Transition metal complexes of phosphine oxides are coordination complex containing one or more phosphine oxide ligands. Many phosphine oxides exist and most behave as hard Lewis bases. Almost invariably, phosphine oxides bind metals by formation of M-O bonds. [1]
![Structure of NiCl2[OP(C6H5)3]2. Selected bond lengths: 1.96 (Ni-O) and 1.51 A (P-O). The Ni-O-P angles are 151deg. Color code: red = O, orange = P, green = Cl, Ni. CSD CIF BIPKER.png](http://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/CSD_CIF_BIPKER.png/220px-CSD_CIF_BIPKER.png)
The structure of the phosphine oxide is not strongly perturbed by coordination. The geometry at phosphorus remains tetrahedral. The P-O distance elongates by ca. 2%. In triphenylphosphine oxide, the P-O distance is 1.48 Å. [3] In NiCl2[OP(C6H5)3]2, the distance is 1.51 Å (see figure). A similar elongation of the P-O bond is seen in cis-WCl4(OPPh3)2. [4] The trend is consistent with the stabilization of the ionic resonance structure upon complexation.
Typically, complexes are derived from hard metal centers. Examples include cis-WCl4(OPPh3)2 [4] and NbOCl3(OPPh3)2 [5] Trialkylphosphine oxides are more basic (better ligands) than triarylphosphine oxides. One such complex is FeCl2(OPMe3)2 (Me = CH3). [6]
Most complexes of phosphine oxides are prepared by treatment of a labile metal complex with preformed phosphine oxide. In some cases, the phosphine oxide is unintentionally generated by air-oxidation of the parent phosphine ligand.
Since phosphine oxides are weak Lewis bases, they are readily displaced from their metal complexes. This behavior has led to investigation of mixed phosphine-phosphine oxide ligands, which exhibit hemilability. Typical phosphine-phosphine oxide ligands are Ph2P(CH2)nP(O)Ph2 (Ph = C6H5) derived from bis(diphenylphosphino)ethane (n = 2) and bis(diphenylphosphino)methane (n = 1). [1]
In one case, coordination of the oxide of dppe to W(0) results in deoxygenation, giving an oxotungsten complex of dppe. [7]
Secondary phosphine oxides have the formula R2P(O)H. [8] They tautomerize to small amounts of the hydroxy tautomer R2P-OH. Regardless, the hydroxy tautomer forms a wide variety of complexes with transition metals. In contrast to O-bonded phosphine oxide ligands, the P-bonded phosphine oxides are strong field ligands. These ligands, which tend to engage in intramolecular hydrogen bonds. Illustrative is the complex derived from dimethylphosphine oxide, PtH(PMe2OH)2(PMe2O) (Me = CH3). [9]
The pattern also applies to several phosphorus compounds including phosphorous acid, which forms complexes as P(OH)3. The complex platinum pop is one example.
The Kläui ligand is the anion {(C5H5)Co[(CH3O)2PO]3}−. It is derived from the trimethylphosphite ligand by dealkylation. In this case the "ligand" is a complex of cobalt that also binds to other metals in a tridentate manner. [10]
Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.
Organophosphorus chemistry is the scientific study of the synthesis and properties of organophosphorus compounds, which are organic compounds containing phosphorus. They are used primarily in pest control as an alternative to chlorinated hydrocarbons that persist in the environment. Some organophosphorus compounds are highly effective insecticides, although some are extremely toxic to humans, including sarin and VX nerve agents.
1,2-Bis(diphenylphosphino)ethane (dppe) is an organophosphorus compound with the formula (Ph2PCH2)2 (Ph = phenyl). It is a common symmetrical bidentate ligand in coordination chemistry. It is a white solid that is soluble in organic solvents.
In coordination chemistry, hapticity is the coordination of a ligand to a metal center via an uninterrupted and contiguous series of atoms. The hapticity of a ligand is described with the Greek letter η ('eta'). For example, η2 describes a ligand that coordinates through 2 contiguous atoms. In general the η-notation only applies when multiple atoms are coordinated. In addition, if the ligand coordinates through multiple atoms that are not contiguous then this is considered denticity, and the κ-notation is used once again. When naming complexes care should be taken not to confuse η with μ ('mu'), which relates to bridging ligands.
Phosphine oxides are phosphorus compounds with the formula OPX3. When X = alkyl or aryl, these are organophosphine oxides. Triphenylphosphine oxide is an example. An inorganic phosphine oxide is phosphoryl chloride (POCl3). The parent phosphine oxide (H3PO) remains rare and obscure.
