Organosilicon backbone containing pyridyl/quinolyl ligands: Synthesis, complexation reactions and single crystal structures of metallamacrocyclic Pd(II) and Cu(II) complexes

Organosilicon backbone containing ligands 1,2-bis(dimethyl(2-pyridyl)silyl)ethane (L1) and 1,2-bis(dimethyl(3-quinolyl)silyl) ethane (L2) have been synthesized by treating 2-bromopyridine and 3-bromoquinoline with n-butyllithium and reacting the resulting lithiated products with 1,2-bis(chlorodimethylsilyl)ethane. The ligation of L1 and L2 with Pd(II), Ag(I) and Cu(II) has been investigated. The single crystal structures of L2, [Pd(L1)Cl2] (1), [Cu(L1)Br2] (3) and [PdCl2(L2)]2 (4) have been solved. All the three complexes are metallamacrocyclic in nature. The last one is 22-membered and the first example which has ligands containing organosilicon backbone. The geometry of Pd as well as Cu is very close to square planar. The Pd–N, Pd–Cl, Cu–N and Cu–Br bond distances (2.010(1)–2.027(3), 2.3063(10)–2.3114(4), 2.004(4)–2.018(5) and 2.4137(10)–2.4172(10) Å) are very close to sum of covalent radii, indicating strong ligation of L1 and L2 with the metal ions.

Graphical abstract1,2-Bis(dimethyl(2-pyridyl)silyl)ethane (L1) and 1,2-bis(dimethyl(3-quinolyl)silyl)ethane (L2) have been synthesized and their ligation with Pd(II), Ag(I) and Cu(II) has been investigated. The single crystal structures of L2 and metallamacrocyclic complexes [Pd(L1)Cl2] (1), [Cu(L1)Br2] (3) and [PdCl2(L2)]2 (4) have been solved. The 4 is 22-membered and the first example, which has ligand containing organosilicon backbone.Figure optionsDownload full-size imageDownload as PowerPoint slide