Cobalt-mediated [3+1] fragmentation of white phosphorus : access to Acylcyanophosphanides

Hauer, Sebastian and Horsley Downie, Thomas M. and Balázs, Gábor and Schwedtmann, Kai and Weigand, Jan J. and Wolf, Robert (2024) Cobalt-mediated [3+1] fragmentation of white phosphorus : access to Acylcyanophosphanides. Angewandte Chemie International Edition, 63 (6). e202317170. ISSN 1433-7851 (https://doi.org/10.1002/anie.202317170)

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Abstract

Despite the accessibility of numerous transition metal polyphosphido complexes through transition-metal-mediated activation of white phosphorus, the targeted functionalization of Pn ligands to obtain functional monophosphorus species remains challenging. In this study, we introduce a new [3+1] fragmentation procedure for cyclo-P4 ligands, leading to the discovery of acylcyanophosphanides and -phosphines. Treatment of the complex [K(18c-6)][(Ar*BIAN)Co(?4-P4)] ([K(18c-6)]3, 18c-6=[18]crown-6, Ar*=2,6-dibenzhydryl-4-isopropylphenyl, BIAN=1,2-bis(arylimino)acenaphthene diimine) with acyl chlorides results in the formation of acylated tetraphosphido complexes [(Ar*BIAN)Co(?4-P4C(O)R)] (R=tBu, Cy, 1-Ad, Ph; 4?a?d). Subsequent reactions of 4?a?d with cyanide salts yield acylated cyanophosphanides [RC(O)PCN]? (9?a?d?) and the cyclo-P3 cobaltate anion [(Ar*BIAN)Co(?3-P3)(CN)]? (8?). Further reactions of 4?a?d with trimethylsilyl cyanide (Me3SiCN) and isocyanides provide insight into a plausible mechanism of this [3+1] fragmentation reaction, as these reagents partially displace the P4C(O)R ligand from the cobalt center. Several potential intermediates of the [3+1] fragmentation were characterized. Additionally, the introduction of a second acyl substituent was achieved by treating [K(18c-6)]9b with CyC(O)Cl, resulting in the first bis(acyl)monocyanophosphine (CyC(O))2PCN (10).

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