Reactivity of lithium n-butyl amidinates towards group 14 metal(ii) chlorides providing series of hetero- and homoleptic tetrylenes

Abstract

The new class of homo- and heteroleptic n-butyl-N,N′-disubstituted amidinato group 14 metal(II) complexes were prepared by salt elimination from starting lithium amidinates and metal(II) chlorides both in stoichiometric ratio 2 : 1 and 1 : 1, respectively. The target amidinates contain less bulky isopropyl or cyclohexyl as well as a sterically demanding aromatic substituent. Desired 1 : 1 Pb(II) complexes are not accessible by the described procedure. Ligand transfer from Pb to Sn is taking place if homoleptic Pb(II) compounds are reacted with SnCl₂. Prepared tetrylenes were characterized by ¹H, ¹³C, ¹¹⁹Sn and ²⁰⁷Pb NMR spectroscopy in C₆D₆ or THF-d₈. X-Ray diffraction studies of one heteroleptic Ge(II) monomeric where the coordination polyhedron of the three coordinated germanium atoms is a trigonal pyramid, two different dimeric structures of heteroleptic Sn(II) complexes, one amidine hydroiodide byproduct and the oxidation product of the heteroleptic chloro Sn(II) amidinate as a tetranuclear species with two Sn(IV) and two Sn(II) atoms in central Sn₂O₂ planar ring were performed on appropriate single crystals. The dimer of one of the heteroleptic stannylenes reveals a new type of monomeric units connection, weak Sn–Cl contact and an interaction of the tin atom with delocalized N–C(C)–N system of the amidinato ligand of the second molecule.