Syntheses, structural elucidation and reactions of allylamino compounds of the type, [η5-C5R5(CO) 2Fe(NH2CH2CHCH2)]BF4

Article abstract of DOI:10.1016/j.poly.2012.03.039

The reaction of 3-aminoprop-1-ene (allylamine) with the etherate complexes [(η⁵-C₅R₅)(CO)₂Fe(L)] ⁺ (R = H; L = Et₂O; R = CH₃; L = THF) have been investigated and found to give air stable allylamino complexes [(η⁵-C₅R₅)(CO)₂Fe(NH ₂CH₂CHCH₂)]⁺ (R = H (3) or CH ₃ (4)) with the vinyl functionality pendant on the alkyl chain. These complexes have been isolated as the tetrafluoroborate salts. They undergo halogenation reactions on the pendant vinyl group to give high yields of the dihalopropylamino complexes [(η⁵-C₅H ₅)(CO)₂Fe{NH₂CH₂CH(X)CH ₂X}]⁺ (X = Cl (5), Br (6)) and [{η⁵-C ₅(CH₃)₅}(CO)₂Fe{NH ₂CH₂CH(Br)CH₂Br}]⁺, (7), respectively. Complexes 3 and 4 also react with the etherate complexes [(η⁵-C₅R₅)(CO)₂Fe(L)] ⁺ to yield dinuclear complexes of the type, [(η⁵- C₅R₅)(CO)₂Fe(NH₂CH ₂CHCH₂)Fe(CO)₂(η⁵-C ₅R₅′)]²⁺ (R not necessarily equal to R′), in which the two iron moieties are in different electronic environments. The NMR and IR data of the dinuclear complexes show that the allylamine ligand bridges the two metal systems. It is coordinated to the metal on one end via the nitrogen of the amine functionality in a η¹- fashion and on the other end via the vinylic functionality in a η²-fashion forming a chiral metallacyclopropane type structure. The reaction of the dinuclear salt [{(η⁵-C₅H ₅)(CO)₂Fe}₂(NH₂CH ₂CHCH₂)](BF₄)₂ with NaI in acetone gives [(η⁵-C₅H₅)(CO)₂Fe(NH ₂CH₂CHCH₂)]I and [(η⁵-C ₅H₅)Fe(CO)₂I] indicating that the iodide displaces the η²-coordinated metal center. All these compounds have been fully characterized. The molecular structures of [3][BF₄], [4][BF₄] and [7][BF₄] have been determined by single crystal X-ray diffraction.