1.3- Diborolyl sandwich complexes

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 ... 

Few examples have been reported of metals coordinated to six-membered boron-sulfur heterocycles. Ashe et al. prepared 4-methyl-l,4-thiaborin (SC4H4BMe) which forms a stable molybdenum tricarbonyl sandwich complex 144.158 jn g etjert s laboratory, the reaction of the diborolyl complex 33 (Section 3.01.3.2) with COS afforded the dinuclear complex 145 whose structure was determined crystallographically.36 Other products, not involving boron-sulfur heterocycles and hence outside the scope of this discussion, were obtained via the treatment of 33 with different sulfur reagents such as CS2.36... 

Arene-displacement reactions, characteristics, 1, 97 Arene-ene substrates, in C-H bond alkylation, 10, 218 Arene-ferracarboranes, characteristics, 3, 225-226 I // -Arene liruliiim complexes, preparation, 7, 388 (Arene)metal(diborolyl) sandwiches, synthesis, 3, 12... 

A simple sandwich complex with only one 1,3-diborolyl ligand is shown in Figure 5 <78ZN(B)1410>. 

The synthesis of a tricarbonyl cobalt 1,3-diborolyl complex has been reported. The same ligand features in symmetrical and unsymmetrical multidecker complexes of platinum with iron, cobalt and nickel and in the first reported hexadecker sandwich complex. Thia-dlborole complexes of nickel and cobalt have also... 

Pentamethylcyclopentadienyl iron(II) complexes involving T 5-2,3,5-tricarbahexaboranyl and n5-2,3-dihydro-l,3-diborolyl ligands have been synthesised and spectroscopically characterised. A crystal structure analysis of the 16 v.e. sandwich complex (7) illustrates that there is extreme folding of the C3B2-ring and thus stacking cannot occur below this ring. ... 

The reactions between [Rh( -G1)(C2FI4)2]2 arid 2,3-dihydro-l,3-diborole derivatives in toluene and benzene yielded sandwich 7 -arene- -dihydro-diborolyl-rhodium complexes 441, which were fully characterized. ... 

The borole ring and various 1,3-diborolyl anions have been extensively employed as ligands to prepare a huge array of transition metal complexes and multidecker sandwich compounds.96 97 Inevitably, the electronic character of the borole is profoundly changed upon complexation, so a study of such complexes can reveal nothing certain about B—C multiple bonding in the isolated ligand. 

Complexes of C3B2 (Diborolyl) Rings 3.01.3.1 C3B2 Ring Double-decker Sandwiches... 

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