Triphos is the name for two organophosphorus compounds. Both are air sensitive white solids that serve as tridentate ligand

Ligand

In coordination chemistry, a ligand is an ion or molecule that binds to a central metal atom to form a coordination complex. The bonding between metal and ligand generally involves formal donation of one or more of the ligand's electron pairs. The nature of metal-ligand bonding can range from...

s in coordination and organometallic chemistry

Organometallic chemistry

Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...

. One is C₃-symmetric and the other has C_s symmetry.

Bis(diphenylphosphinoethyl)phenylphosphine

Bis(diphenylphosphinoethyl)phenylphosphine is called triphos, is a linear tridentate triphosphine.

Synthesis

Bis(diphenylphosphinoethyl)phenylphosphine is prepared by the free-radical-catalysed addition of phenylphosphine

Phenylphosphine

Phenylphosphine is a primary phosphine with the chemical formula C6H5PH2. It is the phosphorus analog of aniline. Like all other primary phosphines, phenylphosphine has an intense penetrating odor...

 to vinyldiphenylphosphine:

2 Ph₂PCH=CH₂ + H₂PPh → [Ph₂PCH₂CH₂]₂PPh

Coordination chemistry

This isomer of triphos is more flexible and can bind to an octahedral metal center give either a facial or meridional isomers. Many of its derivatives are square planar complexes of the type [MX(triphos)]⁺ (M = Ni, Pd, Pt; X = halide).

1,1,1-Tris(diphenylphosphinomethyl)ethane

1,1,1-Tris(diphenylphosphinomethyl)ethane is called triphos.

Synthesis

Triphos is prepared by the reaction of sodium diphenylphosphide and CH₃C(CH₂Cl)₃:

3 Ph₂PNa + CH₃C(CH₂Cl)₃ → CH₃C[CH₂PPh₂]₃ + 3 NaCl

The required sodium diphenylphosphide is conveniently obtained by cleaving triphenylphosphine

Triphenylphosphine

Triphenylphosphine is a common organophosphorus compound with the formula P3 - often abbreviated to PPh3 or Ph3P. It is widely used in the synthesis of organic and organometallic compounds. PPh3 exists as relatively air stable, colorless crystals at room temperature...

 with sodium in liquid ammonia.

Coordination chemistry

Triphos forms complexes with many transition metal

Transition metal

The term transition metal has two possible meanings:*The IUPAC definition states that a transition metal is "an element whose atom has an incomplete d sub-shell, or which can give rise to cations with an incomplete d sub-shell." Group 12 elements are not transition metals in this definition.*Some...

s. It usually functions as a tripodal ligand that occupies three adjacent coordination sites. Triphos complexes often exhibit high thermal stability. Such complexes are used to analyze mechanistic aspects of homogenous catalysts. For example, rhodium

Rhodium

Rhodium is a chemical element that is a rare, silvery-white, hard and chemically inert transition metal and a member of the platinum group. It has the chemical symbol Rh and atomic number 45. It is composed of only one isotope, 103Rh. Naturally occurring rhodium is found as the free metal, alloyed...

 forms complexes with CH₃C[CH₂PPh₂]₃ like [(triphos)RhCl(C₂H₄)], [(triphos)RhH(C₂H₄)], and [(triphos)Rh(C₂H₅)(C₂H₄)], provide model intermediates in the catalytic

Catalysis

Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....

 cycle for hydrogenation of alkenes.

Triphos sometimes behaves as a bidentate-chelating ligand. Illustrative cases include fac-[Mn(CO)₃Br(η²-triphos)] and [M(CO)₄(η²-triphos)],where M is Cr, Mo, or W. Triphos serves as a tridentate-bridging ligand in an icosohedral

Icosahedron

In geometry, an icosahedron is a regular polyhedron with 20 identical equilateral triangular faces, 30 edges and 12 vertices. It is one of the five Platonic solids....

Au₁₃ cluster. The phosphine bridges three chlorogold(I) groups to form the tripod molecule of trichloro-1,1,1-(diphenylphosphinomethyl)ethanetrigold(I), CH₃C[CH₂PPh₂AuCl]₃.