Construction of alkyl-substituted pentaphosphido ligands in the coordination sphere of cobaltDedicated to Professor Dietmar Stalke on the occasion of his 60th birthday.Electronic supplementary information (ESI) available. CCDC 1861829-1861837 and 1874059. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c8sc04745f

• Main Authors: Ziegler, Christoph G. P, Maier, Thomas M, Pelties, Stefan, Taube, Clemens, Hennersdorf, Felix, Ehlers, Andreas W, Weigand, Jan J, Wolf, Robert
• Format: Article
• Language: English
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/c8sc04745f

Rare mono- and diorganopentaphosphido cobalt complexes are accessible by P-P condensation using the unprecedented, reactive cobalt-gallium tetraphosphido complex [K(dme) 2 {( Mes BIAN)Co(μ-η 4 :η 2 -P 4 )Ga(nacnac)}] ( 2 ). Compound 2 was prepared in good yield by reaction of [K(Et 2 O){( Mes BIAN)Co(η 4 -1,5-cod)}] [ 1 , BIAN = bis(mesitylimino)acenaphthene diimine, cod = 1,5-cyclooctadiene] with [Ga(nacnac)(η 2 -P 4 )] (nacnac = CH[CMeN(2,6-iPr 2 C 6 H 3 )] 2 ). Reactions with R 2 PCl (R = iPr, t Bu, and Cy) selectively afford [( Mes BIAN)Co( cyclo -P 5 R 2 )] ( 3a-c ), which feature η 4 -coordinated 1,1-diorganopentaphosphido ligands. The mechanism of formation of these species has been studied by 31 P{ 1 H} NMR spectroscopy and DFT calculations. In the case of 3a (R = iPr), it was possible to identify the intermediate [( Mes BIAN)Co(μ-η 4 :η 2 -P 5 iPr 2 )Ga(nacnac)] ( 4 ) by single-crystal X-ray diffraction. A related, monosubstituted organopentaphosphido cobalt complex [( Mes BIAN)Co(μ-η 4 :η 1 -P 5 t Bu)GaCl(nacnac)] ( 5 ) was isolated by reacting dichloroalkylphosphane t BuPCl 2 with 2 . Heterobimetallic complexes such as 2 thus may enable the targeted construction of a range of new metal-coordinated polyphosphorus frameworks by P-P condensation. P-P condensation reactions in the coordination sphere of cobalt give access to unique organyl-substituted pentaphosphido complexes.