J. Bickley, M. Copsey, J. Jeffery
Mar 19, 2004
Citations
0
Influential Citations
20
Citations
Journal
Dalton transactions
Abstract
The tetraanilino phosphonium cation, [P(N(H)Ph)4]+, 1+, is sequentially deprotonated by Bu(n)Li in thf. The deprotonation reaction of the chloride derivative, Cl, was monitored by (31)P 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-, 4(2-), and finally the trianionic species [P(NPh)(4)](3-), (3-). Considering the isoelectronic relationship of oxo, =O, and imino groups, =NR, as well as hydroxy, -OH, and amino groups, -N(H)R, the neutral complex corresponds to phosphoric acid, H3PO4, whereas the anions 3-, 4(2-) and 5(3-) are analogues of dihydrogen phosphate, H2PO4-, monohydrogenphosphate, HPO4(2-), and orthophosphate ions, PO4(3-), respectively. Solid state structures were obtained of 1Cl, 2LiCl(thf)(2), 3Li(thf)(3.5), 3Li(2)Cl(thf)(4.25), 3Li(2)Cl(thf)(6) and 5Li(4)Cl(thf)(4). All systems provide two separate N-P-N 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 PN(2), 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.