- Title
- Palladium(II) as a versatile template for the formation of tetraaza macrocycles via Mannich-type reactions
- Creator
- Lawrance, Geoffrey A.; Maeder, Marcel; Napitupulu, Mery; Nolan, Annette L.; Rossignoli, Monica; Tiwow, Vanny; Turner, P.
- Relation
- Inorganica Chimica Acta Vol. 358, no. 11, p. 3227-3235
- Publisher
- Elsevier Science
- Resource Type
- journal article
- Date
- 2005
- Description
- The versatility of palladium(II) as a template for Mannich-type macrocyclization is illustrated. Reaction of (bis(3-aminopropyl)piperazine)palladium(II) with formaldehyde and nitroethane in basic aqueous solution yields the 'reinforced' macrocycle 7-methyl-7-nitro-1,5,9,13-tetraazabicyclo[11.2.2]heptadecane as its palladium(II) complex. The crystal structure shows the palladium ion lies in a slightly tetrahedrally distorted square plane of four nitrogen donors, with distances to the two tertiary donors [av. 2.059(3) angstrom] slightly shorter than those to the secondary amines [av. 2.066(3) angstrom]. The 3-methyl-3-nitro-1,5,9,13-tetraazacyclohexadecane as its palladium(II) complex was prepared by an analogous route. In a separate reaction based on the [Pd(en)(chxn)](2+) (en = ethane-1,2-diamine; chxn = cyclohexane-1,2-diamine) intermediate, an unsymmetrical macrocycle with a fused cyclohexane ring, 4,11-dimethyl-4,11-dinitro-2,6,9,13-tetraazabicyclo[12.4.0]octadecane was isolated as its palladium(II) complex. Accessibility to an isolable mixed-ligand precursor is a key to this reaction, provided by using palladium(II) as the templating metal. Reaction of (4,8-diazaundecane-1,11-diamine)palladium(II) with formaldehyde and diethyl malonate in basic aqueous solution yields, with ester hydrolysis and decarboxylation, the carboxylate-pendant macrocycle 1,5,9,13-tetraazacyclohexadecane-3-carboxylic acid as its palladium(II) complex. The crystal structure is comprised of hydrogen-bonded dimers {[Pd(L)][Pd(L-H)]}(3+) where the pair of inversion related square-planar complexes share a single proton between their pendant carboxylates. Bis(3-aminopropyl)(piperazine)palladium(II) yields the macrocyclic complex ion (1,5,9,13-tetraazabicyclo[11..2.2]heptadecane-7-carboxylic acid)palladium(II), in a similar reaction.
- Subject
- macrocycle; pendant arm; template reaction; palladium(II); X-ray; crystal structure; metal-directed synthesis; pendant-arm macrocycle; crystal-structure; reinforced macrocycle; molecular mechanics; copper(ii) complexes; polyaza macrocycles; carbon acids; amine groups; formaldehyde
- Identifier
- uon:383
- Identifier
- http://hdl.handle.net/1959.13/25363
- Identifier
- ISSN:0020-1693
- Language
- eng
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