Oxo-bridged metal carbene complexes. Synthesis, structure and reactivities of {[Os(Por)(CPh2)](2)O} (Por equals porphyrinato dianion)

Dinuclear mu-oxo osmium porphyrins containing terminal Os=CPh2 bonds with a linear C=Os-O-Os=C moiety were prepared, which are reactive toward pyridine to form [Os(Por)(CPh2)(py)] and are active catalysts for inter- and intra-molecular cyclopropanation of alkenes and for carbene insertion into saturated C-H bonds.