Synthesis, structure and thermolysis of cis-dialkylplatinum(II) complexes - Experimental and theoretical perceptions

Article abstract of DOI:10.1016/j.jorganchem.2016.05.023

The formation of new C-C bonds by metal complexes always stimulates great interest because these fundamental reaction types possess numerous potential applications in organic synthesis. These reactions are well documented for a variety of transition metal complexes. Herein we report synthesis and characterization of a series of platinum-dialkyl complexes (1-10) of the type [Pt(L₂)R₂], (where L₂ = dppp (1,3-bis(diphenylphosphino)propane or L = PPh₃; R = n-butyl to n-nonyl) with a view to understand the organic product distribution patterns on thermolysis. The single crystal X-ray structures of the complexes [Pt(dppp){CH₂(CH₂)₃CH₃}₂] (1) and [Pt(dppp){CH₂(CH₂)₆CH₃}₂] (7) are reported. Thermal decomposition studies of these complexes show interesting behaviour; the longer chain dialkyls i.e. C₇-C₉ complexes undergo reductive elimination whereas the shorter chain dialkyl complexes and C₃-C₆ prefer only the β-hydride elimination reaction. Possible mechanistic aspects are discussed. Theoretical calculations reveal the strongest delocalizations in both complexes involve the interaction of Pt-C bond pair electron density with the trans positioned Pt-P antibonding orbital and vice-versa.

Full text of DOI:10.1016/j.jorganchem.2016.05.023

Accepted Manuscript
Synthesis, structure and thermolysis of cis-Dialkylplatinum(II) complexes –
Experimental and theoretical perceptions
Sadhana Venkatesh, Chinduluri Sravani, Sannapaneni Janardan, Pothini Suman, E.
Veerashekhara Goud, B.B. Pavankumar, Vardi Leninkumar, Haamid R. Bhat, Akella
Sivaramakrishna, Kari Vijayakrishna, Prakash C. Jha, Gregory S. Smith
PII:
S0022-328X(16)30238-8
10.1016/j.jorganchem.2016.05.023
JOM 19514
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 2 April 2016
Revised Date: 18 May 2016
Accepted Date: 31 May 2016
Please cite this article as: S. Venkatesh, C. Sravani, S. Janardan, P. Suman, E.V. Goud, B.B.
Pavankumar, V. Leninkumar, H.R. Bhat, A. Sivaramakrishna, K. Vijayakrishna, P.C. Jha, G.S. Smith,
Synthesis, structure and thermolysis of cis-Dialkylplatinum(II) complexes – Experimental and theoretical
perceptions, Journal of Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.05.023.
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ACCEPTED MANUSCRIPT
Graphical Abstract
Reaction Pathways in Platinum-Dialkyl Complexes – Reductive elimination is more preferred than β-
hydride elimination with longer chain lengths

ACCEPTED MANUSCRIPT
Synthesis, Structure and Thermolysis of cis-Dialkylplatinum(II)
Complexes - Experimental and Theoretical Perceptions
Sadhana Venkatesh,[a]Chinduluri Sravani,[a], Sannapaneni Janardan,[a]Pothini Suman,[a]E.
Veerashekhara Goud,[a]B.B. Pavankumar,[a] Vardi Leninkumar[a], Haamid R. Bhat, [b] Akella
Sivaramakrishna*,[a] Kari Vijayakrishna,[a] Prakash C. Jha,[b] and Gregory S. Smith,[c]
[a]Department of Chemistry, School of Advanced Sciences, VIT University, Vellore 632 014,
Tamil Nadu, India
[b]School of Chemical Sciences, Central University of Gujarat, Sector-30, Gandhinagar, Gujarat,
India
[c]Department of Chemistry, University of Cape Town, Rondebosch 7701, Cape Town, South
Africa
E-Mail: asrkrishna@vit.ac.in; Tel (O) # +91 416 2202351; Fax # +91 416 2243092
============================================================
ABSTRACT: The formation of new C-C bonds by metal complexes always stimulates great
interest because these fundamental reaction types possess numerous potential applications in
organic synthesis. These reactions are well documented for a variety of transition metal
complexes. Herein we report synthesis and characterization of a series of platinum-dialkyl
complexes (1-10) of the type [Pt(L2)R2], (where L2 = dppp (1,3-bis(diphenylphosphino)propane
or L = PPh3; R = n-butyl to n-nonyl) with a view to understand the organic product distribution
patterns on thermolysis. The single crystal X-ray structures of the complexes
[Pt(dppp){CH2(CH2)3CH3}2] (1) and [Pt(dppp){CH2(CH2)6CH3}2] (7) are reported. Thermal
decomposition studies of these complexes show interesting behaviour; the longer chain dialkyls
i.e. C7-C9 complexes undergo reductive elimination whereas the shorter chain dialkyl complexes
and C3-C6 prefer only the β-hydride elimination reaction. Possible mechanistic aspects are
discussed. Theoretical calculations reveal the strongest delocalizations in both complexes
involve the interaction of Pt–C bond pair electron density with the trans positioned Pt–P
antibonding orbital and vice-versa.
Keywords: platinum(II)-dialkyl complex, synthesis, structure, thermolysis, reductive
elimination, β-hydride elimination.

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INTRODUCTION
Reductive elimination of C–H, C–C and C–X bonds is a key step in numerous metal-catalysed
reactions [1]. Among them, catalytic reactions involving of Group 10 metals has been
extensively studied for the formation of new C-C bonded products, where the alkyl or aryl
groups consist of a variety of substituents with pronounced electronic effects [2-4]. This is of
interest to understand the factors influencing the direct reductive elimination reactions in metal-
alkyl complexes [5]. A comprehensive DFT study revealed the reductive elimination barrier in
alkyl-, vinyl-, or arylpalladium(II) complexes is dramatically affected by the nature of ancillary
ligands [6].
In general, metal-alkyls are a very important class of compounds in organometallic chemistry as
key intermediates in a variety of catalytic reactions [7]. The most striking feature of metal-alkyls,
with shorter alkyl chains, is that they can undergo β-hydride elimination at ambient temperatures
prior to either the reductive elimination or α-hydride elimination reactions. These reactions are
also shown by related compounds such as metal-alkenyls and metallacycloalkanes [8]. The β-
hydride elimination is also a fundamental termination step in many catalytic reactions [9]. In the
past, Whitesides and co-workers studied thermal decomposition reactions of some platinum(II)-
dialkyl compounds PtL2R2 (where R = Me, Et and L2 = PPh3, Bu3P), and suggested mechanistic
pathways [10].
Current studies of the fundamental chemistry at platinum centres are essential to intrinsic modes
of platinum reactivity, particularly those that possess longer alkyl chains. Herein we report the
preparation of platinum-dialkyl complexes (1-10) of the type [Pt(L2)R2], containing two metal-
carbon σ- bonds with short and long alkyl chains (where L2 = dppe and dppp; R = n-butyl to n-
nonyl). In addition, we also report a surprising competition between two different decomposition
pathways i.e. β-hydride elimination vs reductive elimination associated with a slight change in
the length of the alkyl chains. These studies could play a crucial role in the design and rational
development of novel reagents/ catalysts for the selective reductive elimination reactions of C-X
(X = carbon or any heteroatom) [11].

