Cationic Group 13/14/15 Element Chain Compounds with Pnictogen-Donor Ligands

The reactivity of IDipp·GeH2BH2OTf (1) (IDipp = 1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) toward monodentate N-donor and bidentate pnictogen-donor ligands is reported. In the reaction of 1 with triethyl amine, the cationic adduct [IDipp·GeH2BH2·NEt3]+(2+) is formed. In contrast, primary and secondary amines exhibit a proton transfer to the germanium center, resulting in the formation of [IDipp·GeH3]+ (4+) and [IDipp·BH2·NHR’R’’]+ (3+a−c) species. DFT calculations reveal that the driving force for the observed difference in reactivity is the tendency of NHEt2 to transfer a proton to 1, leading to the formation of 3a, 4, and [IDippH]+. Pyridine and aminopyridine also form stable adducts [IDipp·GeH2BH2·Py]+ (5+) and [IDipp·GeH2BH2·DMAP]+ (6+). Reactions with bidentate ligands (bipyridine and 1,2-bis(diphenylphosphino)ethane) lead to the formation of unprecedented dicationic chains composed of two [IDipp·GeH2BH2]+ units connected via the linker to form [IDipp·GeH2BH2·bipy·BH2GeH2·IDipp]2+ (72+) and IDipp·GeH2BH2·dppe·BH2GeH2·IDipp]2+ (82+), respectively. All synthesized compounds are characterized by SC-X-ray crystallography, NMR spectroscopy, and mass spectrometry, providing insights into their structural features.