Metal-organophosphonate chemistry: Hydrothermal syntheses and structures of copper(II)-xylyldiphosphonates with organonitrogen coligands

The hydrothermal reactions of copper(II) acetate monohydrate or copper(II) chloride dihydrate with xylyl-phosphonic acid derivatives in the presence of organonitrogen coligands yielded a series of compounds of the Cu(II)/ligand/xylyl-diphosphonate system. The materials structurally characterized in the study include the parent compound [Cu2(H2O)2(1,4-O3PC8H8PO3)] (1); the o-phenanthroline derivatives: [Cu(H2O)(o-Phen)(1,4-HO3PC8PO3H)]·3H2O (2·3H2O), [Cu2(H2O)2(1,4-O3PC8H8PO3)]·3H2O (3·3H2O), [Cu(o-phen)(1,4-HO3PC8H8PO3H)]·3H2O (4·3H2O), [Cu(o-phen)(1,2-HO3PC8H8PO3H)] (5), and [Cu(o-phen)(1,3-HO3PC8H8PO3H)] (6); the 2,2′-bipyridine derivatives: [Cu2(H2O)2(bpy)2(1,4-HO3PC8H8PO3H2)2(HO3PC8H8PO3H)]·H2O (7·H2O); [Cu(bpy)(1,4-HO3PC8H8PO3H)]·2H2O (8·2H2O), and [Cu(bpy)(1,3-HO3PC8H8PO3H)] (9); the tetra-2-pyridylpyrazine materials: [Cu2(H2O)2(tpypyz)(1,4-HO3PC8H8PO3H)2·(1,4-H2O3PC8H8PO3H2)2·2H2O (10·(H62O3PC8H8PO3H2)2·2H2O), [Cu2(tpypyz)(1,2-HO3PC8H8PO3H)2]·2H2O (11·2H2O), and [Cu4Cl4(tpypyz)2(1,4-H2O3PC8H8PO3H)2]Cl2·H2O3PC8H8O3H2·8H2O (12·H2O3PC8H8O3H2·8H2O); and the di-2,2′-pyridylamine compound [Cu(2,2dpy)(HO3PC8H8PO3H)] (13). The role of the coligand in modifying the overall dimensionality of the ultimate products is apparent. Rather than observing the common pillared layer frameworks characteristic of metal-diphosphonate materials, the o-phenthroline derivatives, compounds 4 and 5 are two-dimensional, 3 and 6 are one-dimensional and 2 is molecular. For the 2,2′-bipyridyl analogues, 8 is two-dimensional while 9 is one-dimensional and 7 is molecular. Similarly, the tetra-2-pyridylpyrazine derivatives provide a one-dimensional material 10 and two molecular species 11 and 12.