Synthesis, Structure, and Stability of Lithium Arylphosphanidyl‐diarylphosphane Oxide

Abstract

The reaction of LiP(H)Tipp (2a) and KP(H)Tipp (2b, Tipp = C6H2‐2,4,6‐iPr3), which are accessible via metalation of Tipp‐PH2 (1), with bis(4‐tert‐butylphenyl)phosphinic chloride yields Tipp‐P=P(OM)Ar2 [M = Li (3a) and K (3b)]. These complexes show characteristic chemical 31P shifts and large 1JPP coupling constants. These compounds degrade with elimination of the phosphinidene Tipp‐P: and the alkali metal diarylphosphinites M–O–PAr2 [M = Li (4a) and K (4b)]. The phosphinidene forms secondary degradation products (like the meso and R,R/S,S‐isomers of diphosphane Tipp‐P(H)–P(H)Tipp (5) via insertion into a P–H bond of newly formed Tipp‐PH2), whereas the crystallization of [Tipp‐P=P(OLi)Ar2·LiOPAr2·LiCl·2Et2O]2 (i.e. [3a·4a·LiCl·2Et2O]2) succeeds from diethyl ether. The metathesis reactions of LiP(SiiPr3)Tipp and LiP(SiiPr3)Mes (Mes = C6H2‐2,4,6‐Me3) with Ar2P(O)Cl yield Ar*‐P=P(OSiiPr3)Ar2 (Ar* = Mes, Tipp) which degrade to Ar2POSiiPr3 and other secondary products.

Facile synthesis ofcyclo-(P4tBu3)-containing oligo- and pnictaphosphanes

“…46 The P1-Li1 bond (2.574(4) Å) is also in the range of P-Li bonds with the lithium atom being coordinated by THF and TMEDA. [47][48][49][50][51] Lithium cyclotetraphosphanide 1 can be used in salt elimination reactions with element halides as a versatile cyclo-(P4 t Bu3) transfer reagent with formation of lithium halide. However, oxidative coupling of two cyclo-(P4 t Bu3) fragments can also occur depending on the element halide used, resulting in formation of {cyclo-(P4 t Bu3)}2 (2).…”

Versatile Access to Very Short P═P Double Bonds in Mixed-Valent 1λ5-Diphosphenes via 1,3-Silyl Migration

“…13 In contrast to the rather stable 1λ 5 -diphosphenes of the type R 3 PPR′, derivatives of the type R 2 (LiO)PPR′ and R 2 (R″ 3 SiO)PPR′ are thermally extremely labile. 14,15 Furthermore, constitution isomers of the type R 2 P(O)−P(SiR″ 3 )-R′ have been discussed as yet unobserved intermediates during the reaction of R′P(H/Li)SiR″ 3 with ClP(O)R 2 yielding R 2 (R″ 3 SiO)PPR′ 11 despite the fact that diphosphane monoxides R 2 P(O)−P(H)R′ have already been observed and have been recognized as the preferred isomer. 4,16 In another procedure, the reaction of water with an NHC-stabilized diphosphene Ar*(NHC)PPAr* gave the imidazolium (Im) salt [(Im)•••O−P(H)(Ar*)P−Ar*] with a PP bond length of 210.99(10) pm.…”

Primary Phosphines and Phosphine Oxides with a Stereogenic Carbon Center Adjacent to the Phosphorus Atom: Synthesis and Anti-Markovnikov Radical Addition to Alkenes

“…Organophosphorus compounds, and particularly those with three or four substituents on the phosphorus atom, i.e., tertiary phosphines, phosphine oxides, and their isologues, are of great importance in organic synthesis and medicinal chemistry [1][2][3]. The synthesis and reactions of primary phosphines [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and phosphine oxides [19][20][21] which contain two phosphorus-hydrogen (P-H) bonds have received increasing attention because these highly reactive bonds undergo various types of phosphorus-carbon (P-C) bond-forming reactions. Their highly efficient addition reactions to alkenes have been achieved with transition metal catalysts [22][23][24].…”