High-spin carboxylate polymers [M(OOCCMe3)2]n of group VIII 3d metals

A coordination polymer of the general formula [Co(OOCCMe3)(2)](n) (2) was prepared by mild thermolysis of the coordination polymer of variable composition [(HOOCCMe3)(x)Co(OH)(n)(OOCCMe3)(2-n) ](m), the dinuclear cobalt complex Co-2(mu-H2O)(OOCCMe3)(4)(HOOCCMe3)(4), the tetranuclear cobalt cluster Co-4(mu(3)-OH)(2)(OOCCMe3)(6)(HOEt)(6), and the hexanuclear cluster [Co-6(mu(4)-O)(2)(mu(n)-OOCCMe3)(10)(C4H8O)(3)(H2O)]center dot 1.5(C4H8O) (7) in organic solvents. In the crystal, the polymer has a chain structure. Unlike thermolysis of cobalt pivalates, thermolysis of the dinuclear complex Ni-2(mu-H2O)(OOCCMe3)(4)(HOOCCMe3)(4) gave rise to the hexanuclear complex Ni-6(mu(2)-OOCCMe3)(6)(mu(3)-OOCCMe3)(6) (3). The magnetic properties of compound 2 are substantially different from those of 3. Compound 2 undergoes the magnetic phase transition into the ordered state at T (c) = 3.4 K (H = 1 Oe), whereas compound 3 exhibits antiferromagnetic properties. Solid-state decomposition of polymeric cobalt carboxylate 2 (below 350 degrees C) afforded the octanuclear cluster Co-8(mu(4)-O)(2)(mu(2)-OOCCMe3)(6)(mu(3)-OOCCMe3)(6) (9) as the major product, which sublimes without decomposition. Decomposition of 3 gave nickel oxide as the final product. Pivalates 2 and 3 reacted with 2,3-lutidine in acetonitrile at 80 degrees C to form the isostructural dinuclear complexes (2,3-Me2C5H3N)(2)M-2(mu-OOCCMe3)(4) (M = Co or Ni). The structures of compounds 3 and 7 were established by X-ray diffraction. The structure of polymer 2 was determined by powder X-ray diffraction analysis.