Synthesis and structural characterization of zinc complexes of the imido–amido phosphate anions OP[(NHR)3–x(NR)]x– (R = Me, t-Bu; x = 1–3) and EP[(NH-t-Bu)2(N-t-Bu)]– (E = S, NSiMe3)

The reaction of OP(NH-t-Bu)3 with 1 equiv. of ZnMe2 generates the dimeric eight-membered ring {MeZn[(µ-NH-t-Bu)(µ-N-t-Bu)P(NH-t-Bu)(µ-O)]}2 (5) and the cubane {[MeZn]3[OP(N-t-Bu)3][OP(NH-t-Bu)3]} (6), which contains the first known trisimidophosphate trianion. A related complex {Zn[ZnMe]2[OP(N-t-Bu)(NH-t-Bu)2][OP(N-t-Bu)3]} (7) is obtained by the reaction of OP(NH-t-Bu)3 with ZnMe2 in a 2:3 molar ratio. The treatment of OP(NHMe)3 with 1 equiv. of ZnMe2 produces the oxide-templated cluster {Zn4(µ4-O)[OP(NMe)(NHMe)2]4[OP(NMe)2(NHMe)]}2 (8). Each half of this centrosymmetric dimer contains a tetrahedral arrangement of four 4-coordinate Zn2+ ions surrounding the central µ4-O2- anion. The reaction of SP(NH-t-Bu)3 with ZnMe2 in a 1:1 molar ratio generates the dimer {MeZn(µ-S)(µ-N-t-Bu)P(NH-t-Bu)2}2 (10), which has a ladder-type structure. When a 2:1 molar ratio of the same reagents is employed, the bis(N,S)-chelated complex {Zn[(µ-S)(µ-N-t-Bu)P(NH-t-Bu)2]2} (11) is obtained. The monomeric N,N′-chelated complex {MeZn[(µ-N-t-Bu)(µ-NSiMe3)P(NH-t-Bu)2]} (12) results from the reaction of Me3SiNP(NH-t-Bu)3 with 1 equiv. of dimethylzinc. All new compounds have been characterized by multinuclear (1H, 13C, and 31P) NMR spectroscopy and, in the case of 5, 6, 7, 8, and 10, by X-ray structural determinations.Key words: zinc, phosphate, imido ligands, sulfur.