Plumbocenes with sec ‐ und tert ‐Alkyl Substituents

Abstract [(C 5 H 2 t Bu 3 ‐1,2,4) 2 Pb] ( 1 ), [(C 5 H i Pr 4 ) 2 Pb] ( 2 ), and [(C 5 i Pr 5 ) 2 Pb] ( 3 ) have been obtained from PbCl 2 and Li(C 5 H 2 t Bu 3 ‐1,2,4), Na(C 5 H i Pr 4 ) and Na(C 5 i Pr 5 ), respectively. 3 exists as a 1 : 1 mixture of meso ‐ 3 and rac ‐ 3 which interconvert at elevated temperature via one‐at‐a‐time rotation of isopropyl groups with ΔG # = 73.0 ± 1.5/73.7 ± 1.5 kJ/mol at 348 K. 3 is slightly bent in the solid state with an angle of 170(1)° between the ring normals.