“…Synthesis and Properties of the Free Ligand and Ni II and Ni 0 Complexes. The bidentate ligand arom-PSMe was first prepared and used in the synthesis of transition metal complexes by Livingstone and co-workers, and later by others. 3a,c-e, We find that the use of KI instead of CuBr in the synthesis of o -halothioanisole in the first step 16 of the ligand synthesis and the subsequent use of o -iodothioanisole for introduction of the PPh 2 group leads to products of higher purity and yield, eq 4. …”
Section: Resultsmentioning
confidence: 88%
“…o -(Diphenylphosphino)thioanisole, (Ph 2 P(o- C 6 H 4 )SCH 3 , arom-PSMe). o -Aminothioanisole was prepared from the reaction of o -mercaptoaniline with sodium followed by iodomethane in methanol − Likewise procedures for the preparation of o -iodothioanisole- methyl - d 3 (I( o -C 6 H 4 )SCD 3 ) and o -(diphenylphosphino)thioanisole- methyl - d 3 (Ph 2 P( o -C 6 H 4 )SCD 3 , arom-PSCD 3 ) are deposited as supporting information.…”
Section: Methodsmentioning
confidence: 99%
“…Group VIII metal complexes of N,S, P,S, and As,S donor chelates have been extensively studied for their ability to transfer alkyl groups from sulfur to suitable nucleophiles. − Such alkyl transfers from nickel(II) and palladium(II) complexes of the o -(diphenylphosphino)thioanisole ligand (Ph 2 P- o -C 6 H 4 SMe, designated hereafter as arom-PSMe) to amines have been characterized as Menschutkin type S N 2 reactions. 3b, Roundhill and Benefiel have provided kinetic monitors of reaction (eq 1), demonstrating bimolecular kinetic behavior with Δ H ⧧ in the range of +13 to +19 kcal mol -1 and Δ S ⧧ in the range of −14 to −30 cal K -1 mol -1 . (Note: The representation of cis stereochemistry for (Ph 2 P- o -C 6 H 4 SEt) 2 Pt II is as suggested by Roundhill and Benefiel . In contrast the two known structures of bidentate phosphino thioether derivatives of Ni II are trans .)…”
The molecular structure of a nickel(0) complex with P,S-donor
atom ligands has been characterized by
X-ray crystallography. Complex 1,
(Ph2P(o-C6H4)SCH3)2Ni0,
prepared by Na/Hg amalgam reduction of the
NiII
complex
[(Ph2P(o-C6H4)SCH3)2Ni](BF4)2
([2](BF4)2), degrades
photochemically with loss of CH3 radicals to
yield
complex 3,
(Ph2P(o-C6H4)S)2NiII.
Crystallographic parameters for the three compounds are as
follows: 1, monoclinic
space group C2/c with a =
11.467(2) Å, b = 17.613(3) Å, c =
15.733(2) Å, β = 96.450(10)°, V =
3157.5(9) Å3,
and Z = 4;
[2](BF4)2, monoclinic space
group P2
1
/
c
with a = 9.417(4) Å, b = 14.822(9)
Å, c = 13.773(2) Å, β =
98.55(3)°, V = 9101(14) Å3, and
Z = 2; and 3, monoclinic space group
P21/c with a =
9.651(2) Å, b = 12.971(8)
Å, c = 12.540(2) Å, β = 110.46(2)°,
V = 1470.7(11) Å3, and Z =
2. While complex 1 has a distorted
tetrahedral
geometry, complexes [2](BF4)2
and 3 are square planar with trans
stereochemistry. The cyclic voltammogram of
[2](BF4)2 in
CH3CN shows two redox events assigned to
NiII/I and NiI/0, whereas the thiolate
3 reveals only one
reversible wave assigned to NiII/III. The chemical
reduction of [2](BF4)2 with
Cp2Co provided a NiI species,
[(Ph2P(o-C6H4)SCH3)2NiI]+,
characterized at 100 K by an axial EPR signal with
g
x
=
g
y
= 2.10 and
g
z
= 1.96.
Hyperfine
spectral features resulting from coupling to two 31P nuclei
suggests a retention of substantially square planar
geometry.
