The azide ligand

The bond lengths for the azide MN3 fragment cover a wide range, as shown in Table 20, and are of a similar range to the organic azide fragments. The mean bond lengths are not 

Azide coordinated complexes, particularly copper complexes, have been extensively studied in recent years to try and understand the enormous variation of magnetic spin 

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The influence of boron-bonded ligands on the kinetics and mechanistic pathways of hydrolysis of amine boranes has been examined (37,38). The stoichiometry of trimetbyl amine azidoborane [61652-29-7] hydrolysis in acidic solution is given in equation 10. It is suggested that protonation occurs at the azide ligand enabling its departure as the relatively labile HN species. 

Coordinated azide ion will undergo a number of reactions which involve attack at the azide ligand. A number of examples are summarized in Scheme 9.1172-1175 The azide ligand is photochemically dissociated from bis azide complexes. Irradiation of Pt(CN)4(N3) gives Pt(CN)4 and the azide radical (equation 366),1176 whereas with Pt(N3)2(PPh3)2 the nitrogen-containing product is believed to be N6 (equation 367).1177... 

So far only terminal N-bonding of the azide ligand has been reported for Co azide com-plexes.218,273,280 In the case of the Rh azide compounds both terminal274,275 (see 97) and 1,1-/ bonding276 have been found. 

Ligand exchange reactions with nitrido molybdenum complex 56 has been documented (Eq. (19)). Treatment of 56 with 2 equiv. of HX (X = Cl or Br) leads to the formation of 57 which, following treatment with triethylamine, afforded 58, wherein a halide has been substituted for the azide ligand found in 56 [27]. The introduction of a nitride onto a Mov complex has been carried out by treatment of Mom or Mo ... 

Infrared spectroscopy and 13CO experiments show that in this reaction a five-coordinate nickel carbonyl complex with a v(CO) band at 2127 cm 1 forms as an intermediate. In this intermediate, the azide ligand, which had been inert in the [Ni(N3)(S3)] starting complex, evidently is labilized so much that it spontaneously dissociates N2 to form the NCO ligand of the final [Ni(NCO)-(83)] complex. Scheme 28 illustrates the suggested reaction mechanism. 

Coordinated azide ion will imdergo a number of reactions which involve attack at the azide ligand. A number of examples are summarized in Scheme The azide ligand is... 

A list of second-order contributions and corrections in the ab initio calculation of J is available. The spin polarization mechanism of exchange is different from the charge transfer mechanisms discussed so far and is perhaps best illustrated by the exchange between metals ions bridged by the azide ligand (Scheme 3). 

The azide ligand of a PMes complex reacts with isonitrile to form a complex with 67-coordinated tetrazolate rings (243-245, Equations (69) and (70)). " " Insertion of isonitrile into the Pt-N bond is followed by cyclization via intramolecular nucleophilic attack at the coordinated carbon atom. Since the tetrazolato ring is perpendicular to the square-planar coordination plane, the trans-complcx with two 5-alkyltetrazolate ligands exists as a mixture of isomers with the alkyl substituents in syn- and < //-orientations 244 and 245. 

Esr studies wth organic spin traps have shown that azide radicals (N3) are formed in the reaction of hydroxyl radicals with azide ions, and that the radicals N 3 and OCN are formed by persulfate oxidations of azide and cyanide. However, azide radicals could not be detected in the photochemical reductive cis elimination of cw-diazidobis(triphenylphosphine)platinum(II) to give Pt(PPh3)2, even though they have been observed in the esr spectra of the photolysis products of other azido complexes. It is suggested, therefore, that the azide ligands are cleaved off as Ne (hexaazabenzene). Calculations have shown that Ne is slightly stabilized and could therefore be stable at the low temperatures of these experiments. 

While the copper(II) complex is completely stable in the solid state and in solution, the palladium(II) compound decomposes slowly in dichloromethane solution to give the corresponding complex with an amine (-NH2) function in the position of the azide (-N3). The azide unit of the palladium complex is still capable of undergoing slow [2-i-3]-cycloaddition with EtOOC-C=C-COOEt to yield the corresponding triazole. However, it is not yet clear whether this is due to decoordination of the azide ligand in solution or whether it takes place at the 77 -coordinated ligand. 

The azide ligands in the complexes [M(N3)aL2] (M = Pd or Pt L = tertiary phosphine) can act as 1,3-dipoles and form a number of [2 + 3] cycloaddition products with organic nitriles, isocyanides, thiocyanates, isothiocyanates, carbon disulphide, and dimethyl acetylenedicarboxylate. Some of the reactions are summarized in Scheme 2. The rate of reaction of cis-[Pt(N3)2L2] with pam-substituted benzonitriles RCeHiCN increases in the... 

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