Abstract
This work has involved the reaction of kinetically stable 2-tert-bury-l lambda(3)-phospha-alkyne, Bu-t-C equivalent to P, with dichloro(dialkylamino)arsines, in which the isolated products were characterized by spectroscopic methods; additionally, the results of X-ray structure analyses were confirmed by quantum chemical calculations using Gaussian 98 molecular modeling software. The arsenic component of the starting material is completely lost, probably as a precipitate of insoluble "arsenic(I) chloride," and unusual oligocycle 2,4,6-tri-tert-butyl-3-chloro-1-dialkylamino-1 lambda(5)sigma(4),3 lambda(3)sigma(3),5 lambda(3)sigma(2)-triphosphabicyclo[22.0]hexa-1,5-diene (1) - an ylide with an unusually long P-Cl bond (245.5 p.m.) - could be isolated. From these reactions, compounds 1a to 1d differing by their substituents at nitrogen were isolated as deep red, cuboid-shaped single crystals. X-ray structure analyses reveal molecules which are characterized by an ylidic and a regular P-C double bond of almost equal length [P1(circle plus)-C2(av.)(circle dot)172.2 p.m., P5-C6(av.)169.6 p.m.]. In addition to these two characteristic features the average bond length P3-C2 is found to be considerably shortened to a value of 172.7 p.m., whereas the adjacent phosphorus-chlorine bond P3-Cl1 is strongly elongated to 245.5 p.m. (C) 2017 Elsevier B.V. All rights reserved.