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-NtBu)2PO(NHtBu)] reacted with two equivalents of diethylzinc to form the centrosymmetric dimer {[(OPNtBu)2(NtBu)2ZnEt](ZnEt · THF)}2 (1) while under identical conditions, the sulfur and selenium analogues afforded only the monoethylzinc compounds {[(tBuHN)EP(μ-NtBu)2PE(NtBu)](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-NtBu)2PS(NHtBu)] (5) was synthesized from cis-[ClP(μ-NtBu)2P(NHtBu)] (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-NtBu)2PS(NPh)]2Zn} (6). A second asymmetrically-substituted cyclodiphosph(V)azane, namely [(tBuNH)SP(μ-NtBu)2PNp-tol(NHtBu)] (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-NtBu)2PNp-tolyl(NtBu)](ZnEt)} (8).