The Stereospecific Synthesis of Neutral and Cationic Tertiary Phosphine Complexes of Platinum(II)

Stereospecific synthetic methods for the preparation of complexes of the type cis- and trans[PtClL(PEt3)2]+ and cis-[PtClX(PEt3)2] have been developed. Preparations of complexes where L = py, PPh3, PClPh2, or P(OPh)3 and X = SCN, NO2, NO3, N3, NCO, or Br are described and it is shown that bridge cleavage reactions in square planar platinum(II) complexes occur with retention of stereo chemistry.

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ChemInform Abstract: THE STEREOSPECIFIC SYNTHESIS OF NEUTRAL AND CATIONIC TERTIARY PHOSPHINE COMPLEXES OF PLATINUM(II)

Chemischer Informationsdienst ◽

10.1002/chin.197418421 ◽

1974 ◽

Vol 5 (18) ◽

pp. no-no

Author(s):

KEITH R. DIXON ◽

KENNETH C. MOSS ◽

MARTIN A. R. SMITH

Keyword(s):

Stereospecific Synthesis ◽

Tertiary Phosphine ◽

Phosphine Complexes

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Mechanistic Studies of Isomerization Reactions of Tetragonal Planar Tertiary Phosphine Complexes of Palladium(II)

Canadian Journal of Chemistry ◽

10.1139/v73-245 ◽

1973 ◽

Vol 51 (10) ◽

pp. 1634-1644 ◽

Cited By ~ 32

Author(s):

David G. Cooper ◽

John Powell

Keyword(s):

Variable Temperature ◽

Kinetic Studies ◽

Ionic Species ◽

Tertiary Phosphine ◽

First Order ◽

Phosphine Complexes ◽

Trans Isomerization ◽

Halogen Exchange ◽

Cis And Trans ◽

Isomerization Processes

The complexes [PdCl2(Me2RP)2] (R = o-tolyl; α-napthyl) may be isolated in both cis and trans forms. In CHCl3 solution cis-trans isomerization processes for these complexes are slow and this is ascribed to steric hindrance by the bulky R groups. The cis-trans isomerization is catalyzed by a variety of added ligands L. These isomerization processes have been extensively studied for the complexes cis-and trans-[PdCl2(Me2o-tolylP)2] in CHCl3 solution. The results of variable temperature n.m.r. and u.v. kinetic studies are fully consistent with a consecutive displacement mechanism with an ionic species of the type [PdCl(Me2o-tolylP)2L]+Cl− as an intermediate. The kinetic characteristics are determined by the nature and relative stability of this ionic intermediate. For L = Me2o-tolylP the rate of isomerization is zero order in complex and second order in added phosphine concentration. (At 38° kcis→trans = 6.2 × 103 l mol−1 s−1, ktrans→cis = 6.3 × 103 l mol−1 s−1) For L = PPh3 the rate of isomerization is considerably slower and first order in both complex and added PPh3 concentrations (kcis→trans6.3 = × 10 l mol−1 s−1, ktrans→cis = 6.7 × 10 l mol−1 s−1). Isomerization is also effected in neat methanol and the rate is first order in complex concentration. N.m.r. studies of mixtures of trans-[PdI2(Me2o-tolylP)2] and cis-[PdCl2(Me2o-tolylP)2] in CHCl3 solution show halogen exchange to occur more rapidly than isomerization. However a cis-diiodo complex is not observed and instead isomerization to the trans-diiodo complex is observed to occur.

