Beryllium(II) complexes of the Klaui tripodal ligand cyclopentadienyltris (diethylphosphito-P)cobaltate(-)

The interactions of the beryllium(II) ion with the cyclopentadienyltris(die thylphosphito-P)cobaltate monoanion, L-, have been investigated, in aqueous solution, by synthetic methods, potentiometry, ESMS, and H-1, P-31, and Be -9 NMR spectroscopy. L- has been found able to displace either two or three water molecules in the beryllium(II) coordination sphere, to form mononucl ear, dinuclear, and trinuclear derivatives, in which the metal ion is pseud otetrahedrally coordinated. The species [BeL(H2O)](+) and [Be2L2(mu -OH)]have been identified in solution while complexes of formula BeL2 and [Be3L4 ](ClO4)(2) have been isolated as solid materials. The species [BeL(OPPh2)]( +), closely related to [BeL(H2O)](+), has been characterized in acetone sol ution and isolated as tetraphenylborate salt. The structure of the unusual trimeric complex [Be3L4](2+) has been elucidated by an unprecedented 2D Be- 9-P-31 NMR correlation spectrum showing the presence of a single central be ryllium nucleus and two equivalent terminal beryllium nuclei. The three ber yllium centers are held together by four cobaltate ligands, which display t wo different bonding modes: two ligands are terminally linked with all the three oxygen donors to one terminal beryllium, and the other two bridge two metal centers, sharing the oxygen donors between central and terminal bery llium atoms.