Cationic Organobismuth Complex with 5,6,7,12-Tetrahydrodibenz[c,f][1,5]azabismocine Framework and Its Coordination Complexes with Neutral Molecules

A cationic eight-electron three-coordinate organobismuth complex with a weakly coordinating borate anion, [tBuN(CH2C6H4)2Bi]+[B(C6F5)4]- (3), and its coordination complexes with neutral donor molecules were synthesized and structurally characterized. The reaction of tBuN(CH2C6H4)2Bi−X (1a: X = Br, 1b: X = Cl) with Li[B(C6F5)4] afforded the ionic complex 3. Complex 3 reacted with 1a or 1b to form halogen-bridged dinuclear complexes [{tBuN(CH2C6H4)2Bi}2(μ-X)]+[B(C6F5)4]- (6: X = Br, 7: X = Cl). Various neutral donor molecules coordinated to the cationic bismuth atom of 3, and four coordination complexes [{tBuN(CH2C6H4)2Bi}(Do)]+[B(C6F5)4]- (8: Do = MeCHO, 9: Do = MeOH, 10: Do = MeCN, 11: Do = CH2Cl2) were isolated. The structures of complexes 3 and 6−11 were determined by single-crystal X-ray analysis. In complex 3, one of the fluorine atoms of the [B(C6F5)4] anion weakly coordinates to the cationic bismuth center, making its coordination geometry equatorially vacant trigonal bipyramidal. The same coordination geometry was also found for the bismuth centers in 6−11. The cationic character of the bismuth center in 3 is reflected in the Bi−N coordination distance, which is ≥0.2 Å shorter than those in the neutral azabismocines such as 1a and 1b. The Bi−N coordination distances in 6−11 elongated depending on the coordination strength of the donor molecules.