Heterobi- and -trinuclear Complexes with an Amino(ethynyl)carbene as Bridging Ligand

Abstract

The sequential reaction of the amino(trimethylsilyl)carbene complex [(CO)5W=C(NH2)C≡CSiMe3] (1) with nBuLi and [I-Fe(CO)2Cp] affords the C(carbene)-N bridged heterobinuclear complex [(CO)5W=C{NHFe(CO)2Cp}C≡CSiMe3] (2). Desilylation of 1 is achieved by treatment with KF in THF/MeOH. From the reaction of the resulting complex [(CO)5W=C(NH2)C≡CH] (3) with nBuLi and [I-Fe(CO)2Cp] two binuclear WFe compounds in a ratio of approximately 1:1 are obtained: the C(carbene)-C≡C bridged complex 4 and the C(carbene)-N bridged complex 5. Repetition of the deprotonation/metallation sequence yields the trinuclear WFe2 complex 6. One Fe(CO)2Cp fragment in 6 is bonded to the amino group and the other one to the terminal carbon atom of the ethynyl substituent. The analogous reaction of 3 with nBuLi and [Br-Ni(PMe2Ph)2Mes] gives a ca. 1:1 mixture of two heterobinuclear complexes (7 and 8). Complex 7 is bridged by the C(carbene)-C≡C and complex 8 by the C(carbene)-N fragment. Subsequent reaction of 7 with BuLi and [Br-Ni(PMe2Ph)2Mes] finally affords the trinuclear WNi2 complex 9 related to 6. The solid-state structure of 2 is established by an X-ray diffraction analysis. The spectroscopic data of the bi- and trinuclear complexes indicate electronic communication between the metal centers through the bridging group.