Alkaline earth metal salts of 1-naphthoic acid

Abstract

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 thatcatena-poly[[[diaquabis(1-naphthoato-κO)magnesium(II)]-μ-aqua] dihydrate], {[Mg(C11H7O2)2(H2O)3]·2H2O}n, exists as a one-dimensional coordination polymer that propagates only through Mg—OH2—Mg interactions along the crystallographicbdirection. 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 \over 2) and all have the common namecatena-poly[[diaquametal(II)]-bis(μ-1-naphthoato)-κ3O,O′:O;κ3O:O,O′], [M(C11H7O2)2(H2O)2]n, whereM= 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 threeM—O bonds. The polymeric chains propagatevia c-glide planes and throughMOMO 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.