Versatile reactivity of dioxaneferrocenylimine palladacycles by controlled acid hydrolysis. Crystal and molecular structure of [Pd{CpFe[η5-C5H2{CH(OMe)2}C(H)[dbnd]N-2,4,6-Me3C6H2]}(Cl)(PPh2Et)

Abstract

Treatment of a or b with Li2[PdCl4] in methanol at room temperature for 48 h, gave the tetrametallic chlorine bridged complexes [Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NR]}(μ-Cl)]2, 1a and 1b, containing a cyclic acetal on the metallated cyclopentadienyl ring. The reactions of 1a and 1b with the Ph2P(CH2)nPPh2 diphosphines in a 1:1 ratio gave the tetrametallic species [{Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NR]}(Cl)}2(μ-Ph2P(CH2)nPPh2)], n = 1–4 as appropriate, 2a–5a and 2b–5b, with the diphosphine in a bridging mode and terminal chlorine ligands. Treatment of 1a and 1b with monophosphines yielded the dimetallic compounds [Pd{CpFe[η5-C5H2{C(H)O(CH2)3O}C(H)NR]}(Cl)(L)] (L = PPh3, PPh2Me, PPh2Et) 6a–8a and 6b–7b. Reaction of the phosphine derivatives with aqueous acetic acid gave the corresponding functionalized compounds with transformation of the 1,3-dioxane ring into a formyl group on the metallated ring 9a–15a and 9b–14b. Reaction of 8a with acetic acid in methanol gave [Pd{CpFe[η5-C5H2{CH(OMe)2}C(H)N-2,4,6-Me3C6H2]}(Cl)(PPh2Et)] 16a, after a transacetalization reaction with an acetal moiety –CH(OMe)2 on the metallated five-membered ring. The molecular structure of compound 16a has been determined by X-ray diffraction analysis.