Cyanomethylene-bis(phosphonate) as ditopical ligand: stepwise formation of a 2-D heterometallic Fe(iii)Ag(i) coordination networkElectronic supplementary information (ESI) available: IR and UV-Vis spectra, PXRD diagram. CCDC reference numbers 844929 (2) and 844930 (3). For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c2ce06261e

A new heteroditopic ligand, cyanomethylene-bis(5,5-dimethyl-2-oxo-1,3,2 5 -dioxa-phosphorinane) 1 (bphosCN), has been reacted with Fe(ClO 4 ) 3 to afford the mononuclear complex Fe(bphosCN) 3 2 which crystallized in the cubic system, space group Pa 3&cmb.macr;. The iron center, chelated by the oxygen atoms of the ligand, shows an almost perfect octahedral geometry, with the CN groups disposed at 120 each other. Further reaction with AgClO 4 provided the heterometallic coordination polymer 2 {[(Fe(bphosCN) 3 ) 3 Ag 3 (H 2 O) 2 ](ClO 4 ) 3 } 3 as the unique crystalline polymorph, in the monoclinic space group P 2 1 / a . The targeted 2D honeycomb type structure has been achieved through an interplay between coordinative CNAg bonds and CNH 2 O bonds. The magnetic measurements demonstrate the existence of isolated paramagnetic Fe( iii ) centers in both complexes. The stepwise synthesis of a honeycomb type heterometallic FeAg coordination network has been achieved with a ditopical cyano-bis(phosphonate) ligand.