Diimines, macrocyclic

The zinc iodide complex of a 15-membered diamine diimine macrocycle has been structurally... 

Diimines, macrocyclic, 54, 88 Diiododurene, from durene and iodine, 51, 95 ... 

The complex [MnL](PF6)2, where L is the pendant arm ligand (184), also based on a N5 diimine macrocycle, was obtained directly by a template procedure." . The coordination geometry is pentagonal bipyramidal with the pendant amino groups occupying the axial sites. The aqueous HNMR relaxation rate enhancement in the presence of this complex is small in comparison to... 

The polyether-diimine macrocycle (108) forms a catenate [Fe(cat)] which proved impossible to oxidize to [Fe(cat)] " but which is readily reducible, electrochemically in dichloromethane solution on a Pt or Hg surface, to [Fe(cat)]+ and to [Fe(cat)]°. " [Fe(bmpphen)2] (bmpphen = (109) can be electroreduced to [Fe(bmpphen)2] and to [Fe(bmpphen)2]. The relatively high stabilities of all three bmpphen complexes may be due to their entwined character. Here and below one should bear in mind the possibility, outlined in Section 5.4.1.3 above, that it is the ligand rather than the metal which is being reduced. 

The template condensation of 2,3-butanedione dihydrazone with aldehydes or ketones affords a variety of octaazabis(a-diimine) macrocyclic complexes of nickel(II), according to the Scheme 48.2655 NH deprotonation with py or Et3N of the aforementioned cationic complexes leads to neutral NiL species. 

The hexahydropyrimidine (58), formed from l-phenylpropane-l,2-dione and propane-1,3-diamine, is an excellent precursor for the a-diimine macrocyclic complexes (60), presumably via the amino ketone (59) (Scheme 36).126 In this case, intramolecular cyclization of (59) to (58) is reversible, so that the metal ion can exert a thermodynamic template effect in formation of the complex (60). This represents a further example of a long-known phenomenon in which a metal ion can stabilize an a-diimine structure by virtue of the formation of stable five-membered chelate rings. Many 2-hydroxy- or 2-mercapto-amines undergo reaction with a-dicarbonyl compounds to yield heterocyclic compounds rather than a-diimines. However, in the presence of suitable metal... 

Condensations of diamines with dicarbonyl compounds are a fruitful source of imino macrocycles. Condensations can be 2 2 with diamines to form tetraimine macrocycles, or 1 1, with additional heteroatoms present for the amine and/or carbonyl components, to form diimine macrocycles, as for (9) and (10) formed from 1,2-dicarbonyl compounds. 

Ligand oxygenation (112 -> 113) of Fe11 complexes of bis(/ -diimine) macrocycles by molecular oxygen has also been observed. Again, an Feni-mediated radical mechanism has been suggested for this oxidation.397... 

The achiral 14-membered trans-diimine macrocycle (f , S )-102, in the presence of trifluoroacetic acid, rearranges quantitatively into the chiral seven-membered monoimine ( )-103 (Section Ill.C.l.h)". If the rearrangement of (i , S )-102 is carried out in methanol containing a suspension of ( )-(—)-78, an orange solution is obtained from which pure [I ,(Sas,I as)] ( )-1 6 can be isolated by the addition of ammonium hexafluorophosphate. The yield of the complex was ca 50%. The addition of more acid and halide in an attempt to facilitate racemization of the free arsine and thereby promote the further crystallization of the complex by second-order asymmetric transformation was unsuccessful. Nevertheless, this highly stereoselective synthesis of [H,(Sas,IIas)] ( ) 106 is a more expedient route to (R,I )-(—)-102 than the one involving resolution of the benzyl alcohol complex (R, SA.)-(-)-92a. 

Complexes of Ni11 or Cu11 with 1,2- 1,3- or 1,4-diamines react with acetone in 2+2 condensations to form [14]-, [15]-, [16]-, or [18]-membered diamine-diimine macrocycle compounds, e.g., (15) and (16), formed from en, or with 3,3-tri or tetraamines in 1 + 1 condensations to form a diamine-monoimine or triamine-monoimine macrocycle compounds, respectively, e.g., (19) formed from 2,2,2-tet (Scheme 5).31... 

Monoprotonated diamines react with acetone or /3-enones, to form diamine-diimine macrocycle salts (20), with rings of up to [22]-members,32 with a variety of C-substituents33 (including 1,2-cyclohexdiyl (22), formed from trans-cyc 1 ohexane-1,2-diamine),34 or with X-substituents (Scheme 6)35 2 2... 

Cu-diimine macrocycle compounds (31) are formed by Jaeger template condensations of diamines with acyl-substituted /3-keto imines (30) (Scheme 9). The acyl substituents on the macrocycles are labile and undergo a variety of reactions. Reaction with trifluoromethyl sulfonate produces reactive methoxy ethylidene diimine compounds (32), which react with amines to form saddle-shaped cyclidenes. With bulky substituents these compounds have a hydrophobic void above the metal ion which can accommodate a guest molecule, an effect enhanced when the... 

Cz+diimine macrocycle compounds are formed by template condensations of an a-diketone (usually 2,3-butanedione or benzil), 2 + 2 with diamines, e.g., (34), or 1 +1 with tetraamines, e.g., (35) (Scheme 10). The resulting flat macrocycle cations form many stacked compounds, often with flat metal ion-containing anions, which exhibit spin coupling. The imine groups for the Ni11 compounds are reduced with NaBH4 and one of each cz+diimine function for the Co111 compounds by hypophosphorous acid.44... 

Further, it should be noted that the same macrocycle as in Figure 1 could be obtained by using condensation dimers of acetone, such as diacetone alcohol or mesityl oxide (8). It was also found that several kinds of a,0-unsaturated ketones and 0-hydroxyketones may be used to prepare macrocyclic diamino-diimines (8 ). This observation is very important, because by using suitable ketones it becomes possible to introduce desired substituent(s) into the three carbon atom linkage. In fact, a variety of diamino-diimine macrocycles has been prepared and used as ligands in recent years (9 - 14 ). However, almost all of the macrocycles were synthesized under reaction conditions not requiring metal ions such as nickel(II). 

Ligand oxygenation (112 113) of Fe complexes of bis(/ -diimine) macrocycles by molecular... 

Figure 7.13 The reaction of a pyridine dialdehyde with several diamines forms a dynamic combinatorial library. From this library, several diimine macrocycles can be obtained in good yield when template ions (symbolized by polygons) of proper size are added. Magnesium ions give a ring size of 15, calcium ions one of 18, and barium ions stabilize the 21-membered rin ...

The use of interlocked polyether-diimine macrocycle ligand (Fig. 5) has interesting implications for the coordination of metal ions, especially those of iron [32]. 

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