UEBERGANGSMETALL-FULVEN-KOMPLEXE XXVI. DUALE REAKTIVITAET DES 5-(C5H4CHO)Cr(CO)3>--ANIONS GEGENUEBER ELEKTROPHILEN: EIN NEUER SYNTHESEWEG ZU FUNKTIONELL SUBSTITUIERTEN CYCLOPENTADIENYL-KOMPLEXEN UND (FULVEN)Cr(CO)3-DERIVATEN. MOLEKUEL- UND KRISTALLSTRUKTUR VON ...

Article abstract of DOI:10.1016/S0022-328X(00)99576-7

The reactivity of the (η⁵-formylcyclopentadienyl)M(CO)3 anions (M = Cr, Mo, W) towards electrophilic reagents has been studied.Electrophilic attack at the metal was found for molybdenum and tungsten, while the chromium derivative exhibits a novel type of dual reactivity.Oxidation of the anions leads to the dimeric formylcyclopentadienyl complexes <(η⁵-C5H4CHO)M(CO)3>2.Seven-coordinated compounds of the general type (η⁵-C5H4CHO)M(CO)3X (X = I, Sn(CH3)2Cl, Au(PPh3)) are obtained by treatment of the anions with I2, (CH3)2SnCl2 and (Ph3P)AuCl, respectively.The molecular structure of (η⁵-C5H4CHO)Cr(CO)3Au(PPh3) has been determined by X-ray diffraction.The molecule has a linear Cr-Au-P geometry and contains two semi-bridging carbonyl groups.Protonation of the <(η⁵-C5H4CHO)M(CO)3>^- anions (M = Mo, W) via the unstable hydrides (η⁵-C5H4CHO)M(CO)3H yields the dimers <η⁵-C5H4CHO)M(CO)3>2.The chromium derivative <(η⁵-C5H4CHO)Cr(CO)3>^- is also accessible to electrophilic attack at the oxygen atom of the formyl substituent.In this way a series of new (η⁶-fulvene)Cr(CO)3 complexes has been prepared by treatment of <(η⁵-C5H4CHO)Cr(CO)3>^- with various acyl halides RCOCl (R = CH3, t-C4H9, C6H5, p-ClC6H4, OC2H5).A binuclear η⁶-fulvene complex has been synthesized from the Cr anion and ClOC(CH2)6COCl.The complex (η⁶-fulvenylbenzoate)Cr(CO)3 was characterized by X-ray crystallography.The fulvene ligand is coordinated in the η⁶-fashion with a strong Cr-C_exo interaction (d(Cr-C_exo) 238.7(5) pm).