Complexes with Nitrogen Ligands

Crystallography has shown that the product of the reaction of [TcNBr4] with 2,2 -bipyridine in ethanol is cw-[TcvNBr(bpy)2] 2[TenBr4]. This remarkable and unprecedented reaction involves loss of a nitrido ligand and reduction of Tcvl to Tc11 under mild conditions to yield the previously unknown [TcBr4]2. With methanol as the solvent the product is [9JBP1U [56,57]. 

Other structurally characterized complexes are cw-[TcNCl(phen)2]PF6, in which the complex cation exhibits a pseudo two-fold symmetry axis that gives 

Complex 10 is prepared by substitution of [TcNBr2(PPh3)2]. The Tc-N bond length of the tertiary amine N atom coordinated trans to the nitrido ligand is 2.47(1) A and of the pyridine N atoms coordinated cis is 2.141 av. A. The thioether sulfur atom is not coordinated in the solid, but the H NMR spectrum shows that in solution there is an equilibrium between the dibromo form and one in which Br is expelled and the thioether sulfur is coordinated [62], 

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Coordination Compounds. Osmium in oxidation states from +2 to +8 forms a wide range of complexes with nitrogen ligands. Amine... 

Coordination Compounds. A large number of indium complexes with nitrogen ligands have been isolated, particularly where Ir is in the +3 oxidation state. Examples of ammine complexes include pr(NH3)3] " [24669-15-6], prCl(NH3)] " [29589-09-1], and / j -pr(03SCF3)2(en)2]" [90065-94-4], Compounds of A/-heterocychc ligands include trans- [xCX py)][ [24952-67-8], Pr(bipy)3] " [16788-86-6], and an unusual C-metalated bipyridine complex, Pr(bipy)2(C, N-bipy)] [87137-18-6]. Isolation of this latter complex produced some confusion regarding the chemical and physical properties of Pr(bipy)3]3+ (167). 

Mononuclear silver(I) complexes with nitrogen ligands can have several coordination numbers, the simplest is dicoordinated and compounds of the type [AgL2]+ occur for a variety of ligands... 

Finally, merely as a postscript, it is apparent that NMR techniques will become increasingly useful to study platinum complexes with nitrogen ligands.1222,1223... 

Like other transition metals, notably Ti, V, Nb, Ta, Mo, and W, chromium forms peroxo compounds in the higher oxidation states. Most of them are unstable, and in the solid state some of them are dangerously explosive or flammable in air. Bis(peroxo)chromium(IV) complexes with nitrogen ligands are remarkably stable, e.g., (17-C-XII).40... 

Dinitrogen, Phosphine, Phosphite, and Related Complexes Complexes with Nitrogen Ligands Nitrosyl and Thionitrosyl Complexes Technetium(II)... 

Platinum complexes with nitrogen ligands also exhibit easy C-H activa-tion to form five- or less common six-membered cyclometallation products [Eq. (6.70)] ... 

Again such complexes are more prevalent in palladium chemistry. Examples in platinum(Il) chemistry are found with azobenzene,A,A-dialkylbenzylamine, benzoquin-oline, 8-methylquinoline, acetophenone oxime and iV-alkyl-A-nitrosoanilines. Finally, merely as a postscript, it is apparent that NMR techniques will become increasingly useful to study platinum complexes with nitrogen ligands. 

C-C cross coupling catalyzed by palladium complexes with nitrogen ligands (a) van Asselt R, Elsevier CJ (1994) Organometallics 13 1972 (b) van AsseltR,Elsevier CJ (1994) Tetrahedron 50 323... 

It was mentioned earlier that EPR spectra may show fine structure due to interaction between the unpaired electron(s) and nuclei with non-zero spin. These nuclei may be those of the paramagnetic ion (for example, Mn, with spin and 100% natural abundance) or those of a ligand. EPR spectra of copper(II) complexes with nitrogen ligands show evidence for interactions of this sort and have been extensively studied—an example is shown in Fig. 

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