Piano-stool metal centers

There are very few examples of MOFs that have organometallic complexes as metalloligands, or so-called organometalloligands . However, Sweigart and co-workers (139-144) studied a number of such compounds. Their organo-metalloligand of choice was the piano stool complex [(Tj -benzoquinone)Mn (CO)3] , or /i-QMTC (Fig. 33). The C=0 moieties of the quinones can associate to secondary metal centers to form supramolecular networks with a rich diversity of... 

An important contribution of photoelectron spectroscopy to inorganic chemistry has been the use of this technique to understand the bonding capabilities of different ligands to metal centers. If the bonding for a series of ligands is to be compared, the metal fragment to which those ligands are bound must be similar. The d piano-stool complexes... 

In triphenylphosphine complexes the propeller sense is one element of chirality. If the metal atom in a three-legged piano stool complex is an additional stereogenic center, e.g. (C5H5)Fe(CO)(X)PPh3 in Scheme 16, diastereomers arise. In the acetyl complex, X = COMe, the barrier for the propeller inversion in solution was... 

The interest in different ligand combinations on a metal center is due to the multiple reactive coordination sites offering multiple reactive positions at the neutral electrophilic metal center on a pseudo bent metallocene coordination sphere. The structure of the borohydride complex (COT)U(BH4)2(OPPh3) (Baudry et al. 1990a) consists of discrete molecules with a piano stool configuration, it is the first to be determined for a mono-COT U derivative. Mixed ligand Th derivatives can be obtained by the reaction... 

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