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EXPERIMENTAL SECTION
General Methods. All manipulations were carried out under a nitrogen atmosphere unless
otherwise stated. The solvents were commercially available and distilled from dark purple
solutions of benzophenone ketyl. Reagents were purchased from Sigma-Aldrich. GC analyses
were carried out using a Varian 3900 gas chromatograph equipped with an FID and a 30 m x
0.32 mm CP-Wax 52 CB column (0.25 µm film thickness). The carrier gas was helium at 5.0 psi.
The oven was programmed to hold at 32°C for 4 min and then to ramp to 200°C at 10 deg/min
and hold 5 min. (COD)PtCl2[12], (PPh3)2PtCl2[13], (dppp)PtCl2[14], (dppm)PtCl2, alkyl
Grignard reagents (BrMgCH2CH2(CH2)nCH2CH3; n = 1, 2, 3, 4, 5) were prepared according to
literature procedures [15].
Instrumentation. NMR spectra were recorded on a Bruker DMX-400 spectrometer operating at
1
500.13 and 202.46 MHz, respectively, for H and 31P spectra. Spectra are reported in δ (ppm)
1
relative to TMS, as determined from standard residual solvent-proton (or carbon) signals for H
13
and C, relative to external (capillary) H3PO4 for 31P. Melting points were measured in sealed
capillaries using a Büchi melting point instrument and are uncorrected. GC-MS analyses for peak
identification were performed using an Agilent 5973 gas chromatograph and Perkin-Elmer
Clarus 600 C equipped with MSD and a 60 m x 0.25 mm Rtx-1 column (0.5 µm film thickness).
The carrier gas was helium at 0.9 mL/min. The oven was programmed to hold at 50°C for 2 min
and then ramp to 250°C at 10 deg/min and hold 8 min. Elemental analyses were performed with
a Thermo Flash 1112 Series CHNS–O analyzer instrument, upon crystalline samples that had
been dried in vacuo.
Single Crystal X-Ray Analysis. A microscope was used to identify suitable crystals of the same
habit. The crystallographic data for all the single crystals was collected at 113 K on a Nonius
Kappa CCD diffractometer using graphite- monochromated Mo-Kα radiation (λ = 0.71073 Å).
Space groups were determined on the basis of systematic absences and intensity statistics. The
structures were solved by direct methods and refined by full-matrix least-squares refinement on
F2. Anisotropic displacement parameters were determined for all non-hydrogen atoms. Hydrogen
atoms were placed at idealized positions and refined with fixed isotropic displacement
parameters.

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Synthesis of cis-Pt(n-pentyl)2(dppp) (1): A Schlenk flask was charged with Pt(COD)Cl2 (501
mg, 1.34 mmol) and diethyl ether (25 mL). The mixture was cooled to T = -78°C and n-pentyl
Grignard reagent (3.25 mL, 1.24 M, 4.02 mmol) was added. The solution was brought to around
0°C and then stirred until the solution becomes clear. To this, dppp (552 mg, 1.34 mmol) was
added and stirred for 1h until a clear solution is formed. The excess Grignard reagent was
removed by hydrolyzing the reaction mixture with 5 mL of saturated aqueous NH4Cl at -78°C.
The aqueous layer was washed with 2 x 5 mL of dichloromethane and the organic layer was
separated by a separating funnel. The solvent was removed under reduced pressure and the
residue recrystallized from a CH2Cl2/hexane mixture (3:5) at -10°C for 48 h. The colorless
crystalline solid was separated by decanting the mother liquor and dried under vacuum for
several hours. For 1: m.p. 152-154°C (dec); Yield 96%; Anal. Calcd for C37H48P2Pt: C, 59.27; H,
1
6.45. Found: C, 59.46; H, 6.63; H NMR: δ 7.24-8.17 (m, 20H, Ph); 2.43-2.56 (m, 6H, P-
CH2CH2), 0.66-2.59 (m, 22H, -CH2 and –CH3); 31P{1H} = δ 3.38 (s) (JPt-P = 1665 Hz).
Synthesis ofcis-Pt(n-pentyl)2(PPh3)2 (2): A similar procedure was followed using Pt(COD)Cl2
(406 mg, 1.085 mmol) in diethyl ether (20 mL), n-pentyl Grignard reagent (2.6 mL, 1.24 M,
3.26 mmol) and PPh3 (570 mg, 2.173 mmol) was added and stirred for 36 h until a clear solution
is formed. The reaction mixture was worked up as described above. For 2: m.p. 162-164°C; yield
97%; Anal. Calcd. for C46H52P2Pt: C, 64.10; H, 6.08. Found: C, 64.14; H, 6.11; 1H NMR: δ 7.22-
7.82 (m, 30H, Ph), 0.86-2.08 (m, 22H, -CH2 and –CH3); 31P{1H} = δ 26.92 (s), J(Pt-P) = 1724.24
Hz.
Synthesis of cis-Pt(n-hexyl)2(dppp) (3): A similar procedure was followed using (dppp)PtCL2
(0.502 g, 0.71 mmol) in dry diethyl ether (30 mL) and MgBr(CH2)5CH3 (4.0 ml, 1.0 M, 4.0
mmol) under N2 at -78oC. The obtained pale yellow solid was dried under vacuum for 1 hour to
give 3 as a pale yellow solid (0.34 g, 62%), m.p. 90–95oC. Anal. Calcd. for C39H52P2Pt: C, 60.22;
H, 6.74; Found: C, 59.60; H, 6.81. 1H-NMR (CDCl3): δ 7.60 – 7.14 (m, 20H, Ph), 2.46-2.60 (m,
6H, P-CH2CH2), 0.73 – 2.38 (m, 26H, -CH2 and –CH3). 31P NMR (CDCl3): δ 3.44 (s), J(Pt-P) =
1623 Hz.

