Synthesis and homomolecular metalation of trialkylsilylphosphanides of calcium and barium

Metalation of triisopropylsilylphosphane with bis(tetrahydrofuran-O)calcium bis[bis(trimethylsilyl)amide] in tetrahydropyran (thp) in a molar ratio of 3:2 yields (Me3Si)(2)NCa[mu-P(H)SiiPr(3)](3)Ca(thp)(3) (1) containing a tr igonal-bipyramidal Ca2P3 core, the metal atoms occupying apical positions. Reaction of two equivalents of triisopropylsilylphosphane or -arsane with b is(tetrahydrofuran-O)barium bis[bis (trimethylsilyl) amide] in tetrahydrofu ran gives the corresponding bis(phosphanide) 2 and bis(arsanide) 3, compoun ds of the type (thf)(3)Ba[mu-E(H)SiiPr(3)]Ba(thf)(2)E(H)SiiPr(3) with E = P , As. The equimolar reaction of (tri-tert-butylsilyl)phosphane with (thf)(2 )Ba[N-(SiMe3)(2)](2) in toluene yields heteroleptic dimeric (thf)(2)Ba[N(Si Me3)(2)][P(H)SitBu(3)] (4). Addition of a further equivalent of H(2)PSitBu( 3) leads to the formation of homoleptic (thf)(n)Ba[P(H)SitBu(3)](2) (5). Di ssolution of the latter in aromatic hydrocarbons leads to the elimination o f H(2)PSitBu(3), yielding dimeric (thf)Ba-3(PSitBu(3))(2)[P(H)SitBu(3)](2) (6) The inner core of 6 consists of the tetramer (BaPSitBu(3))(4) based on a Ba4P4 heterocubane unit, two opposite faces being capped with (thf)Ba[P(H )SitBu(3)](2) molecules.