Isoreticular Investigation into the Formation of Four New Zinc Alkylbisphosphonate Families

Through the systematic investigation
of zinc alkylbisphosphonates,
four new structural families have been obtained. These families are
named zinc alkyl-tunnel, -gate, -cation, and -sheet (ZAT, ZAG, ZAC,
and ZAS) for convenience and have been synthesized and further extended
through isoreticular design utilizing alkylbis­(phosphonic acid) ligands
of the formula H2O3P­CnH2n­PO3H2 (n = 3–6) (H4Ln). Both even-
and odd-length chains were utilized to help determine the effect of
chain conformation on structure formation. The investigation lead
to two known compounds (ZAG-4, and ZAS-3) and nine new compounds,
two of which contain large 1-D channels. The crystal structures of
all compounds were determined by single-crystal X-ray diffraction.
Of the nine new compounds, only seven of them fall into the new families.
In three of the four families, the structure is controlled by alkyl-chain
length and conformation (i.e., odd vs even), and in the fourth, a
conformational distortion allows both odd and even lengths to form
the given structure. Isoreticular species using n = 3 and 5 were obtained in both the ZAT and the ZAS families; using n = 4 and 6 were obtained in the ZAG family; and n = 4–6, in the ZAC family.