A Synthetic and X-ray Crystallographic Study of Zinc and Platinum Complexes of 4,5-Diazafluoren-9-one (Dafone) and Dicobalt Hexacarbonyl Derivatives of 9-Phenylethynyl-4,5-Diazafluoren-9-ol: Chelation versus Monocoordination

Coordination chemistry and applications of versatile 4,5-diazafluorene derivatives

This review article highlights the versatile nature of 4,5-diazafluorene derivatives as ligands, and details some recent advances made using this ligand family.

Steric control over C=O...C=O interactions in M(S2COR)2(dafone) compounds: M = Zn and Cd; R = Me, Et and iPr; dafone = 4,5-diazafluoren-9-one-N,N′

Crystallography shows that with the smaller xanthate-bound methyl groups in Zn(S2COMe)2(dafone) (1) and Cd(S2COMe)2(dafone) (3) anti-parallel C=O…C=O interactions link molecules into dimers. These are further associated via π—π interactions into a supramolecular chain, and in the case of 3 into a supramolecular two-dimensional array via C—H…S contacts. Increasing the size of the organic residue, i.e. to ethyl and isopropyl in Zn(S2COEt)2(dafone) (2), Cd(S2COEt)2(dafone) (4) and Cd(S2CO-iPr)2(dafone) (5), does not allow for the formation of this supramolecular architecture. Instead, supramolecular chains are sustained by C—H…S and C—H…π(chelate) interactions (the latter exclusively in the case of 5). The presence of recognisable/significant π—π and C—H…S and C—H…π(chelate) interactions is not consistent amongst the series yet only two crystal packing patterns are noted depending on the presence of the C=O…C=O interactions. This observation points to the importance of overall crystal packing considerations of binuclear species in 1 and 3, and mononuclear species in 2, 4 and 5.