REACTIONS OF DIHALOGENOTRIORGANO-PHOSPHORUS, DIHALOGENOTRIORGANO-ARSENIC AND DIHALOGENOTRIORGANO-ANTIMONY COMPOUNDS WITH [FE2(CO)9] - SINGLE-CRYSTAL STRUCTURES OF THE IRON(III) COMPLEXES [(PH3PO)2H][FEBR4] AND[PH4SB][FEI4]CENTER-DOT-PH3SBI2 AND OF [FE(CO)3(PH3P)2]

The reaction of [Fe2(CO)9] with compounds of stoichiometry R3EX2 [R3E = Ph3P, (p-MeOC6H4)3P, Me2PhP, Me3As or Ph3Sb, X = I; R3E = Ph3P, Ph3A s or Me3As, X = Br] has been investigated and shown to yield diverse p roducts. A series of complexes with the ionic structure [R3EX][Fe(R3E) X3] [E = P, R3 = Ph3, Me2Ph or (p-MeOC6H4)3, X = I; R3E = Me3As; X = I or Br] has been obtained. The reaction of [Fe2(CO)9] with Ph3PBr2 and Ph3AsBr2, however, resulted in the formation of the iron(III) complex es [(Ph3E)2Br][FeBr4]. Hydrolysis of [(Ph3P)2Br][FeBr4] by trace quant ities of water produces [(Ph3PO)2H][FeBr4], the crystal structure of w hich has been determined. Triphenylantimony diiodide reacted with [Fe2 (CO)9] yielding the surprising ionic adduct [Ph4Sb][FeI4].Ph3SbI2, rem arkable not only for the phenyl migration at the antimony atom, but al so for the formation of the rare [FeI4]- anion from a zerovalent iron carbonyl complex. The reaction of [Fe2(CO)9] with the milder diphosphi ne tetraiodide, I2Ph2PCH2CH2PPh2I2, produced [Fe(CO)3(Ph2PCH2CH2PPh2)I ][I3], a complex in which three CO ligands are retained.