Facile synthesis of cyclo-(P₄Bu₃)-containing oligo- and pnictaphosphanes

The cyclo-(P₄Bu₃) synthon [Li{cyclo-(P₄Bu₃)}(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 LiBu. The use of 1 as a cyclo-(P₄Bu₃) building block enables the rational synthesis of cyclo-(P₄Bu₃)-containing oligophosphanes, namely {cyclo-(P₄Bu₃)}₂ (2), {cyclo-(P₄Bu₃)}₂PBu (3) and {cyclo-(P₄Bu₃)}₂CH₂ (4), C₃-symmetric pnictaphosphanes E{cyclo-(P₄Bu₃)}₃ (E = Bi, Sb, As; 5-7) as well as AsCl{cyclo-(P₄Bu₃)}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.