Ansa ‐Complexes of [Mn(η 5 ‐C 5 H 5 )(η 6 ‐C 6 H 6 )]: Preparation, Characterization, and Reactivity of [ n ]Manganoarenophanes ( n =1, 2, 3)

We report the synthesis of [ n ]manganoarenophanes ( n =1, 2) featuring boron, silicon, germanium, and tin as ansa ‐bridging elements. Their preparation was achieved by salt‐elimination reactions of the dilithiated precursor [Mn(η 5 ‐C 5 H 4 Li)(η 6 ‐C 6 H 5 Li)]⋅pmdta (pmdta= N , N , N′ , N′ , N′′ ‐pentamethyldiethylenetriamine) with corresponding element dichlorides. Besides characterization by multinuclear NMR spectroscopy and elemental analysis, the identity of two single‐atom‐bridged derivatives, [Mn(η 5 ‐C 5 H 4 )(η 6 ‐C 6 H 5 )Sn t Bu 2 ] and [Mn(η 5 ‐C 5 H 4 )(η 6 ‐C 6 H 5 )SiPh 2 ], could also be determined by X‐ray structural analysis. We investigated for the first time the reactivity of these ansa ‐cyclopentadienyl–benzene manganese compounds. The reaction of the distannyl‐bridged complex [Mn(η 5 ‐C 5 H 4 )(η 6 ‐C 6 H 5 )Sn 2 t Bu 4 ] with elemental sulfur was shown to proceed through the expected oxidative addition of the SnSn bond to give a triatomic ansa ‐bridge. The investigation of the ring‐opening polymerization (ROP) capability of [Mn(η 5 ‐C 5 H 4 )(η 6 ‐C 6 H 5 )Sn t Bu 2 ] with [Pt(PEt 3 ) 3 ] showed that an unexpected, unselective insertion into the C ipso Sn bonds of [Mn(η 5 ‐C 5 H 4 )(η 6 ‐C 6 H 5 )Sn t Bu 2 ] had occurred.