Octaazamacrocyclic complexes

The octaazamacrocyclic complex (83) is capable of undergoing numerous transformations to give complexes with different patterns ofligand unsaturation (Scheme 36).191... 

The metal-promoted reactions of 1,2-dihydrazones with formaldehyde (see Scheme 35) can be compared with the purely organic reactions of 1,2-dihydrazones with orthoesters, which lead directly to macrocyclic compounds from which complexes of stnwtural type (85) can be prepared. The octaazamacrocyclic complex (83) is capable of undergoing numerous transformations to give complexes with different patterns ofligand unsaturation (Scheme 36). ... 

The reduction of imBT ligand with NaBH4 in methanol led to the formation of a saturated octaazamacrocyclic amBT ligand that forms binuclear complexes with zinc(II) and copper(II) [199] and mononuclear clathrochelates with manganese, iron, cobalt, nickel, and zinc (II) [203] by treatment of the free ligand with the corresponding metal ion salts. 

Attempts to synthesise manganese(II) and zinc(II) octaazamacrocyclic compounds had no success. Complexes of these metals with 2,3-butanedione dihydrazone react with formaldehyde, but in this case products containing the acyclic tetradentate ligand L37 are isolated [2]. 

Attempts to obtain complexes with the 16-membered octaazamacrocycle L44 by interaction of diacetyl with hydrazinium halides, followed by the subsequent addition of nickel(II) or copper(Il) salts and prolonged heating of the reaction mixture, led to the isolation of [M(L45)]X2 H20, where X = Cl , Br , N03 , C104 or BF4 andn = 0,2(Eq. 2.8) [13],... 

Thus pSTi(L90)] can be regarded as an intermediate in the synthesis of synunetric octaazamacrocyclic products [Ni(L84)]. It is also a suitable precursor for building up other non-symmetric systems, such as [Ni(L91)]. The coordinated ligand in [Ni(L91)] is rather acidic. An X-ray diffraction study, carried out on recrystallised product from acetonitrile-pyridine mixture [Ni(L91)] (R = CH3), showed that the complex consists of the cation PyH and the anion [Ni(L91)] . The structure of the latter is given in Figure 2-16 [130]. 

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