Substitution of the chloro ligands in cis-[CoCl<inf>2</inf>(2-C<inf>5</inf>H<inf>4</inf>N-CO<inf>2</inf>Prⁱ)<inf>2</inf>]: Structural characterization of four mononuclear products showing both cis and trans configurations at Co(II)

Cobalt(II) complexes obtained by the reaction of cis-[CoCl2(2-C5H4N-CO2Pr i)2] (1) with aqueous solutions of simple alkali metal salts have been prepared and characterized. While the reaction of 1 with KPF6 affords both trans-[Co(2-C5H4N-CO2Pri) 2(H2O)2](PF6)2 ·2(2-C5H4N-CO2Pri) (2) and trans-[Co(2-C5H4N-CO2Pri) 2(H2O)2](PF6)2 (3), that with NaBPh4 leads to trans-[Co(2-C5H4N-CO2Pri) 2(H2O)2](BPh4)2 ·2H2O (5) exclusively. X-ray diffraction data show that the mononuclear cationic units in 2, 3 and 5 share common structural features. The reaction of 1 with KSCN leads to cis-[Co(NCS)2(2-C5H4N-CO2Pr i)2] (4), whose crystal structure shows that it consists of mononuclear discrete molecules. The analogous reaction with NaN3 yields the very slightly soluble complexes [Co(N3)2(2-C5H4N-CO 2Pri)] (7) and [Co2(N3)(2-C5H4N-CO 2Pri)4(H2O)]·3H 2O (8) and that with NaOAc results in the formation of the already known complex trans-[Co(2-C5H4N-CO2)2(H 2O)2] (6) as the only product. Electronic UV-Vis and NIR spectral data for 2-5, 7 and 8 and the calculated magnetic moments from NMR measurements on 2-4 and 7 are indicative of high-spin octahedral Co(II) complexes, as already reported for 1 of known structure. © 2002 Elsevier Science B.V. All rights reserved.