Synthesis and Structures of Ruthena‐octahydrotetraborane Complexes

Abstract

AbstractThe reactivity ofκ2‐N,S‐chelated ruthenium borate complexes, [Ru(PPh3)(κ2‐N,S‐(NC7H4S2)Ru{κ3‐H,S,S′‐H2B (NC7H4S2)2}] (1 a) and [Ru(PPh3)(κ2‐N,S‐(NC5H4S){κ3‐H,S,S′‐H2B(NC5H4S)2}] (1 b) with monoboranes have been explored. The prolonged room temperature reaction of [Ru(PPh3){κ2‐N,S‐(NC7H4S2)}{κ3‐H,S,S′‐H2B(NC7H4S2)2}],1 awith an excess of [BH3 ⋅ THF] led to the formation of hydrogen‐rich complex,arachno‐[PPh3(κ2‐B3H8)Ru{κ3‐H,S,S′‐H2B(NC7H4S2)2] (2). In a similar fashion, the isomeric ruthenatetraborane complexes of [Ru(PPh3)(κ2‐N,S‐(B3H8){κ3‐H,S,S′‐H2B(NC5H4S)2}],4and5were isolated from the room temperature reaction of1 bwith [BH3 ⋅ THF]. In complex2, the borate ligand, [H2B(NC5H4S)2] and the PPh3occupy theendoandexosites of the butterfly‐shaped RuB3core, respectively. In contrast, the borate unit [H2B(NC5H4S)2] in4sits on theexoposition of the butterfly core, while the phosphine ligand occupies theendosite. Multinuclear spectroscopic analyses were done to characterize all new complexes and the structures were further confirmed by single‐crystal X‐ray diffraction analysis. Density functional theory (DFT) calculations were performed to probe into the bonding modes of these complexes.