3040-63-9Relevant articles and documents
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Issleib et al.
, p. 77,86 (1968)
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Synthesis of 1,2-bis[(diorgano)phosphino]ethanes via Michaelis-Arbuzov type rearrangements
Baldwin, Lawrence C,Fink, Mark J
, p. 230 - 238 (2007/10/03)
A three-step process for the synthesis of the bis(diorganophosphino)ethanes R2PCH2CH2PR2 where R = Et, Ph, iPr, Cy and tBu 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, iPr and Cy, the bisphosphinites R2POCH2CH2OPR2 were obtained in high yield. For R = Et, the bisphosphinite could not be isolated but may be formed in 80% mixtures with tetraethyldiphosphine, Et2PPEt2, 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, tBu2PH(O), as the only phosphorus-containing product. Thermolysis of the bisphosphinites R2POCH2CH2OPR2 (R = Ph, iPr and Cy) at 190-260 °C for 24 h gave the bisphosphine oxides, R2P(O)CH2CH2(O)PR2 in 9% (Ph), 90% (iPr) and 93% (Cy) yields. A DSC study of the thermal rearrangement of Cy2POCH2CH2OPCy2 to Cy2P(O)CH2CH2(O)PCy2 yielded an enthalpy of isomerization of -40.4 ± 0.6 kcal mol-1. Reduction of the bisphosphine oxides, R2P(O)CH2CH2(O)PR2 (R = Ph, iPr and Cy) with trichlorosilane gave the bisphosphines, R2PCH2CH2PR2 in 80-85% yield. The overall yields of the bisphosphines R2PCH2CH2PR2 (R = iPr 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.
Lewis acidic titanium species: the synthesis, structure, bonding and molecular modelling considerations of the complexes Ti(NR2)3Cl (R = Me, Et)
Dick, David G.,Rousseau, Roger,Stephan, Douglas W.
, p. 357 - 362 (2007/10/02)
Reaction of simple amides with TiCl4 affords mixed amido-chloride species Ti(NR2)4-nCln.The trisamide-chloride species Ti(NR2)3Cl can be prepared directly employing three equivalents of amide or by reaction Ti(NR2)4 with TiCl4.The compound Ti(NMe2)3Cl, 1, crystallizes in the trigonal space group , with a = 11.525(5), c = 14.939(3) Angstroem, Z = 6, and V = 1718(1) Angstroem3.The compound Ti(NEt2)3Cl, 2, crystallizes in the monoclinic space group P21/c, with a = 8.385(2) Angstroem, b = 15.958(2) Angstroem, c = 14.230(4) Angstroem, β = 107.79(1) deg, Z = 4, and V = 1813(1) Angstroem3.The geometry of the Ti coordination sphere in these complexes is best described as pseudo-tetrahedral.The structural data are consistent with Ti-N multiple bonding.Preliminary results of EHMO calculations are consistent with d?-p? Ti-N bonding.Attempts to replace the halides with phosphides (LiPR2, R = Me, Et, Ph) led not to the Ti(IV) phosphido species, but rather to redox chemistry yielding Ti(III) amides and P2R4.The barrier to rotation about the Ti-N bonds has been considered.Variable temperature 1H NMR studies reveal that the barrier is small.Extended Hueckel total energy minimization calculations have been performed.In addition, MMX calculations of the barrier Ti-N rotation are reported.The results of these calculations imply that the rotational barrier is dominated by steric effects. Key words: titanium amides, structures, Ti-N bonding.
