24 research outputs found
ASEAN Synergy to Overcome Challenges in Investment Arbitration
Cambodia, Indonesia, Lao, Malaysia, Thailand, and the Philippines, have been sued by foreign investors through International investment arbitrations (IIA). No matter whether the outcome is favorable or not, those countries have spend significant time, energy, and financial resources to arbitrate. ASEAN countries are not in advantageous position in IIA.The first and the most obvious reason is language barrier. Arbitration proceedins are mainly conducted in English. Consequently, the arbitrators and counsels more often than not come from English speaking countries. Not only do they lead to high cost, but also they lack of familiarity with South East Asia\u27s social, politics, economic, culture and customs. This may influence how they treat the cases such as the interpretation of provisions specifically designed to protect foreign investors such as: national treatment; fair and equitable treatment; most favored nation; and also in deciding jurisdictional issues. regional news as a legal basis for foreign investment activities aim to provide protection for foreign investor. On the other hand, it also serves as a mean to facilitate economic development in the host states of investment. Unfortunately, BITs often contain excessive and limitless protection clauses in order to attract foreign investors. This may endanger host states position as it can be used as a weapon by the investors to sue the host states. In responding to this fact, it is necessary to strengthen cooperation among ASEAN members in dealing with foreign investors through BIT. The ideal picture will be that SEA is pro-market and pro-arbitration reform. It is unavoidable that in order to protect themselves from harsh investors as well as intricate arbitration, ASEAN would be better off having its own investment arbitration center run by its experts. Thus, the short-term challenge is to equip legal practitioners, business players and academicians with more knowledge, skills and experiences in dealing with investment disputes. The long-term step will be to negotiate model of investment treaties applicable in the region and to harmonize national investment laws. These efforts are strategic opportunities for ASEAN as single market to keep balance between promoting investment, protecting investors and the host states at the same time
Preparation and Isolation of Dithiolene Thiophosphoryl Molecules as Stable, Protected Forms of Dithiolene Ligands
The reaction of P4S10 with acyloins, RC(O)CH(OH)R, in refluxing dioxane, followed by the addition of alkylating
agents, forms dithiolene thiophosphoryl thiolate compounds, (R2C2S2)P(S)(SR‘), which are readily isolated and
purified. The compounds that have been prepared and identified spectroscopically are those with R = p-anisyl, R‘
= Me (1); R = p-anisyl, R‘ = Bz (2); R = Ph, R‘ = Me (4); R = Et, R‘ = Bz (5). Compounds 1, 2, and 4 were
structurally characterized by X-ray crystallography and found to possess a tetrahedral coordination geometry about
the phosphorus atom, with overall Cs symmetry. In each case, the mirror plane bisects the dithiolene S−P−S
chelate and contains the thiophosphoryl bond, which ranges in length from 1.9241(8) to 1.9361(7) Å. The use of
2-(bromomethyl)naphthalene as organic electrophile in the P4S10/acyloin reaction produced bis(2-methylnaphthalenyl)
disulfide as the only identifiable product. The substitution of Lawesson's reagent for P4S10 in reactions with acyloins
produced deoxy acyloin rather than products resulting from chalcogen exchange. Compounds 1−2 and 4−5 are
Group 5 analogues of 1,3-dithiol-2-ones, (R2C2S2)CO, and undergo a similar hydrolysis in aqueous base to
liberate ene-1,2-dithiolate dianions from which corresponding metal dithiolene complexes may be prepared.
