stable than 12. Structural reasons for this tendency can be found from the X-ray structure analyses of 9, 13, and 16. In these structures the 0-H ... 0 distances between the phenolate oxygen atoms and the aqua ligands are 2.72 (9), 2.70 (13), and 2.68 A (16). The 0 ... 0 distances within one triangular face of the octahedron, in whose corners are situated the phenolate oxygen atoms, are on average in 9: 2.82, in 13: 2.89, and in 16: 2.89 A, whereas this distance for the surface of the [M"(OH,),12+ octrahedron, which is bound through 0-H ... 0 contacts to 1 or 2 is in 9: 3.07, in 13: 3.07, and in 16: 2.88 A. From this it can be concluded that the triangular faces involving the oxygen atoms which lie opposite each other in 16 are better matched with respect to their size than those in 9 and 13, and thus 16 is more stable in solution. The effects are small and different bond strengths of the 0- H ... 0 interactions, a result of the differences in basicity of the phenolate and water oxygen atoms, may be a further factor.
We are at present investigating the possibility of binding complexes of the type 1 and 2 with different 0 ... 0 distances and residual basicity of the 0 atoms to a polymer, in order to achieve the separation and selective enrichment of [M~~(oH,),]~+ ions in aqueous solutions in very small concentrations.
Experimental Procedure
The synthesis of complexes 1.2, and 3 was recently described . Synthesis of the complexes 4, 5a, 6-8 and 5b: To a solution of 3 (1.0mmol) in acetone (50 mL) was added the hexdaquametal(I1) perchlorate M(OH,),, (0.60 mmol) (M = Mn, Fe, Co, Ni, Zn) under exclusion of air at 20 "C. After the mixture had been stirred for 30 min and subsequently filtered, NaCIO,.H,O (0.10 g) was added and half of the solvent was removed on a rotary evaporator.
Red crystals of the desired complex grew within 12 h (-75% yield). Sb was prepared analogously with Fe(OH,),, (0.60 mmol). Temperature-independent magnetic moments (80-295 K; Faraday method): 4: 5.9,s: 5.5,6: 4.8, 7: 3.1 pg; 8: diamagnetic; 5 a : 5 . 9 ~~. Synthesis of the complexes 9-16: To a solution of 1 or 2 (1.0 mmol) in acetone (50 mL) was added M(OH,),, (0.60 mmol) (each of M = Mn, Co, Ni, Zn) at 20Β°C and stirred. After the mixtures had been stirred for 30 min, Na[BPh,] (0.20 g) and ethanol (15 mL) were added to the clear solutions. From these solutions crystals precipitated in an open vessel ( ~7 0 % yield) after approximately 3-5 d. From temperature-dependent (4.2-295 K) magnetic susceptibility measurements it followed that the spins in 9-11, and 13-15 were weakly coupled in an intramolecular antiferromagnetic manner. Temperatureindependent magnetic moments of 3.8 pLn/Cr and 5.9 p,/Fe were found for 12 and 16. All complexes gave satisfactory elementary analyses (C, H, N. metal).