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) COMPLEXES OF 1-PHENYLPHOSPHETANE AND 1-PHENYLARSETANE

The complexes (R*,R*)-(+/-)-[(eta(5)-C5H5){1,2-C6H4(PMePh)(2)}FeL]PF6, where L = 1-phenyl-phosphetane, -phospholane, -phosphorinane, and -phosphepane, have been prepared in high yields from the corresponding phenylphosphine complex by treatment with the appropriate alpha,omega-dibromoalkanes and potassium tert-butoxide. The 1-phenylarsetane complex was obtained by deprotonation of the corresponding complex of (+/-)-(3-chloropropyl)phenylarsine. The 1-phenylphosphirane, the 1-phenylphosphetane, and the 1-phenylarsetane complexes were also prepared by direct reactions of the free ligands with (R*,R*)-(+/-)-[(eta(5)-C5H5){1,2-C6H4(PMePh)(2)}FeMeCN]PF6. The molecular structures of (R*,R*)-(+/-)-[(eta(5)-C5H5){1,2-C6H4(PMePh)(2)}Fe(PhPCH(2)CH(2)CH(2))]PF6 and (R*,R*)-(+/-)-[(eta(5)-C5H5){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 of slightly different geometries in each unit cell; the four-membered phosphetane 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. The four-membered ring of the arsetane complex is also puckered with the corresponding angle being 25(1)degrees.