T-butyl Phosphine Research Articles

Unprecedented carbocyclization of 1,6-allenynes on addition of organoboronic acids under Pd-catalysis

In contrast to the ene behavior of allenes in Pauson–Khand reactions and other cyclization reactions, 1,6-allenynes undergo unprecedented carbocyclization followed by regioselective addition of organoboronic acids in the presence of Pd(OAc) 2 and tri- t-butyl phosphine under mild reaction conditions.

Fabrication of a P-stabilized InP(0 0 1) surface at low pressure and temperature using t-butylphosphine (TBP)

Fabrication of a P-stabilized InP(0 0 1)-(2 × 1) surface at low pressure and temperature using t-butylphosphine (TBP) has been studied. The (2 × 1) surface was fabricated at 260 °C using TBP (5 × 10 −6 Torr) cracked with a hot W-filament although the (2 × 4) structure was not changed by exposing to TBP (5 × 10 −6–1 × 10 −5 Torr) at 260–280 °C without the filament. Mass spectra of the cracked TBP indicate that the relative spectral intensities of P and P 2 are increased by 1.3–1.5 times higher than TBP without the filament, leading to the result that the surface can be fabricated at low pressure and temperature. The formation rate of the (2 × 1) surface by our method is higher by about one order of magnitude even at lower pressure and temperature than the reported ALE method. The (2 × 1) surface is stable at 260–280 °C in an ultrahigh vacuum. This suggests that atomic layer epitaxy (ALE) of InP can be performed at low pressure and temperature using the hot W-filament. The Auger electron spectroscopy (AES) result indicates that carbon contamination does not occur on the surface by adsorption of TBP cracked by the filament.

Adsorption and decomposition of t-butylphosphine (TBP) on an InP(0 0 1)–(2 × 4)/c(2 × 8) surface studied by STM, TPD, and HREELS

Adsorption and decomposition of t-butylphosphine (TBP) on an InP(001)–(2×4)/c(2×8) surface have been studied by scanning tunneling microscopy (STM), temperature programmed desorption (TPD), and high-resolution electron energy loss spectroscopy (HREELS). It is found that TBP is adsorbed at the edge of the dimer rows (about 60%), in the missing dimer rows (about 30%), and at the center of the dimer rows (about 10%) at RT. The TPD result indicates that t-butyl radical and isobutylene are evolved from the TBP-adsorbed InP(001) surface. HREELS spectra suggest that TBP is partially dissociated on the surface at 300K and that most of TBP is evolved up to 600K through decomposition. The decomposition mechanism for TBP on the surface is discussed.

Synthesis of 1,2-bis[(diorgano)phosphino]ethanes via Michaelis–Arbuzov type rearrangements

A three-step process for the synthesis of the bis(diorganophosphino)ethanes R 2PCH 2CH 2PR 2 where R=Et, Ph, i Pr, Cy and t Bu was examined. In the first step, diorganochlorophosphines were allowed to react with ethylene glycol in the presence of triethylamine at room temperature in THF solution. For R=Ph, i Pr and Cy, the bisphosphinites R 2POCH 2CH 2OPR 2 were obtained in high yield. For R=Et, the bisphosphinite could not be isolated but may be formed in 80% mixtures with tetraethyldiphosphine, Et 2PPEt 2, as a minor component. The reaction of di- t-butylchlorophosphine with ethylene glycol occurs at temperatures greater than 130 °C giving di- t-butyl phosphine oxide, t Bu 2PH(O), as the only phosphorus-containing product. Thermolysis of the bisphosphinites R 2POCH 2CH 2OPR 2 (R=Ph, i Pr and Cy) at 190–260 °C for 24 h gave the bisphosphine oxides, R 2P(O)CH 2CH 2(O)PR 2 in 9% (Ph), 90% ( i Pr) and 93% (Cy) yields. A DSC study of the thermal rearrangement of Cy 2POCH 2CH 2OPCy 2 to Cy 2P(O)CH 2CH 2(O)PCy 2 yielded an enthalpy of isomerization of −40.4±0.6 kcal mol −1. Reduction of the bisphosphine oxides, R 2P(O)CH 2CH 2(O)PR 2 (R=Ph, i Pr and Cy) with trichlorosilane gave the bisphosphines, R 2PCH 2CH 2PR 2 in 80–85% yield. The overall yields of the bisphosphines R 2PCH 2CH 2PR 2 (R= i Pr and Cy) in the three-step process were 61 and 75%, respectively, suggesting that this process should be an attractive synthetic pathway to these two bisphosphines.

