Chemistry of coinage metal complexes with functionalized and strongly donating scorpionates

Poly(azolyl)borate systems or scorpionates are unsurpassed in their value as tridentate ligands in coordination chemistry, organometallic chemistry, catalysis, bioinorganic chemistry and enzyme modeling. The success and versatility of poly(pyrazolyl)borates has inspired the development of scorpionate ligands that are based on other donor groups. In this field, we have recently explored the chemistry of functionalized scorpionates by using carboxylic acid, ester-, amide-, trifluoromethyl- or nitro- containing R groups on the azole rings to provide an additional set of sites able to interact with metals. We also showed that, under non thermolytic condition, it is possible to synthesize 5-substituted trihydro(pyrazolyl)borate systems exhibiting k2-H,N coordination mode and we further described a synthetic pathway to an asymmetrically bis(pyrazolyl)borate system. More recently we have developed the synthesis of new strongly donating scorpionates, in particular pincer scorpionate type carbene ligands and related carbene-silver(I) and gold(I) complexes. We have isolated trimetallic carbene complexes of general formula {Ag3[HB(RIm)3]2}Br (R = Bn, Mes and tBu), which were successfully employed in the synthesis of related Au(I) and Cu(I) complexes by transmetallation; silver(I) and copper(I) complexes have also been proved to be active catalysts in the Sonogashira- and Ullmann-type reactions. Moreover we have also reported the synthesis of hydrophilic bimetallic complexes of general formula {Na2[H2C(AzR)2]2Ag2} (Az = Im or Tz; R = PrSO3 or EtCOO). At the present we are developing the chemistry of some new water soluble zwitterionic mono-NHC ligands and of the related Ag(I) and Au(I) carbene complexes {(Im1R,3R)MCl} (R = PrSO3 or CH2COOR′).