REACTIONS OF COORDINATED PHOSPHINES AND ARSINES - IRON(II)-FACILITATED AND DIRECT SYNTHESES OF 3-MEMBERED TO 7-MEMBERED HETEROCYCLES CONTAINING PHOSPHORUS AND ARSENIC - CRYSTAL-STRUCTURES OF IRON(II) COMPLEXESOF 1-PHENYLPHOSPHETANE AND 1-PHENYLARSETANE

The complexes )-(+/-)-[(eta(5)-C5H5){1,2-C6H4(PMePh)(2)}FeL]PF6, where L = 1-phenyl-phosphetane, -phospholane, -phosphorinane, and -phosphep ane, have been prepared in high yields from the corresponding phenylph osphine complex by treatment with the appropriate alpha,omega-dibromoa lkanes and potassium tert-butoxide. The 1-phenylarsetane complex was o btained by deprotonation of the corresponding complex of (+/-)-(3-chlo ropropyl)phenylarsine. The 1-phenylphosphirane, the 1-phenylphosphetan e, and the 1-phenylarsetane complexes were also prepared by direct rea ctions of the free ligands with +/-)-[(eta(5)-C5H5){1,2-C6H4(PMePh)(2) }FeMeCN]PF6. The molecular structures of 5H5){1,2-C6H4(PMePh)(2)}Fe(Ph PCH(2)CH(2)CH(2))]PF6 and 5){1,2-C6H6(PMePh)(2)}-Fe(PhAsCH(2)CH(2)CH(2 ))]PF6 have been determined by X-ray crystallography. The phosphetane complex crystallized in a solvated form with two independent cations o f slightly different geometries in each unit cell; the four-membered p hosphetane rings are puckered with the angles between the C-P-C and C- C-C planes being 18(2) and 24(2)degrees for the respective cations. Th e four-membered ring of the arsetane complex is also puckered with the corresponding angle being 25(1)degrees.