Electron rare gases

The energy shift due to a rare gas atom at R due to the electron-rare gas interaction is given by... 

The various atoms in a compound have the tendency to give up, or take on, or share electrons in such a way as to be surrounded by a shell of eight electrons (rare gas configuration). When electrons are shared, they may be shared equally, as in Hg and unequally, as in NaCl, so that one has aU possible... 

Most metal cluster compounds are prepared by the oligomerization of coordinatively unsaturated species in which the central metal atom has less than the 18-electron rare gas configuration. In forming the metal cluster compound, the central metal atom attains coor-dinative saturation and, in most cases, acquires the... 

A diamagnetic mixed metal derivative (C5H5)3Ni2Co(CO)2, presumably obtained from 058500(00)2 and [0585810012, has been briefly mentioned (363) this compound can be formulated to give each metal atom the favored 18-electron rare gas configuration. 

All these structures 87-90, inclusive) give each of the four ruthenium atoms the favored 18-electron rare gas configuration. Since the primary question concerning the structures of the isomers of H2Ruij(CO)i3 and HitRui+(CO) 12 is the location of the hydrogen atoms, these structures will remain somewhat uncertain until neutron-diffraction studies become available. However,... 

Co, Rh, and Ir), in which each metal atom of the metal tetrahedron has the favored 18-electron rare gas... 

A possible open five-atom cliister is the square pyramid. A square pyramidal cluster of five iron atoms is found in the black carbide Fe5(CO)i5C, which is obtained in trace quantities (0.5% yield) as a minor by-product in the reaction of Fe3(CO)i2 with pentyne at 90°C (41). X-Ray crystallography on Fe5(CO)i5C indicates structure 109, with the five iron atoms at the vertices of a square pyramid whose edges range from 2.59 to 2.67 A. The isolated carbon atom in Fe5(CO)i5C (109) apparently holds open the square face of the square pyramid so that the system of five iron atoms does not collapse into a trigonal bipyramid. Each iron atom in Fe5(CO)i5C (109) has the favored 18-electron rare gas configuration if the isolated carbon atom is regarded as forming four coplanar bonds—a... 

Fig. 3. Typical electron-rare gas pseudopotential. Dotted line is Hartree-Fock results only. Total including polarization is the solid line. Depth of well increases for argon to xenon. The effective depth is very small for neon.

This is a very roundabout v/ay to derive the eight electron rare-gas rule. As v/e v ill see in Section 14.1 an extension of this offers a particularly simple v ray to view the so-called hypervalent molecules and electron counting in organometallic molecules in later chapters. 

The homonuclear rare gas pairs are of special interest as models for intennolecular forces, but they are quite difficult to study spectroscopically. They have no microwave or infrared spectmm. However, their vibration-rotation energy levels can be detennined from their electronic absorjDtion spectra, which he in the vacuum ultraviolet (VUV) region of the spectmm. In the most recent work, Hennan et al [24] have measured vibrational and rotational frequencies to great precision. In the case of Ar-Ar, the results have been incoriDorated into a multiproperty analysis by Aziz [25] to develop a highly accurate pair potential. 

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