In contrast the isotropic character of the EPR signal of
[(Ph2P(o-C6H4)SCH3)(Ph2P(o-C6H4)S)NiI],
presumed to be
the first product of the photochemical demethylation of 1
ultimately yielding the doubly demethylated complex
3,
suggested the intervening thioether/thiolate NiI species to
be pseudotetrahedral. Protonation of the nickel(0)
species
1 produced a five-coordinate nickel hydride complex,
[(H)(arom-PSMe)2Ni]BF4,
4.
“…Synthesis and Properties of the Free Ligand and Ni II and Ni 0 Complexes. The bidentate ligand arom-PSMe was first prepared and used in the synthesis of transition metal complexes by Livingstone and co-workers, and later by others. 3a,c-e, We find that the use of KI instead of CuBr in the synthesis of o -halothioanisole in the first step 16 of the ligand synthesis and the subsequent use of o -iodothioanisole for introduction of the PPh 2 group leads to products of higher purity and yield, eq 4. …”
Section: Resultsmentioning
confidence: 88%
“…o -(Diphenylphosphino)thioanisole, (Ph 2 P(o- C 6 H 4 )SCH 3 , arom-PSMe). o -Aminothioanisole was prepared from the reaction of o -mercaptoaniline with sodium followed by iodomethane in methanol − Likewise procedures for the preparation of o -iodothioanisole- methyl - d 3 (I( o -C 6 H 4 )SCD 3 ) and o -(diphenylphosphino)thioanisole- methyl - d 3 (Ph 2 P( o -C 6 H 4 )SCD 3 , arom-PSCD 3 ) are deposited as supporting information.…”
Section: Methodsmentioning
confidence: 99%
“…Group VIII metal complexes of N,S, P,S, and As,S donor chelates have been extensively studied for their ability to transfer alkyl groups from sulfur to suitable nucleophiles. − Such alkyl transfers from nickel(II) and palladium(II) complexes of the o -(diphenylphosphino)thioanisole ligand (Ph 2 P- o -C 6 H 4 SMe, designated hereafter as arom-PSMe) to amines have been characterized as Menschutkin type S N 2 reactions. 3b, Roundhill and Benefiel have provided kinetic monitors of reaction (eq 1), demonstrating bimolecular kinetic behavior with Δ H ⧧ in the range of +13 to +19 kcal mol -1 and Δ S ⧧ in the range of −14 to −30 cal K -1 mol -1 . (Note: The representation of cis stereochemistry for (Ph 2 P- o -C 6 H 4 SEt) 2 Pt II is as suggested by Roundhill and Benefiel . In contrast the two known structures of bidentate phosphino thioether derivatives of Ni II are trans .)…”
The molecular structure of a nickel(0) complex with P,S-donor
atom ligands has been characterized by
X-ray crystallography. Complex 1,
(Ph2P(o-C6H4)SCH3)2Ni0,
prepared by Na/Hg amalgam reduction of the
NiII
complex
[(Ph2P(o-C6H4)SCH3)2Ni](BF4)2
([2](BF4)2), degrades
photochemically with loss of CH3 radicals to
yield
complex 3,
(Ph2P(o-C6H4)S)2NiII.
Crystallographic parameters for the three compounds are as
follows: 1, monoclinic
space group C2/c with a =
11.467(2) Å, b = 17.613(3) Å, c =
15.733(2) Å, β = 96.450(10)°, V =
3157.5(9) Å3,
and Z = 4;
[2](BF4)2, monoclinic space
group P2
1
/
c
with a = 9.417(4) Å, b = 14.822(9)
Å, c = 13.773(2) Å, β =
98.55(3)°, V = 9101(14) Å3, and
Z = 2; and 3, monoclinic space group
P21/c with a =
9.651(2) Å, b = 12.971(8)
Å, c = 12.540(2) Å, β = 110.46(2)°,
V = 1470.7(11) Å3, and Z =
2. While complex 1 has a distorted
tetrahedral
geometry, complexes [2](BF4)2
and 3 are square planar with trans
stereochemistry. The cyclic voltammogram of
[2](BF4)2 in
CH3CN shows two redox events assigned to
NiII/I and NiI/0, whereas the thiolate
3 reveals only one
reversible wave assigned to NiII/III. The chemical
reduction of [2](BF4)2 with
Cp2Co provided a NiI species,
[(Ph2P(o-C6H4)SCH3)2NiI]+,
characterized at 100 K by an axial EPR signal with
g
x
=
g
y
= 2.10 and
g
z
= 1.96.
