1,2-Dimethoxy ethane ligand

Perhaps because of inadequate or non-existent back-bonding (p. 923), the only neutral, binary carbonyl so far reported is Ti(CO)g which has been produced by condensation of titanium metal vapour with CO in a matrix of inert gases at 10-15 K, and identified spectroscopically. By contrast, if MCI4 (M = Ti, Zr) in dimethoxy-ethane is reduced with potassium naphthalenide in the presence of a crown ether (to complex the K+) under an atmosphere of CO, [M(CO)g] salts are produced. These not only involve the metals in the exceptionally low formal oxidation state of —2 but are thermally stable up to 200 and 130°C respectively. However, the majority of their carbonyl compounds are stabilized by n-bonded ligands, usually cyclopentadienyl, as in [M(/j5-C5H5)2(CO)2] (Fig. 21.8). 

Another synthetic route involves ligand exchange between Sm(C6Fs)2 with cyclopenta-diene [19]. LnCp3 (Ln = Er, Yb) has been synthesized by the reaction of LnCL with TICp in tetrahydrofuran or dimethoxy ethane [20],... 

Tab, 5,3. Binding energies (in eV) of crown ethers and simple analogues (DME = dimethyl ether, DXE = dimethoxy ethane) to alkali metal ions. Each value refers to the binding energy of one ligand (e.g. 

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