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]
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.
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.
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.
Bis(triphenylphosphine)palladium chloride is a coordination compound of palladium containing two triphenylphosphine and two chloride ligands. It is a yellow solid that is soluble in some organic solvents. It is used for palladium-catalyzed coupling reactions, e.g. the Sonogashira–Hagihara reaction. The complex is square planar. Many analogous complexes are known with different phosphine ligands.
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.
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.
Bis(triphenylphosphine)platinum chloride is a metal phosphine complex with the formula PtCl2[P(C6H5)3]2. Cis- and trans isomers are known. The cis isomer is a white crystalline powder, while the trans isomer is yellow. Both isomers are square planar about the central platinum atom. The cis isomer is used primarily as a reagent for the synthesis of other platinum compounds.
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.
Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.
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.
Transition metal pyridine complexes encompass many coordination complexes that contain pyridine as a ligand. Most examples are mixed-ligand complexes. Many variants of pyridine are also known to coordinate to metal ions, such as the methylpyridines, quinolines, and more complex rings.
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.
Tricarbonylbis(triphenylphosphine)iron(0) is a coordination complex with the formula Fe(CO)3(PPh3)2 (Ph = C6H5). A yellow solid, this complex is derived from iron pentacarbonyl by replacement of two carbonyl ligands by triphenylphosphine (PPh3).
Transition metal thioether complexes comprise coordination complexes of thioether (R2S) ligands. The inventory is extensive.
In organometallic chemistry, transition metal complexes of nitrite describes families of coordination complexes containing one or more nitrite ligands. Although the synthetic derivatives are only of scholarly interest, metal-nitrite complexes occur in several enzymes that participate in the nitrogen cycle.
A transition metal nitrate complex is a coordination compound containing one or more nitrate ligands. Such complexes are common starting reagents for the preparation of other 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.