Deprotection of 1 in MeO-/MeOH, followed by the addition of NiCl2·6H2O and then I2, produces square planar
[Ni(S2C2(C6H4-p-OCH3)2)2] (8) in 93% yield. A high-resolution structure of 8 (P1̄) reveals dithiolene C−C and C−S
bond lengths that are clearly indicative of the thionyl radical monoanionic nature of the ligand. The use of isolated
(R2C2S2)P(S)(SR‘) compounds as a dithiolene ligand source for the preparation of metal dithiolene complexes
offers the advantages of clean reactivity and high yield
Preparation and Isolation of Dithiolene Thiophosphoryl Molecules as Stable, Protected Forms of Dithiolene Ligands
The reaction of P4S10 with acyloins, RC(O)CH(OH)R, in refluxing dioxane, followed by the addition of alkylating
agents, forms dithiolene thiophosphoryl thiolate compounds, (R2C2S2)P(S)(SR‘), which are readily isolated and
purified. The compounds that have been prepared and identified spectroscopically are those with R = p-anisyl, R‘
= Me (1); R = p-anisyl, R‘ = Bz (2); R = Ph, R‘ = Me (4); R = Et, R‘ = Bz (5). Compounds 1, 2, and 4 were
structurally characterized by X-ray crystallography and found to possess a tetrahedral coordination geometry about
the phosphorus atom, with overall Cs symmetry. In each case, the mirror plane bisects the dithiolene S−P−S
chelate and contains the thiophosphoryl bond, which ranges in length from 1.9241(8) to 1.9361(7) Å. The use of
2-(bromomethyl)naphthalene as organic electrophile in the P4S10/acyloin reaction produced bis(2-methylnaphthalenyl)
disulfide as the only identifiable product. The substitution of Lawesson's reagent for P4S10 in reactions with acyloins
produced deoxy acyloin rather than products resulting from chalcogen exchange. Compounds 1−2 and 4−5 are
Group 5 analogues of 1,3-dithiol-2-ones, (R2C2S2)CO, and undergo a similar hydrolysis in aqueous base to
liberate ene-1,2-dithiolate dianions from which corresponding metal dithiolene complexes may be prepared.
Deprotection of 1 in MeO-/MeOH, followed by the addition of NiCl2·6H2O and then I2, produces square planar
[Ni(S2C2(C6H4-p-OCH3)2)2] (8) in 93% yield. A high-resolution structure of 8 (P1̄) reveals dithiolene C−C and C−S
bond lengths that are clearly indicative of the thionyl radical monoanionic nature of the ligand. The use of isolated
(R2C2S2)P(S)(SR‘) compounds as a dithiolene ligand source for the preparation of metal dithiolene complexes
offers the advantages of clean reactivity and high yield
Structurally Characterized Cationic Silver(I) and Ruthenium(II) Carbene Complexes of 1,2,3-Triazol-5-ylidenes
A novel 1,3,4-substituted 1,2,3-triazolium salt was found to function as an effective precursor for the synthesis of the first structurally characterized cationic silver(I) and ruthenium(II) carbene complexes of overall 1:2 ligand-to-metal stoichiometry. The Ag(I) complex crystallized in the form of an eight silver atom containing cluster, whereas the Ru(II) complex proved to be a discrete species and was found to be capable of initiating the ring-opening metathesis polymerization of norbornene upon activation with (trimethylsilyl)diazomethane
Synthesis, Structures, and Properties of Mixed Dithiolene-Carbonyl and Dithiolene-Phosphine Complexes of Tungsten
A new, high yield synthesis of [Ni(S2C2Me2)2] (3) is described using 4,5-dimethyl-1,3-dithiol-2-one, Me2C2S2CO (1), as dithiolene ligand precursor. Reaction of (Me2C2S2)SnnBu2, 2, with WCl6 produces tris(dithiolene) [W(S2C2Me2)3] (6) and demonstrates the potential synthetic utility of this compound in metallodithiolene synthesis. The series of compounds [W(S2C2Me2)x(CO)6−2x] (x = 1−3), obtained as a mixture via the reaction of [Ni(S2C2Me2)2] with [W(MeCN)3(CO)3], has been characterized structurally. A trigonal prismatic geometry is observed for [W(S2C2Me2)(CO)4] (4) and confirmed by a DFT geometry optimization to be lower in energy than an octahedron by 5.1 kcal/mol. The tris(dithiolene) compound [W(S2C2Me2)3] crystallizes in disordered fashion upon a 2-fold axis in C2/c, a different space group than that observed for its molybdenum homologue (P1̅), which is