Diphosphines, sometimes called bisphosphanes are organophosphorus compounds that are used as 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 inorganic

Inorganic chemistry

Inorganic chemistry is the branch of chemistry concerned with the properties and behavior of inorganic compounds. This field covers all chemical compounds except the myriad organic compounds , which are the subjects of organic chemistry...

 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...

. They are identified by the presence of two phosphino groups linked by a backbone and are usually chelating

Synthesis

The most widely used diphosphine ligands have the general formula Ph₂P(CH₂)_nPPh₂. These compounds can be prepared from the reaction of X(CH₂)_nX (X=halogen) and YPPh₂ (Y=alkali metal):

Cl(CH₂)_nCl + 2 NaPPh₂ → Ph₂P(CH₂)_nPPh₂ + 2 NaCl

Diphosphine ligands can also be prepared by other methods, such as from dilithiated reagents and chlorophosphines or by the addition of secondary phosphines to vinylphosphines.

Chain length and coordinating properties

The short-chain diphosphine dppm

1,1-Bis(diphenylphosphino)methane

1,1-Bismethane , is an organophosphorus compound with the formula CH22. Dppm, a white, crystalline powder, is used in inorganic and organometallic chemistry as a ligand...

 tend to promote metal-metal interactions as illustrated by A-frame complex

A-frame complex

A-frame complexes are coordination compounds that contain two bridging bidentate ligands and a single atom bridge. They have the formula M22L2, where bd is a bidental ligand like dppm, and X and L are a wide variety of ligands...

es. When the two phosphine substituents are linked by 2-4 carbon centres, the resulting ligands often chelate rings with a single metal. The most common diphosphine ligand is 1,2-Bis(diphenylphosphino)ethane

1,2-Bis(diphenylphosphino)ethane

1,2-Bisethane is a commonly used bidentate ligand in coordination chemistry. Dppe is almost invariably chelated, although there are examples of unidentate and of bridging behavior.-Preparation:...

, which forms a 5-membered chelate ring with most metals.

Some diphosphines, such as the extraordinary case of ^tBu₂P(CH₂)₁₀P^tBu₂, give macrocyclic complexes with as many as 72 atoms in a ring.

To position phosphine donor groups trans on a coordination sphere, several atoms are required to link the donor centres and long chain diphosphines are typically floppy and do not chelate well. This challenge has been resolved by the long but rigid diphosphine SPANphos.

Common ligands

Diphosphine ligands that are particularly common are shown in the table below:

Abbreviation	Common Name (from which abbreviation derived)	IUPAC Name (rarely used)
dppm	1,1-Bis(diphenylphosphino)methane 1,1-Bis(diphenylphosphino)methane 1,1-Bismethane , is an organophosphorus compound with the formula CH22. Dppm, a white, crystalline powder, is used in inorganic and organometallic chemistry as a ligand...	Methylenebis(diphenylphosphane)
dmpe	1,2-Bis(dimethylphosphino)ethane 1,2-Bis(dimethylphosphino)ethane 1,2-Bisethane is a diphosphine ligand in coordination chemistry. It can be synthesised by the reaction of methylmagnesium iodide with 1,2-bisethane:...	Ethane-1,2-diylbis(dimethylphosphane)
dippe	1,2-Bis(diisopropylphosphino)ethane	Ethane-1,2-diylbis(di(propan-2-yl)phosphane)
dppe	1,2-Bis(diphenylphosphino)ethane 1,2-Bis(diphenylphosphino)ethane 1,2-Bisethane is a commonly used bidentate ligand in coordination chemistry. Dppe is almost invariably chelated, although there are examples of unidentate and of bridging behavior.-Preparation:...	Ethane-1,2-diylbis(diphenylphosphane)
DIPAMP DIPAMP DIPAMP is an organophosphorus compound that is used as a ligand in homogeneous catalysis. It is a white solid that dissolves in organic solvents. Work on this compound by W. S. Knowles was recognized with the Nobel Prize in Chemistry. DIPAMP was the basis for of the first practical asymmetric...	dimer of phenylanisylmethylphosphine	Ethane-1,2-diylbis[(2-methoxyphenyl)phenylphosphane]
dppp	1,3-Bis(diphenylphosphino)propane 1,3-Bis(diphenylphosphino)propane 1,3-Bispropane is a diphosphine often found as a ligand in coordination chemistry.The diphosphine can be prepared by the reaction of lithium diphenylphosphide and 1,3-dichloropropane.The diphosphine is a precursor to the complex dichloronickel, which is prepared by combining equimolar portions of...	Propane-1,3-diylbis(diphenylphosphane)
dppb	1,4-Bis(diphenylphosphino)butane	Butane-1,4-diylbis(diphenylphosphane)
Chiraphos Chiraphos Chiraphos is a chiral diphosphine employed as a ligand in organometallic chemistry. This bidentate ligand chelates metals via the two phosphine groups. Its name is derived from its description — being both chiral and a phosphine...	2,3-Bis(diphenylphosphino)butane	Butane-2,3-diylbis(diphenylphosphane)
BINAP	2,2'-Bis(diphenylphosphino)-1,1'-binaphthyl BINAP BINAP is an abbreviation for the organophosphorus compound 2,2'-bis-1,1'-binaphthyl. This chiral ligand is widely used in asymmetric synthesis. It consists of a pair of 2-diphenylphosphinonaphthyl groups linked at the 1 and 1´ positions. This C2-symmetric framework lacks stereogenic atom, but...	1,1'-Binaphthalene-2,2'-diylbis(diphenylphosphane)
Xantphos	4,5-Bis(diphenylphosphino)-9,9-dimethylxanthene Xantphos Xantphos is an organophosphorus compound derived from the heterocycle xanthene. It is used as a bidentate ligand and is noteworthy for having a particularly wide bite angle. Such ligands are useful in the hydroformylation of alkenes. Illustrative of its wide bite angle, it forms both cis and...	9,9-Dimethyl-9H-xanthene-4,5-diylbis(diphenylphosphane)
SPANphos SPANphos SPANphos is an organophosphorus compound used as a ligand in organometallic and coordination chemistry. This compound is a rare example of a trans-spanning ligand and rigidly links mutually trans coordination sites. By virtue of its chiral backbone that forms a chiral cavity over the face of a...		4,4,4',4',6,6'-Hexamethyl-2,2'-spirobichromane-8,8'-diylbis(diphenylphosphane)
SEGPHOS SEGPHOS SEGPHOS is a chiral ligand that is used in asymmetric synthesis. It was developed after BINAP and was investigated since it has a narrower dihedral angle between the aromatic faces. This was predicted and then confirmed to increase the enantioselectivity and activity of metal complexes of SEGPHOS....		4,4'-Bi-1,3-benzodioxole-5,5'-diylbis(diphenylphosphane)
dppf	1,1'-Bis(diphenylphosphino)ferrocene 1,1'-Bis(diphenylphosphino)ferrocene 1,1'-Bisferrocene, commonly abbreviated dppf, is a substituted phosphine commonly used, as are other phosphines, as a ligand in organometallic chemistry...
Me-DuPhos	1,2-Bis(2,5-dimethylphospholano)benzene DuPhos DuPhos is a class of asymmetric ligands for asymmetric synthesis. The name DuPhos is derived from the chemical company that developed this type of ligand and the compound class of phospholanes it belongs to. This diphosphine ligand type was introduced in 1991 by M.J...	1,2-Phenylenebis(2,5-dimethylphospholane)