To Be or Not to Be a (4,4) Net: Reactions of 4′-{4-(N,NDiethylaminophenyl)}- and 4′-{4-(N,N-Diphenylaminophenyl)}- 3,2′:6′,3″- and 4,2′:6′,4″-Terpyridines with Cobalt(II) Thiocyanate

The ligands 4′-{4-(N,N-diethylaminophenyl)}-3,2′:6′,3″-terpyridine (1) and 4′{4-(N,N-diphenylaminophenyl)}- 3,2′:6′,3″-terpyridine (2) were prepared and characterized, including the single crystal structure of 2. Along with their 4,2′:6′,4″-terpyridine isomers, 3 and 4, ligands 1 and 2 were reacted with Co(NCS)2 under conditions of crystal growth by layering, using solvent mixtures of MeOH and CHCl3. The single crystal structures of [Co(NCS)2(1)]n.0.8nCHCl3, [Co(NCS)2(2)2(MeOH)2].3CHCl3, [Co(NCS)2(3)]n.2nCHCl3, and [Co(NCS)2(4)]n were determined. The complexes with 1, 3, and 4 assemble into 2D (4,4) nets with the Co(II) centres as 4-connecting nodes, whereas [Co(NCS)2(2)2(MeOH)2] is a discrete molecular species, illustrating that MeOH can act as a non-innocent solvent. The effects on the structure of changing from the 3,2′:6′,3″-terpyridine (3,2′:6′,3″-tpy) to a 4,2′:6′,4″-tpy metal-binding unit, and of introducing R2N functionalities with different steric demands, are discussed. PXRD of bulk samples of all four products confirmed the single- crystal structures as representative of the bulk materials