SUMMARY / RELATED TOPICS

Organoplatinum

Organoplatinum chemistry is the chemistry of organometallic compounds containing a carbon to platinum chemical bond, the study of platinum as a catalyst in organic reactions. Organoplatinum compounds exist in oxidation state 0 with oxidation state II most abundant; the general order in bond strength is Pt-C > Pt-O > Pt-N > Pt-C. Organoplatinum and organopalladium chemistry are similar, but organoplatinum compounds are more stable and therefore less useful as catalysts. Most organoplatinum compounds contain alkyne ligands. Carbonyl complexes are rare, the analogue of Ni4 is elusive; the alkene and alkyne ligands serve as two-electron donors, for example in the complexes 2Pt and 2Pt. The ethylene ligand in 2Pt is labile and exchanges with alkynes and electrophilic alkenes C60 a fullerene. A general synthetic route to 2Pt is reduction of potassium tetrachloroplatinate with ethanolic potassium hydroxide or hydrazine in presence of a phosphine ligand such as triphenylphosphine and the alkene or alkyne.

Such reactions proceed via the intermediacy of cis-dichlorobisplatinum. Nitrogen-based ligands do not support the formation of platinum complexes of alkenes and alkynes. Zerovalent organoplatinum complexes lacking phosphine ligands are prepared via PtCl2. Li2C8H8 + PtCl2 + 3 C7H10 → + 2 LiCl + C8H8 + C8H12 Pt3 + 2 COD → Pt2 + 3 C7H10where C7H10 is norbornene. Platinum compounds are uncommon but are diamagnetic because they have Pt-Pt bonds. An example is the dication 2+. A significant organoplatinum compound is Zeise's salt, obtained from ethylene and potassium tetrachloroplatinate: The colourless diolefin complex dichloroplatinum is a more modern relative, is more used; the stability and diversity of platinum alkene complexes contrasts with the rarity of alkene complexes of nickel. Platinum allyl complexes are common. In contrast to nickel chemistry, where compounds such as CpNiX are common, cyclopentadienyl derivatives of Pt are rare, consistent with the reluctance of Pt to become pentacoordinate.

Alkyl and aryl platinum complexes are prepared by oxidative addition of an alkyl halide or aryl halide to a Pt precursor such as tetrakisplatinum or Pt2. Alternatively, platinum chlorides are susceptible to alkylation: PtCl22 + 2 MeLi → PtMe22 + 2 LiClThe dimethylsulfide ligands in PtMe22 can be displaced by other ligands. Many organoplatinum complexes arise via ortho-metalation and related intramolecular C-H activation processes; the first organoplatinum compound synthesised was trimethylplatinum iodide from platinum chloride and methylmagnesium iodide, reported by Pope and Peachey in 1907. The compound adopts a cubane-like structure with four triply bridging iodide ligands. "Tetramethylplatinum" was claimed in 1952 by Henry Gilman as a derivative of this tetramer, but this claim was shown to be incorrect. Salts of 2− and 2− have been characterized. Organoplatinum hydrides are rare; the first isolated representatives were prepared from organotin halides or acids with orthometalated arylplatinum compounds.

The compound Me2PtOTf reacts reversibly with triflic acid between -60 and -80 °C, forming methane and 2Pt2 at -20 °C. Weak acids suffice water and alcohol and in C-H bond activation the proton source is an alkane. Heterogeneous catalysts based on platinum play a major role in the petrochemical industry, it is assumed that these useful reactions proceed via surface-bound organoplatinum intermediates. Better defined but less commercially significant are homogeneous catalysts based on platinum. For hydrosilylation, H2PtCl6 is an important catalyst. Mechanisms for this catalytic system assume intermediates that contain hydride, silyl ligand, alkene ligands. Cis-dichlorobisplatinum and Karstedt’s catalyst catalyse hydrosilylation. Many metallodendrimers have repeating units based on organoplatinum compounds. Organoplatinum compounds are implicated in the Shilov system for the conversion of methane into methyl chloride. Strenuous efforts have been made, thus far unsuccessfully, to extend this reactivity to practical methods for functionalizing methane.

For example, platinum complexes of bipyrimidine catalyze the conversion of methane and sulfur trioxide into methyl bisulfate

Davoud Danesh-Jafari

Davoud Danesh-Jafari is an Iranian politician and economist, minister of economy and finance affairs of Iran. Born in 1954 in Tehran, Danesh-Jafari graduated with a bachelor's degree in civil engineering from Regional Engineering College, India. In 1992 he received a master's degree in economics from Tehran University and in 2001 he obtained a PhD from Allameh Tabatabaii University, he was a member of the parliament in the 7th term. Since 2006 he was involved in plans to create the Iranian Oil Bourse, a commodity exchange for oil and oil byproducts, which would trade in the Iranian currency and other major currencies In December 2006, he was reported as saying that he intended to reduce US dollar-based transactions as much as possible. In January 2008, he announced that the Iranian Oil Bourse would be opened during the anniversary of the Islamic Revolution a month later. Oil Minister Gholam Hossein Nozari announced that Davoud Danesh-Jafari would become its head; the Oil Bourse opened on 17 February 2008 on Kish Island.

He served as the minister of economy and finance affairs in the cabinet of president Mahmoud Ahmedinejad from 2005 to 2008