Nickel complexes azides

The complex azide is highly explosive and must be handled with extreme care. The analogous potassium and caesium derivatives of zinc azide and nickel azide deflagrate strongly in a flame and some are shock-sensitive [1], The potassium salt alone out of 8 azido-complexes exploded during X-irradiation in an ESCA study [2],... 

Narang, K. K. et al., Synth. React, lnorg. Met.-Org. Chem., 1996, 26(4), 573 The explosive properties of a series of 5 amminecobalt(III) azides were examined in detail. Compounds were hexaamminecobalt triazide, pentaammineazidocobalt diazide, cis- and fram-tetraamminediazidocobalt azide, triamminecobalt triazide [1], A variety of hydrazine complexed azides and chloroazides of divalent metals have been prepared. Those of iron, manganese and copper could not be isolated cobalt, nickel, cadmium and zinc gave products stable at room temperature but more or less explosive on heating [2],... 

Even nickel(II) chloride undergoes ionization, 68 nickel(II) azide undergoes autocomplex formation o Although four azide-units are coordinated at nickel(II) in the anionic azido complex the spectra suggest a hexacoordinated species apparently arising from additional solvent coordination at the apices of the octahedron. 

Maslak P, Sczepanski JJ, Parvez M. Complexation through nitrogen in copper and nickel complexes of substituted meas.J Am Chem Soc. 1991 213 1062-1063. Sczepanski JJ. Divalent metal ion promoted urea solvolysis model studies for Jack Bean Urease and Photochemistry of phosphoryl Azides potential Photoafinity Labels [Ph.D. dissertation]. Pennsylvania The Pennsylvania State University, State College 1994. 

Transition metal hydrazine perchlorate, nitrate, and azide complexes are explosive in nature, as indicated by DTA experiments and impact sensitivity measurements. Special precautions have to be taken during the synthesis and characterization of these materials. Small quantities of up to 1 g can be prepared without any explosion. Special mention should be made of the nickel hydrazine azide complex, which is prepared from NiCli + NaNa-I-2N2H4 H2O. The product is highly friction sensitive, especially in dry state, and so samples are to be handled with a Teflon spatula. A few milligrams are used for DTA and impact sensitivity tests. 

The NHCs have been used as ligands of different metal catalysts (i.e. copper, nickel, gold, cobalt, palladium, rhodium) in a wide range of cycloaddition reactions such as [4-1-2] (see Section 5.6), [3h-2], [2h-2h-2] and others. These NHC-metal catalysts have allowed reactions to occur at lower temperature and pressure. Furthermore, some NHC-TM catalysts even promote previously unknown reactions. One of the most popular reactions to generate 1,2,3-triazoles is the 1,3-dipolar Huisgen cycloaddition (reaction between azides and alkynes) [8]. Lately, this [3h-2] cycloaddition reaction has been aided by different [Cu(NHC)JX complexes [9]. The reactions between electron-rich, electron-poor and/or hindered alkynes 16 and azides 17 in the presence of low NHC-copper 18-20 loadings (in some cases even ppm amounts were used) afforded the 1,2,3-triazoles 21 regioselectively (Scheme 5.5 Table 5.2). 

A reaction known as diazo group transfer produces diazo barbituric acid from barbituric acid and p-toluene sulfonyl azide. Additional barbituric acid affords azo barbituric acid [7]. Subsequent complexation with a nickel (II) salt yields a greenish yellow pigment. 

The acceptor properties of Ni2 + are weaker than those of Co2 + and under analogous conditions the extent of complex formation is smaller. When sodium azide is added to a 10 3 molar nickel (II) perchlorate solution in excess, the only azide-complex is monoazidonickel (II). The monochloro complex is present only in strong hydrochloric acid 81L Due to the low solvating properties of DMA even tetrachloronickelate (II) is found in such solutions. 

To date, the tetraazadiene species RN=N—N=NR have not been isolated as free molecules, but they have been found coordinated to a metal centre when aryl azides are reacted with nickel(0) complexes (equations 42 and 43).213 21i... 

In the square pyramidal complex [Ni(Me4cyclam)N3](C104) (379) (Me4cyclam is 1,4,8,11-tetramethylT,4,8,ll-tetraazacyclotetradecane) the coordinated azide anion is on the same side of the four methyl groups with the nickel atom 33 pm from the N4 plane. The five- and six-membered chelate rings are in the usual gauche and chair conformations respectively.2681 This complex is labile in comparison with the very inert dinuclear complex... 

Nickel-azide complexes have been reported which contain the terminal-285,295 or the 1,3-ju-bonded2S6,29Sb form. The N-coordination in Ni(N3)(NO)(PPh3)2285 is as expected, but not the N(l)—N(2) distance (b) which is unrealistically short (0.98 A), most probably as a result of a contamination of Cl- in the crystal.285 In dimeric [BPh ENij tren CN ]286 the azide is 1,3-/ bridging (see 100). 

The formation of complexes of l,2,3,4-thiatriazole-5-thiol has been well described in CHEC-II(1996) 1,2,3,4-thiatriazole-5-thiol can form complexes with various metals such as palladium, nickel, platinum, cobalt, zinc, etc. <1996CHEC-II(4)691>. These complexes can be prepared either by cycloaddition reactions of carbon disulfide with metal complexes of azide anion (Equation 20) or directly from the sodium salt of l,2,3,4-thiatriazole-5-thiol with metal salts. For instance, the palladium-thiatriazole complex 179 can be obtained as shown in Equation (20) or it may be formed from palladium(ll) nitrate, triphenylphosphine, and sodium thiatriazolate-5-thiolate. It should be noted that complexes of azide ion react with carbon disulfide much faster than sodium azide itself. 

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. 

The first nickel tetrazadiene complex, Ni(C6FjNNNNC6F5XC8H,2), obtained from Ni(CgHj2)2 and pentafluorophenyl azide, reacts with... 

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