Side-on coordination of boryl and borylene complexes to cationic coinage metal fragments

The M-(η(2)-BMn) complex [(η(5)-C(5)H(5))(OC)(2)Mn{μ-B(Cl)(tBu)Au(PPh(3))}] (2) can be functionalized via halide substitution reactions to afford isostructural complexes [(η(5)-C(5)H(5))(OC)(2)Mn{μ-B(R)(tBu)Au(PPh(3))}] (R = Ph, CCPh and NCS). It also reacts with coinage metal complexes [MCl(PPh(3))] (M = Au, Ag and Cu) in the presence of halide abstraction reagents to afford borylene-bridged heteromultinuclear complexes [{(η(5)-C(5)H(5))(OC)(2)Mn}(2){μ(2)-B(tBu)}(2)M][BArx4] (M = Au, Ag and Cu; Ar(x) = 3,5-C(6)H(3)Cl(2), 3,5-C(6)H(3)(CF(3))(2)). Experimental characterization as well as computational studies revealed that these complexes are best viewed as transition metal borylene complexes side-on coordinated to monovalent coinage metal cations, thus representing the first boron analogs of Stone's alkylidyne-bridged multinuclear complexes.