Synthesis and characterization of stable ruthenabenzenes starting from HCCCH(OH)CCH

Abstract

Treatment of RuCl2(PPh3)(3) with HCCCH(OH)CCH/PPh3 at room temperature produces the air-stable ruthenabenzene [Ru(CHC(PPh3)CHC(PPh3)CH)Cl-2(PPh3)(2)]Cl (2) in good yield. The ruthenabenzene 2 can even be obtained from the one-pot reaction of RuCl3, PPh3, and HCCCH(OH)CCH in the mixed solvent of ionic liquid and CH2Cl2 in higher yield. The ruthenabenzene 2 reacts with PMe3, PBu3, tert-butyl isocyanide, 2,2'-dipyridyl (bipy), and 2,2'-dipyridyl/PMe3 to give new stable ruthenabenzenes [Ru(CHC(PPh3)CHC(PPh3)CH)Cl-2(PMe3)(2)]Cl (4), [Ru(CHC(PPh3)CHC(PPh3)CH)Cl-2(PBu3)(2)]Cl (5), [Ru(CHC(PPh3)CHC(PPh3)CH)Cl((BuNC)-Bu-t)(PPh3)(2)]Cl-2 (6), [Ru(CHC(PPh3)CHC(PPh3)CH)Cl(bipy)(PPh3)]Cl-2 (7), and [Ru(CHC(PPh3)CHC(PPh3)CH)(bipy)(PMe3)(2)]Cl-3 (8), respectively. Reaction of ruthenabenzene 2 with AgBF4 gives bisruthenabenzene [Ru(CHC(PPh3)CHC(PPh3)CH)(PPh3)](2)(mu-Cl)(3)(BF4)(3) (9). The thermal decomposition reactions of ruthenabenzene 2 and 7 produce a stable Cp- ion derivative, [CHC(PPh3)CHC(PPh3)CH]Cl (10). 2, 4, 7, 8, 9, and 10 have been structurally characterized. 9 is the first non-metal-coordinated bismetallabenzene. An electrochemical study shows that the metal centers in the bisruthenabenzene 9 slightly interact with each other through the chloro bridges.