Binuclear gold(I) and mereury(II) derivatives of diethynylfluorenes

A new series of bis(alkynyl) gold(I) and mercury(II) d(10) complexes incorp orating fluorenyl-based linking units are reported. The binuclear complexes [LAuC=CRC=CAuL] and their isoelectronic mercury(II) congeners [R'HgC equiv alent to CRC equivalent to CHgR'] (L = tertiary phosphines; R = fluorene-2, 7-diyl, dihexylfluorene-2,7-diyl, 9-((ferrocenylphenylene)methylene) fluore ne-2,7-diyl, fluoren-9-one-2,7-diyl, 9-(dicyanomethylene)fluorene-2,7-diyl; R' = Me, Ph) were prepared in very good yields by the base-catalyzed dehyd rohalogenation reaction of the corresponding metal chloride precursors with the appropriate diethynylfluorene derivatives HC equivalent to CRC equival ent to CH at room temperature. All the compounds have been fully characteri zed by FTIR, NMR and electronic absorption spectroscopies and FAB mass spec trometry. The solid-state molecular structures of [Ph3PAuC equivalent to CR C equivalent to CAuPPh3] (R = 9,9-dihexylfluorene-2,7-diyl, fluoren-9-one-2 ,7-diyl) and [MeHgC equivalent to CRC equivalent to CHgMe] (R = fluoren-9-o ne-2,7-diyl) have been determined crystallographically, the last of which r epresents the first dimercury diacetylide to be structurally characterized. Absorption studies suggest that it is possible to fine-tune the optical ga p of this class of materials by modifying the electronic properties of the substituent at the 9-position of the central fluorene spacer. The solution redox chemistry of these fluorene-linked binuclear complexes as revealed by cyclic voltammetry indicates some degree of electronic communication betwe en the 9-substituent of the fluorenyl ring and the terminal metal groups vi a the conjugated alkynyl bridge. Most of the complexes in this study have b een shown to exhibit rich photophysical behavior, and a discussion on their emission properties in terms of the nature of metal groups and their auxil iary ligands as well as the fluorene spacer was made.