C‐Halophosphaalkenes (1, 2) were prepared in high yield by a one‐pot synthesis from HCX3 or CI4 and Mes* PCl2 (Mes* supermesityl 2,4,6‐tri‐tert‐butylphenyl). The C‐iodophosphaalkenes Mes* P Cl2 (1 C) and Mes*P CHI (2c) undergo halogen‐metal exchange with n‐BuLi at low temperatures. The resulting carbenoids Mes*P CILi (11 c) and Mes*P CHLi (6) reacted with ClMMe3 (M Si, Ge, Sn) to give Mes*PCIMMe3 [(Z)‐13: M Ge; (Z)‐14: M Sn] or Mes*P CHMMe3 (8–10), respectively. Further reaction of (Z)‐13 and (Z)‐14 with nBuLi and ClMMe3 gave Mes*PC(MMe3 (18: MGe; 19: M Sn). The carbenoid (Z)‐11 c decomposed at −85°C; instead of the expected “phosphaisonitrile” Mes*P C : (21), only Mes*CP (15) was obtained which lends experimental support to the theoretically predicted instability of 21.
Polymers derived from the isomeric C, N, monomers cyanogen (NCCN) and isocyanogen (CNCN) are investigated. Although both paracyanogen [poly(NCCN)] and paraisocyanogen [poly(CNCN)] consist of carbon and nitrogen in a close to 1 : 1 ratio, thermogravimetric (TG) and spectroscopic analyses (DRIFT, EPR, UV-VIS-NIR and XPS) reveal that their molecular structures are markedly different. Despite the occurrence of n-conjugation, no regular ladder structures are found. In line with the spectroscopic data, conductivity measurements show that pristine poly(CNCN) and poly(NCCN) are an insulator and a semiconductor, respectively.
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