The monometallic complexes
[(bpy)2Ru(tpphz)]2+ (4) and
[(bpy)2Os(tpphz)]2+ (5),
where tpphz is the poorly
soluble fully aromatic
tetrapyrido[3,2-a:2‘,3‘-c:3‘‘,2‘‘-h:2‘‘‘,3‘‘‘-j]phenazine,
have been obtained by reaction of
5,6-diamino-1,10-phenanthroline with
[(bpy)2M(phendione)]2+ (M =
RuII or OsII). Reaction of 4
and 5 with
metallic precursors yielded the homo- and heterobimetallic complexes
[(bpy)2Ru(tpphz)Ru(NH3)4]4+
(6), [(bpy)2Ru(tpphz)Ru(bpy)2]4+
(7),
[(bpy)2Os(tpphz)Os(bpy)2]4+
(8), and
[(bpy)2Ru(tpphz)Os(bpy)2]4+
(9). The mononuclear
4 and 5 aggregate in solution, probably by
π−π stacking of the tpphz part as shown from proton NMR.
The
complexes show one reversible metal-centered oxidation and several
reversible (except 6) reductions which add
one electron on the tpphz ligand, one electron on one bpy of each
metallic end, a second electron on one bpy of
each metallic end, and then a second electron on the tpphz ligand.
The complexes (except 8) are luminescent
in
acetonitrile. Quenching of the luminescence by water has been
attributed to proton quenching at the phenazine
nitrogen atoms.
A series of dihydrazone and substituted dihydrazone derivatives of biacetyl and of hydrazone and phenylhydrazone derivatives of 2-acetylpyridine bind to [Ru(bipy),CI,] to give [Ru(bipy),( L-L)] -[PF,], complexes {bipy = 2.2'-bipyridine; L-L = biacetyl di(pheny1hydrazone) 1 a, biacetyl di [methyl(phenyl) hydrazone] 1 b, biacetyl di(o-tolylhydrazone) 1 c, biacetyl di(dimethy1hydrazone) 1 d, biacetyl di hydrazone 18, biacetyl di( benzaldehyde azine) 1 f, 2-acetylpyridine phenylhydrazone lg, or 2-acetylpyridine hydrazone 1 h}. The structures of all complexes have been determined using IR, UV/VlS, NMR and microanalysis. The proton NMR spectra of la-lc show an unusual dependence on probe temperature with broadened aromatic resonances, sharpening at both high and low temperature in the case of lb and 1c. No emission was observed for complexes with two hydrazone moieties, whereas it was observed for lg and lh with one hydrazone. The molecular structure of la has been determined and shows a hydrazone phenyl group lying over each of the bipyridyl rings: space group C2/c, a = 25.895(3), b = 10.505(1), c = 17.431 (2) A, p = 106.03(2)" and Z = 4.
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