Fischer-Type Carbene Complexes of Tris(1,4-phenylene)amines and Tri(2-furyl)phosphine

Abstract

Novel chromium and tungsten mono-and multiethoxycarbene complexes were synthesized from tris(4-bromophenyl)amine and tri(2-furyl)phosphine substrates. A comparative study between the amine and phosphine multicarbene complexes revealed small differences between the respective compounds. In solution, an equilibrium situation was observed between the mono-and bis-carbene complexes of tri(2-furyl)phosphine. The monocarbene amine ligand differs from the analogous phosphine ligand in the way the heteroatom lone pair electrons are able to interact with the carbene functionality. Unlike for the phosphine, the greater electron delocalization of the amine affected the coordination ability of the ligand when reacted with [Pt(COD)Cl 2 ]. These properties of the monocarbene-carrying ligands were confirmed and supported by solid state structural studies, spectroscopic data, and density functional theory (DFT) calculations.

The Effect of Remote Donor Substituents on the Properties of Alkoxy and Amino Fischer Carbene Complexes of Tungsten

“…Tables S2 and S3 of the Supporting Information summarize relevant information on the data collection and refinement. The molecular structures of complexes 1 a, [11] 4 a [12] and of the complex [W{C(NHMe)(Ph)}(CO) 5 ], the NHMe-substituted analog of complex 1 b (denoted as 1b NHMe in Table 2), have been previously published and will be used for comparative purposes, along with that of complex 2 c*. MERCURY [13] drawings of the molecular structures of 2 a, 2 b, 2 c and 3 a are displayed in Figure 2, Table 2 lists the most relevant bond lengths, bond angles and torsion angles.…”

Roles played by carbene substituents during ligand transfer reactions between tungsten fischer carbene complexes and [Pt(COD)Cl2]

“…[12][13][14][15][16] Recently FC complexes [W{C(X)(C6H4-4-R)}(CO)5] (X = OEt: a series; X = NMe2: b series) were synthesized in our laboratories from phenyl substrates containing remote tertiary amino substituents. [17][18][19] In addition, [W{C(X)(C6H5)}(CO)5] (a,b), were also synthesized to aid as reference complexes to probe the effects and magnitude of electron donation by remote tertiary nitrogen substituents. The importance of π-resonance effects within carbene substituents is an emerging area of research and aims at fine-tuning of the extent of electron donation and the distribution of electron density in the FC carbene ligand.…”