Syntheses, X‐ray Diffraction Study and Characterisations of Ni and Zn Complexes of Clodronic Acid and Its Dibenzoyl Derivative

Four new nickel and zinc bis(phosphonates) were prepared, and their crystal structures were determined by single‐crystal X‐ray diffractometry: [{Na 2 Ni 3 (Cl 2 C(PO 2 O(C(O)C 6 H 5 )) 2 )(H 2 O) 20 }{Cl 2 C(PO 2 O(C(O)C 6 H 5 )) 2 }] n ( 1 ), [{Na 2 Zn 3 (Cl 2 C(PO 2 O(C(O)C 6 H 5 )) 2 )(H 2 O) 20 }{Cl 2 C(PO 2 O(C(O)C 6 H 5 )) 2 }] n ( 2 ), [Ni 2 {Cl 2 C(PO 3 ) 2 }(H 2 O) 7 ] · 4H 2 O ( 3 ) and [Zn 2 {Cl 2 C(PO 3 ) 2 }(H 2 O) 7 ] · 6H 2 O ( 4 ). In addition, the spectroscopic and thermal properties of the compounds 1 – 4 were studied by infrared spectroscopy and thermogravimetric analysis. The coordination polymers 1 and 2 form, through intermolecular hydrogen bonds, 2D layer‐like structures, whereas the aqua ligands and lattice water molecules of the monomeric compounds 3 and 4 form hydrogen bonds in three dimensions giving rise to a 3D network. In the isomorphous structures 1 and 2 the octahedral Na and Ni/Zn atoms form μ‐H 2 O‐bridged stepped metal chains where the Cl 2 C(PO 2 O(C(O)C 6 H 5 )) 2 2– ligands ( L1 ) are monodentately coordinated to the Na and Ni/Zn atoms, and the lattice L1 ligands are located in a trans position with respect to the chain. The isostructural Ni and Zn complexes of clodronic acid, 3 and 4 , are formed by a hydrolysis method from the L1 ligand. There, the clodronate ligand acts as a bridging and chelating ligand with the octahedral Ni and Zn atoms. The bulky and hydrophopic benzoyl groups of the L1 ligand in structures 1 and 2 lead to dense packing modes. The clodronic acid ligand of structures 3 and 4 , in turn, has a higher coordination flexibility and forms voids, where the water clusters are trapped by hydrogen bonds.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)