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Synthesis of cis-Pt(n-hexyl)2(PPh3)2 (4): The same procedure was followed by using
(COD)PtCl2 (0.3 g, 0.8 mmol) in dry diethyl ether (30 mL), MgBr(CH2)5CH3 (3.2 mL, 1.0 M,
3.2 mmol) and PPh3 (0.42 g, 1.6 mmol). After evaporating the solvent, the product 4 was
obtained as a pale yellow crystalline solid, this was dried under high vacuum for 1 hour. Yield
o
(0.54 g, 76%), m.p. 116–120 C. Anal. Calcd. for C48H56P2Pt: C, 64.78; H, 6.34%; Found: C,
64.02; H, 6.83. 1H-NMR (CDCl3): δ 7.82 – 7.13 (30H, m, Ph), 0.94 – 1.40 (m, 26H, -CH2 and –
CH3). 31P NMR (CDCl3): δ 27.18 (s), J(Pt-P) = 1726.33 Hz.
Synthesis of cis-Pt(n-heptyl)2(dppp) (5): (dppp)PtCl2 (700 mg, 1.032 mmol) was reacted with
n-heptyl Grignard reagent (2.06 ml, 4.126 mmol) in diethyl ether (40 ml). The reaction mixture
was worked up as described above. The oil was recrystallized from a 50:50 mixture of hexane
and diethyl ether (20 ml) to give 5 as colorless crystalline solid, which were dried under vacuum
for 1 hour. Yield 80%; m.p. 97-99°C; Anal. Calcd. for C41H56P2Pt: C, 61.10; H, 7.00, Found: C,
1
61.09; H, 7.24; H NMR (300 MHz, CDCl3): 7.17-7.61 (m, 20H, Ph), 2.28-2.42 (m, 6H, P-
CH2CH2), 0.78-2.23 (m, 30H, -CH2 and –CH3); 31P NMR (CDCl3): δ 3.46 (s), J(Pt-P) = 1623.03
Hz.
Synthesis of cis-Pt(n-heptyl)2(PPh3)2 (6): (COD)PtCl2 (600 mg, 1.600 mmol) was reacted with
n-heptyl Grignard reagent (2.06 mL, 4.126 mmol) in 35 mL of diethyl ether. After the reaction,
PPh3 (839 mg, 3.200 mmol) was added. The obtained oily mass was recrystallized from a 50:50
mixture of hexane and diethyl ether (25 mL) to give 6 as colorless crystalline solid, which was
dried under vacuum for 1 h. Yield (84%); m.p. 99-102°C; Anal. Calcd. for C50H60P2Pt: C, 65.42;
H, 6.59, Found: C, 65.55; H, 6.55; 1H NMR (300 MHz, CDCl3): δ 7.01-7.68 (m, 30H, Ph), 0.73-
1.95 (m, 30H, –CH2 and -CH3); 31P NMR (CDCl3): δ 27.18 (s), J(Pt-P) = 1716.33 Hz.
Synthesis of cis-Pt(n-octyl)2(dppp) (7): (COD)PtCl2 (342 mg, 0.914 mmol) in diethyl ether (30
mL), 3.1 mL of n-octyl Grignard reagent (0.88 M, 2.74 mmol) and dppp (377 mg, 0.914 mmol)
were used to prepare 7 as described above. For 7: mp 78-80°C; yield 94%; Anal. Calcd for
1
C43H60P2Pt : C, 61.93; H, 7.25. Found: C, 62.23; H, 7.28; H NMR: δ 6.92-7.64 (m, 20H, Ph);
2.08-2.19 (m, 6H, P-CH2CH2); 0.83-2.05 (m, 34H, -CH2 and –CH3); 31P{1H} 3.88 (s) (JPt-P
=
1618 Hz).

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Synthesis of cis-Pt(n-octyl)2(PPh3)2 (8): (COD)PtCl2 (336 mg, 0.898 mmol) in diethyl ether (30
mL) was reacted with 3.1 mL of 1-octenyl Grignard reagent (0.88 M, 2.694 mmol). To this,
PPh3 (471 mg, 1.796 mmol) was added and stirred for 36 h until a clear solution is formed. The
reaction mixture was worked up as described above. For 8: mp 110-112°C; yield 92%; Anal.
1
Calcd for C52H64P2Pt : C, 66.01; H, 6.82. Found: C, 66.13; H, 6.88; H NMR: δ 7.12-7.96 (m,
30H, Ph); 0.83-2.05 (m, 34H, -CH2 and –CH3); 31P{1H} 27.84 (s) (JPt-P = 1634 Hz).
Synthesis of cis-Pt(n-nonyl)2(dppp) (9): Pt(COD)Cl2 (256 mg, 0.684 mmol) in diethyl ether (30
mL) was cooled and 1.85 mL of n-nonyl Grignard reagent (1.12 M, 2.05 mmol) was added. The
solution was brought to around 0°C and then stirred until the solution becomes clear. To this,
dppp (282 mg, 0.684 mmol) was added and stirred for 36 h until a clear solution is formed. The
reaction mixture was worked up as described above. For 9: m.p. 68-70°C; yield 94%; Anal.
1
Calcd. for C45H64P2Pt : C, 62.70; H, 7.48. Found: C, 62.84; H, 7.52; H NMR δ 7.02-7.64 (m,
31
20H, Ph, 2.12-2.21 (m, 6H, P-CH2CH2); 0.76-2.08 (m, 38H, -CH2 and –CH3); P{1H} 3.94 (s)
(JPt-P = 1634 Hz).
Synthesis of cis-Pt(n-nonyl)2(PPh3)2 (10): (COD)PtCl2 (286 mg, 0.764 mmol) in diethyl ether
(30 mL) was cooled to T = -78°C and 2.05 mL of n-nonyl Grignard reagent (1.12 M, 2.29 mmol)
was added. The solution was brought to around 0°C and then stirred until the solution becomes
clear. To this, PPh3 (401 mg, 1.53 mmol) was added and stirred for 36 h until a clear solution is
formed. The reaction mixture was worked up as described above. For 10: mp 92-94°C; yield
1
90%; Anal. Calcd. for C54H68P2Pt : C, 66.58; H, 7.04. Found: C, 66.68; H, 7.16; H NMR: δ
6.86-7.88 (m, 30H, Ph); 0.68-2.16 (m, 38H, -CH2 and –CH3); 31P{1H} = δ 27.4 (s) (JPt-P = 1684
Hz).
Synthesis of cis-Pt(n-hexyl)Cl(dppp) (11): 3 (1.245 g, 1.6 mmol) was added to a mixture of 250
mL of CH2Cl2 and 100 mL of methanol. To this, acetyl chloride (125 mg, 1.6 mmol) in 125 mL
of CH2Cl2 was added drop-wise over 2 h using an ice-cold bath under constant stirring. Then the
formed precipitate was filtered and all the volatiles were removed from the filtrate by rotavap.
The product 11 was recrystallized from the solvent mixture of 1:1 CH2Cl2 and methanol. Yield =
0.536 g (46%). mp 198–200°C (dec.). 1H NMR: δ 7.28–7.96 (m, 20H, Ph), 2.65–3.11 (m, 6H, P–

