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Transition metal complexes colour

Flowever, transition metal complexes do absorb in the visible region, giving them a characteristic colour. Flow can this happen if the transitions are forbidden The answer is that interaction may occur between the motion of the electrons and vibrational motions so that some vibronic transitions are allowed (see Section 7.3.4.2b). [Pg.275]

There are a number of particular technical advantages associated with the formation of coloured metal complexes. Commonly, the transition metal complexes of a coloured organic ligand exhibit lightfastness which is significantly better than that of the free ligand. An explanation that has been offered for this effect is that coordination with a transition metal ion... [Pg.66]

The first borinate-transition metal complex to be prepared was actually the first known derivative of borin. Bis(cyclopentadienide)cobalt (94) reacts with organic halides and was analogously found to react with boron halides in a redox reaction to give (95), followed by an insertion to yield (cyclopentadienide)(borinato)cobalt (97) (72CB3413). The product composition depends on the ratio of reactants. Compound (97) is the main product (80% yield when R = Ph, X = Br) when the molar ratio between (94) and the boron halide is 2.5 1. A second and slower insertion occurs to give (28) when (97) is treated with another equivalent of the boron halide (Scheme 13). Compounds (28), (29) and (97) have one electron more than predicted by the 187r-electron rule for transition metal complexes. They are red in colour and, of course, paramagnetic. The mixed complexes (97) are thermally labile, in contrast to (28) and (29), which can be heated to 180 °C and sublimed at 90 °C. Their ionization potentials are low and the complexes are sensitive to air. [Pg.644]

The complexing capacity of hydroxamic acids was predicted by Werner in 1908, who also indicated the metals most likely to form stable complexes.288 Since then, the formation of poorly soluble and intensely coloured hydroxamates has been used for analytical determinations for a number of metal ions, such as Fe3+, Mos+, Vs+ etc. A recent general review of transition metal complexes of hydroxamic adds included the few known examples of silver(I) complexes.289... [Pg.813]

Transition metal complexes have special properties, including colour and unusual magnetic properties that are useful in bioanalysis. Traditionally the most widespread technique for determining transition metals in physiological and biological fluids has been atomic absorption spectrophotometry. [Pg.73]

There is the issue of using an unfamiliar, highly coloured transition metal complex, which can be toxic, and needs to be removed. Interesting attempts have been made to address this issue via polymer supported catalysts. This removes the colour issue substantially (not completely), but polymerisation... [Pg.52]

One role of Lewis acid-base reactions is to bring colour to the world. This remark gives me the opportunity to introduce you to transition metal complexes, which are often brightly coloured and which are formed in what I shall call a Lewis way. The haemoglobin of your blood is an example. [Pg.58]

Transitions between iigand and metai orbitals in transition metai com-piexes. These are called metal to ligand, and ligand to metal charge transfer (MLCT and LMCT) transitions, respectively. These can be fully-allowed transitions and are usually the source of colour in intensely coloured transition metal complexes, e.g. the LMCT transitions in chromate, Cr04 , and permanganate, MnOJ ions, and the intense absorptions in ferroin (tris(phenan-throline) iron(II)) and tris(2,2 -bipyridyl)mthenium(II) (see Chap. 4). [Pg.61]

One of the most distinctive properties of transition metal complexes is their wide range of colours. This demonstrates that some part of the visible spectrum is being removed from white light as it passes through the sample of the coloured complex ion, so the light that emerges is no longer white. The colour of the complex ion is complementary to that which is absorbed. [Pg.476]

The colour in transition metal complexes can readily be explained in terms of crystal field theory, which accounts for the colour of complex ions from d-d transitions resulting from the splitting of the d sub-level by the repulsive effect of ligands. The type of splitting depends... [Pg.476]

Explaining the effect of different ligands on the splitting of the d-orbitals in transition metal complexes and colour observed using the spectrochemical series... [Pg.477]


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See also in sourсe #XX -- [ Pg.24 ]




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Coloured complex

Complexes colour

Metal colourant

Transition metals colour

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