Platinum II phosphine complexes

One or both carbonyls in /3-diketones can be reduced, as well as the carbonyl function in acyl cyanides (210). Similar treatment of a,/3-unsat-urated ketones and aldehydes can lead to the saturated carbonyl products via selective reduction of the olefinic bond (207, 208, 210) see Eq. (51) in Section III,A,4. Some terpenes (a- and /3-ionone, pulegone) were reduced in this way (208). Platinum(II) phosphine complexes have been used for the hydrosilylation of saturated ketones and could be used for the reduction (211). 

Data for a number of platinum (II) phosphine complexes are tabulated in Table II. The coupling constant for the cis isomer is ca. 1.5 times that for the trans isomer. 

A series of cyclometalated platinum(II) phosphine complexes [Pt(bzq)(P-P)](Pp6) (P-P = dppm, dppe, dppp) has been synthesized and stracturally characterized. The absorption bands at ca. 300nm (e... 

Chiral platinum (II) phosphine complex)stannous chloride ... 

New reproducible syntheses of platinum(II) carbonato complexes of the type [Pt(C03)L2] (L mono- or bidentate tertiary phosphine) involve the reaction of Ag2C03 with [PtCl2L2] in water-saturated CH2C12 solution.3 Other methods of preparation include the conversion of the dichloroplatinum(II) complexes to the corresponding bis(alkoxo)- or bis(phenoxo)-platinum(II) species, followed by hydrolysis in the presence of C02. 

Platinum(II) complexes such as [PtCl2(PhMePR)]2 (R = benzyl or propyl) have been used for asymmetric reduction of phenylketones to alcohols with up to 19% ee via the consecutive hydrosilylation-hydrolysis process (Section III,A,4) (2//, 307). A nickel(II) complex with the ben-zylphosphine, and palladium(II) phosphine complexes did not catalyze the hydrosilylation (211). 

Romeo, R., and Alibrandi, G. (1997), Structure-reactivity correlations for the dissociative uncatalyzed isomerization of monoalkylbis(phosphine)platinum(II) solvento complexes, Inorg. Chem., 36,4822—4830. 

Alkenes bonded to platinum(II) can be displaced by strongly coordinating ligands such as cyanide ion or tertiary phosphines. The displacement of ethylene from Zeise s salt by phosphines is a useful method of preparation of complexes trawa-PtCl2(PR3)2.711 Amines will also displace alkenes from coordination to platinum(II), but this reaction can compete with nucleophilic attack at the coordinated alkenic carbon. The stability of platinum(II) alkene complexes follows the sequence C2H4 > PhCH=CH2 > Ph2C=CH2 555 Ph(Me)C=CH2.712... 

Table 7 Pt—P Distances in Platinum(II) Phosphine and Phosphite Complexes...

The compound dissolves in benzene, with dissociation. By leaving the benzene solution in the air, carbonatobis (triphenyl-phosphine) platinum(II) separates slowdy. It reacts easily with carbon tetrachloride giving cfs-dichlorobis(triphenylphos-phine)platinum(II). The complex is tricoordinated in the solid state, and shows a nearly pure hybridization of the platinum atom. ... 

In 1936 K. A. Jensen (2, 3) measured the moments of a number of platinum (II) dihalido complexes with tertiary phosphines and other such hgands. He showed that the cis complexes had moments of up to about 11.0 Debye units (D) and that atom polarization in complex compounds is much higher than in organic compounds. He also showed that all the complexes of this type had had their cis or trans configurations incorrectly assigned on the basis of color, in analogy with the diammine di-chloro platinum (II) complexes. 

The most important reaction of platinum(II) alkene complexes is nucleophilic attack at a coordinated carbon atom. The most studied nucleophile in this context is the amine nitrogen. Amines attack coordinated monoalkenes, and if tertiary phosphine or amine ligands are present these stabilize the Zwitterionic platinum-carbon a-bonded complexes that are formed (equation 239) The attack occurs trans to platinum. Substituents adjacent to the... 

The auxiliary phosphine ligands also play an important role in controlling the physical properties of platinum(ii) alkynyl complexes. Monomeric complexes of trans-[Pt(PR3)2(C=CR )2] usually exist in the crystalline state at room temperature. Cooper et al. recently communicated the synthesis and isolation of platinum alkynyls in the liquid state at room temperature using trioctylphosphine as the auxiliary ligands [97]. It was proposed that these liquids may possess enhanced nonlinear optical properties. 

Owing to the advances in the synthesis of organoplatinum(ii) alkynyl compounds as well as the intriguing physical and photophysical properties exhibited by these materials, the evaluation of their structure-property relationship is therefore attractive and feasible. The spectroscopic properties of mononuclear nickel(ii), palladium(ii) and platinum(ii) alkynyl complexes of the type trans-[M(C=CR)2L2] (R = alkyl, aryl L = phosphine, stibine) have been widely investigated [111-114]. The electronic absorption spectra of this class of complexes have been reported by Masai et al. [115], while the emission properties of a series of closely related platinum(ii) complexes were reported by Demas and coworkers [116]. The lowest... 

---