Outer-sphere coordination of polycyanometallate anions with polyammonium macrocycles: a spectrophotometric study

The spectroscopic determination of the outer-sphere stability constants between polycyanometallate anions with cationic polyammonium macrocycles is reported. The interactions of anions [M(CN)(n)](m-) (M=Au(I), Ni(II), Co(III), Fe(II), Fe(III) and Mo(IV)) of differing geometry and charge are examined with dominantly diprotonated macrocycles. Electrostatic interactions play a major role in determining the strength of the outer-sphere interaction; however, log K-os values (range 1.7-3.9) are influenced in part by the topology of the anions and cations. The X-ray crystal structure of the trichloride diperchlorate dihydrate salt of the pentaprotonated macrocycle 10-methyl-1,4,8,12-tetraazacyclopentadecane-10-amine which crystallises in the P $($) over bar$$ 1 space group with a = 13.24(1), b = 10.699(7), c = 10.458(5) Angstrom, alpha = 92.92(4), beta = 111.95(6), gamma = 109.45(7)degrees is also reported.