Adsorption and decomposition of t-butylphosphine (TBP) on a GaP(0 0 1)-(2 × 1) surface studied by LEED, HREELS, and TPD

Adsorption and decomposition of t-butylphosphine (TBP: (CH3)3CPH2) on a GaP(001)-(2×1) surface have been studied by low-energy electron diffraction (LEED), high-resolution electron energy loss spectroscopy (HREELS), and temperature programmed desorption (TPD). It is found that most of TBP is partially dissociated into H and (CH3)3CPH at 350K. The t-butyl radical and isobutylene are evolved from the surface at about 350–450 and 450–550K, respectively. The activation energy for the radical was estimated to be about 101kJ/mol. The result obtained, here, is different from that on a GaP(001)-(2×4) surface. The decomposition mechanism for TBP on the surface is discussed.

Fabrication of a P-stabilized GaP(0 0 1)-(2×1) surface at very low pressure studied by LEED, STM, AES, and RHEED

Fabrication of a P-stabilized GaP(0 0 1)-(2×1) surface with t-butylphosphine (TBP) at very low pressure (5×10 −7 Torr) has been studied by scanning tunneling microscopy (STM), low-energy electron diffraction (LEED), reflection high-energy electron diffraction (RHEED), and Auger electron spectroscopy (AES). A (3×2) structure is found at small area when a GaP(0 0 1)-(2×4) surface was exposed to TBP (70–240 L) at 623 K. Increasing the amount of TBP leads to formation of a disorder surface. The (2×1) surface structure appeared by exposing the (2×4) surface to about 540 L-TBP. It is found that the (2×1) structure is reconstructed into the (2×4) by annealing the (2×1) surface at 673 K in an ultrahigh vacuum.

Adsorption of t-butylphosphine (TBP) on GaP(001)-(2×4) and the surface structure studied by HREELS and STM

Adsorption of t-butylphosphine (TBP: (CH 3) 3CPH 2) on a GaP(001)-(2×4) surface has been studied by high resolution electron energy loss spectroscopy (HREELS) and scanning tunneling microscopy. The HREELS result suggests that most of TBP molecules are dissociated into (CH 3) 3CPH and H on the surface at room temperature. It is found that all the (CH 3) 3CPH molecules are located at an edge of Ga dimer protrusions in the (2×4) unit cell. This result supports our ‘one Ga dimer model’ and excludes the ‘two Ga dimer model’.

Low temperature chemical beam epitaxy of gallium phosphide/silicon heterostructures

Abstract The low temperature epitaxial growth of GaP on (001) Si by chemical beam epitaxy (CBE) was investigated with the aim of using GaP epilayers for the dielectric isolation of silicon circuits. Optimum CBE of GaP on silicon, using t- butyl phosphine (TBP) and triethylgallium (TEG) as source vapors, is obtained at 310 °C. GaP nucleates on silicon highly selectively with regard to deliberately SiO2 and SiC coated surface regions. This behavior is due to the higher catalytic activity of the GaP surface compared with a silicon dioxide surface with regard to TBP pyrolysis. The efficiencies of incorporating phosphorus and gallium at the GaP surface are substantially different and require flux ratios R TBP:TEG ⩾ 25 for stoichiometric GaP deposition. Atomic force microscopy reveals a typical surface roughness of 75 A for a film thickness of 2000 A. Although the GaP growth occurs initially without interfacial reactions, upon prolonged growth (layer thickness more than 300 A), transport of oxygen and carbon through the GaP film to the GaPSi interface results in the growth of an SiO2/SiC layer between the silicon substrate and the GaP film, which is desirable in the context of dielectric isolation but requires modifications of the growth conditions in the context of opto-electronics.