Masters Theses
Date of Award
12-1997
Degree Type
Thesis
Degree Name
Master of Science
Major
Chemistry
Major Professor
Craig E. Barnes
Committee Members
Jim Chambers, Ben Xue
Abstract
The synthesis and characterization of an unusual dinuclear oganometallic complex derived from Cp3Co3(CO)2 1 is presented. Reaction of 1 with 1,3,4,5-tetramethyl- imidazole-2-ylidene 2 was anticipated to form a trinuclear carbene adduct. The actual product arises from fragmentation of the trinuclear cluster 1 to form the dinuclear monocarbene adduct Cp2CO2(CO)2(C7H12N2) 3. The x-ray crystal structure of 3 has been determined and an ORTEP illustration of the structure in the solid state is shown below.
The x-ray crystal structure of the adduct was solved (space group P-1; a = 8.8600 Å, b = 9.0374 Å, c = 12.1181 Å; α = 92.300; β = 103.979; γ = 109.514; 2403 reflections; R = 0.0220). As the illustration shows, one atom of the imidazole ring, the carbene carbon is coordinated to just one of the cobalt atoms at a distance of 1.899(5) Å. The tilt of the ligand towards the other cobalt atom is approximately 10° such that this center is 2.788 (5) Å away. The Co-Co bond (2.432(1) Å) is asymmetrically bridged by the two carbonyl ligands. The average Cco-Co distances are of 1.955 Å (CCO-Co1) and 1.602 Å (CCO-Co2). The dinuclear adduct 3 can also be made by adding the carbene to Cp2Co2(CO)2. The complex is also formed by fragmentation of electronically saturated Cp3Co3(CO)3 and Cp4Co4(CO)2 in the presence of 2. The imidazole carbene adduct decomposes at room and low temperatures in solution. One of the decomposition products, CpCo(CO)(C7H12N2) 4, will be discussed briefly.
Recommended Citation
Player, Michael Joseph, "Reaction of 1,3,4,5-tetramethylimidazole 2-ylidene with cyclopentadienyl cobalt carbonyl complexes : characterization of a novel dinuclear carbene adduct. " Master's Thesis, University of Tennessee, 1997.
https://trace.tennessee.edu/utk_gradthes/10677