
described in the literature [28]. This species on decomposition gave
9 and three coordinated “[M(I)(Ph)(PPh3)]” which after coordina-
tion with liberated PPh3 yield 6. It is interesting to note that 9 is N-
heterocyclic derivative of a well studied antioxidant organo-
selenium compound, ebselen [29].
From the results discussed above and our recent work on
oxidative addition reactions of M(PR3)4 with organoselenium
ligands, it is evident that, in addition to expected complexes, some
other products may also form depending on the nature of M,
tertiary phosphine ligand and the organic groups attached to
selenium atom. The role of the latter has marked influence on the
overall reactivity of the complex. While the phenylselenolate
compounds, [Pt(I)Ph(PPh3)2] (6), [Pt(Cl0.5 0.5){C5H3(3-CONHPh)
I
N}(PPh3)2]$HCl (7), trans-[PtI2(PPh3)2] (8) and [2-NC5H3(3-CO)
SeNH] (9) could be isolated. They were separated from each other
based on their differences in solubilities in different solvents and by
repeated crystallization. The NMR and analytical data are consis-
tent with the suggested formulations. The former two, 6 and 7, have
been structurally characterized (see later).
When M is palladium, 4b could not be isolated instead a brown
powder of 5b was precipitated out from the reaction. From the
supernatant of this reaction or even leaving 5b in CDCl3 solution for
Table 3
ꢁ
ꢀ
Selected bond lengths (A) and angles ( ) of [Pd{SeC5H3(3-CONHPh)N}2(PPh3)] (1d).
Molecule A
Molecule B
Molecule C
Molecule D
Molecule E
Molecule F
X ¼ A
X ¼ B
X ¼ C
X ¼ D
X ¼ E
X ¼ F
Pd1XeP1X
Pd1XeN1X
Pd1XeSe1X
Pd1XeSe2X
Se1XeC5X
Se2XeC10X
P1XePd1XeN1X
P1XePd1XeSe1X
P1XePd1XeSe2X
Se1XePd1XeN1X
Se1XePd1XeSe2X
N1XePd1XeSe2X
N1XeC5XeSe1X
Pd1XeSe2XeC10X
Pd1XeSe1XeC5X
Pd1XeN1XeC5X
2.252(2)
2.079(7)
2.4411(9)
2.4383(10)
1.887(8)
1.932(8)
173.63(18)
102.35(6)
89.61(6)
71.33(17)
166.96(4)
96.76(17)
108.4(5)
104.8(2)
77.1(2)
2.242(2)
2.088(7)
2.4352(10)
2.4169(11)
1.902(9)
1.919(9)
172.4(2)
101.92(6)
89.25(6)
71.19(19)
168.15(4)
97.87(19)
107.7(6)
102.8(3)
77.4(3)
2.243(2)
2.102(7)
2.4322(11)
2.4259(11)
1.886(9)
1.911(9)
172.0(2)
102.67(6)
89.41(6)
70.6(2)
167.65(4)
97.5(2)
109.1(6)
101.7(3)
77.1(3)
2.242(2)
2.081(7)
2.4478(10)
2.4294(10)
1.896(8)
1.893(8)
174.0(2)
103.37(6)
87.89(6)
70.85(19)
168.10(4)
97.99(19)
108.0(6)
104.0(3)
77.0(3)
2.267(3)
2.028(8)
2.4467(10)
2.4335(16)
1.908(10)
1.890(9)
172.4(2)
101.57(7)
90.30(7)
71.9(2)
166.43(5)
96.6(2)
107.3(7)
106.9(3)
75.9(3)
2.243(2)
2.091(7)
2.4621(10)
2.4256(10)
1.918(9)
1.919(9)
172.4(2)
103.69(6)
88.17(6)
71.30(19)
167.23(4)
97.36(19)
107.4(6)
105.7(3)
77.1(3)
103.1(5)
103.7(5)
103.1(5)
104.1(5)
104.8(6)
104.0(5)

170
R.S. Chauhan et al. / Journal of Organometallic Chemistry 723 (2013) 163e170
complexes are stable in halogenated solvents for several days, the
corresponding SeC5H3(3-R)N derivatives tend to dissociated to give
SeXN chelated products [19,20]. In contrast, the pyr-
imidylselenolate complexes, in addition to SeXN chelation, also
undergo SeeC bond cleavage [17]. Additional functionalization, as
in the present case, leads to the formation of several products
formed by the cleavage of CeSe (e.g. 7)/CeN (e.g. 6) bonds. It
appears that additional bonding sites bind the metal atom in
solution to give transient species which undergo dissociation/
decomposition to give other products.
