Co-ordination of 6,13-dimethyl-1,4,8,11-tetra-azacyclotetradecane-6,13-diamine to platinum(II) and palladium(II). Syntheses, characterisation, and X-ray crystal structures of the perchlorate salts of both complexes

Abstract

Both platinum(II) and palladium(II) complexes of 6,13-dimethyl-1,4,8,11-tetra-azacyclotetradecane-6,1 3-diamine (L¹) as a quadridentate ligand have been prepared in facile reactions as perchlorate salts, and characterised by electronic and n.m.r. spectroscopy, and voltammetry. The platinum(II) complex, [Pt(H₂L¹)][ClO₄]₄, represents the first structurally characterised with a saturated macrocyclic tetra-amine ligand. It crystallises in the triclinic space group P, with a= 10.006(4), b= 8.691 (3), c= 8.173(2)Å, α= 75.74(2), β= 79.00(3), and γ= 83.54(3)°, as does the complex [Pd(H₂L¹)][ClO₄]₄·6H₂O, with a= 11.123(5), b= 8.609(5), c= 8.541 (3)Å, α= 91.27(4), β= 96.09(3), and γ= 98.20(4)°. The cell of the palladium complex is derivative of that of the platinum simply by expansion, albeit with variations in some individual parameters. The Pt–N distances [2.045(7) and 2.043(6)Å] and Pd–N distances [2.044(3) and 2.036(3)Å] are slightly shorter than in non-cyclic M^IIN₄ analogues.