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This report describes our progress in the development of indigo di-imines (‘Nindigos’) as a new kind of bridging ligand. In the area of ligand synthesis, we have developed a simple and practical protocol for the conversion of indigo (a commercially available and inexpensive reagent) into its bis-ketimine (i.e. the ‘Nindigo’ structure) by reation with primary amines RNH2. The relatively low reactivity of the carbonyl groups in indigo and the very poor solubility in most common solvents are two challenges which required refluxing bromobenzene (b.pt. 150 degrees C) for the reaction to work; under these conditions, with TiCl4 as a catalyst, a wide range of substituted anilines can be installed onto indigo in high yield. The reactions benefit from relatively short reaction times (1-3h) and no chromatography in the workup. This reaction is therefore a versatile way to make a wide variety of Nindigo derivatives in which the steric and/or electronic properties of the ligand can be controlled by the choice of amine. The ligands retain the intense visible absorption endemic to indigo itself and as such are very intense blue compounds. Moreover the new ligands all show unusual concentration- and temperature-dependent electronic spectra, suggesting aggregation effects in solution. This feature of the Nindigo family is currently being examined in more detail. In the arena of transition metal coordination chemistry, we’ve made a series of palladium complexes of eight different Nindigo derivatives. For most derivatives the expected binuclear structure was obtained, but in cases where the imine substituent was larger some unexpected structural changes were evident (X-ray crystallography). In one case (from tBuNH2) the R groups are large enough to ‘warp’ the nominally planar ligand skeleton, leading to large twisting about the central C=C bond of the Nindigo ligand (with concomitant large blue shift in the absorption maximum). Other derivatives with even larger R groups (e.g. Mes, Dipp) lead to ligand isomerization from a trans to a cis Nindigo core and the resulting rearranged ligand has bound only one metal. All of the Pd complexes show very interesting physical properties - all except the tBu derivative noted above absorb strongly (extinction coefficients in excess of 20,000) in the near infrared (>900nm) and all the complexes show multiple ligand-centered oxidation and reduction processes in their cyclic voltammograms. We’ve also begun to explore making boron complexes of our new Nindigo ligands. The initial idea was to make bis-boron chelate complexes, the reason being that the introduction of boron would create a rigid pi conjugated ligand which might have interesting near infrared absorption and emission properties. Our initial forays consisted of reactions of the ligands with BF3 in attempt to make bis-BF2 complexes. However we consistenty obtained mono-BF2 complexes in which the second binding site remained unoccupied . The mono-BF2 complexes were successfully bound to palladium, showing the potential offered by the monoBF2 Nindigos as capping ligands in their own right. However, very recently we’ve had a major breakthrough in our ability to make and handle the bis-BF2 complexes (they turn out to decompose on exposure to moisture, giving mainly the moisture-stable monoBF2). Immediate term plans are to investigate the redox, absorption, and fluorescence properties of the new bis-boron Nindigos.