Publication Date:
2017-09-21
Description:
3a,6a-Diaza-1,4-diphosphapentalene (DDP) reacts with hexachlorocyclopentadiene to form a stable adduct (ClC) 4 C=DDP ( 4 ). The phosphorus atom involved into coordination has a pyramidal arrangement but retains partial double bonding with carbon [1.752(3) Å]. At the same time, the P–N bond remains covalent [1.824(3) Å]. The adduct 4 is better described as a zwitterionic compound with strongly delocalized positive and negative charges. A similar zwitterionic adduct DDP=C(CN) 2 was prepared by the reactions of dichloro-DDP ( 7 ) with malononitrile in the presence of Et 3 N. DFT calculations showed that related structures are formed in the case of the substituents (ClC) 4 C=, (HC) 4 C=, (NC) 2 C=, and (MeCO) 2 C=, possessing electron-delocalizing properties. Compounds with other R 2 C groups ( R = Ph, Me, C 6 F 5 , Cl), possessing electronegative properties as well, but insufficient e-delocalization, demonstrate the noncovalent P–N bonding and a little shorter R 2 C–P bond lengths (ca. 1.70 Å).
Print ISSN:
0044-2313
Electronic ISSN:
1521-3749
Topics:
Chemistry and Pharmacology
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