Ligand binucleating

Do binucleating ligands have a biological relevance D. E. Fenton, Adv. Inorg. Bioinorg. Mech., 1983,2,188 (264). 

The binucleating bis (amidinate) ligands based on the 9,9-dimethylxanthene backbone have also been used to prepare new dititanium(lV) complexes of the general formula [bis(amidinate)]Ti2Cp2R4 (R = CH3, CD3). Reaction of... 

Based on these observations a selective receptor for lithium 117 has been synthesized from a smaller diazadioxa macrocycle [160]. Ligands 110 and 117 may be regarded also as binucleating ligands capable of binding two cations at a time. 

The final category of binucleating ligands are those which incorporate more than one linkage between the cyclic subunits [see (118)]. The additional linkages between rings will tend to reduce the flexibility of the system and, for example, usually enable the relative positions of the metal centres to be controlled more precisely. The most common examples in this category have been termed co-facial dimers. 

Related structures to the binucleating crown (206), in which three or four individual macrocycles are linked by spiro-groups, have been synthesized (Weber, 1979 Weber, 1982). Other ligands of this general type, showing a variety of topological arrangements, are also known (Weber ... 

Fig. 30. Binucleating aza-thioethers 40c-40p and amine-thiophe-nolate macrocycles H2L24-H2L31 (see Table I for ligand designations).

The S-oxygenation of the hexaamine-dithiophenolate macrocycles should provide a potential entry into the novel class of binucleating polyamine-disulfonate and -disulfinate macrocycles. Indeed, such ligands can be prepared by the oxidation of dinuclear nickel complexes of the parent hexaaza-dithiopheno-late macrocycles followed by the decomposition of the oxidation products in acidic solution. The dinuclear nickel complexes [Nin2(L36)(L )]+ (L = Cr (70) and OAc (71)) of the hexaaza-diphenylsulfonate ligand (L36)2- (Fig. 38) are obtained by... 

We thank Professors M. Malachowski and T. Sorrell for providing us with samples of binucleating ligands. Support of this work by the National Science Foundation is gratefully acknowledged. 

Several polydentate SBs may act as binucleating ligands see Section 33.5.12.1. Only a few miscellaneous polydentate SBs will be included here. A complex with the SB obtained in the reaction of two moles of benzoyl hydrazide with acetylacetone had v(V=0) = 995 cm 1, Pea =1.7BM and was monomeric square pyramidal (117).792 A few complexes with the ethylenediamine derivatives of 2,2 -dihydroxychalcones (118) were prepared in ethanol.793 The stoichiometry is 1 1 and the atoms involved in the coordination were two deprotonated oxygens and two nitrogen atoms. v(V—O) (970-985 cm-1) and f4 (1.73-1.83 BM) suggest a monomer however, molecular weights in nitrobenzene suggest a dimer. 

From the reaction between isophthalaldehyde (Hfsal) and substituted derivatives and aminophenol in boiling methanol, the ligand H3fsal(ap)2 (180) may be obtained, which in its trianionic form may act as a binucleating agent. Several V02+ complexes with SBs (180 R = Me and R variable) were studied by Okawa et al. and were formulated as... 

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