Bis triphenylphosphine platinum Complexes

Carbonatobis(triphenylphosphine)platinum(II) is useful for the preparation of dianionobis(triphenylphosphine)platinum(II) complexes as well as olefin, acetylene and carbonyl derivatives of platinum(0). The method can be used to prepare Pt[P(C6Hs)2CH3] jCCOa) and Pt[As(C6Hs)3] 2(C03). A procedure is available for the preparation of ds-[diacetatobis(diphenylphosphino)pla-tinum] (ds-[Pt(CH3C02)2[P(C6Hs)2l 2]). 

Carbon dioxide and oxygen are bubbled through a solution of 5 g of tetrakis-(triphenylphosphine)platinum, Pt [P(CgH5)3] 4, (4 mmole) in 120 mL of benzene. After 30 minutes the mixture is very pale yellow. The solid is recovered using a medium-porosity filter and is washed with benzene (50 mL). The crude product (3-3.5 g) is a mixture of the carbonato and peroxycarbonato complexes. To complete the conversion to the carbonato complex, the crude product is dissolved in 75 mL of dichloromethane, and 5 g (19 mmole) of triphenylphos-phine is added. The mixture is refluxed overnight. Benzene (75 mL) is added to the mixture and the volume is reduced by half on a rotary evaporator. The colorless solid is recovered using a medium-porosity filter, washed with benzene (50 mL) and diethyl ether (25 mL), and then dried in vacuo. The yield is 2.5 g (73%). Anal, (as benzene solvate) Calcd. for PtC43H36P203 C, 60.2 H, 4.2. Found C 59.6 H, 4.1. 

The compound is an air-stable white solid. Prolonged exposure to room light results in some decomposition. It is soluble in chloroform and dichloromethane and insoluble in alcohols, benzene, and diethyl ether. The peroxycarbonato complex may be detected, if present as an impurity, by an infrared band at 780 (m) cm assigned to v(0—O). The infrared spectrum of the carbonato complex shows v(C=0) at 1685 (vs) cm mp 202-205° (dec.). 

The preparation is based on a convenient starting compound that may be stored readily. The procedure can be used to prepare adducts of other olefins and acetylenes. The ethylene complex is of widespread use in the study of oxidative addition reactions of platinum(O).  

A suspension of 1.5 g (1.75 mmole) of [Pt [P(C6Hs)3] aCCOa)] CgHg (Sec. A) in 40 mL of ethanol is placed in a 100-mL, two-necked flask. An addition funnel is fitted to one neck and a tube delivering a slow stream of ethylene below the surface of the mixture is connected by way of the other neck. The mixture is stirred rapidly as 20 mL of 0.1 M sodium tetrahydroborate(l-), NaBH4, in ethanol is added dropwise over a period of 20 minutes. The white suspension is stirred for 1 hour, during which time the flow of ethylene is maintained. The solid is recovered by filtration using a medium-porosity filter, washed with ethanol (20 mL), water (25 mL), and finally ethanol (25 mL), and then dried in vacuo. The yield is 1.2 g (90%).Anal. Calcd. for PtC3sH34P2 C, 61.03 H, 4.59. Found C, 60.76 H, 4.68. 

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