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CH2CH2), 0.66–1.38 (m, 13H, CH2 and CH3); 31P NMR: δ −1.5 (s) (JPt-P = 3842 Hz). Anal. calcd
for C33H39P2PtCl: C, 54.43; H, 5.40. Found: C, 54.56; H, 5.48.
Synthesis of cis-Pt(n-hexyl)(n-octyl)(dppp) (12): 11 (282 mg, 0.3873 mmol) and dry diethyl
ether (30 mL) were taken in a Schlenk flask and 1.5 mL of n-octyl Grignard reagent (0.92 M,
0.78 mmol) was added to the flask at -78°C. The solution was brought to around 0°C and then
stirred until the solution becomes clear. The reaction mixture was worked up as described for
1
compound 1. For 12: mp 106-108°C (dec.); yield 82%; H NMR: δ 6.96–7.84 (m, 20H, Ph),
2.32–2.52 (m, 6H, P-CH2CH2), 0.65–2.38 (m, 30H, -CH2 and -CH3); 31P NMR: δ 2.56, 2.69 ppm
and 4.23, 4.12 ppm (JPt-P = 1675 and 1689 Hz). Anal. calcd for C41H56P2Pt: C, 61.10; H, 7.00.
Found: C, 61.16; H, 7.11.
General procedure for thermolysis:
Thermolysis reactions were carried out in dry, sealed and evacuated vertical Schlenk tubes of 1-
cm o.d. and 10-cm lengths. The platinum complexes were dissolved in DCM and transferred into
the tube; the solvent was removed under vacuum and dried at least for 6 hours before
thermolysis. The samples were then immersed in a thermostated oil bath constant at 170±5 ºC.
The tubes were removed at intervals (2 h) and quenched by immersion in liquid nitrogen.
Decomposition products were extracted by 0.5 mL pentane containing 20 µL of chlorobenzene
as internal standard and analyzed by GC/GCMS. Products were identified by comparison of
retention times to those of authentic samples. Product yields were determined by response
relative to the internal standard (chlorobenzene).
4. Computational Details
All the calculations were based on density functional theory (DFT) and Gaussian 09 package was
exploited to carry out these calculations [16]. The optimization of the geometries was done by
employing Becke’s hybrid three-parameter exchange functional and the nonlocal correlation
functional of Lee, Yang and Parr (B3LYP)[17-19] and the standard 6-31G* basis set function of
DFT for all atoms except the Platinum (Pt) atom for which effective core potential (ECP) of
Wadt and Hay pseudopotential with a double- ζ basis set LANL2DZ has been employed. For the
structural calculations of transition metal complexes, the relativistic LANL2DZ pseudopotential
is the typical basis set and is identified to give close agreement between optimized and

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experimentally determined structures for organoplatinum complexes [20]. In order to see the
identity of each stationary point found as a global minimum, frequency calculation was
performed too by employing the same level of theory. The population analysis has been
performed by the natural bond orbital (NBO) method [21] at B3LYP/631G* level of theory using
NBO 3.1 version of Gaussian 09 program package.
RESULTS AND DISCUSSION
Synthesis and Spectroscopic Characterization of Platinum-Dialkyl complexes. The dialkyl-
platinum(II) complexes 1-10 were obtained by the transmetalation reaction of alkyl Grignard
reagents with either [Pt(COD)Cl2] or [PtL2Cl2](L2 = dppp or L = PPh3) precursors as shown in
Scheme 1. Complexes 1-10 were obtained as colorless solids in high yield after recrystallization
from CH2Cl2/diethyl ether. These new compounds were found to be quite stable at room
temperature and the thermal stability of the complexes follows the order PPh3 < dppp due to the
31
chelating effect. The P{1H} NMR spectra of all the compounds displayed a singlet around 3.4
ppm for 1, 3, 5, 7, 9 compounds and 26.4 ppm for 4, 6, 8, 10 compounds respectively with Pt
satellites. The average coupling constants (1JPt-P) of these compounds were found to be 1620 Hz
for 1, 3, 5, 7, 9 and 1800 Hz for 4, 6, 8, 10 respectively, which are quite similar to their bis(1-
alkenyl)platinum(II) analogs [22]. All new compounds described in Scheme 1 were characterized
by analytical and spectroscopic methods.
Alkyl-Grignard
Cl
n
Reagent
Pt
Pt
Cl
n
n = 1- 5
1, n = 1, L2 = dppp
2, n =1, L2 = dppm
3, n = 2, L2 = dppp
4, n = 2, L = PPh3
5, n = 3, L2 = dppp
6, n = 3, L = PPh3
7, n = 4, L2 = dppp
8, n = 4, L = PPh3
9, n = 5, L2 = dppp
10, n = 5, L = PPh3
L
+ L2
-COD
n
Pt
L
n
L2 = dppp; L = PPh3

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Scheme 1.Preparation of various platinum-dialkyl complexes
Careful reaction of 3 with either 1 mole of acetyl chloride solution in a solvent mixture of
methanol-dichloromethane (1:1) yielded the mono-hexyl compound 11. The reaction of 11 with
the n-octyl Grignard reagent gave compound 12, which now contains two different alkenyl
chains of the type [(dppp)Pt(n-hexyl)(n-octyl)] (Scheme 2). The unsymmetrical nature of this
molecule is clearly seen in the 31P NMR spectrum which shows two doublets, each with platinum
satellites showing the signals at 2.56, 2.69 ppm and 4.23, 4.12 ppm (JPt-P = 1675 and 1689 Hz).
L
L
L
1:1 HCl
nꢀoctylMgBr
3
Pt
Pt
Methanol ꢀ
dicholromethane
Et2O
L
Cl
L2 = dppp
11
12
Scheme 2: Preparation of [(dppp)Pt(n-hexyl)(n-octyl)]
Crystallographic Characterization of Platinum-Dialkyls. The molecular structures of 1 and 7
are shown in Fig.1 and Fig.2 respectively [23]. To the best of our knowledge, these are the first
examples of structurally characterized dipentyl or dioctylplatinum(II) compounds reported in the
literature. The main structural features of complex 1 and 7 are given in some of the bond angles
and bond lengths. The Pt-C and Pt-P bond lengths are slightly different in 1 when compared to
7but comparable to the bis(1-heptenyl)platinum(II) analogs and the other literature reports
[22,24]. (Pt-C, 2.099(4)-2.101(4) Ǻ for 1; 2.114(3)-2.118(3) Ǻ for 7 and Pt-P, 2.2811(9)-
2.2824(10) Ǻ for 1; 2.2749(8)-2.2922(8) Ǻ for 7 respectively). The P-Pt-P and C-Pt-C bond
angles in 1 and 7 are significantly different and vary from 93.05(4)-93.12(3)° and 85.96(16)-
85.15(12)°. The minimum distance between metal and β-hydride is found to be 3.079 and 3.215
(Ǻ) for 1 and 7 respectively.

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Figure 1. Molecular structure of 1 with bis(diphenylphosphino)propane ligand (dppp), showing
the atom numbering scheme. Displacement ellipsoids are drawn at the 40% probability level and
H atoms are shown as small spheres of arbitrary radii. Selected bond lengths (Ǻ) and Bond
angles (°): Pt(1)-C(61) 2.099(4); Pt(1)-C(51) 2.101(4); Pt(1A)-P(1A) 2.2811(9); Pt(1)-P(2)
2.2824(10);
C(61)-Pt(1)-C(51) 85.96(16); C(61)-Pt(1)-P(1) 174.67(11); C(51)-Pt(1)-P(1)
90.46(11); P(1)-Pt(1)-P(2) 93.05(4).
Figure 2. Molecular structure of 7 with bis(diphenylphosphino)propane ligand (dppp), showing
the atom numbering scheme. Displacement ellipsoids are drawn at the 40% probability level and
H atoms are shown as small spheres of arbitrary radii. Selected bond lengths (Ǻ) and Bond
angles (°): Pt(1)-C(61) 2.114(3); Pt(1)-C(51) 2.118(3); Pt(1)-P(1) 2.2749(8); Pt(1)-P(2)

