Pt complexe

In the presence of [PtC ] and a base. 2-aminothiazole undergoes ring cleavage of the C-S bond to give PtLCF (L=HSCH=CHNHCN) (699). The Pd and Pt complexes of 2-aminothiazoles show biological activity (1596i. 

Cyclic Carhene Complexes. The reaction of aziridines with carbonyl, thiocarbonyl, or isonitrile ligands in Mn, Re, Fe, Ru, Pd, or Pt complexes leads to formation of cycHc carhene complexes (324—331). 

Pt-complexes with heterocyclic ligands and Pt-chelates as antitumor drugs 99CRV2451. 

Even Sip4 in (Ph3P)2PtSiF4 can be substituted by BCI3 to form (Ph3P)2PtBCl3. Tensimetric titrations in benzene show the same ratio of Pt complex and absorbed BCI3. 

In 6.5.2.1 it is shown that BF3 and BCI3 add to phosphine Pt complexes without cleaving the B—X bond. In contrast, aryl and alkyl boron halides are added oxidatively with phosphine Pt complexes - ... 

The Pt complex Pt(PPh3)3 reacts with Hg derivatives, such as Hg(Cp3)2, by oxidative addition ... 

Hidai et al. have reported the reaction of a diruthenium complex, (RuCp )2(yU-Si-Pr)2(//-S2), with zerovalent complexes of group 10 metals, [M(PPh3)4] (M=Pd, Pt) (Scheme 65) [146]. The reaction with the Pt complex... 

Silanes with electronegative ligands did not react, except in the presence of the tertiary base EtjN [e.g., Eq. (19)] (62, 63). This then provides an attractive route to Si—Pt(II) compounds since the starting materials are readily available and the reaction gives pure products in high (60-90%) yields. Only aromatic phosphine Pt complexes reacted readily, and the use of an excess of silane failed to bring about replacement of the second halogen atom. 

Chitin (Fig. 27) was supported on silica by grinding the two solids together. The Pt complex was tested as a catalyst in the enantioselective hydrogenation of racemic 1-phenylethanol to obtain (i )-l-cyclohexylethanol [82]. Up to 65% yield with 100% ee was obtained and the catalyst was reused five times with almost the same results. 

Platinum was added to Nation before Incorporating CdS In order to avoid the reduction of CdS during the platlnlzatlon process. Nation (DuPont 117, 0.018 cm thick) films were soaked In Pt(NH2)2l2 (0.1 mM) solution for 4 hr. The amount of the Pt complex Incorporated was determined by measuring the optical absorption change In the liquid phase. The films were subsequently reduced with NaBH (0.1 M) solution for one day to produce Pt metal dispersed throughout the polymer film. The amount of Pt was found to be about 0.02 mg cm 2. 

Diboration of terminal alkenes has also been studied with other d " metals (Fig. 2.12) including the Ag and Au complexes 75-77 and the Pt" complexes 78-79. Styrene is diborylated with 100% selectivity and good conversions in THF (46% for 75 and 94% for 77 at 5 mol%, 60 h) using equimolecular amounts of (Bcat)j. The difference in activity between the Ag and Au complexes has been ascribed to the increased lability of the Ag-NHC bond, which may lead to catalyst decomposition under the reaction conditions, hi both catalytic systems it is believed that the active species involves only one coordinated NHC ligand. Complex 77 is less active than 74 and 75, possibly due to steric reasons. The enantioselectivity of 77 in the diboration of prochiral alkenes is very low [63]. 

Scheme 5.22 Reductive cychsation of diynes or enynes catalysed by NHC-Pt complex...

Casas, J.M., Diosdado, B.E., Falvello, L.R., Fornies, J., Martin, A. and Rueda, A.J. (2004) Hydrogen-bond mediation of supramolecular aggregation in neutral bis-(C5F5)Pt complexes with aromatic H-bond donating ligands. A synthetic and structural study. Dalton Transactions, (17), 2733-2740. 

Naturally, the number of surface sites limits the amount of Pt complexes that can be adsorbed. Typically, the.se catalysts contain up to 1 wt% Pt. Adsorption is a fast process and in general an eggshell catalyst will be formed. Figure 3.29 shows the processes that occur. 

The reactivities of hydrido(phenoxo) complexes of trons-[MH(OPh)L2] (6 M = Ni 7 M = Pt) (L = phosphine) were examined (Eqs. 6.29, 6.30 Scheme 6-16), and a high nucleophiUdty for the metal-bound phenoxide was suggested [9, 10]. Reaction with methyl iodide produced anisole and trans-[MH(I)L2] for both Ni and Pt complexes. Phenyl isocyanate also provided the insertion products into the metal-phenoxo... 

Some Pt complexes bearing electron-donating phosphines can also catalyze the hydration of the C=C double bond of acrylonitrile or crotonitrile and yielded P-hy-droxypropionitrile or P-hydroxybutyronitrile respectively besides the corresponding amide (Eq. 6.38) [22, 75], Among the platinum phosphine complexes examined, [Pt(PEt3)3] (26a), carrying less bulky ligands, was the most effective for the hydration of the olefmic bond. The present catalyst system was ineffective for hydration of other olefins, however. 

Unlike the case of the Ni-catalyzed reaction, which afforded the branched thioester (Eq. 7.1), the PdCl2(PPh3)3/SnCl2-catalyzed reaction with 1-alkyne and 1-alkene predominantly provided terminal thioester 6 in up to 61% yield in preference to 7. In 1983, a similar hydrothiocarboxylation of an alkene was also documented by using a Pd(OAc)2/P( -Pr)3 catalyst system with t-BuSH to form 8 in up to 79% yield (Eq. 7.6) [16]. It was mentioned in the patent that the Pt-complex also possessed catalyhc activity for the transformation, although the yield of product was unsatisfactory. In 1984, the hydrothiocarboxylation of a 1,3-diene catalyzed by Co2(CO)g in pyridine was also reported in a patent [17]. In 1986, Alper et al. reported that a similar transformation to the one shown in Eq. (7.3) can be realized under much milder reaction conditions in the presence of a 1,3-diene [18], and the carboxylic ester 10 was produced using an aqueous alcohol as solvent (Eq. 7.7) [19]. 

Trimethylsilyl enol ethers can also be prepared by 1,4-reduction of enones using silanes as reductants. Several effective catalysts have been found,38 of which the most versatile appears to be a Pt complex of divinyltetramethyldisiloxane.39 This catalyst gives good yields of substituted silyl enol ethers (e.g., Scheme 1.2, Entry 7). 

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