Acknowledgments
One of the authors(RSC) is grateful to DAE for theaward ofSRF. We
thank Drs. T. Mukherjee and D. Das for encouragement of this work.
Appendix A. Supplementary material
CCDC 888243, 888242, 888245 and 888244 for [Pt{
CONH2)N}{SeC5H3(3-CONH2)N}(PPh3)] (1a), [Pd{
h
h
2-SeC5H3(3-
2-SeC5H3(3-
CONHPh)N}{SeC5H3(3-CONHPh)N}(PPh3)] (1d), [Pt(I)(Ph)(PPh3)2]
(6) and [Pt(Cl0.5 0.5){C5H3(3-CONHPh)N}(PPh3)2]. HCl (7), respec-
I
tively, contain the supplementary crystallographic data for this
paper. These data can be obtained freeof charge fromThe Cambridge
Crystallographic Data Centre www.ccdc.cam.ac.uk/data_request/cif.
3.1. X-ray crystallography
The molecular structures of [Pt{
{SeC5H3(3-CONH2)N}(PPh3)] (1a), [Pd{
2-SeC5H3(3-CONHPh)N}
{SeC5H3(3-CONHPh)N}(PPh3)] (1d), [PtI(Ph)(PPh3)2] (6) and
[Pt(Cl0.5 0.5){C5H3(3-CONHPh)N}(PPh3)2]$HCl (7) were established
h
2-SeC5H3(3-CONH2)N}
h
References
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I
by X-ray diffraction analyses. The molecular structures are shown
in Figs. 1e4 while selected interatomic parameters are summarized
in Tables 2e4.
The coordination environments around central metal atom in
1a and 1d are similar and are defined by PPh3, monodentate and
chelating bidentate (SeXN) selenolate ligands. There are six
independent molecules in the crystal lattice of 1d which differ
marginally from each other in various bond lengths, angles and
torsion angles. Two of these independent molecules are highly
disordered. The four-membered “PdSeNC” and SeC5H3(3-CONR)N
rings are coplanar. The two MeSe distances in each complex are
slightly different and the one with chelating selenolate ligand is
longer than the monodentate selenolate. The MeSe distances are
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well in agreement to those reported in [Pd(
m-SeCH2CH2
-
COOEt)(
h
3-C3H5)]3 [30] and other related derivatives [5,31,32].
The MeN distances are as expected [32e34]. The short bite of the
chelating selenolate ligands leads to an acute NeMeSe angle
(w70ꢁ) as a consequence adjacent angles are opened up.
The complex, [PtI(Ph)(PPh3)2] (6) adopts a distorted square
planar configuration around platinum as observed for trans-
[PtCl(Ph)(PPh3)2] [35] and [PtCl(C4H3S)(PPh3)2] [36]. The PteC
distance is in agreement with the one reported for
ꢀ
[PtCl(Ph)(PPh3)2] (PteC ¼ 2.01(1) A) [35], but slightly longer than
ꢀ
that found in trans-[PtI(C6H4CF3-4)(PPh3)2] (1.963(9) A) [37]. The
ꢀ
PteI distance (2.6979(9) A) is similar to the one reported in trans-
ꢀ
[PtI(C6H4CF3-4)(PPh3)2] (2.7011(9) A) [37], but is slightly longer
ꢀ
than [PtI2(PPh3)2] (2.6647(6), 2.6448(5) A) [38] owing to the strong
trans influence of the phenyl group.
The overall molecular structure of [Pt(Cl0.5 0.5){C5H3(3-
I
CONHPh)N}(PPh3)2]$HCl (7) is similar to 6. Distorted square
planar platinum atom is coordinated to two trans triphenylphos-
phine ligands and Cl/I and C atom of the C1 carbon atom of the
nicotinoyl ring of the C5H3(3-CONHPh)N fragment. One of the
nitrogen atoms is protonated and chloride is found at two posi-
tions both of which are 50% occupied. The PteC and PteP distances
are as expected [35,38].
4. Conclusions
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Oxidative addition reactions of nicotinoyl based selenides
with [M(PPh3)4] (M ¼ Pt, Pd) give a variety of complexes which
have been characterized thoroughly. The complexes of the type
[M(I){SeC5H3(3-CONHPh)N}(PPh3)2] in CH2Cl2/CHCl3 undergo,
initially dissociation of PPh3 ligand, followed by decomposition
to several other products including [M(I)(Ph)(PPh3)2] and
[(C5H3N)SeC(NH)CO].
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