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2.2922(8); C(61)-Pt(1)-C(51) 85.15(12); C(61)-Pt(1)-P(1) 174.83(8); C(51)-Pt(1)-P(1) 89.89(9);
C(61)-Pt(1)-P(2) 91.71(9); C(51)-Pt(1)-P(2) 174.67(9); P(1)-Pt(1)-P(2) 93.12(3).
Thermolysis Studies.
β-Hydride elimination is the most important mechanism for metal alkyl decomposition through
the agostic interaction [25, 26] and metal-catalyzed isomerization with involvement of d-orbitals
of the metal in the reaction pathway and this is a lower energy process than many others, such as
α-elimination, γ-elimination, reductive elimination, and transmetalation [27]. It is very important
to suppress the β-hydride elimination for the success of many transition metal mediated reactions
achieving the efficiency [28].
In the present work, thermolysis of shorter chain (< C7) platinum(II)-dialkyl compounds showed
the formation of a mixture of 1-alkenes and 2-alkenes through β-hydride elimination (Scheme 3
and Table 1), which is consistent with the literature data for small chain compounds [5, 25]. It is
significant to note that the nature of the ligand does not influence the decomposition pathway,
though PPh3 complexes decompose at relative low temperatures (< 100 ºC) than the diphosphine
analogues. Surprisingly, the reductive elimination reaction dominated over β-hydride elimination
when the chain length was increased (Eq.1). It seems that this reaction pathway is governed by
the distance between metal and β-hydrogen. In the case of 1 with relatively shorter alkyl chains
(C5), the β-hydride elimination is more predominant as the metal- β-hydrogen distance is shorter
((3.079 Ǻ) whereas 7 with longer alkyl chains (C8) exhibits reductive elimination due to the
significantly longer distance i.e. 3.215 (Ǻ) (Fig.3 and Table 1).
This phenomenon can be explained with the co-planar conformation of M-C-C-H unit in an
organometallic complex to accommodate the 4-centered concerted planar transition state to lead
to β-hydride elimination. As the length of alkyl chains increases, it is less feasible for the M-C-
C-H unit to adopt a planar conformation to favour β-hydride elimination [29]. On the other hand,
strongly bound or unlabile ligands [29], reduced electron density on the metal and strong π-
acceptor ligands attached to the metal [30] retard β-hydride elimination in organoplatinum(II)
complexes. Further, the large bite angle of bidentate phosphine ligands accelerates reductive
elimination by forcing the two alkyl groups closer together about the metal center [31]. The

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bidentate bis(diphenylphosphino)ferrocene ligand also favors reductive elimination by enforcing
a cis geometry for the vinyl and alkyl ligands on square planar Pd(II) [32]. If a slight increase in
chain length prefers the reductive elimination due to the steric bulk, it should have happened in
the decomposition of cis-bis(alkenyl)-platinum(II) complexes [33]. But no such reductive
elimination was observed in the latter complexes as the presence of unsaturated olefinic double
bond shows a different chemistry.
Scheme.3 β-hydride elimination shown by dialkyl-platinum(II) complexes with shorter alkyl
chains (C3-C6)
Eq.1. Reductive elimination shown by dialkyl-platinum(II) complexes with longer alkyl chains
(C7-C9)
There are two other instances where the reductive elimination was preferred over β-hydride
elimination as given in Scheme 4. Firstly, the addition of free dppp ligand was tested i.e. on
heating, the interaction of dppp with [L2PtR2] yielded the products [(dppp)2Pt] and R-R

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quantitatively by reductive elimination reaction as reported earlier [29,34]. Secondly, reductive
elimination was favoured in the presence of either alkyl halides (MeI) [35] or Ru3(CO)12[36]
through the oxidative addition reaction with [L2PtR2] complexes and subsequent formation of
hexacoordinate tetravalent platinum species. A similar trend was obtained for the [(dppp)NiR2]
complexes i.e. when R =
n
-pentyl, β-hydride elimination is more predominant and only the
-decyl [37].
reductive elimination product was observed when R =
n
Scheme.4. Other routes for reductive elimination reactions
On thermolysis, 12 yielded the organic product distribution as shown in Eq.2. As expected, the
major product was the reductively eliminated
n-butadecane in 64% yield. The selective
formation of products through either β-hydride elimination or reductive elimination was more
difficult to envision, as the formation of these products requires completely different conditions.
In the case of complex 7 with octyl chains, the rate of C-C bond forming reductive elimination
would need to be faster than the competing β-hydride elimination. We show here that it is
feasible to achieve selectivity for complex 7 by employing same chelating ligands to minimize
the rate of β-hydride elimination. The dihedral angles of the M-dialkyl complexes might be
different in solution as well as the solid state during the decomposition at high temperatures.

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Eq.2: Organic product distribution of 12 upon thermolysis
79.5
94
99
100
90
80
70
60
% Reductive
50
Elimination
40
30
20
10
0
5
6
7
8
9
10
Number of carbon atoms in a chain
Fig.3: Reductive elimination of dialkyl complexes (where L2 = dppp ligand) as a function
of length of carbon chains.

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Table 1: Thermal decomposition products of
n
-dialkyl-platinum(II) complexes (1-11)
Organic products identified*, %**
Compound Ligand
1-pentene
2-pentene
n
n
n
-pentane
n
-decane
dppp
PPh3
38
33
29
0
0
1
2
59
0
41
1-hexene
2-hexene
n
-hexane
n-dodecane
dppp
PPh3
37
26
35
2
5
3
4
35
22
38
-heptane
13
1-heptene
2-heptene
n
-tetradecane
dppp
PPh3
14
5
68
91
5
6
4
1
4
1-octene
2-octene
n-octane
n
-hexadecane
dppp
PPh3
0
2
0
98
81
7
8
9
4
6
1-nonene
2-nonene
-nonane
n
-octadecane
dppp
PPh3
0
1
0
0
99
99
9
0
1-pentene
8
1
2-pentene
10
10
1-octene
4
2-octene
14
n
-tetradecane
dppp
64
12
*determined by GC-MS analysis; **average of three determinations each
Theoretical Aspects: In Pt-complexes (1 and 7) the co-ordination environment of the central
metal atom displays a slightly distorted square planar geometry with minute deviations from
experimental numbers. The bonding parameters from the X-ray crystal structure are compared
with the optimized geometrical parameters (supporting information). The difference in calculated
and observed bonding parameters is negligible and does not provide any useful additional
outcome. The comparison of some DFT computed key geometrical parameters between 1 and 7
is highly essential. Focussing on the distance parameters only, it is indispensable to target the β-
hydrogens as they are highly involved in the reaction mechanism of the complexes. The
important geometrical parameters related to β- hydrogens are summarised in Table 2. The Pt(1) –

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H(62) and Pt(1) – H(63) distances in 1 are 3.380Å and 3.329 Å respectively though both on the
same atom C(58) while as the distance between Pt(1) and Hs on C(70) is almost same. Similarly
in 7, the distance between Pt(1) and hydrogens on C(58) is almost the same but different between
the Pt(1) and hydrogens on C(70). It is clear that Pt(1)- H(β) distances are smaller in 1 in
comparison to 7 and the complexes show varying distances between the Pt centre and β-
hydrogens within a single complex which may have a significant effect on the reaction
mechanism. The optimized geometries of 1 and 7 are traced out in Fig. 4 and 5 respectively.
Table 2: Theoretically calculated distances between the Pt(1)-Hs(β)of 1 and 7.
Molecule
1
Centers involved
Theoretical distances a
Pt(1) – H(62)
Pt(1) – H(63)
Pt(1) – H(74)
Pt(1) – H(75)
3.380
3.329
3.281
3.281
Pt(1) – H(62)
Pt(1) – H(63)
Pt(1) – H(74)
Pt(1) – H(75)
3.374
3.378
3.310
3.298
7
ͦ
aDistances are in angstroms (A) and numbering of atoms is given as in optimized
geometries at DFT level.
Fig. 4. Optimized structure of 1.
Fig 5. Optimized structure of 7.

