Transitions tropolonate

The complexes [Ru(bpy)2L]+ (HL = acetylacetone, trifluoroacetylacetone, hexafluoroacetylace-tone, tropolone or dibenzoylmethane) have been prepared and characterized they act as catalysts for the oxidation of alcohols, 3,5-di-tert-butylcatechol and alkanes in the presence of appropriate co-oxidants." Perchlorate salts of [Os(bpy)2L] in which HL = salicylaldehyde, 2-hydroxyaceto-phenone or 2-hydroxynaphthaldehyde, are formed from reactions of [Os(bpy)2Br2] with HL. The structure of the salicylaldehyde derivative has been determined. Chemical and electrochemical oxidations of [Os(bpy)2L]" yield the corresponding low-spin Os species from which [Os(bpy)2L]+ can be regenerated." " [Ru(bpy)2L]" (HL = salicylic acid) has been prepared and structurally characterized as the tetrahydrate. Absorptions at 590 nm, 400 nm, and 290 nm in the electronic spectrum have been assigned to Ru bpy CT transitions electrochemical oxidations of the complex have been investigated." ... 

Figure 6.5. Fluorescence excitation spectrum of jet-cooled tropolone. The broken lines indicate transitions for the high-wave-numbered tunneling doublet components. The bands due to the hydrogen-bonded complex between tropolone and water are indicated by the asterisks. (From Sekiya et al. [1990b].)...

Scandium is more like an element of the first transition series (or like aluminum) than like the rare earths. For example, it characteristically has a coordination number of 6 (6-coordinate radius, 0.89 A compared to 1.00-1.17 A for the lanthanides), although coordination numbers 8 and 9 are known. Examples of CN 8 are Na5[Sc(C03)4] -6H20 and the tropolonate, [SeT4] . There is but one example of CN 9, namely the tricapped trigonal prismatic [Sc(H20)9]3+ ion found in Sc(CF3S03)3-9H20.38 The aqua ion in solution, [Sc(H20)6]3+, is appreciably hydrolyzed and OH-bridged di- and trinuclear species are formed. 

The tropolones form transition-metal complexes of high affinity constants, for example [M(77 )3] with M = Co(n), Ni(H) and Zn(H), but M(77 )2 with M = Cu(II)2 . Moreover, these compounds form complexes with heavy metals (Os, Ir, Pt, Mo and W) , the lanthanides(in) and main-group metal ions (Ga, In, Sn, Sb and Pb) many have crystal structures determined and some show biological activities and potential... 

Figurel.1 Symbolic representation of equal double-well potential energy functions for (A) tropolone and (B) malonaldehyde in the So ground and lowest S, singlet electronic states. The spectral doublet of the S,-So zero-point transitions is shown. The doublet separation is (H, - 0°) = Ao - Ao " -...

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