attributed to a slightly smaller chelate fold angle, α, in the former. The reactivity of 4 and [W(S2C2Me2)2(CO)2] (5) toward PMe3 has been examined. Compound 4 yields only [W(S2C2Me2)(CO)2(PMe3)2] (7), while 5 produces either [W(S2C2Me2)2(CO)(PMe3)] (8) or [W(S2C2Me2)2(PMe3)2] (9) depending upon reaction conditions. Crystallographic characterization of 5, 8, and 9 reveals a trend toward greater reduction of the dithiolene ligand (i.e., more ene-1,2-dithiolate character) across the series, as manifested by C−C and C−S bond lengths. These structural data indicate a profound effect exerted by the π-acidic CO ligands upon the apparent state of reduction of the dithiolene ligand in compounds with ostensibly the same oxidation state
Synthesis, Structures, and Properties of Mixed Dithiolene-Carbonyl and Dithiolene-Phosphine Complexes of Tungsten
A new, high yield synthesis of [Ni(S2C2Me2)2] (3) is described using 4,5-dimethyl-1,3-dithiol-2-one, Me2C2S2CO (1), as dithiolene ligand precursor. Reaction of (Me2C2S2)SnnBu2, 2, with WCl6 produces tris(dithiolene) [W(S2C2Me2)3] (6) and demonstrates the potential synthetic utility of this compound in metallodithiolene synthesis. The series of compounds [W(S2C2Me2)x(CO)6−2x] (x = 1−3), obtained as a mixture via the reaction of [Ni(S2C2Me2)2] with [W(MeCN)3(CO)3], has been characterized structurally. A trigonal prismatic geometry is observed for [W(S2C2Me2)(CO)4] (4) and confirmed by a DFT geometry optimization to be lower in energy than an octahedron by 5.1 kcal/mol. The tris(dithiolene) compound [W(S2C2Me2)3] crystallizes in disordered fashion upon a 2-fold axis in C2/c, a different space group than that observed for its molybdenum homologue (P1̅), which is attributed to a slightly smaller chelate fold angle, α, in the former. The reactivity of 4 and [W(S2C2Me2)2(CO)2] (5) toward PMe3 has been examined. Compound 4 yields only [W(S2C2Me2)(CO)2(PMe3)2] (7), while 5 produces either [W(S2C2Me2)2(CO)(PMe3)] (8) or [W(S2C2Me2)2(PMe3)2] (9) depending upon reaction conditions. Crystallographic characterization of 5, 8, and 9 reveals a trend toward greater reduction of the dithiolene ligand (i.e., more ene-1,2-dithiolate character) across the series, as manifested by C−C and C−S bond lengths. These structural data indicate a profound effect exerted by the π-acidic CO ligands upon the apparent state of reduction of the dithiolene ligand in compounds with ostensibly the same oxidation state
Long-Range Spin Coupling: A Tetraphosphine-Bridged Palladium Dimer
The dipalladium compound [{(adt)Pd}2(μ-tpbz)] (1) (adt = bis(p-anisyl)-1,2-ethylenedithiolate, tpbz = 1,2,4,5-tetrakis(diphenylphosphino)benzene) has been synthesized from [{Cl2Pd}2(μ-tpbz)] by transmetalation employing (adt)SnMe2. The cyclic voltammogram (CV) of 1 reveals reversible oxidation waves at 0.00 V and +0.50 V (vs [Fc]+/Fc) with current amplitude twice that for identical processes in the monopalladium compound [(adt)Pd(dppb)] (2) (dppb = 1,2-bis(diphenylphosphino)benzene), an observation indicating each wave involves simultaneous one-electron oxidations at each metallodithiolene fragment. This assignment is affirmed by density functional theory (DFT) calculations that show the redox-active molecular orbital (MO) is principally composed of the dithiolene S2C2 π-system, and by spectroelectrochemical UV−vis of [1]2+, which displays hallmark low energy charge transfer (CT) bands. Dication [1]2+ is a diradical with a near degenerate singlet−triplet ground state; fluid solution electron paramagnetic resonance (EPR) spectra validate the DFT-derived isotropic exchange coupling, J′ = −6.3 cm−1. The frozen solution X-band EPR spectrum of [1]2+ is consistent with a spin-triplet bearing a very faint half-field (“ΔMS = 2”) signal. It is successfully simulated with an amazingly small zero field splitting, D = −15 × 10−4 cm−1 and negligible rhombicity (E/D = 0.008). These zero-field splitting parameters, which stem from the long-range dipolar spin coupling, are very accurately reproduced using a multipoint dipole model with an optimized interspin distance of 12.434 Å. With the framework reported herein for understanding how the weak interaction of two spins is mediated by tpbz, this bridging ligand can now be incorporated into extended systems with tailored chemical and physical properties for use in a variety of molecular-based electronic and magnetic devices
