Linear complex

Microwave studies in molecular beams are usually limited to studying the ground vibrational state of the complex. For complexes made up of two molecules (as opposed to atoms), the intennolecular vibrations are usually of relatively low amplitude (though there are some notable exceptions to this, such as the ammonia dimer). Under these circumstances, the methods of classical microwave spectroscopy can be used to detennine the stmcture of the complex. The principal quantities obtained from a microwave spectmm are the rotational constants of the complex, which are conventionally designated A, B and C in decreasing order of magnitude there is one rotational constant 5 for a linear complex, two constants (A and B or B and C) for a complex that is a symmetric top and tliree constants (A, B and C) for an... 

The solid readily dissolves chemically in concentrated hydrochloric acid, forming a complex, and in ammonia as the colourless, linear, complex cation [H3N -> Cu <- NHj] (cf AgCl) if air is absent (in the presence of air, this is oxidis to a blue ammino-copper(II) complex). This solution of ammoniacal copper(I) chloride is a good solvent or carbon monoxide, forming an addition compound CuCl. CO. H2O, and as such is used in gas analysis. On passing ethyne through the ammoniacal solution, a red-brown precipitate of hydrated copper(I) dicarbide (explosive when dry) is obtained ... 

Silver chloride is readily soluble in ammonia, the bromide less readily and the iodide only slightly, forming the complex cation [Ag(NH3)2]. These halides also dissolve in potassium cyanide, forming the linear complex anion [AglCN) ] and in sodium thiosulphate forming another complex anion, [Ag(S203)2] ... 

Like Ag, Au also readily forms linear 2-coordinate complexes such as [AuX2] (X = Cl, Br, I) " and also the technologically important [Au(CN)2] . But it is much more susceptible to oxidation and to disproportionation into Au and Au which renders all its binary compounds, except AuCN, unstable to water. It is also more clearly a class b or soft metal with a preference for the heavier donor atoms P, As and S. Stable, linear complexes are obtained when tertiary phosphines reduce Au in ethanol. 

In a linear complex, the coordination number is 2, corresponding to one group on each side of the central atom. The silver-ammonia complex, which generally forms when a very slightly soluble silver salt such as silver chloride dissolves in aqueous ammonia, is an example, as shown in Figure 22-6. Another example of a linear com-... 

Silver forms a linear complex ion with 2 neutral ammonia molecules as ligands. 

The cyclic carbene complex shown in equation 3.4 was studied by X-ray diffraction [66], it shows a linear complex (angle C—Au—C 178.6(4)°) and the gold aryl bond distance is 1.993(10) A which is in accordance with such bonds in other known pentafluorophenyl complexes. The gold carbene carbon distance is 1.961(9) A, the dihedral angle between the planes formed by the two organic ligands is 5.35° and the shortest intermolecular Au—Au distance is 3.95 A. 

Alkoxystilbazoles can react with a variety of silver salts, AgX, to yield the two-coordinate linear complexes (19). They show liquid crystalline behavior that strongly depends on the anion, the alkoxy chain length, and other substituents which may be present on the stilbazole.59-65... 

The activation energy for the charge reduction reaction is due to two factors the bond stretching and distortions of the originally near linear complex, so as to achieve the internal proton transfer and the increase of energy due to the Coulombic repulsion between the two charged products, a repulsion that leads to a release of kinetic energy on their separation. 

Likewise, it is easy to rationalize how Ag+ (a d10 ion) can form a linear complex with two ligands like NH,. 

Consider a linear complex with the two ligands lying on the z axis. Sketch the splitting pattern for the d orbitals that would result. 

In conclusion, Gdm complexes currently used as MRI contrast agents can be considered as safe drugs, due to their high thermodynamic stability, kinetic inertness as well as to an efficient excretion from the body. Nevertheless, in case of renal impairment, the stability issues become much more important and macrocyclic chelates, which have considerably higher kinetic inertness, should be used instead of linear complexes. We should... 

Such symmetrization (reduction of AT ) is evidently enhanced toward the interior of the linear complexes as CT increases, and becomes complete (AT = 0, D,lh symmetry) in the cyclic complexes, where CT delocalization is strongest. 

In this language, the cyclic (LiF) complexes are closed-CT structures (and thus maximally cooperative), whereas the corresponding linear complexes have reactive open-CT sites at both ends. As shown in Table 2.1, the energetic consequences of such open-CT versus closed-CT topology are considerable, with cyclic (LiF) complexes being stabilized, e.g., by more than 40kcalmol 1 for n = 3. Thus, a simple ion-dipole or dipole-dipole picture is clearly inadequate for chemical accuracy. 

OLIGO-2-PYRIDYLAMIDES AS BRIDGING LIGANDS IN POLYNULEAR LINEAR COMPLEXES... 

Complex 4b reacts with [M(CO)5(thf)] (M=Cr, W) to form initially complexes 12, which could be characterized by their NMR data, although a second substitution in the trans-position is preferred leading to the linear complexes 13a,b [17]. The driving force of the trans substitution was calculated via the corresponding isodesmic reaction and was found to be the formation of [M(C0)6] [17]. 

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