Opening “Jaws”: Functionalisation of the hexaphosphapentaprismane cage, P6C4Bu4, affording X2P6C4Bu4 (X = Me, I), crystal and molecular structures of X2P6C4Bu4 (X = Me, I) and [cis-PtCl2Me2P6C4Bu4]

An Approach to Rigid, Optically Active Chelate Ligands with C2 Symmetry: Dialkylhexaphosphapentaprismanes

“…Unlike its racemic counterparts, 12′g is formed by one defined enantiomer of the P 6 C 4 t Bu 4 cage only and the two identical ( S )‐2‐methylbutyl side‐chains embrace the square‐planar cis ‐P A P A PdCl 2 complex fragment. The two P–P bond lengths of 2.1754(12) Å, for example, are comparable to those of complexes 9a ,9 9b , and 12c , and the same holds for the chelate ligand bite angle P1–Pd1–P1A of 79.47(5)°, which is almost identical to the other Pd and Pt complexes that contain the dialkylhexaphosphapentaprismane ligands in this study.…”

“…The spectroscopic and analytic data of 7 are identical to those reported in the literature within the margins of error,9 but the spectra of the novel species 10 proved to be uninterpretable without a rational structure hypothesis, which required an X‐ray structure determination of the crystalline material. Compound 10 crystallizes in the monoclinic space group P 2 1 / n .…”

“…Unlike the report on dimethylhexaphosphapentaprismane 8a ,9 target products dialkylhexaphosphapentaprismanes 8b – h are always accompanied by alkyl(iodo)hexaphosphapentaprismanes 11b – h as a second product, even in the presence of the large excesses of alkylating Grignard or alkyllithium reagents that are employed in these syntheses (Scheme ).…”

“…As an example, cis ‐(diallyl‐tetra‐ tert ‐butylhexaphosphapentaprismane)PtCl 2 9b forms colorless single crystals of 9b· 3CH 2 Cl 2 from CH 2 Cl 2 / n ‐hexane (1:1) at –20 °C. Unlike its dimethyl derivative 9a ,9 molecular 9b crystallizes in the space group C 2/ c , which is compatible with a crystallographic C 2 symmetry. A racemate of two symmetry related enantiomers of 9b are located in the unit cell on a C 2 axis (Figure 3).…”

“…This reaction occurs by the oxidative coupling of di‐ tert ‐butyl‐1,2,4‐triphospholyl potassium salt (K 6a ) to form 4 in the first step and then diiodo‐tetra‐ tert ‐butylhexaphosphapentaprismane 7 by adding another equivalent of I 2 to the mixture. Prismane 7 is readily converted into its dimethylated analogue 8a , the target C 2 ‐symmetric chelate P–C cage ligand prototype for Pt II complex 9a 9 (Scheme ).…”