ISSN:
0009-2940
Keywords:
1,3-Diphosphabenzene derivatives
;
Chemistry
;
Inorganic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Syntheses, NMR spectra, and X-ray molecular structures of three (2-hetero-)1,3-diphosphabenzenes are reported which constitute an isoelectronic triade of compounds with BH2, CH, and N bridging units between the two phosphorus atoms. The remaining three carbon atoms of the rings are part of a 2-methallylic system. The 2-borataheterocycle 3 has been prepared by the reaction of CH2 = C(CH2)PPh2)2 (1) with Me2S—BH2Br to give an intermediate 2 still containing the exocyclic olefinic bond. Treatment of 2 with a base, deprotonation of one ring CH2 group, and proton migration from the other one to the olefinic CH2 group afford the 5-methyl-1λ5-phospha-3-phosphonia-2-boratabenzene 3. The PBP unit is tilted by 144.0(2)° against the planar C3P2 part of the ring. A heterocyclic precursor 4 for the carbon analog is generated from 1 and CH2I2, which on reaction with a strong base yields the diphosphabenzene 5 with a fully planar ring skeleton. For the synthesis of the aza analog 7, CH2=C(CH2Cl)2 is treated with HN(PPh2)2 to give the precursor 6, which can be deprotonatad at nitrogen and carbon with a base. In the crystals of 7, two independent molecules of very similar structure are present. The molecules show planar heterocycles.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/cber.19911240708
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