Bisaminophosphane - Synthese, Struktur und Reaktivität

Abstract

Professor Rolf Appel zum 80. Geburtstag gewidmet Inhaltsu È bersicht. Zwei unterschiedliche Synthesewege zur Darstellung von Bis(alkylamino)phosphanen RP(N(H)R') 2 werden vorgestellt. Die Kristallstruktur von t-BuP-(N(H)Dipp) 2 (Dipp = 2,6-(i-Pr) 2 ±C 6 H 3 ) wurde durch Einkristallro È ntgenstrukturanalyse bestimmt. Die Reaktivita È t der Verbindungen gegenu È ber Organoaluminium-Verbindungen wurde exemplarisch anhand verschiedener Reaktionen von t-BuP(N(H)t-Bu) 2 untersucht. Reaktionen mit Me 3 Al bzw. R 2 AlH (R = Me, Et, i-Bu) in 1 : 1-und 1 : 2-Sto È chiometrie fu È hren jeweils zum Monosubstitutionsprodukt t-BuP-(N(H)t-Bu)(N(AlR 2 )t-Bu).Abstract. Different pathways for the synthesis of bis(alkylamino)phosphanes RP(N(H)R') 2 are described. t-BuP(N(H)-Dipp) 2 (Dipp = 2,6-i-Pr 2 ±C 6 H 3 ) was structurally characterized by single crystal X-ray diffraction. The reactivity of the compounds was examplarily investigated using t-BuP-(N(H)t-Bu) 2 . Its reaction with Me 3 Al and R 2 AlH (R = Me, Et, i-Bu) in 1 : 1 and 1 : 2 stoichiometrie yield monosubstituted compounds of the type t-BuP(N(H)t-Bu)(N(AlR 2 )t-Bu).

Reactivity of Bis(organoamino)phosphanes with Aluminum(III) Compounds: Straightforward Access to Diiminophosphinates by Means of Hydrogen‐Atom Migration – An Experimental and Theoretical Study

“…The RMSD calculated for 3c increases to 0.27 Å for the BP86‐D‐optimized geometry (Figure 8). Finally, the replacement of the phenyl ring attached to the phosphorus atom by a t Bu group in e again leads to a stabilization of the corresponding NH tautomer t BuP(NH t Bu)(N t Bu)AlMe 2 , which is consistent with previously reported results 11…”

“…Importantly, the optimized geometries and the relative energies computed with the BP86‐D functional are very similar to that computed with B3LYP‐D. For comparison, the relative energies for known phosphane 1e 11 were calculated and show that the NH form is again significantly more stable than the PH tautomer.…”

“…Phosphane 1e was included into this study because it contains an aliphatic t Bu group bonded to the phosphorus atom instead of the phenyl group. It was also previously demonstrated that 1e did not show any tendency for NH–PH tautomerism 11…”

“…These findings suggest that, although the reaction between the phosphanes 1a – c and Me 3 Al produced analogous diiminophosphinates 3a – c , the reaction paths are completely different (see below). In contrast to the NH–PH tautomerism observed in the reaction of 1a – c with Me 3 Al, the analogous reaction of phosphane 1e (Figure 2) was shown to produce compound t BuP(NH t Bu)(N t Bu)AlMe 2 and no hydrogen‐atom migration was observed (see below for further discussion) 11…”

“…Starting phosphanes 1a ,10 1c ,10 and 1d 11 were synthesized according to the literature procedures, whereas 1b was prepared by the reaction of PhP(NHDip)(Cl)12 with two molar equivalents of t BuNH 2 . Compound 1b was isolated as a white solid in reasonable yield (82 %) and characterized with the help of 1 H, 13 C{ 1 H}, and 31 P NMR spectroscopy (see the Experimental Section).…”