Facile synthesis of cyclo-(P4tBu3)-containing oligo- and pnictaphosphanes

Abstract

The cyclo-(P₄^tBu₃) synthon [Li{cyclo-(P₄^tBu₃)}(thf)(tmeda)] (1) (thf = tetrahydrofuran, tmeda = N,N,N′,N′-tetramethylethane-1,2-diamine) is readily accessible in a one-pot synthesis from P₄ and Li^tBu. The use of 1 as a cyclo-(P₄^tBu₃) building block enables the rational synthesis of cyclo-(P₄^tBu₃)-containing oligophosphanes, namely {cyclo-(P₄^tBu₃)}₂ (2), {cyclo-(P₄^tBu₃)}₂P^tBu (3) and {cyclo-(P₄^tBu₃)}₂CH₂ (4), C_3v-symmetric pnictaphosphanes E{cyclo-(P₄^tBu₃)}₃ (E = Bi, Sb, As; 5–7) as well as AsCl{cyclo-(P₄^tBu₃)}₂ (8). Compounds 5 and 6 represent the first neutral homoleptic bismuthane and stibane that contain only bonds to phosphorus. All new compounds were isolated in moderate to good yields and fully characterised. The ³¹P{¹H} NMR spectral data of 1, 2, 4, and 8 have been determined by automated line-shape analysis.