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Cyclopalladation of trimesitylarsine. The X-ray crystal structure for

Canadian Journal of Chemistry ◽

10.1139/v88-488 ◽

1988 ◽

Vol 66 (12) ◽

pp. 3162-3165 ◽

Cited By ~ 4

Author(s):

Elmer C. Alyea ◽

George Ferguson ◽

John Malito ◽

Barbara L. Ruhl

Keyword(s):

Crystal Structure ◽

Cleavage Product ◽

Phosphine Ligands ◽

Monoclinic Space Group ◽

Dimeric Complex ◽

Tertiary Phosphine ◽

X Ray ◽

H Nmr ◽

Square Planar ◽

Cleavage Reactions

The bulky trimesitylarsine ligand, As(mes)3, undergoes facile cyclopalladation to yield the dimeric complex, [Formula: see text], characterized by microanalysis, IR and 1H NMR spectroscopy. This complex is very stable but readily undergoes bridge-cleavage reactions with tertiary phosphine ligands having ligand cone angles less than 170°. The crystal structure for the PPh3 bridge-cleavage product is reported. This complex, [Formula: see text] is monoclinic, space group P21/c with a = 20.469(2), b = 12.702(2), c = 15.401(4) Å, β = 98.46(1)°, V = 3961 Å3Z = 4, R = 0.0284 and Rw = 0.0305. The Pd geometry is distorted square-planar with principal dimensions, Pd—Cl 2.395(1), Pd—P 2.318(1), Pd—C 2.056(3), and Pd—As 2.437(1) Å; As—Pd—Cl 96.5(1), Cl—Pd—P 90.9(1), P—Pd—C 93.7(1), As—Pd—C 78.9(1), As—Pd—P 172.6(1), and Cl—Pd—C 171.7(1)°. The average C—P—C angle (104.3(1)°) is smaller than expected and is rationalized on the basis of steric effects operative within the complex.

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Complexes of hybrid ligands. The synthesis of a thioanisole-substituted fluoro-alcohol and its complexes with Pd2+ and Pt2+; the structure of a palladium(II) complex containing alkoxide, phosphine, thioether, and chloride donors

Canadian Journal of Chemistry ◽

10.1139/v87-135 ◽

1987 ◽

Vol 65 (4) ◽

pp. 798-803 ◽

Cited By ~ 3

Author(s):

René T. Boeré ◽

David E. Esser ◽

Christopher J. Willis ◽

Douglas W. Stephan ◽

Taras W. Obal

Keyword(s):

Least Squares ◽

Dihedral Angle ◽

Chelate Ring ◽

Monoclinic Space Group ◽

Structural Determination ◽

Bond Lengths ◽

Square Planar ◽

Planar Molecules ◽

Hybrid Ligands ◽

Cis And Trans

The compound 2-thioanisole-1,1,1,3,3,3-hexafluoro-2-propanol, CH3S—C6H4—C(CF3)2OH, HL2, has been prepared, and shown to act (in the ionized form) as a hybrid, chelating, ligand. Neutral bis-complexes M(L2)2 are formed with Pd2+ and Pt2+; the former reacts with PdCl42− to give the Cl-bridged dinuclear complex (L2)Pd(μ-Cl)2Pd(L2), which may in turn be cleaved by PPh3 or PPh2Me to give PdCl(L2)(PR3).A complete structural determination has been made for PdCl(L2)(PPh2Me); C23H20ClF6OPPdS. Crystals are monoclinic, space group P21/n, a = 15.526(5), b = 12.966(9), c = 12.900(8) Å, β = 101.84°, V = 2542(2) Å3, Z = 4. Least-squares refinement on F of 198 variables using 2801 observations converged at R1 = 0.0434, R2 = 0.0559. The complex consists of discrete square-planar molecules with phosphine and alkoxide trans-disposed. Bond lengths are Pd—O, 2.053(3); Pd—P, 2.242(1); Pd—Cl, 2.323(2); Pd—S, 2.252(2) Å. In the six-membered chelate ring, all atoms with the exception of Pd are close to coplanarity; there is a dihedral angle of 127.9° between the O—Pd—S plane and that of the aromatic ring.Multinuclear nmr measurements are used to show that both cis- and trans-forms of complexes PdCl(L2)(PR3) are present in solution, with inversion at coordinated sulfur occurring much more rapidly in the latter.

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