1229447-19-1Relevant articles and documents
Imino-bridged bisphosphaalkenes (2,4-diphospha-3-azapentadienes)
Birzoi, Roxana M.,Bugnariu, Delia,Gimeno, Rafael Guerrero,Lungu, Daniela,Zota, Vera,Daniliuc, Constantin,Jones, Peter G.,Benko, Zoltan,Koenczoel, Laszlo,Nyulaszi, Laszlo,Bartsch, Rainer,Mont, Woif-W. Du,Niecke, Edgar
, p. 4843 - 4851 (2010)
Deprotonation of aminophosphaalkenes (RMe2Si)2C= PN(H)(R') (R = Me, iPr; R' = tBu, 1adamantyl (1-Ada), 2,4,6-tBu 3C6H2 (Mes*)) followed by reactions of the corresponding Li salts Li[(RMe2Si)2C= P(M)(R')] with one equivalent of the corresponding P-chlorophosphaalkenes (RMe2Si)2C=PCl provides bisphosphaalkenes (2,4-diphospha-3-azapentadienes) [(RMe2Si)2C=P] 2NR'. The thermally unstable tert-butyliminobisphosphaalkene [(Me3Si)2C=P]2NtBu (4a) undergoes isomerisation reactions by Me3Si-group migration that lead to mixtures of four-membered heterocyles, but in the presence of an excess amount of (Me 3Si)2C=PCl, 4a furnishes an azatriphosphabicyclohexene C3(SiMe3)5P3NtBu (5) that gave red single crystals. Compound 5 contains a diphosphirane ring condensed with an azatriphospholene system that exhibits an endocylic P=C double bond and an exocyclic ylidic P(+)-C(-),(SiMe3) 2unit. Using the bulkier tPrMe2Si substituents at three-coordinated carbon leads to slightly enhanced thermal stability of 2,4-diphospha-3-azapentadienes [(tPrMe2Si)2C=P] 2NR' (R' = tBu: 4b; R' = l-Ada: 8). According to a low-temperature crystal-structure determination, 8 adopts a non-planar structure with two distinctly differently oriented P=C sites, but 31P NMR spectra in solution exhibit singlet signals. 31P NMR spectra also reveal that bulky Mes* groups (Mes* = 2,4,6-tBu 3C6H2) at the central imino function lead to mixtures of symmetric and unsymmetric rotamers, thus implying hindered rotation around the P-N bonds in persistent compounds [(RMe2Si) 2C=P]2NMes* (11a, 11b). DFT calculations for the parent molecule [(H3Si)2C=P]2NCH 3 suggest that the non-planar distortion of compound 8 will have steric grounds.
