Nacnac-Cobalt-Mediated P4 Transformations

A comparison of P-4 activations mediated by lowvalent beta-diketiminato (L) cobalt complexes is presented. The formal Co-0 source [K-2((LCo)-Co-3)(2)(mu(2):eta(1), eta(1)-N-2)] (1) reacts with P-4 to form a mixture of the monoanionic complexes [K(thf)(6)] [((LCo)-Co-3)(2)(mu(2):eta(4), eta(4)-P-4)] (2) and [K(thf)(6)][((LCo)-Co-3)(2)(mu(2):eta(3),eta(3)-P-3)] (3). The analogue Co-I precursor [(LCo)-Co-3(tol)] (4a), however, selectively yields the corresponding neutral derivative [((LCo)-Co-3)(2)(mu(2):eta(4),eta(4)-P-4)] (5a). Compound 5a undergoes thermal P atom loss to form the unprecedented complex [((LCo)-Co-3)(2)(mu(2):eta(3),eta(3)-P-3)] (6). The products 2 and 3 can be obtained selectively by an one-electron reduction of their neutral precursors 5a and 6, respectively. The electrochemical behaviour of 2, 3, 5a, and 6 is monitored by cyclic voltammetry and their magnetism is examined by SQUID measurements and the Evans method. The initial Co-I-mediated P-4 activation is not influenced by applying the structurally different ligands L-1 and L-2, which is proven by the formation of the isostructural products [(LCo)(2)(mu(2):eta(4),eta (4)-P-4)] [L= L-3 (5a), L-1 (5b), L-2 (5c)].