Absolute rate theory is combined with molecular models in the study of the annealing of metals and of glass. It is thus possible to obtain expressions which are in close agreement with experimental data. Both the observed first-order data for metals and the second-order data for glass are predicted in this way. A virtue of the rate theory treatment is that it replaces the earlier macroscopic theories with a treatment in molecular terms.

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An X-ray diffraction study of [(THF)(C2H3)GaFe(CO)4]2 (THF = tetrahydrofuran) reveals a dimeric, planar, four-membered, metal-metal-bonded ring structure analogous to the isoelectronic [(bpy)ZnFe(CO)4]2 and [(C2H5)2GeFe(CO)4]2 structures (bpy = 2,2'-bipyridine). Several distortions are observed in the structure that can be attributed to partial ionic character and the resultant bending of the axial carbonyl ligands over the metal ring. These distortions are intermediate in degree between those observed in the above-mentioned isoelectronic dimers and include a contraction of the M-Fe-M bond angle and a twisting of the idealized Fe(CO)4 tetrahedra to opposite sides of the centrosymmetric dimers. The distortions arise in order to help maintain Oax---Oax nonbonded contacts at no less than ca. 3.04 A. A number of comparisons have been made between the isoelectronic dimers. Other parameters of interest include Ga-Fe = 2.516 (3) Á, Ga-C = 2.069 (5) A, Ga-O = 2.129 (4) A, Fe-C(ax) = 1.775 (4) A, Fe-C(eq) = 1.788 (3) A, /Ga-Fe-Ga = 71.55 (4)°, ZFe-Ga-Fe = 108.45 (4)°, and zCax-Fe-Cax = 156.85 (21)°. The structure has been refined (Mo Ka radiation) to a conventional R index (on F) of 0.036 for 2650 unique reflections having I > 3

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