Sterically Tuned P‐Phosphanylamino Phosphaalkenes (Me3Si)2C=PN(R)PPh2 and (iPrMe2Si)2C=PN(R)PPh2

• Published in: Zeitschrift für anorganische und allgemeine Chemie (1950) 2018-04, Vol.644 (7), p.381-390
• Main Authors: Bîrzoi, Roxana M., Lungu, Daniela, Jones, Peter G., Bartsch, Rainer, du Mont, Wolf‐W.
• Format: Article
• Language: English
• Subjects: Aromatic compounds; Conformational analysis; Iminophosphanes; Line broadening; NMR; Nuclear magnetic resonance; Phosphaalkenes; Phosphane ligands; π‐interaction
• ISSN: 0044-2313; 1521-3749
• DOI: 10.1002/zaac.201700446

Deprotonation of the aminophosphanes Ph2PN(H)R 1a–1h [R = tBu (1a), 1‐adamantyl (1b), iPr (1c), CPh3 (1d), Ph (1e), 2,4,6‐Me3C6H2 (Mes) (1f), 2,4,6‐tBu3C6H2 (Mes*) (1g), 2,6‐iPr2C6H3 (DIPP) (1h)], followed by reactions of the phosphanylamide salts Li[Ph2PNR] 2a, 2b, 2g, and 2h with the P‐chlorophosphaalkene (Me3Si)2C=PCl, and of 2a–2g with (iPrMe2Si)2C=PCl, gave the isolable P‐phosphanylamino phosphaalkenes (Me3Si)2C=PN(R)PPh2 3a, 3b, 3g, and (iPrMe2Si)2C=PN(R)PPh2 4a–4g. 31P NMR spectra, supported by X‐ray structure determinations, reveal that in compounds 2a, 2b, 3a, and 3b, with bulky N‐alkyl groups the Si2C=P–N–P skeleton is non‐planar (orthogonal conformation), whereas 3g, 3h, and 4g with bulky N‐aryl groups exhibit planar conformations of the Si2C=P–N–P skeleton. Solid 3g and 4g exhibit cisoid orientation of the planar C=P–N–C units (planar I) but in solid 3h the transoid rotamer is present (planar II). From 3g, 4d, and 4g mixtures of rotamers were detected in solution by pairs of 31P NMR patterns (3h: line broadening).