Thermally induced endo to exo isomerization in the o-xylylene complexes of zerovalent ruthenium and osmium, M(η6-C6Me6){η4-o-(CH2)2C6Me4} (M=Ru, Os)

Abstract The endo -tetramethyl- o -xylylene complexes M( η 6 -C 6 Me 6 ){ η 4 - o -C 6 Me 4 (CH 2 ) 2 } (M=Ru ( endo - 1 ), Os ( endo - 2 )) isomerize to their exo -isomers on heating in the solid state at 400°C for 5 min. The osmium compound exo - 2 forms a 1:1 adduct with PMe 3 , Os(PMe 3 )( η 6 -C 6 Me 6 )[ κ 2 - o -(CH 2 ) 2 C 6 Me 4 } ( 5 ) in which the tetramethyl- o -xylylene is a bidentate σ -donor; the ruthenium compound exo - 1 is unreactive.