Macrocycles with pendant functional groups

Many ligands of this category offer the prospect of inducing axial metal-ion coordination even for those cases where the pendant arms incorporate weak donor functions. Coordination will be enhanced simply because the donors are held near to the metal and hence their effective  

The varying participation of the alcohol functions in metal coordination in these complexes is undoubtedly a reflection of both the moderate donor capacity of alcohol oxygens and the different coordination preferences of the respective metal ions involved. 

The product from heating cyclam directly in acrylonitrile is the tetranit-rile derivative (98, X = ON) which does not use any of its nitrile groups for coordination to Ni(n) or Cu(u) (Wainwright, 1980 Hay Bembi, 1982 Freeman, Barefield Van Derveer, 1984). This behaviour con- 

A related pH-induced change to that just discussed had been reported earlier for the nickel complex of (99) which undergoes a colour change 

A variety of other mono-A-substituted tetraazamacrocycles have been prepared (Lotz Kaden, 1978 Hediger Kaden, 1978 Keypour  

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The metal-templated cyclocondensation of the appropriate dicarbonyl precursor with a functionalized diamine gives the so-called bibracchial (doubly pendant-armed) SB macrocycles (Scheme 20). This area has been reviewed.20 Pendant arm macrocycles and their metal complexes have also attracted attention. Arms bearing additional potential ligating groups have been introduced at both carbon and nitrogen atoms of macrocycles which have generally been based on polyaza or... 

For instance, in the functionalized macrocycle 2 the donor atom of the ethylamine pendant arm is a primary, rather than a tertiary, amine nitrogen atom, which gives rise to a stronger axial interaction with the metal. In fact, the pKA of the pendant amine group in the [Ni(II)-(2)]2+ complex, 2.8, is much lower than observed for the corresponding complex of 1. Noticeably, in the... 

Methods 0-6, 0-7, and 0-8 are simple procedures for preparing the polyaza macrocycles with reactive secondary amine groups in the ring or on pendant alkyl groups or a hydroxy group on a ring carbon atom. These reactive functional groups allow these macrocycles to be further reacted to add other species or to be attached to a solid support. 

Azamacrocyclic ligands with pendant arms have recently attracted considerable attention mainly due to their analytical, biological and catalytic applications [l]. Compounds of this class combine the properties of a rigid macrocyclic structural unit with those of a flexible side-chain to which the functional group can be bound. Such systems are especially interesting for studying the influence of axial coordination on the properties of the coordinated metal ion. 

The Staudinger reaction has also been employed for synthetic purposes other than the preparation of iminophosphoranes. Thus, reactions between appropriate k -phosphorus azides and phosphines gave the amine functionalized dendron (68) that could be grafted onto a tetraphosphorus macrocycle with four pendant P-N=P(C6H5)2(p-C6H4-CHO) groups in order to obtain the expected topologicaly amplified compound as a mixture of diastereoisomers. ... 

The sulfimide group R2S = NR is isoelectronic with R2S = O, and recent studies have revealed the first examples of macrocyclic derivatives from reaction of the thia crown with MSFI.155,156 These compounds are of interest as ligands in their own right, and also because they provide a means of functionalizing the thiacrown at the S atom and hence the possibility of introducing pendant groups. 

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