Iridium pyrazolate complexes

Dinuclear pyrazolate bridged iridium(I) complexes were prepared by employing a synthetic route analogue to that used for the rhodium(I) derivatives,... 

Just as with nondoped red fluorescent dyes, nondoped phosphorescent iridium complexes consisting of two chelating phenyl-substituted quinazoline and one (2-pyridyl) pyrazolate or triazolate have recently been reported by Chen et al. (278-280) (Scheme 3.88) [308]. All of these complexes exhibited bright red phosphorescence with relatively short excited state lifetimes of 0.4-1.05 ps. PHOLEDs fabricated using the compounds A and B with relatively... 

As mentioned above, iridium complexes are also active in the formation of amines via the hydrosilylation/protodesUylation of imines. In the presence of 2 equiv. of HSiEts, the cationic complex [lr bis(pyrazol-l-yl)methane (CO)2][BPh4] (C4) catalyzes the reduction of various imines, including N-alkyl and N-aryl imines and both aldimines and ketimmes. Excellent conversions directly to the amine products were achieved rapidly at room temperature in a methanol solution (Scheme 14.7) [53]. 

When a pyrazole ring is used as a scaffold to two pendant carbene donor groups, dime-tallic complexes can be formed [75] (see Figure 3.22). Similar complexes were also synthesised for nickel, rhodium and iridium [76,77]. Appreciable metal-metal interactions could not be observed in any of these complexes, with the exception of argentophilic [77,78] or aurophilic [79] interactions. As with other functionalised carbenes, these pyrazole bridged ones have precedences, in this case amine [80,81], phosphino [82] and Cp [83] functionalised pyrazole ligands. 

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