Dimethylphenylphosphine

Template:Chembox image cellTemplate:Chembox AllOtherNamesTemplate:Chembox headerbarTemplate:Chembox IndexlistTemplate:Chembox JmolTemplate:Chembox ChEMBLTemplate:Chembox ECHATemplate:Chembox E numberTemplate:Chembox IUPHAR ligandTemplate:Chembox UNIITemplate:Chembox CompToxTemplate:Chembox headerbarTemplate:Chembox SolubilityInWaterTemplate:Chembox headerbarTemplate:Chembox headerbarTemplate:Chembox GHS (set)Template:Chembox SDSTemplate:Chembox Datapage checkTemplate:Chembox Footer

Dimethylphenylphosphine

Template:Chembox image sbs cell
Template:Longitem	Template:Unbulleted list
ChEBI	Template:Unbulleted list
ChemSpider	Template:Unbulleted list
DrugBank	Template:Unbulleted list
EC Number	Template:Unbulleted list
KEGG	Template:Unbulleted list
Template:Longitem	Template:Unbulleted list
RTECS number	Template:Unbulleted list
Template:Longitem	C8H11P
Molar mass	138.14 g/mol
Appearance	transparent light pale yellow liquid
Density	0.971 g/cm3
Melting point	Template:Chembox CalcTemperatures
Boiling point	Template:Chembox CalcTemperatures
Template:Longitem	Pyramidal
Flash point	Template:Chembox CalcTemperatures

Dimethylphenylphosphine is an organophosphorus compound with a formula P(C₆H₅)(CH₃)₂. The phosphorus is connected to a phenyl group and two methyl groups, making it the simplest aromatic alkylphosphine. It is colorless air sensitive liquid. It is a member of series (CH₃)_3-n(C₆H₅)₂P that also includes n = 0, n = 2, and n = 3 that are often employed as ligands in metal phosphine complexes.

Preparation

Dimethylphenylphosphine is prepared by the reaction of methylmagnesium halide with dichlorophenylphosphine.

(C₆H₅)Cl₂P + 2CH₃MgBr → (C₆H₅)(CH₃)₂P + 2MgBrCl

The phosphine is purified by distillation under reduced pressure. A solution of (C₆H₅)(CH₃)₂P in CDCl₃ shows proton NMR signals at δ 7.0-7.5 and a doublet at δ 1.2. The phosphorus-31 NMR spectrum shows a singlet at -45.9 ppm in CDCl₃.

Structure and properties

Dimethylphenylphosphine is a pyramidal molecule where the phenyl group and two methyl groups are connected to the phosphorus. The bond length and angles are the following: P-C_Me: 1.844, P-C_Ph: 1.845 Å, C-C: 1.401 Å, C-H_Me: 1.090 Å, C-H_Ph: 1.067 Å, C-P-C: 96.9°, C-P-C (ring): 103.4°, P-C-H: 115.2°.

When attached to chiral metal centers, the P-methyl groups are diastereotopic, appearing as separate doublets in the ¹H NMR spectrum.

Comparisons with related phosphine ligands

The ν_CO of IrCl(CO)(PPh₃)₂ and IrCl(CO)(PMe₂Ph)₂ are both at 1960 cm⁻¹, whereas ν_CO for IrCl(CO)(PMe₃)₂ is at 1938 cm⁻¹.

In terms of basicity, dimethylphenylphosphine is intermediate between that of trialkyl- and triphenylphosphine:

• [HPEt₃]⁺ = 8.7
• [HPMe₂Ph]⁺ = 6.8
• [HPPh₃]⁺ = 2.7

The ligand cone angle (θ) is the apex angle of a cylindrical cone, which is centered 2.28 Å from the center of the P atom. However, the cone angle of an unsymmetrical ligand cannot be determined in the same. In order to determine an effective cone angle for an unsymmetrical ligand PX₁X₂X₃, the following equation is used:

$\theta =\frac{2}{3}\sum _{i=1}^3\frac{{\theta }_i}{2}$

Where θ_i represent the half angle.

The resulting angles for PMe₃, PMe₂Ph, PPh₃ are: PMe₃ = 118°, PMe₂Ph = 122°, PPh₃ = 145°. Thus, PMe₂Ph is intermediate in size relative to PMe₃ and PPh₃.