Phosphorus ring expansion at cobalt: targeted synthesis of P4, P5, and P7 ligands

Abstract

We report the synthesis of extended polyphosphorus ligands through the condensation of CoP3 and CoP4 frameworks with P1 and P2 units. Tetraphosphido complexes [(L)Co(CN)(η3-P4R2)] (1a-R: L = PHDI; R = Cy, Ph; 1b-R: L = Ar*BIAN; R = Cy, N(iPr)2) were obtained by treatment of the anionic cyclo-P3 complexes [nBu4N][(PHDI)Co(CN)(η3-P3)] (H, PHDI = bis(2,6-diisopropylphenyl)phenanthrene-9,10-diimine) and [K(18c-6)][(Ar*BIAN)Co(CN)(η3-P3)] (I, BIAN = 1,2-bis(arylimino)acenaphthene diimine with aryl being 2,6-dibenzhydryl-4-isopropylphenyl) with diorganochlorophosphanes (R2PCl, R = Cy, Ph, or N(iPr)2). Similar reactions of the cyclo-P4 complex [K(18c-6)][(Ar*BIAN)Co(η4-P4)] (K) yielded pentaphosphido complexes [K(18c-6)][(Ar*BIAN)Co(η4-P5R2)] (2b-R; R = tBu, N(iPr)2). Importantly, we show that the previously reported cationic cyclo-tetraphosphane [(LC)4P4][OTf]4 (G[OTf]4, LC = 4,5-dimethyl-1,3-diisopropylimidazol-2-yl) can be used to introduce [LC–P]+ and [LC–P]22+ units. Depending on the stoichiometry and reaction conditions, the reaction of G[OTf]4 with complex H furnishes complexes [(PHDI)Co(CN)(η3-P4LC)] (3a) and [(PHDI)Co(CN)(η3-P5(LC)2)][OTf] (4a[OTf]) with η3-coordinated tetra- and pentaphosphido ligands. Expanding this strategy, the cyclo-P5 and cyclo-P7 complexes [(PHDI)Co(μ:η41-P5LC){W(CO)5}] (5a-W(CO)5) and [(PHDI)Co(μ32211-P7LC){W(CO)5}2] (6a-{W(CO)5}2) were isolated from the reaction of G[OTf]4 with [K(18c-6)][(PHDI)Co(η4-P4)] (J) upon addition of W(CO)5(THF) to the reaction mixture. Intermediates en route to products 5a and 6a were detected by 31P{1H} NMR spectroscopy. The Ar*BIAN complexes I and K afford structurally analogous compounds 3b to 6b. Compounds 3–6 were isolated as crystalline materials and characterized by single-crystal X-ray diffraction and multinuclear NMR spectroscopy.

Graphical abstract: Phosphorus ring expansion at cobalt: targeted synthesis of P4, P5, and P7 ligands

Supplementary files

Article information

Article type
Research Article
Submitted
24 Oct 2024
Accepted
11 Jan 2025
First published
17 Jan 2025

Inorg. Chem. Front., 2025, Advance Article

Phosphorus ring expansion at cobalt: targeted synthesis of P4, P5, and P7 ligands

K. Trabitsch, S. Hauer, K. Schwedtmann, P. Royla, J. J. Weigand and R. Wolf, Inorg. Chem. Front., 2025, Advance Article , DOI: 10.1039/D4QI02683G

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