Tetrakis(triphenylphosphine)platinum(0)

Tetrakis(triphenylphosphine)platinum(0) is the chemical compound with the formula Pt(P(C6H5)3)4, often abbreviated Pt(PPh3)4. The bright yellow compound is widely used as a precursor to other platinum complexes.

Structure and behavior
The molecule is tetrahedral, with point group symmetry of Td, as expected for a four-coordinate metal complex of a metal with the d10 configuration. Even though this complex follows the 18 electron rule, it dissociates triphenylphosphine in solution to give the 16e- derivative containing only three PPh3 ligands:
 * Pt(PPh3)4 --> Pt(PPh3)3 + PPh3

Synthesis and reactions
The complex is typically prepared in one-pot reaction from potassium tetrachloroplatinate(II). Reduction of this platinum(II) species with alkaline ethanol in the presence of excess triphenylphosphine affords the product as a precipitate. The reaction occurs in two distinct steps. In the first step, PtCl2(PPh3)2 is generated. In the second step, this platinum(II) complex is reduced. The overall synthesis can be summarized as:
 * K2[PtCl4] + 2KOH + 4PPh3 + C2H5OH → Pt(PPh3)4 + 4KCl + CH3CHO + 2H2O

Both Pt(PPh3)4 and Pt(PPh3)4 react with oxidants to give platinum(II) derivatives:
 * Pt(PPh3)4 +  Cl2  →  cis-PtCl2(PPh3)2  +  2 PPh3

Most mineral acids give the corresponding hydride complex:
 * Pt(PPh3)4 +  HCl2  →  trans-PtCl(H)(PPh3)2  +  2 PPh3

The reaction with oxygen affords a dioxygen complex:
 * Pt(PPh3)4 +  O2  →  Pt(&eta;2-O2)(PPh3)2  +  2 PPh3

This complex is a precursor to the ethylene complex
 * Pt(&eta;2-O2)(PPh3)2 +  C2H4  →  Pt(&eta;2-C2H4)(PPh3)2   +  "NaBH2(OH)2"