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To extract more meaningful and comprehensible understanding of Pt-complexes regarding the
nature of bonding, the electronic structure was evaluated (supporting information). Natural
population analysis (NPA) revealed a partial charge on the Pt atom while a positive charge on the
bonded phosphorous (P2, P3) atoms and a negative charge on the bonded carbon (C57, C69)
atoms were observed respectively (supporting information). The significant covalent interactions
between the central metal atom and ligands have been obtained from quantum chemistry wave
function-based Wiberg bond index analysis (supporting information). The polar nature of these
covalent bonds and resonance stabilization of the Pt-complex was obtained from the natural bond
orbital (NBO) analysis. Perturbation theory energy analysis revealed that the strongest
delocalizations in both complexes involve the interaction of Pt–C bond pair electron density with
the trans positioned Pt–P antibonding orbital and vice-versa. These geminal interactions stabilize
the complexes (supporting information). The electron density plots for the complexes of interest
are given in Fig.6 and Fig.7.
Fig. 6 HOMO of 1
Fig. 7: HOMO of 7
Conclusions
We report the synthesis, spectroscopic characterization, X-ray single crystal structures, and
thermolysis studies of platinum-dialkyl complexes of the type [Pt(L2)R2], (where L2 = dppp (1,3-
bis(diphenylphosphino)propane or L = PPh3; R =
n-butyl to n-nonyl). Thermal decomposition
studies of these complexes provided interesting patterns; the longer chain dialkyls i.e. C7-C9

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complexes undergo reductive elimination whereas the shorter chain dialkyl complexes and C3-C6
prefer only the β-hydride elimination reaction. Theoretical calculations reveal that Pt(1)- H(β)
distances are smaller in 1 in comparison to 7 and the complexes show varying distances between
the Pt centre and β-Hs within a single complex which may have a significant effect on the
reaction mechanism. It is also clear that strongest delocalizations in both complexes involve the
interaction of Pt–C bond pair electron density with the trans positioned Pt–P antibonding orbital
and vice-versa.
Acknowledgements
Dr. ASRK is highly grateful to Council of Scientific and Industrial Research (CSIR, New Delhi,
India) (Ref. No. 01(2541)/11/EMR-II) for the financial support. Our sincere thanks are due to
DST-VIT-FIST for NMR and SIF-VIT for GC-MS facilities. Mr. Venkatesh Sadhana is thankful
to CSIR for the Junior Research Fellowship.
References
[1].a) R. H. Grubbs, Hand Book of Metathesis, Wiley-VCH, Weinheim, Germany, 2003; b)
R. B. Bedford, C. S. J. Cazin, D. Holder, Coord. Chem. Rev., 248 (2004) 2283-2321; c)
A. L. Smith, K. I. Hardcastle, J. D. Soper, J. Am. Chem. Soc., 132 (2010) 14358-14360;
d) A. Nijamudheen, S. Karmakar, A. Datta, Chem. A Eur. J., 20 (2014) 14650–14658;
e) I. Pappas, P. J. Chirik, Angew. Chem. Int. Ed., 53 (2014) 6241-6244; f) B. Zheng, F.
Tang, J. Luo, J. W. Schultz, N. P. Rath, L. M. Mirica, J. Am. Chem. Soc., 136 (2014)
6499-6504; g) J. M. Brown, N. A. Cooley, Chem. Rev., 88 (1988) 1031–1046; h) W. J.
Wolf, M. S. Winston, F. D. Toste, Nature Chem., 6 (2014) 159-164; i) Hartwig, J. Inorg.
Chem. 46 (2007) 1936-1947; j) H. Braunschweig, A. Damme, Chem. Commun., 49
2013 5216-5218; k) M. Armelin, M. Schlangen, H. Schwarz, Chem. A Eur. J., 14 (2008)
5229-5236; l) C. M. Anderson, M. Crespo, N. Kfoury, M. A. Weinstein, M. J. Tanski,
Organometallics, 32 (2013) 4199-420; m) L. Tuxworth, L. Baiget, A. Phanopoulos, O.
J. Metters, A. S. Batsanov, M. A. Fox, J. A. K. Howard, P. W. Dyer, Chem. Commun.,
48 (2012) 10413-10415; n) M. Safa, M. C. Jennings, R. J. Puddephatt, Organometallics,
30 (2011) 5625-5635.

ACCEPTED MANUSCRIPT
[2].a) T.T. Tsou, J. K. Kochi, J. Am. Chem. Soc., 101 (1979) 7547–7560; b) S. Komiya, Y.
Abe, A. Yamamoto, T. Yamamoto, Organometallics, 2 (1983) 1466–1468; c) S.
Komiya, Y. Akai, K. Tanaka, T. Yamamoto, A. Yamamoto, Organometallics, 4 (1985)
1130–1136; d) B. L. Lin, C. R. Clough, G. L. Hillhouse, J. Am. Chem. Soc., 124 (2002)
2890–2891; e) L. Jin, H. Zhang, P. Li, J. R. Sowa, A. Lei, J. Am. Chem. Soc., 131
(2009) 9892–9893.
[3].a) D. Milstein, J. K. Stille, J. Am. Chem. Soc. 101 (1979) 4981–4991; b) A. Moravskiy,
J. K. Stille, J. Am. Chem. Soc., 103 (1981) 4182–4186; c) J. J. Low, W. A. Goddard, J.
Am. Chem. Soc., 108 (1986) 6115–6128; d) P. K. Byers, A. J. Canty, M. Crespo, R. J.
Puddephatt, J. D. Scott, Organometallics, 7 (1988) 1363–1367; e) R. A. Widenhoefer, S.
L. Buchwald, J. Am. Chem. Soc., 120 (1998) 6504–6511; f) K. Osakada, H. Onodera,
Y. Nishihara, Organometallics, 24 (2005) 190–192; g) J. F. Hartwig, Inorg. Chem., 46
(2007) 1936–1947.
[4].M. P. Brown, R. J. Puddephatt, C. E. E. Upton, J. Chem. Soc. Dalton Trans., (1974)
2457–2465; b) L. Abis, A. Sen, J. Halpern, J. Am. Chem. Soc., 100 (1978) 2915–2916;
c) S. S. Stahl, J. A. Labinger, J.E. Bercaw, J. Am. Chem. Soc., 117 (1995) 9371–9372;
d) S. Shekhar, J. F. Hartwig, J. Am. Chem. Soc., 126 (2004) 13016–13027; e) J. E.
Bercaw, G. S. Chen, J. A. Labinger, B.-L. Lin, Organometallics, 29 (2010) 4354–4359;
f) M. P. Lanci, M. S. Remy, D. B. Lao, M. S. Sanford, J. M. Mayer, Organometallics,
30 (2011) 3704–3707; g) A. L. Liberman-Martin, R. G. Bergman, T. D. Tilley, J. Am.
Chem. Soc., 135 (2013) 9612–9615.
[5].E. B. Hager, A. Sivaramakrishna, H. S. Clayton, M. M. Mogorosi, J. R. Moss, Coord.
Chem. Rev., 252 (2008) 1668-1688.
[6].a) M. Mendez, J. M. Cuerva, E. Gomez-Bengoa, D. J. Cardenas, A. M. Echavarren,
Chem. Eur. J., 8 (2002) 3620; b) M. Perez-Rodrǐguez, A. A. C. Braga, A. R. De Lera, F.
Maseras, P. E. Rosana-Alvarez, Organometallics, 29 (2010) 4983–4991; c) M. Pérez-
Rodrıguez, J. Am. Chem. Soc., 131 (2009) 3650–3657.

