The guanidines 1, 4, 6, 8, 10, and 12 react with carbon dioxide in the presence of traces of water to give the guanidinium hydrogen carbonates 3, 5, 7, 9, 11, and 13. The crystal structures of the salts reveal the presence of centrosymmetric hydrogen carbonate ion dimers, which are connected by O-H・ ・ ・O hydrogen bonds. Additionally the cations are associated with the anions via N-H・ ・ ・O hydrogen bonds. The reaction of the N-(aminoalkyl)guanidine 14 with CO2 in the presence of traces of water affords a stable hygroscopic carbamic acid as the hydrogen carbonate salt 15. In the crystal structure of 15 the hydrogen carbonate ion is connected with the carbamic acid moiety by strong O-H・ ・ ・O hydrogen bonds
The ligands TMG2e [bis(N,N,N´,N´-tetramethylguanidino)ethane] and DMEG2e [N1,N2-bis(1,3-dimethylimidazolin-2-ylidene)ethane-1,2-diamine] were used in the complexation of copper cations to give the new complexes [Cu(TMG2e)2][Cu2I4], [Cu(TMG2e)Cl2] and [Cu(DMEG2e)2]-[CuCl2]. Single-crystal structure determination shows that the complexes [Cu(TMG2e)Cl2] and [Cu(DMEG2e)2][CuCl2] both crystallise in the monoclinic space group C2/c, the complex [Cu(TMG2e)2][Cu2I4] in the orthorhombic space group Pbca. The copper atoms in all complex cations reside in a coordination environment between tetrahedral and square-planar geometry. The application of copper complexes with TMG2e and DMEG2e as ligands in atom transfer radical polymerisation (ATRP) was investigated with styrene as monomer. The polymerisation process with both ligand systems shows even at low temperature unexpected high conversions and molecular weight distributions that are evidence of a well controlled ATRP. These first results in the application of guanidine ligands in ATRP show that these ligands have high potential, but that further process optimisations and ligand tuning are necessary to develop highly active catalysts for ATRP.