Syntheses and crystal structures of mono- and bi-metallic zinc compounds of symmetrically- and asymmetrically-substituted bis(amino)cyclodiphosph(V)azanes

The dioxocyclodiphosph(V)azane cis-(^tBuHN)OP(μ-N^tBu)₂PO(NH^tBu)] reacted with two equivalents of diethylzinc to form the centrosymmetric dimer {(OPN^tBu)₂(N^tBu)₂ZnEt](ZnEt · THF)}₂ (1) while under identical conditions, the sulfur and selenium analogues afforded only the monoethylzinc compounds {(^tBuHN)EP(μ-N^tBu)₂PE(N^tBu)](ZnEt · THF)}ES(2), Se (3). To further probe the apparent ligand effects on coordination number and coordination site, cis-(PhHN)SP(μ-N^tBu)₂PS(NH^tBu)] (5) was synthesized from cis-ClP(μ-N^tBu)₂P(NH^tBu)] (4) and both were characterized by single-crystal X-ray diffraction. Two equivalents of 5 reacted with diethylzinc to produce the homoleptic, trispirocyclic complex {(^tBuHN)SP(μ-N^tBu)₂PS(NPh)]₂Zn} (6). A second asymmetrically-substituted cyclodiphosph(V)azane, namely (^tBuNH)SP(μ-N^tBu)₂PNp-tol(NH^tBu)] (7), was also synthesized and structurally characterized. In contrast to 5, only one equivalent of this ligand reacted with excess diethylzinc, via its N,N^′, rather than its N,S side, to afford {(^tBuHN)SP(μ-N^tBu)₂PNp-tolyl(N^tBu)](ZnEt)} (8).