ACCEPTED MANUSCRIPT
[7].a) J. P. Collman, J. R. Norton, L. S. Hegedus, R. G. Finke, Principles and Applications
of Organotransition metal Chemistry, University Science Books, Mill Valley,
California, 1987; b) A. Yamamoto, J. Organomet. Chem., 689 (2004) 4499.
[8].a) A. Sivaramakrishna, H. Clayton, C. Kaschula, J. R. Moss, Coord. Chem. Rev., 251
(2007) 1294; b) G. R. Newkome, W. E. Puckett, V. K. Gupta, G. Kiefer, Chem. Rev. 86
(1986) 451-489; c) F. M. Conroy-Lewis, L. Mole, A. D. Redhouse, S. A. Litster, J. L.
Spencer, J. Chem. Soc. Chem. Commun., (1991) 1601-1603; d) L. Mole, J. L. Spencer,
N. Carr, A. G. Orpen, Organometallics, 10 (1991) 49-52; e) R. G. Nuzzo, T. J.
McCarthy, G. M. Whitesides, Inorg. Chem., 20 (1981) 1312; f) I. Omae, Chem. Rev., 79
(1979) 287-321.
[9].a) P. L. Theofanis, W. A. Goddard, Organometallics 30 (2011) 4941-4948; b) R. J.
Cross, The chemistry of Metal-Carbon Bond, Wiley, New York, 1985; c) J. K. Kochi,
Organometallic Mechanism and Catalysis, Academic Press, New York, 1978; d) M. L.
H. Green, P. L. I. Nagy, J. Organomet. Chem., 1 (1963) 58; e) S. Komiya, Y. Morimoto,
A. Yamamoto, T. Yamamoto, Organometallics, 1 (1982) 1528; f) G. Erker, K. Kropp, J.
Am. Chem. Soc., 101 (1979) 3659; g) G. W. Parshall, Homogeneous Catalysis, Wiley,
New York, 1980.
[10]. a) T. J. McCarthy, R. G. Nuzzo, G. M. Whitesides, J. Am. Chem. Soc., 103 (1981)
3396-403; b) G. M. Whitesides, Pure and Appl. Chem., 53 (1981) 287-292; b) T. J.
McCarthy, R. G.Nuzzo, G. M.Whitesides, J. Am. Chem. Soc., 103 (1981) 1676.
[11]. (a) R. H. Crabtree, The Organometallic Chemistry of the Transition Metals, John
Wiley & Sons: New York, 2005; (b) G. W. Parshall, S. D. Ittel, Homogeneous
Catalysis: The Applications and Chemistry of Catalysis by Soluble Transition Metal
Complexes, Wiley-Interscience: New York, 1992; c) A. V. Pawlikowski, A. D. Getty,
K. I. Goldberg, J. Am. Chem. Soc. 129 (2007) 10382-10393.
[12]. H. C. Clark, L. E. Manzer, J. Organomet. Chem., 59 (1973) 411-428.
[13]. a) D. A. Slack, M. C. Baird, Inorg. Chim. Acta, 24 (1977) 277-280. b) M. Hackett, G.
M. Whitesides, J. Am. Chem. Soc. 110 (1988) 1449-1462.

ACCEPTED MANUSCRIPT
[14]. J. X. McDermott, J. F. White, G. M. Whitesides, J. Am. Chem. Soc., 98 (1976) 6522.
[15]. A. Sivaramakrishna, B. C. E. Makhubela, J. R. Moss , G. S. Smith, J. Organomet.
Chem., 697 (2010) 1627; b) A. Sivaramakrishna, B. C. E. Makhubela, F. Zheng, G. S.
Smith, H. Su, J. R. Moss, Polyhedron, 27 (2008) 44-52.
[16]. M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb, J. R.
Cheeseman, G. Scalmani, V. Barone, B. Mennucci, G. A. Petersson, H. Nakatsuji, M.
Caricato, X. Li, H. P. Hratchian, A. F. Izmaylov, J. Bloino, G. Zheng, J. L.
Sonnenberg, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T.
Nakajima, Y. Honda, O. Kitao, H. Nakai, T. Vreven, J. A. Montgomery, J. E. Peralta,
F. Ogliaro, M. Bearpark, J. J. Heyd, E. Brothers, K. N. Kudin, V. N. Staroverov, R.
Kobayashi, J. Normand, K. Raghavachari, A. Rendell, J. C. Burant, S. S. Iyengar, J.
Tomasi, M. Cossi, N. Rega, N. J. Millam, M. Klene, J. E. Knox, J. B. Cross, V.
Bakken, C. Adamo, J. Jaramillo, R. Gomperts, R. E. Stratmann, O. Yazyev, A. J.
Austin, R. Cammi, C. Pomelli, J. W. Ochterski, R. L. Martin, K. Morokuma, V. G.
Zakrzewski, G. A. Voth, P. Salvador, J. J. Dannenberg, S. Dapprich, A. D. Daniels, Ö.
Farkas, J. B. Foresman, J. V. Ortiz, J. Cioslowski, D. J. Fox, Gaussian 09, Revision
B.01, Gaussian, Inc., Wallingford, CT, (2009).
[17]. (a) A. D. Becke, Phys. Rev. A, 38 (1988) 3098. (b) A. D. Becke, J. Chem. Phys., 98
(1993) 5648.
[18]. C. Lee, W. Yang, R. G. Parr, Phys. Rev., B 37 (1988) 785.
[19]. S. H. Vosko, L. Wilk, M. Nusair, Can. J. Phys., 58 (1980) 1200.
[20]. (a) P. J. Hay, W. R. Wadt, J. Chem. Phys., 82 (1985) 284. (b) P. J. Hay, W. R. Wadt,
J. Chem. Phys., 82 (1985) 299. (c) A. Schaefer, H. Horn, R. Ahlrichs, J. Chem. Phys.,
97 (1992) 2571; (d) P. J. Hay, W. R. Wadt, J. Chem. Phys., 82 (1985) 270.
[21]. A. E. Reed, L. A. Curtiss, F. Weinhold, Chem. Rev., 88 (1988) 899.
[22]. a) A. Sivaramakrishna, H. Su, J. R. Moss, Angew. Chem. Int. Ed., 46 (2007) 3541-
3543; b) A. Sivaramakrishna, H. Su, J. R. Moss, Dalton Trans., (2008) 2228–2231; c)
A. Sivaramakrishna, E. Hager, F. Zheng, G. S. Smith, H. Su, J. R. Moss, J.
Organomet. Chem., 692 (2007) 5125; d) A. Sivaramakrishna, J. R. Moss, H. Su, Inorg.
Chim. Acta, 363 (2010) 3345.
[23]. a) Structure determination and crystallographic data for 1: crystals were obtained by
slow diffusion of n-hexane into a solution of 1 in dichoromethane. C43H60P2Pt, Mr =

