N-versus O-silylation in cis-[(tBuHN)OP(μ-NtBu)2PO(NHtBu)] and [Me2Si(μ-NtBu)2PO(NHPh)]. Solid-state structures of their silylation products, of co-crystalline cis-[(tBuHN)OP(μ-NtBu)2PO(NHtBu)], and of {[Me2Si(μ-NtBu)2PO(N(SiMe3)Ph)]VCl3}

The solid-state structure of cis-[(tBuHN)OP(μ-NtBu)2PO(NHtBu)] (A), isolated as a 2-phenyl-2-propanol/2-phenyl-2-propanehydroperoxide co-crystal (1), is reported. Treatment of pure A with two equivalents of n-butyllithium, followed by addition of Me3SiCl, afforded the bis-O,O′-silylated cis-[(Me3SiO)tBuNP(μ-NtBu)2PNtBu(OSiMe3)] (2), whose solid-state structure was determined. When the cyclic N,N,N-phosphoramidate [Me2Si(μ-NtBu)2PO(NHPh)] (B) was subjected to the same treatment as A, however, the N-silylated [(Me2Si(μ-NtBu)2PO(N(SiMe3)Ph)] (3), was obtained. Its solid-state structure was determined. The reaction of 3 with VCl3(THF)3 did not produce the intended N,O-chelated V(II) complex, but furnished instead the adduct {[Me2Si(μ-NtBu)2PO(N(SiMe3)Ph)] VCl3(THF)}, in which 3 binds the trigonal-bipyramidally coordinated vanadium center through its oxygen atom only.

Despite silicon’s well known affinity for oxygen, the silylations of two closely-related cyclic N,N,N-phosphoramidates furnished N- and O-silylated derivatives, respectively, as thermodynamic products. The syntheses and solid-state structures of these molecules and those of a vanadium(III) complex of one of them are presented.Figure optionsDownload as PowerPoint slide