Platinum group metals iodides

Palladium (Pd, at. mass 106.42) is a platinum-group metal, and occurs in the II and IV oxidation states. Palladium(II) compounds are the more stable. Unlike the other platinum metals, palladium is soluble in cone. HNO3. Brown-red Pd(OH)2 precipitates at pH 4, but dissolves in excess of an alkali-metal hydroxide. Palladium(ll) gives stable nitrite, ammine, cyanide, chloride, bromide, and iodide complexes. Palladium(ll)- and (IV) are reduced to the metal by SO2, Fe(II), and ethanol. 

The catalyst for the oxidative carbonylation to give PhNHCOOEt was metallic palladium with iodide compounds as promoters [11]. The selectivity was superior to 97 %, with a turnover of 300 g/g Pd h. Other platinum group metals, particularly rhodium, were active, although less efficient as catalysts [12], The reaction is conducted under 80 atm of CO and 6 atm of O2 at 160-170 °C and can also be applied to aliphatic amines. Diphenylurea is intermediately formed. 

The halides of the palladium and platinum groups of metals closely resemble in character those of gold, which have already been described. The dihalides of the palladium group are all soluble, save Pdl2, which is prepared by precipitation with potassium iodide. Nitro-hydro-chloric acid yields the higher chloride it remains on evapo-... 

Bromide complexes of Pt and other metals of this group are extracted from acid media with TBP, MIBK, amyl acetate [12] or TOPO [6]. Pt and Pd can be separated from Rh and Ir by extraction (with TBP) from iodide solution [13]. The same method has been used for separating platinum from copper [14]. 

Classical synthetic routes to arylsilanes consist of the reaction of aryl Grignard or aryllithium compounds with silicon electrophiles and many of these routes are presented in the various reviews. Recently, metal-catalyzed reactions of aryl halides with silanes have proven to be useful routes to functionalized arylsilanes. Alami reported the first platinum-catalyzed selective silylation of aryl iodides and bromides 9 having electron-withdrawing group to give arylsilanes 10 with triethylsilane and sodium... 

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