Dinitrogen electrophilic attack

Cyanides or nitriles, RC=N, have two regions for electrophilic attack, namely the triple bond TT-electrons and the lone pair on nitrogen. The two possibilities of attack are illustrated by the behaviour of cyanides with respect to transition metal ions. In their gas-phase studies on the interaction between cyanides and transition-metal ions Chen and Millerconcluded that both side-on and end-on interaction is present. In this respect cyanides resemble the isoelectronic dinitrogen. 

A close analogy also exists between the behaviour of dinitrogen, cyanides and isocyanides in their attachment to electron-rich d metal centres, e.g. Mo(0), W(0) and Re(I). This attachment activates the ligand for electrophilic attack. This activation plays a role in the reduction by nitrogenases. For cyanides the following type of reaction has been observed... 

This ligand polarization favors electrophilic attack on the terminal nitrogen atom. Reactions that activate dinitrogen are of interest as the basis for the fixation of nitrogen as ammonia. 

The susceptibility of coordinated dinitrogen to attack by electrophiles and radicals and their relationship to the electron-richness of dinitrogen complexes has been addressed in an important series of articles using E /2 and (N2) data. " " The successful attack of an electrophile or radical upon coordinated dinitrogen depends upon there being a certain degree of electron-richness. However, in many cases where alkylation or... 

Sceats EL, Figueroa JS, Cummins CC, Loening NM, Van der Wei P, Griffin RG. Complexes obtained by electrophilic attack on a dinitrogen-derived terminal molybdenum nitride electronic structure analysis by solid state CP/MAS NMR in combination with DPT calculations. Polyhedron. 2004 23 2751-2768. 

Cyclopentadienyl Carbonyl and Related Complexes.—Successive attack of CHs and CH3+ on [CpMn(CO)2(N2>] yields the azomethane complex [CpMn(CO>2 N-(Me)=NMe ], which can also be synthesized by oxidation of [CpMn(CO)2 MeN-(H)NHMe ]. Similar nucleophilic and electrophilic attacks on the dinitrogen complex using Ph and H+ gives [CpMn(CO)a N(Ph)=NH ]. The pyrrolyl nitrogen atom of [(> -C4H4N)Mn(CO)3] acts as a donor in the formation of the complexes [(OC)3Mn( -C4H4N)M(CO)2Cp] (M = Mn or Re).i The adducts RsP.CSa (R=Bu or Cy) have been assessed as reagents for the preparation of thiocarbonyl complexes. Unfortunately reactions such as [CpMn(CO)2(as-cyclo-octene)] with R3P,CSa lead mainly to [CpMn(CO)2(PR3)] with very low yields of [CpMn(CO)2(CS)].i ... 

Pell and Armor found entirely different products in alkaline solution. Above pH 8.3, the sole ruthenium product of the reaction of Ru(NH3)g+ with NO was the dinitrogen complex Ru(NH3)5(N2)2+. Under these conditions the rate law proved to be first-order in [Ru(NH3)g+], [NO] and [OH-]. A likely mechanism is the reversible reaction of Ru(NH3)3+ with OH- to give the intermediate Ru(NH3)5(NH2)2+, followed by electrophilic NO attack at the amide ligand and release of water. However, the kinetic evidence does not exclude other sequences. 

The ligand NNR has been referred to as alkyl- or arylazo, diazo, or diazenato, but diazenido is preferred. The aryl compounds are commonest they can be obtained from diazonium compounds (ArN2) and from hydrazines such as PhNNH2 or ArC(0)NNH. They are also formed by electrophilic or nucleophilic attacks on dinitrogen compounds, for example,... 

A classical example of a thermal method via radicals is the Meerwein arylation of alkenes, which is based on the copper-mediated reduction of aryldiazonium salts, causing dinitrogen loss and attack of the resulting phenyl radical onto an electrophilic alkene (see Sechon 13.4.1). The reachon can be also photochemicahy induced (path a. Scheme 14.1), for example through the photodecomposition of phenyl iodides. However, these compounds absorb only weakly in the near ultraviolet (UV) and the reachon is synthehcally less prachcal. 

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