Synthesis and Characterization of a New Chiral Phosphinothiol Ligand Derived from (-)-Menthone and Its Palladium(II) and Platinum(II) Complexes
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- 作者：Josep Duran ; Nú ; ria Brugat ; Alfonso Polo ; Cristó ; bal Segura ; Julio Real ; Xavier Fontrodona ; and Jordi Benet-Buchholz
- 刊名：Organometallics
- 出版年：2003
- 出版时间：August 18, 2003
- 年：2003
- 卷：22
- 期：17
- 页码：3432 - 3438
- 全文大小：135K
- 年卷期：v.22,no.17(August 18, 2003)
- ISSN：1520-6041
文摘
The chiral ligand (1R,2S,5R)-1-((diphenylphosphino)methyl)-2-isopropyl-5-methylcyclohexanethiol (4) has been prepared from low-cost commercial (-)-menthone in a three-stepenantioselective synthesis. Oxidative addition of 2 equiv of this phosphinothiol ligand to[Pd0(PPh3)4] gave the enantiopure bis(phosphinothiolate)palladium(II) complex 5, which onlyexists as the trans-P,P geometrical isomer, in both the solid state and solution, owing to thepreference of the chelate rings to adopt the 
conformation in which the position of thementhane ring does not allow a conformation of the phenyl groups compatible with the moresterically hindered cis geometry. These stereoelectronic coordination preferences of the chiralphosphinothiolate ligand have been confirmed by the structure of the analogous Pt(II)complex 6, which also exhibits the trans-P,P geometry exclusively, both in the solid stateand in solution. Crystals of 5·1/2CH2Cl2 and 6·1/2CH2Cl2 are isomorphic, belonging to themonoclinic crystal system C2. Both chiral structures show mononuclear square-planar transcomplexes with locked chelate ring conformations. Compound 6 represents the first exampleof a structurally characterized mononuclear bis(phosphinothiolate)platinum(II) complex.Addition of 1 equiv of ligand 4 to a solution of [PdCl2(PPh3)2] gave the less sterically hinderedcomplex chloro(phosphinothiolate)(triphenylphosphine)palladium(II) (7), which exhibits theexpected cis-trans equilibrium in solution, but strongly displaced to the more stericallystable trans isomer.
conformation in which the position of thementhane ring does not allow a conformation of the phenyl groups compatible with the moresterically hindered cis geometry. These stereoelectronic coordination preferences of the chiralphosphinothiolate ligand have been confirmed by the structure of the analogous Pt(II)complex 6, which also exhibits the trans-P,P geometry exclusively, both in the solid stateand in solution. Crystals of 5·1/2CH2Cl2 and 6·1/2CH2Cl2 are isomorphic, belonging to themonoclinic crystal system C2. Both chiral structures show mononuclear square-planar transcomplexes with locked chelate ring conformations. Compound 6 represents the first exampleof a structurally characterized mononuclear bis(phosphinothiolate)platinum(II) complex.Addition of 1 equiv of ligand 4 to a solution of [PdCl2(PPh3)2] gave the less sterically hinderedcomplex chloro(phosphinothiolate)(triphenylphosphine)palladium(II) (7), which exhibits theexpected cis-trans equilibrium in solution, but strongly displaced to the more stericallystable trans isomer.