Group IVB Donors

Inorganic and organic ligands contain the following electron donor atoms from Groups IVB to VIIB of the Periodic Table ... 

Organolead-alkali compounds are the least stable of the group-IVB-alkali compounds. They are thermolabile and air and moisture sensitive but are stabilized in such donor solvents as Et O, tetrahydrofuran (THF) or NHj. Information on their isolation is sparse and no physical properties of pure R PbM (M = alkali metal) or R2PbM2 are available. Nevertheless, RjPbM in situ is a powerful tool for synthesizing unsymmetrical RjPbR tetraorganoleads ... 

Few metal-metal-bonded metal carbonyl complexes contain three-electron donor group IVB ligands. Dimers containing allyl ligands are known [e.g., (C3H5NiCl)2], but these do not contain metal-metal bonds. These are prepared in high yield M = Pd will... 

Ligand displacement reactions for [MX]+ and [MX2]+ ions may be used as a measure of ligand strength for a wide variety of donor molecules. The M-O bond in the [MO]+ ion varies from very strong for the groups 3 (IIIB), 4 (IVB), and 5 (VB) metals to weak in the later transition metals. 

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