of excellence in metalloporphyrin chemistry
metal complexes with multiple metal-metal bonds.
- Over the past 25 years the Collman group has
for syntheses of a wide variety of homodinuclear and heterodinuclear
multiply bonded transition metal cores supported by porphyrins.
- The high-vacuum solid-state pyrolysis is the
only method developed so far that is applicable to most 2nd and
3rd row transition metals. Indeed, our group has prepared more
novel heterodinuclear multiply bonded transition metal cores than any
other group in the world.
- Porphyrin has proven to be a
uniquely suitable ligand to stabilize dinuclear cores containing multiple
metal-metal bonds. Some of the properties of the porphyrin ligand include:
(i) relative rigidity and planarity; (ii) inability to bridge two metals;
(iii) very high stability of the complexes (metalloporphyrins); (iv) ease
of derivatization at the periphery, which can affect the steric,
electronic properties or both.
- These porphyrin’s
properties allowed our lab to carry out unique physicochemical
measurements, such as the barrier for rotation around the quadruple-bond,
and the resonance Raman vibrational frequencies of the multiple
- Our most recent success (see
the picture) was synthesis and characterization of a complex containing
the first example of a quadruple metal-metal bond between elements from
different groups of the periodic table. Until our work, heterodinuclear
quadruple bonds were limited to group 6 metals. Some even thought that
other elements can not form such bonds.
- We recently reviewed the
progress in the field of heterodinuclear transition metal complexes with
multiple metal-metal bonds in Angewandte