Dynamic and Static Stereochemistry in Dimolybdenum and Ditungsten Compounds Containing a Central (M Triple Bond M) +6 Unit.

The chemistry of molybdenum and tungsten in oxidation state 3 is now dominated by compounds containing a central M triple bond M 6 core, with metal-to-metal distances in the range of 2.2 to 2.3 A. The metal atoms may be bonded to three, four, five or six ligand atoms. Examples of each are given and for a given coordination number the preferred geometry is discussed. Low temperature nmr studies support the view that the structures found in the solid state are also present in solution. Variable temperature nmr studies reveal a wealth of knowledge concerning the dynamic behavior of those molecules in solution.