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= TriphenylBismuth = Triphenylbismuth is an elemental organic substance derived from arylbismuth. It is composed by three aromatic cycles, and a central metal: the Bismuth (III). It is in the form of white crystals, which has applications in many areas of chemistry.

Synthesis :
In literature, the first synthesis of triphenyl bismuth was carried out by De Katelaere and al, in 1971, by reacting an anhydrous bismuth (III) halide with an organomagnesium.2

Caracteristics:
Triphenylbismuthine is a crystalline solid with a white color, easy to handle and stable. Its crystallization temperature is 78-80 ° C, and is readily soluble in benzene, dichloromethane, ether, THF and ethyl acetate, but is sparingly soluble in hexane and insoluble in water. It is not toxic (LD50 180g / kg for dogs (orally)). 3

The protonic basicity (pKb) of triphenylBismuth was estimated at 8.81 by a potentiometric method in acetic acid.4

The dipole moment of triphenylbismuth is zero in benzene, cyclohexane and octane. This observation suggests two hypothesis: either each Ph-Bi group is apolar, or the dipolar moments of the three Ph-Bi bonds are compensated by the non-bonding doublet5

The Bi-C bonding distance in triphenylBismuth is 2.24 A, and the C-Bi-C angle is 94°, indicating a small contribution of 6s-6p orbital hybridization to the Bismuth6

Chemistry :
TriphenylBismuth,by its Lewis acid character and low toxicity allows its use in coupling reactions as a source of aromatic nucleophile7 but also in protection/deprotection reactions and in oxidation processes8.

Indeed, these reaction systems, often catalytic, are sometimes used in aqueous medium or without solvent and involve a metal of low toxicity. However, compounds based on bismuth (III) have a low toxicity compared to that of other heavy metals whose toxicity generally increases with their position in the periodic table.9

The thermal decomposition of triphenylbismuth at 192-224 ° C make possible to obtain ethylene, butane and butylenes, mainly in the gaseous phase.10

Uses :
The major use of triphenylbismuth, is mainly for the formation of C-C bonds, by its properties, it is then used for many reactions such as:
 * Cross-coupling reactions, especially mediated by palladium catalysis using aryl halides, for example11.
 * They have also been used with halide derivatives of the Baylis Hillman adduct, allowing the formation of C-C bonds with a very good yield (greater than 75%).12
 * Triphenyl bismuth can also be involved in  the Heck 13 reaction, but they are also widely used for O-Arylation and C-Arylation reactions.14

Absorbtion spectrum15 :
TriphenylBismuth shows characteristic absorptions at lmax 248 and 280 nm. The band at 280 nm is thought to be due to the p-p* transition of benzene, whereas the band at 248 nm is due to the dissociation reaction of triphenylBismuth

Vibrational spectra:
Recently, two teams of researchers have studied the vibrational spectra of Ph3Bi using the Whiffen nomenclature to assign the different frequencies observed 16.

Shobatake team 17:
Shobatake and al. Reported IR and Raman spectra of Ph3Bi in a solution of benzene and Nujol.

In the benzene solution, the vibration t, which is the main stretching vibration of the phenyl-heavy elements, is attributed to strong bands at 237 and 220 cm-1 in infrared spectroscopy. They also observed a moderately polarized band at 237 cm-1 and a depolarized band (a shoulder) at 219 cm-1 in the Raman spectrum.

In the solid state, the IR and Raman spectra are more complex; therefore, the conclusions regarding the structure of Ph3Bi have been deduced only from the spectra in solution

Parrett team 18:
In agreement with Shobatake and his colleagues, Parrett attributes the vibration t to the 235 and 225 cm-1 bands in the IR spectrum and the 236 and 223 cm-1 bands in the Raman spectrum. The vibration u, however, is assigned to a moderately polarized band at 216 cm-1 and a shoulder at 199 cm-1 in the IR spectrum and a strong band at 210 cm-1 and a shoulder at 201 cm-1 in the spectrum Raman.

The assignments for the vibration are similar for the two research teams, but the assignments for the vibration x differs.

Symetry:
Shobatake's team concluded, on the basis of their spectral data, that triphenylbismuth possesses either C3 symmetry or C3n. 17

Nevertheless, these two groups of symmetry can not be distinguished by means of the observed spectral data. However, a comparison of the stretching and bending modes (t and u) with those calculated on the basis of C3n symmetry gave an excellent agreement between the observed and the theoretical values, which favors the hypothesis of this symmetry. 16

Analysis in en RMN 1H 19 :
In proton NMR spectroscopy in chloroform, the spectrum shows the proton resonance in ortho, meta and para at 8.7, 7.4 and 7.39 ppm, respectively.

Bismuth having a spin of 9/2, triphenylbismuth reveals four peaks whose frequencies :n1 = 29.785, n2 = 55.214, n3 = 83.516 and n4 = 111.438.

The coupling constant of this quadruplet (eQqzz) is 669.06 ± 0.13 MHz, which indicates that the Bismuth bonds have a s character at 8-9% (NQR spectrum = Nuclear Quadrupole Resonance or NMR with a zero magnetic field).