Syntheses and structures of zinc and tin(II) compounds with hemilabile N-silyl-tert-butylamido and N-silyl-p-tolylamido ligands that contain pendent tert-butoxy groups

Syntheses and solid-state structures of zinc and tin(II) compounds, containing the N-silyl-amide ligands (OtBu)(NR)SiMe2, R = tBu (LtBu), or R = p-tolyl (LpTol), are reported. The N-silyl amines were synthesized by modified published procedures from commercially available Me2SiCl2, tBuOH, and tBuNH2, or p-Me-C6H4NH2, respectively. Treatment of SnCl2 with LiLpTol furnished Sn(LpTol)2, which was X-ray structurally characterized and shown to contain two covalent Sn–N bonds and two asymmetrical O → Sn donor bonds. The single-crystal X-ray structure of Sn(LtBu)2 revealed a much more symmetrically-coordinated, pseudo-trigonal-bipyramidal tin atom. Aminolysis of diethylzinc with HLpTol produced [EtZn(LpTol)]2, which crystallized as a centrosymmetric dimer, containing four-coordinate zinc atoms connected by bridging amides. Zinc dichloride, by contrast, reacted with two equivalents of LiLtBu to produce the homoleptic, pseudo-spirocyclic Zn(LtBu)2.

Hemilabile N,O amido-dimethylsilylalkoxy ligands create, depending on their mode of introduction, structurally-different metal complexes. Metatheses reactions of SnCl2 and ZnCl2 with the lithium salts of the amides gave mononuclear compounds with apparent spirocyclic structures. Aminolysis of ZnEt2, by contrast, furnished a tricyclic ladder structure, containing bridging amide ligands.Figure optionsDownload as PowerPoint slideHighlights
► Hemilabile N-silyl-tert-butylamides and N-silyl-p-tolylamides were synthesized.
► These ligands yield tin heterocarbenoids with pseudo-spirocyclic structures.
► The zinc derivatives of these ligands exhibit both spirocyclic and ladder-type structures.