Chloro(triphenylphosphine)gold(I) or triphenylphosphinegold(I) chloride is a coordination complex with the formula (Ph3P)AuCl. This colorless solid is a common reagent for research on gold compounds.
Triphenylphosphine oxide (often abbreviated TPPO) is the organophosphorus compound with the formula OP(C6H5)3, also written as Ph3PO or PPh3O (Ph = C6H5). It is one of the more common phosphine oxides. This colourless crystalline compound is a common but potentially useful waste product in reactions involving triphenylphosphine. It is a popular reagent to induce the crystallizing of chemical compounds.
Organophosphines are organophosphorus compounds with the formula PRnH3−n, where R is an organic substituent. These compounds can be classified according to the value of n: primary phosphines (n = 1), secondary phosphines (n = 2), tertiary phosphines (n = 3). All adopt pyramidal structures. Organophosphines are generally colorless, lipophilic liquids or solids. The parent of the organophosphines is phosphine (PH3).
Martin Arthur Bennett FRS is an Australian inorganic chemist. He gained recognition for studies on the co-ordination chemistry of tertiary phosphines, olefins, and acetylenes, and the relationship of their behaviour to homogeneous catalysis.
Organoplatinum chemistry is the chemistry of organometallic compounds containing a carbon to platinum chemical bond, and the study of platinum as a catalyst in organic reactions. Organoplatinum compounds exist in oxidation state 0 to IV, with oxidation state II most abundant. The general order in bond strength is Pt-C (sp) > Pt-O > Pt-N > Pt-C (sp3). Organoplatinum and organopalladium chemistry are similar, but organoplatinum compounds are more stable and therefore less useful as catalysts.
Dichlorotris(triphenylphosphine)ruthenium(II) is a coordination complex of ruthenium. It is a chocolate brown solid that is soluble in organic solvents such as benzene. The compound is used as a precursor to other complexes including those used in homogeneous catalysis.
Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, such as palladium chloride.
A metal-phosphine complex is a coordination complex containing one or more phosphine ligands. Almost always, the phosphine is an organophosphine of the type R3P (R = alkyl, aryl). Metal phosphine complexes are useful in homogeneous catalysis. Prominent examples of metal phosphine complexes include Wilkinson's catalyst (Rh(PPh3)3Cl), Grubbs' catalyst, and tetrakis(triphenylphosphine)palladium(0).
trans-Bis(dinitrogen)bis[1,2-bis(diphenylphosphino)ethane]molybdenum(0) is a coordination complex with the formula Mo(N2)2(dppe)2. It is a relatively air stable yellow-orange solid. It is notable as being the first discovered dinitrogen containing complex of molybdenum.
Dichlorobis(triphenylphosphine)nickel(II) refers to a pair of metal phosphine complexes with the formula NiCl2[P(C6H5)3]2. The compound exists as two isomers, a paramagnetic dark blue solid and a diamagnetic red solid. These complexes function as catalysts for organic synthesis.
(2-Bromophenyl)diphenylphosphine is an organophosphorus compound with the formula (C6H4Br)P(C6H5)2. It is a white crystalline solid that is soluble in nonpolar organic solvents. The compound is used as a precursor to the 2-lithiated derivative of triphenylphosphine, which in turn is a precursor to other phosphine ligands.
2-(Diphenylphosphino)anisole is the organophosphorus compound with the formula (C6H5)2PC6H4-2-OCH3. It is a white solid that is soluble in organic solvents. The compound is used as a ligand in organometallic chemistry and homogeneous catalysis. It is the prototypical hemilabile ligand. This compound is prepared from 2-bromoanisole.
In chemistry, a transition metal chloride complex is a coordination complex that consists of a transition metal coordinated to one or more chloride ligand. The class of complexes is extensive.
In chemistry, transition metal silyl complexes describe coordination complexes in which a transition metal is bonded to an anionic silyl ligand, forming a metal-silicon sigma bond. This class of complexes are numerous and some are technologically significant as intermediates in hydrosilylation. These complexes are a subset of organosilicon compounds.
Palladium forms a variety of ionic, coordination, and organopalladium compounds, typically with oxidation state Pd0 or Pd2+. Palladium(III) compounds have also been reported. Palladium compounds are frequently used as catalysts in cross-coupling reactions such as the Sonogashira coupling and Suzuki reaction.