Hyperfine
spectral features resulting from coupling to two 31P nuclei
suggests a retention of substantially square planar
geometry.
In contrast the isotropic character of the EPR signal of
[(Ph2P(o-C6H4)SCH3)(Ph2P(o-C6H4)S)NiI],
presumed to be
the first product of the photochemical demethylation of 1
ultimately yielding the doubly demethylated complex
3,
suggested the intervening thioether/thiolate NiI species to
be pseudotetrahedral. Protonation of the nickel(0)
species
1 produced a five-coordinate nickel hydride complex,
[(H)(arom-PSMe)2Ni]BF4,
4.
“…This was achieved by reacting the The results described above need to be put into a more general context. The first example of dealkylation of a coordinated thioether by a nucleophile, of which we are aware, was reported by Roundhill and co-workers (28). Displacement of alkyl groups from the ligand o-Ph 2 PC 6 H 4 SR coordinated to Pd(II) or Pt(II) can be accomplished with an amine.…”
Selected C-S bond-breaking and bond-making reactions from our work are discussed that have implications to the modeling of both industrial and biological processes. The complexes WCl5(SR) were found to be subject to elimination of RCl, with concomitant formation of WCl4S via a carbonium ion mechanism. Attempts to emulate the C-S bond cleavage step of hydrodesulfurization by introduction of hydride into the coordination sphere, or by reaction with a second transition metal hydride, resulted in the synthesis of a variety of homonuclear and heteronuclear complexes, with elimination of the appropriate alkane. The synthesis of complexes of the type Cl 3 W(µ-R 2 S) 3 WCl 3 led to the discovery of the reactivity of the C-S bonds toward nucleophiles, including hydride. A computational study provides an explanation for this lability. Reactions of the [MoS4]2-and [WS4]2-ions with organic halides, have been reinvestigated.[PPh4][WS 3 (SR)] (R = Et, i Pr, t Bu) and [PPh4][MoS3(S t Bu)] have been characterized crystallographically. These complexes undergo reductive elimination reactions forming polynuclear sulfidometalates such as W3S92-. The synthetic potential and possible biological significance of these reactions is discussed.The rich chemistry of molybdenum and tungsten with sulfide and organosulfur ligands has been recognized for more than two decades. It is punctuated by complicated redox behavior of both metal and ligands, and also by unexpected reactions of the coordinated ligands. In this regard the metal-assisted cleavage of C-S bonds has been of particular interest, since this process is believed to be involved in the catalytic hydrodesulfurization of fossil fuels. The reverse process, namely the formation of C-S bonds has attracted less attention, but it is interesting to speculate as to the possible importance of this process in the biosynthesis of metalloenzymes.
“…Studies concerning the structural preference of the palladium bis-chelate showed slow isomerisation from the cis geometry in solution, until a cis/trans equilibrium mixture could be observed [120]. Analogously to the palladium bis-chelate, [Pt{(PS)-κ 2 S,P} 2 ] was also synthesised for the first time by an S-dealkylation process [123], but its stereochemistry could not be determined. Later it was assumed to be trans [124], but in 2003 cis-[Pt{(PS)-κ 2 S,P} 2 ] was reported, as the product of a transmetallation reaction [121].…”
This review article describes the synthesis and coordination chemistry of three types of thiophenol-based heterodonor ligands containing tertiary phosphine and/or arsine groups in combination with sulfur. Phenylthio(diphenyl)phosphine and -arsine ligands, EPh2(SPh) (E = P, As), incorporate an E–S bond in their structures. Upon reaction with different metal carbonyls, metal-mediated cleavage of the E–S bonds of these ligands has been observed, leading to a variety of sulfur- and phosphorus- or arsenic-containing metallacycles. The structurally isomeric phosphino- and arsinoarylthiols HSC6H4-2-EPh2 (ESH) combine a phosphine or arsine centre with a thiol functionality, which is usually deprotonated on coordination. These compounds have been shown to be very versatile ligands that form stable complexes with a wide range of transition metals. The heterotopic ligand 1-Ph2AsSC6H4-2-PPh2 (P,SAs) not only combines the properties of phenylthio(diphenyl)arsine and 2-diphenylphosphanylbenzenethiol by incorporating all three donor atoms in its structure, but also allows the effect of the PPh2 group in the ortho position on the cleavage of the As–S bond to be studied.
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