(6-Acetyl-1,3,7-trimethyllumazine-κ³O⁴,N⁵,O⁶)bis(triphenylphosphine-κP)copper(I) hexafluoridophosphate

Abstract

The title compound, [Cu(C11H12N4O3)(C18H15P)2]PF6, is the third example reported in the literature of a five-coordinated CuIP2NO2 system. The metal is coordinated to both PPh3 mol­ecules through the P atoms and to the pyrazine ring of the lumazine mol­ecule through an N atom in a trigonal–planar arrangement; two additional coordinated O atoms, at Cu—O distances longer than 2.46 Å, complete the coordination. The coordination environment can be described as an inter­mediate square-pyramidal/trigonal–bipyramidal (SP/TBP) polyhedron.

Electrochemical Evidence for Hemilabile Coordination of 1,3-Dimethyllumazine to [1,1′-Bis(diorganophosphino)ferrocene]copper(I)

“…In vitro, an O,N chelation of transition metals is often found in pertinent biorelevant molecules containing the α-iminoketo function. , Soft metal centers are found to be strongly N 5 bonded (pyrazine-N) with comparatively weak O 4 coordination in a five-membered chelate arrangement, whereas hard metal centers bind more strongly to O 4 and more weakly to N 5 . Although reports on crystal structures of Cu I –lumazine complexes can be found in the literature, the electrochemical and spectroelectrochemical properties of these and other metal compounds of lumazines have not been discussed in detail . The limited biochemical relevance of lumazines is partially due to their less reversible electron transfer behavior.…”

“…The limited biochemical relevance of lumazines is partially due to their less reversible electron transfer behavior. Electrochemical studies of substituted lumazine complexes with various metals showed that reduction of these complexes proceeds mostly in an irreversible fashion, , although a few reversibly formed radical complexes have been described. , The irreversible character of charge transfer diminishes the catalytic and biocatalytic potential of such complexes, and the search for new, reversibly behaving lumazine complexes is therefore desired. Here we report coordination compounds of 1,3-dimethyllumazine with the moderately π-donating organometallic fragments [Cu(dippf)] + (dippf = 1,1′-bis(diisopropylphosphino)ferrocene) and [Cu(dppf)] + (dppf = 1,1′-bis(diphenylphosphino)ferrocene).…”