Alkaline earth metal salts of 1-naphthoic acid

The structures of the Mg, Ca, Sr and Ba salts of 1-naphthoic acid are examined and compared with analogous structures of salts of benzoate derivatives. It is shown that catena-poly[[[diaquabis(1-naphthoato-kappa O)magnesium(II)]-mu-aqua]dihydrate], {[Mg(C11H7O2)(2)(H2O)(3)]center dot 2H(2)O}(n), exists as a one-dimensional coordination polymer that propagates only through Mg-OH2-Mg interactions along the crystallographic b direction. In contrast with related benzoate salts, the naphthalene systems are large enough to prevent inorganic chain-to-chain interactions, and thus species with inorganic channels rather than layers are formed. The Ca, Sr and Ba salts all have metal centres that lie on a twofold axis (Z'=1/2) and all have the common name catena-poly[[diaquametal(II)]-bis(mu-1-naphthoato)-kappa O-3,O':O;kappa O-3:O,O '], [M(C-11-H7O2)(2)(H2O)(2)](n), where M = Ca, Sr or Ba. The Ca and Sr salts are essentially isostructural, and all three species form one-dimensional coordination polymers through a carboxylate group that forms three M-O bonds. The polymeric chains propagate via c-glide planes and through MOMO four-membered rings. Again, inorganic channel structures are formed rather than layered structures, and the three structures are similar to those found for Ca and Sr salicylates and other substituted benzoates.