Controlled Ring Opening of a Tetracyclic Tetraphosphane with Twofold Metallocene Bridging

• Published in: Chemistry : a European journal Vol. 30; no. 24; pp. e202400194 - n/a
• Main Authors: Dey, Subhayan, Szathmári, Balázs, Franz, Roman, Bruhn, Clemens, Kelemen, Zsolt, Pietschnig, Rudolf
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 25.04.2024
• Subjects: Chlorine; Cyclic Oligophosphine; Ferrocene; Intermediates; Methylation; Monovalent Aluminum; P-Catenation; Regioselective Ring-expansion; Ring opening polymerization; Selenium; Structural analysis; Cyclic Oligophosphine; Regioselective Ring-expansion; Monovalent Aluminum; P-Catenation; Ferrocene
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.202400194

A direct route to a doubly ferrocene bridged tetracyclic tetraphosphane 1 was developed via reductive coupling of Fe(CpPCl2)2 (2 a), where a chlorine terminated linear P4‐compound 3 could be identified as an intermediate. Selective P−P bond activation was further achieved by reacting 1 with elemental selenium or [Cp*Al]4, where regioselective insertion of Se or Al atoms resulted in ferrocenylene bridged [P4Se] (4) or [P4Al] (7) moieties. Compound 7 can be transformed to a hydrogen terminated linear P4 species, 8, with protic solvents. Methylation of compound 1 with MeOTf, proceeds via intermediate formation of monomethylated species 5, which gradually produced Me2‐terminated dicationic 6, again containing a linear P4‐unit. Besides spectroscopic characterization, the structural details of compounds 1, 4, 6, and 8 could be determined by SC‐XRD. Moreover, DFT calculations were used to rationalize the reactivity of 1, derived compounds and intermediates. As a key feature, 1 undergoes ring opening polymerization to a linear polyphosphane 9. An unprecedented and highly symmetric twofold bridged P4‐cycle has been embedded into a tetracyclic bisferrocenophane scaffold. Selective P−P bond can be achieved giving straightforward access to well‐defined linear P4‐snippets of different polarity or ultimately all‐trans polyphosphanes.