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833.94 gmol-1, triclinic, space group P-1, a = 12.5422(2), b = 12.5954(2), c =
14.9657(3) Ǻ, α = 109.0670(10), β = 90.8960(10), γ = 115.2990(10), V = 1986.56(6)
Ǻ3, Z = 2, ρcalcd = 1.394 gcm-3, T = 113(2) K, m = 3.640 mm-1, F(000)= 852,
4.44°<2θ<25.65°, λ-(MoKα)=0.71073 Ǻ, crystal size 0.13 X 0.17 X 0.21 mm3.
Intensity data were collected with a Nonius Kappa CCD diffractometer. 56406
reflections, 7458 independent (Rint=0.0349), empirical absorption correction
(SADABS), structure solution using direct methods (SHELXS-97), structure
refinement on F2 using full-matrix least-squares procedures (SHELXL-97), R1=
0.0257 [I>2σ(I)], wR2=0.0536 (all data), GOF=1.041; b) Structure determination and
crystallographic data for 7: crystals were obtained by slow diffusion of n-hexane into a
solution of 7 in dichoromethane. C37H48P2Pt, Mr = 749.78 gmol-1, triclinic, space
group P-1, a = 13.3720(10), b = 14.1812(10), c = 18.4824(2) Ǻ, α = 88.7040(10), β =
75.0170(10), γ = 89.2170(10), V = 3384.70(5) Ǻ3, Z = 4, ρcalcd= 1.471 gcm-3, T =
223(2) K, m = 4.263 mm-1, F(000) = 1512, 1.14°<2θ<26.11°, λ-(MoKα) = 0.71073 Ǻ,
crystal size 0.06 X 0.09 X 0.11 mm3. Intensity data were collected with a Nonius
Kappa CCD diffractometer. 87254 reflections, 10362 independent (Rint= 0.0670),
empirical absorption correction (SADABS), structure solution using direct methods
(SHELXS-97), structure refinement on F2 using full-matrix least-squares procedures
(SHELXL-97), R1 = 0.0301 [I>2σ(I)], wR2 = 0.0575 (all data), GOF = 1.055. CCDC-
1403607 (1) and CCDC-1403608 (7) contain the supplementary crystallographic data
for this paper. These data can be obtained free of charge from The Cambridge
Crystallographic Data Centre via http://www.ccdc.cam.ac.uk/ data_request/cif.
[24]. F. H. Allen, O. Kennard, D. G. Watson, R. Taylor, International Tables for
Crystallography, Kluwer Academic Publishers, Dordrecht, (1992).
[25]. F. Zheng, A. Sivaramakrishna, J. R. Moss, Coord. Chem. Rev., 25 (2007) 5063.
[26]. R. J. Klinger, J. C. Huffman, J. K. Kochi, J. Organomet. Chem., C7 (1981) 206.
[27]. a) J. W. Rathke, E. L. Muetterties, J. Am. Chem. Soc., 97 (1975) 3272–3273. b) D. L.
Thorn, R. Hoffmann, J. Am. Chem. Soc., 100 (1978) 2079–2090.
[28]. a) R. J. Cross, The Chemistry of the Metal-Carbon Bond, Frank R. Hartley, Saul Patai
Chapter 8: Transition metal—carbon bond cleavage through β-hydrogen elimination, 2

ACCEPTED MANUSCRIPT
(1985) 559–624. b) J. P. Collman, R. G. Finke, J. R. Norton, Principles and
Applications of Organotransition Metal Chemistry, Chapter 6, University Science
Books, Mill Valley 2nd Edition, (1987). c) R. H. Crabtree: The Organometallic
Chemistry of Transition Metals, Chapter. 7, Insertion and Elimination, 4th Edition,
Wiley- Interscience, (2005); d) G. O. Spessard, G. L. Miessler, Organometallic
Chemistry 2nd Edition, Oxford University Press, (2010). ISBN: 0195330994.
[29]. J. X. McDermott, J. F. White, G. M. Whitesides, J. Am. Chem. Soc., 98 (1976) 6521–
6528.
[30]. J. Tsuji, Transition Metal Reagents and Catalysts:ꢁ Innovations in Organic Synthesis,
Chichester. Wiley, 2000.
[31]. J. E. Marcone, K. G. Moloy, J. Am. Chem. Soc., 120 (1998) 8527–8528.
[32]. a) S. R. Chemler, D. Trauner, S. J. Danishefsky, Angew. Chem. Int. Ed., 40 (2001)
4545. b) Netherton, M. R, Dai, C, Neuscutz, K, Fu, G. C. J. Am. Chem. Soc., 123
(2001) 10099.
[33]. a) F. Zheng, A. Sivaramakrishna, J. R. Moss, Inorg. Chim. Acta, 361 (2008) 2871-
2878. b) C. Sravani, S. Venkatesh, A. Sivaramakrishna, K. Vijayakrishna, Appl.
Organomet. Chem., 28 (2014) 733-746.
[34]. a) F. Ozawa, T. Ito, Y. Nakamura, A. Yamamoto, Bull. Chem. Soc., 54 (1981) 1868-
80. b) A. Sivaramakrishna, H. Su, J.R. Moss, Organometallics 26 (2007) 5786-5790.
[35]. a) M. Safa, M. C. Jennings, R. J. Puddephatt, Organometallics, 30 (2011) 5625-5635.
b) G. B. Young, G. M. Whitesides, J. Am. Chem. Soc. 10 (1978) 5808-5815.
[36]. C. Sravani, S. Venkatesh, A. Sivaramakrishna, K. Vijayakrishna, H. S. Clayton, J.R.
Moss, V. Moberg, H. Su, Polyhedron 62 (2013) 169–178.
[37]. S. Venkatesh, R. Steby, V. Leninkumar, K. Vijayakrishna and A. Sivaramakrishna,
Unpublished results.

ACCEPTED MANUSCRIPT
Highlights
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Platinum(II)-dialkyl complexes were synthesized and structurally characterized.
On heating, the shorter chain dialkyl complexes prefer to undergo only the β-hydride
elimination pathway.
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On contrary, the longer chain dialkyls i.e. C7-C9 complexes undergo selectively reductive
elimination.
DFT calculations reveal the shorter Pt(1)-H(β) distances in shorter chain dialkyl
complexes in comparison to longer chain dialkyls.