Reversible, Electrochemically Controlled Binding of Phosphine to Iron and Cobalt Bis(dithiolene) Complexes
The homoleptic bis(dithiolene) complexes [M(S2C2R2)2]2 (M = Fe,
Co; R = p-anisyl) undergo two successive reductions to form
anions that display [M(S2C2R2)2]22- ↔ 2[M(S2C2R2)2]1- solution
equilibria. The neutral dimers react with Ph3P to form square
pyramidal [M(Ph3P)(S2C2R2)2]0. Voltammetric measurements upon
[M(Ph3P)(S2C2R2)2]0 in CH2Cl2 reveal only irreversible features at
negative potentials, consistent with Ph3P dissociation upon reduction. Dissociation and reassociation of Ph3P from and to [Fe(Ph3P)(S2C2R2)2]0 is demonstrated by spectroelectrochemical measurements. These collective observations form the basis for a cycle of
reversible, electrochemically controlled binding of Ph3P to
[M(S2C2R2)2]2 (M = Fe, Co; R = p-anisyl). All members of the
cycle ([M(S2C2R2)2]20, [M(S2C2R2)2]21-, [M(S2C2R2)2]22-, [M(S2C2R2)2]1-,
[M(Ph3P)(S2C2R2)2]) for M = Fe, Co have been characterized by
crystallography. Square planar [Fe(S2C2R2)2]1- is the first such
iron dithiolene species to be structurally identified and reveals Fe−S
bond distances of 2.172(1) and 2.179(1) Å, which are appreciably
shorter than those in corresponding square planar dianions
Reversible, Electrochemically Controlled Binding of Phosphine to Iron and Cobalt Bis(dithiolene) Complexes
The homoleptic bis(dithiolene) complexes [M(S2C2R2)2]2 (M = Fe,
Co; R = p-anisyl) undergo two successive reductions to form
anions that display [M(S2C2R2)2]22- ↔ 2[M(S2C2R2)2]1- solution
equilibria. The neutral dimers react with Ph3P to form square
pyramidal [M(Ph3P)(S2C2R2)2]0. Voltammetric measurements upon
[M(Ph3P)(S2C2R2)2]0 in CH2Cl2 reveal only irreversible features at
negative potentials, consistent with Ph3P dissociation upon reduction. Dissociation and reassociation of Ph3P from and to [Fe(Ph3P)(S2C2R2)2]0 is demonstrated by spectroelectrochemical measurements. These collective observations form the basis for a cycle of
reversible, electrochemically controlled binding of Ph3P to
[M(S2C2R2)2]2 (M = Fe, Co; R = p-anisyl). All members of the
cycle ([M(S2C2R2)2]20, [M(S2C2R2)2]21-, [M(S2C2R2)2]22-, [M(S2C2R2)2]1-,
[M(Ph3P)(S2C2R2)2]) for M = Fe, Co have been characterized by
crystallography. Square planar [Fe(S2C2R2)2]1- is the first such
iron dithiolene species to be structurally identified and reveals Fe−S
bond distances of 2.172(1) and 2.179(1) Å, which are appreciably
shorter than those in corresponding square planar dianions
Reversible, Electrochemically Controlled Binding of Phosphine to Iron and Cobalt Bis(dithiolene) Complexes
The homoleptic bis(dithiolene) complexes [M(S2C2R2)2]2 (M = Fe,
Co; R = p-anisyl) undergo two successive reductions to form
anions that display [M(S2C2R2)2]22- ↔ 2[M(S2C2R2)2]1- solution
equilibria. The neutral dimers react with Ph3P to form square
pyramidal [M(Ph3P)(S2C2R2)2]0. Voltammetric measurements upon
[M(Ph3P)(S2C2R2)2]0 in CH2Cl2 reveal only irreversible features at
negative potentials, consistent with Ph3P dissociation upon reduction. Dissociation and reassociation of Ph3P from and to [Fe(Ph3P)(S2C2R2)2]0 is demonstrated by spectroelectrochemical measurements. These collective observations form the basis for a cycle of
reversible, electrochemically controlled binding of Ph3P to
[M(S2C2R2)2]2 (M = Fe, Co; R = p-anisyl). All members of the
cycle ([M(S2C2R2)2]20, [M(S2C2R2)2]21-, [M(S2C2R2)2]22-, [M(S2C2R2)2]1-,
[M(Ph3P)(S2C2R2)2]) for M = Fe, Co have been characterized by
crystallography. Square planar [Fe(S2C2R2)2]1- is the first such
iron dithiolene species to be structurally identified and reveals Fe−S
bond distances of 2.172(1) and 2.179(1) Å, which are appreciably
shorter than those in corresponding square planar dianions
