Synthesis And Characterization Of Low-valent Group 14 (Ge Sn Pb) Complexes Based On Hexakis (2,6-Dissopropylaniline) Triphenlene

The heavier group 14 analogues of carbenes (R2C:), tetrylenes of the general formula R2E: feature anelectron-deficient group 14 element (E:) display quite similar properties to their light congeners. Tetrylenes, particularly N-heterocyclic tetrylenes received resurgent attention. This thesis focuses on the development of synthesis and reactivities of stable heavier carbene analogues and decribes synthesis of three new tris-N-heterocyclic tetrylenes, electronic properties of them calculated by DFT and UV-vis spectra. This thesis consists of two sections:The first section, we describe the kinetic stabilization of the metallylenes by using bulky ligand and the thermodynamic stabilization of the metallylenes by using Group 15 (N orP) and 16 (O or S) elements, as well as influence of the different size ligand to structure in the soild state.The second section, three tris-N-heterocyclic germylene, stannylene and plumbylene, [Ge3(L)](1), [Sn3(L)]-toluene(2) and [Pb3(L)]·6toluene(3) were synthesized by transmetalation of the lithiumsalts [Li6L] with heavier group 14 element halides. Besides, the 2 and 3 could be prepared from free ligand LH6 and the corresponding E[N(TMS)2]2(E=Sn,orPb). The metallylenes have been investigated by NMR and X-ray diffraction. X-ray crystal diffraction shows that metal atoms(without solvation) not only in germylene 1 and stannylene 2 but also in plumbylene 3 are each chelated by two N atoms in a "PDA" arm of the (L)6-ligand, Notably, in contrast to the most related germylene 1 and stannylene 2, which are discrete monomer in the solid state, the heaviest analogue 3 exists as a polymer with incontrovertible contacts of the Pb atoms to the aryl rings of Dipp substituents on adjacent molecules in the η6 or η-fashion. DFT calculations (PBE1PBE-SVP) elucidate that as the E atom in tetrylenes becomes heavier, weakening of σ donation ability and increasing π accepting ability appear. UV-vis spectra of 1-3 and TD-DFT show lowest-energy band in visible region corresponds to π-π* transition instead of n-p transition. This bathochromic shift of the lowest-energy band is attributed to enhanced electron delocalizationon the three tetrylenes 1-3.