Diazene ligand complexes

The total electronic coordination energy of frans-diazene is —73.1 kJ/mol including the estimated total hydrogen bond energy of (—)20 kJ/mol for the mononuclear complex irons-2(N2H2) (see above). Thus, the stabilization of the unstable diazene ligand by hydrogen... 

Oxidation of the hydrazine complex formed by the reaction of (t] -C5H5)Mn(CO)2(THF) with hydrazine (Scheme 9.2) gives a dinitrogen complex (t -C5H5)Mn(CO)2(N2). Methylation of the N2 ligand with MeLi followed by treatment with methyl cation converts the N2 complex into a dimethyldiazene complex, from which the diazene ligand is released by applying N2 pressure (eq (3)) [10]. 

Neither 77 nor 79 could be converted to diazene complexes Cp2M=N—NH2 (M = Ti, V) by desilylation with ethereal hydrochloric acid because along with the Me3Si/H exchange, the diazene ligand is dislodged (49). The protolysis [Eq. (125)] takes place in 90% (Ti) and 75%... 

Insertion reactions of arenediazonium ions into metal-carbon bonds are rather rare. Legzdins et al. (1989) found the chromium complex 10.40 with a methyl-(aryl)diazene ligand in the reaction of [Cr(C5H5)(NO)2(CH3)] with 4-nitrobenzene-diazonium tetrafluoroborate. 

Insertion of mono- or bis(aryldiazonium) cations into the Re—bonds of the hydride complexes [ReH(CO)5 (PR3)J (PR3 = P(OEt)3, PPh(OEt)2, PPh2(OEt) =1 ) results in the formation of cationic aryldiazene complexes of the compositions [Re(HNNAr)(CO)5 (PR3) ]" or [ Re(CO)5 (PR3) 2(/r-HNNArNNH)] +. " Bifunctional diazene/diazonium derivatives which can be prepared in this way are excellent building blocks for heterobinuclear and heterotrinuclear compounds with bis(aryldiazene) bridging ligands as has been demonstrated for Re-Ru, Re-Os,... 

Diazadiphosphetidines nomenclature of, 14 3 synthesis of, 14 71 Diazaphosphetidinone, 14 85 1,6-Diazatriptycene, 33 1-2 Diazene, see also Diimide complexes, osmium, 37 260 ligand, 27 227-235 complexes, 27 230-235, 256-257 free state, 27 227-230 in preparation of dinitrogen complexes, 27 222, 232... 

R(H)N—N ], and diazenido (R—N=N ) [68, 71, 72] ligands have been isolated and characterized. Among them, the amido/imido complexes are related by a reduction step. Also, cleavage of the N=N bond of diazene or isodiazene/hydrazido(2—) ligands, to produce imido or amido derivatives, requires several Fl+/e transfer steps. 

Sometimes an ancillary ligand is also lost upon deprotonation. Dehydrohalogenation of neutral diazene complexes is generally more difficult but can be accomplished in some cases. The nature of the base is important (equation 127). 

Other Lewis acids including transiton metals also bind to N in these complexes.386 Hydride sources can attack diazenido ligands at N forming the expected diazene complex (equation 152). 

As in the case of (cis-diazene)Fe(C0)4 complexes the diazeno ligand disturbs the local symmetry (C4v) in L-M(CO)s and gives rise to four or five v(CO) bands instead of three. The low-energy absorption band of (benzo[c]cinnoline) M(CO)s (M=Cr, Mo, W) was assigned to an rt- -n transition5 ). However, in view of the assignments made for the spectra of LCr(CO)s compounds (L = amines, phosphines)52) this transition may be rather of "d-d" or CTML character. 

---