| Abstrakt: |
The tetraanilino phosphonium cation, [P{N(H)Ph}4]+, 1+, is sequentially deprotonated by BunLi in thf. The deprotonation reaction of the chloride derivative, 1Cl, was monitored by 31P NMR, which revealed the successive formation of the neutral [P{N(H)Ph}3(NPh)], 2, the monoanionic [P{N(H)Ph}2(NPh)2]−, 3−, the dianionic [P{N(H)Ph}(NPh)3]2−, 42−, and finally the trianionic species [P(NPh)4]3−, 53−. Considering the isoelectronic relationship of oxo, &z.dbd;O, and imino groups, &z.dbd;NR, as well as hydroxy, OH, and amino groups, N(H)R, the neutral complex 2 corresponds to phosphoric acid, H3PO4, whereas the anions 3−, 42− and 53− are analogues of dihydrogen phosphate, H2PO4−, monohydrogenphosphate, HPO42−, and orthophosphate ions, PO43−, respectively. Solid state structures were obtained of 1Cl, 2LiCl(thf)2, 3Li(thf)3.5, 3Li2Cl(thf)4.25, 3Li2Cl(thf)6 and 5Li4Cl(thf)4. All systems provide two separate NPN chelation sites at opposite ligand faces, either consisting of the di(amino) arrangement P(NH)2, acting as a double H-bond donor, the di(imino) arrangement PN2, donating two electron pairs, or the mixed amino imino arrangement P(N)(NH), which supplies both electron pair and H-donor site. Interesting in this aspect is the mixed amino imino derivative 3− which has the ability to chelate a Lewis acid, such as a metal ion, at one face and a Lewis base, such as an anionic or neutral donor at the opposite ligand face. The formation of 1-D aggregates and the entrapment of lithium chloride are key characteristics of the supramolecular structures of the discussed complexes. |
