The reaction of [M(CN)(6)](3-) (M = Cr3+, Fe3+, Co3+) with the nickel(II) complex of 2,4-diamino-1,3,5-triazin-6-yl-{3(1,3,5,8,12-pentaazacyclotetradecane)} ([NiL](2+)) in excess of ANO(3) or ACl (A = Li+, Na+, K+, Rb+, Cs+, NH4+) leads to the cyano-bridged dinuclear assemblies A{[NiL][M(CN)(6)]} center dot x H2O (x =2-5). X-ray structures of Li {[NiL][Cr(CN)(6)]} center dot 5H(2)O, NH4 {[NiL][Cr(CN)(6)]}, 3.5H(2)O, K{[NiL][Cr(CN)(6)]} center dot 4H(2)O, K{[NiL][Fe(CN)(6)]} center dot 4H(2)O, Rb{[NiL][ Fe(CN)(6)]}, 3.5H(2)O, and Cs{[NiL][Fe(CN)(6)]} center dot 3.5H(2)O, as well as the powder diffractometry of the entire Fe-III series, are reported. The magnetic properties of the assemblies are dependent on the monocation A and discussed in detail. New efficient pathways for ferromagnetic exchange between Ni-II and Fe-III or Cr-III are demonstrated. Field dependencies of the magnetization for the Fe-III samples at low temperature and low magnetic field indicate a weak interchain antiferromagnetic coupling, which is switched to ferromagnetic coupling at increasing magnetic field (metamagnetic behavior). The interchain magnetic coupling can be tuned by the size of the A cations.