further metal-localized oxidations and/or DPA'-localized oxidations. For 3 only irreversible reduction waves are seen at very negative potentials. Consistent with the other results is the appearance of an additional oxidation wave for 3 ( = 2). For 1 visible charge-transfer bands indicating transitions from Ru(II) to both the bpy :r* orbitals (~450 nm) and the HDPA pyridyl it* orbitals (350 nm) are observed. The emission remains dir* from bpy as in the = 0 complex. For 2 ( = 1 and 2) very low energy charge-transfer transitions (558 and 605 nm, respectively) assigned as dir* (bpy) are seen.The energies of these bands correlate well with the electrochemically predicted values. These results confirm that substantial changes occur in coordinated HDPA on deprotonation, and the results for 2 suggest that a metal-ligand interaction unique to Ru imine complexes exists.

The tris complex of Ru(II) with 2,2'-dipyridylamine (HDPA) has been prepared and characterized. Luminescence spectra, lifetimes, and photoselection spectra have been measured for various protonated and deprotonated forms of the complex in aqueous and nonaqueous solution. The fully protonated [Ru(HDPA)3]2+ shows a weak, broad, symmetric, and structureless emission of microsecond lifetime at low energy assigned as a dd* phosphorescence. The complexes of the deprotonated dipyridylamine ligand (DPA") exhibit broad, asymmetric, and structureless emission at higher energy with microsecond lifetimes. The emission for these deprotonated complexes is assigned as charge-transfer nd* emission, and, as a consequence, the emission for the [Rh(DPA)2Cl2]™ and [Ir(DPA)2Cl2]~complexes (previously reported as dll* emitters) is reconsidered. The [Ru(HDPA)2DPA]+ and [Ru(DPA)3]™ complex ions show spatially isolated (single-ring) emission in nonaqueous solvents; however, evidence exists that the emission for the neutral [Ru(HDPA)(DPA)2]°complex is multiring in nature. Spectral data are also presented for an equated form of the fully deprotonated complex, [Ru(DPA)3-H20]~, which has also been isolated as a solid product.

Low-temperature (77 K) luminescence spectra and lifetimes have been measured for the Cu(PPh3)2BH4 (PPh3 is triphenylphosphine) and Cu(prophos)BH4 (prophos is l,3-bis(diphenylphosphino)propane) complexes. Cu(PPh3)2BH4 exhibits multiple emission from 3 * and 3(a-aT) excited states in appropriate solvents, while Cu(prophos)BH4 shows only a single 3(o-aT) emission in most of the solvents chosen for this study. The electronic transition associated with the -a, assignment is analogous to the l-aT transition for the free phosphine ligand. These unique emission results are discussed in terms of intramolecular and intermolecular (solvent-solute) effects.

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Für eine Reihe von Komplexen (I)‐(III) werden cyclisch‐voltammetrische Untersuchungen bei Raumtemp. und bei ‐40°C durchgeführt und absorptionsspektroskopische Daten in Acetonitril mitgeteilt.