Triple bonds in nitrogen

Practical systems based on Eq. (66), but using Ni(COD)2/RNC mixtures, were reported. Catalysis via Ni(CNR)3 or Ni(CNR)2 intermediates could not be completely ruled out in these cluster systems. The nickel isonitrile and acetylene clusters did not effect hydrogenation of the triple bond in nitrogen (394). 

The correct answer is (D). The triple bond in nitrogen is the strongest and will cause the nitrogen atoms to be the closest together. 

C3H3N3 and also the tetrazines C2H2N4 are very stable compounds, pentazine CHN5 and hexazine N6, a polymer of nitrogen, do not exist. This is not due to the instability of these molecules as such but to the very special stability of the triple bond in nitrogen and in HCN, compared with the corresponding single and double bonds, while this holds to a much smaller extent for the triple carbon-carbon bond (Table 18). 

Figure 2.9 represents nitrogen s triple bond through orbital notation. Like the single bonds in hydrogen and halogen molecules, the triple bond in nitrogen molecules is nonpolar. 

The triple bond in nitrogen is much stronger than the double bond in oxygen, so it is much harder to break. This makes it less likely that the bond in nitrogen will be broken. 

Nitriles are susceptible to nucleophilic addition. In their hydrolysis, water adds to the carbon-nitrogen triple bond. In a series of proton-transfer steps, an anide is produced ... 

FIGURE 2.16 The bond dissociation energies, in kilojoules per mole of nitrogen, oxygen, and fluorine molecules. Note how the bonds weaken in the change from a triple bond in N, to a single bond in F,... 

Addition to R—" "N=C is not a matter of a species with an electron pair adding to one atom and a species without a pair adding to the other, as is addition to the other types of double and triple bonds in this chapter and Chapter 15. In these additions, the electrophile and the nucleophile both add to the carbon. No species add to the nitrogen, which, however, loses its positive charge by obtaining as an unshared pair one of the triple-bond pairs of electrons ... 

Hidai M, Mizobe Y (1999) Activation of the N-N Triple Bond in Molecular Nitrogen Toward its Chemical Transformation into Organo-Nitrogen Compounds. 3 227-241 Hirao T, see Moriuchi T (2006) 17 143-175... 

From work performed in 1983 by Burnier and Jorgensen [15], the following ab initio calculations for the HOMO and LUMO energies of the synthons were developed. The function n(x, parent) returns the number of atoms of type x in the parent. This function is abbreviated below as simply n(x) where the parent is understood. The symbols UU, O, N, S represent triple bonds, oxygen, nitrogen, and sulfer, respectively. The subscripts c and t denote central and terminal locations respectively in the parent for the elements which they modify. For brevity, the terms diene-synthon and dienophile-synthon will be replaced with diene and dienophile respectively. 

A novel complex, Mo[N( Bu) (Ar)]3 140, was prepared and shown to activate the triple bond in molecular nitrogen in a stoichiometric fashion. However, the complex, when used for alkyne metathesis, does not affect the expected transformation, but undergoes a vigorous endothermic process in a CH2CI2 solution. The resultant solution... 

An analogue of the above transformations is the ring closure depicted in 3.33., which involves the formal addition of the phenylpalladium complex formed in the opening step of the catalytic cycle onto the carbon-nitrogen triple bond. In the above process o-methylamino-benzonitrile is also formed as by-product in 38% yield, indicating the presence of competing pathways.41... 

The stable form of nitrogen at room temperature is N2, which has an extraordinarily strong (946 kJ mol-1) triple bond In contrast, white phosphorus consists of P4 molecules (see Chapter 16), and the thermodynamically stable form is black phosphorus, a polymer. At temperatures above 800 °C dissociation to P> molecules does take place, but these are considerably less stable than N2 with a bond energy of488 kJ mol 1. In this case. too. in the heavier element several single bonds arc more effective than the multiple bond. 

SAMPLE SOLUTION (a) The structure shown accounts for all the electrons in hydrogen cyanide. No unshared electron pairs are associated with carbon, and so the structure is determined by maximizing the separation between its single bond to hydrogen and the triple bond to nitrogen. Hydrogen cyanide is a linear molecule. ... 

---