Triple-decked complexes formation

Dihydro-l,3-diborolenes are accessible as pentaorgano derivatives " and serve as ideal precursors of the diborolyl radieal. The formation of the radical and its interaction with a metal center is formally described as a metal oxidation. The resulting 2,3-dihydro-1,3-diborolyI ligand is either a three-electron donor or an anionic four-electron donor. l,3,4,5-Tetraethyl-2-methyl-2,3-dihydro-l,3-diborole reacts with [T -CpNi(CO)2] or (T7 -Cp>2Ni in hot mesitylene to yield a sandwich complex and a triple-decked complex ... 

Of the pentaphospholide ion only ) -coordination is known, sometimes with additional g -coordination. A characteristic feature is the formation of triple-decker complexes with P5 as the middle deck <94CCR1>. Their electronic structure has been explored <89JA2030>. 

The 1,3-doborolyl ligand (4-H) functions as a 3e donor and as a good electron acceptor (formally 3e), which allowed the formation of the first complete family of triple-decker sandwich complexes (26+-30 ) (6) ranging from FeFe+ cation (28 VE) to NiNi- anion (34 VE). In addition, the unsymmetrical triple-decker 31-34 have been reported however, we did not succeed in the synthesis of any triple-decker with CO ligands in both terminal decks. The complexes 26-34 exhibit an interesting redox behavior and reactivity. The paramagnetic triple-decker 29 and 30 react with... 

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