Nitrido ligands

The conversion of coordinated NSCI into a nitrido ligand provides a useful synthesis of transition-metal nitrides. For example, treatment of ReCl4(NSCl)(POCl3) with triphenylphosphine generates the nitrido complex ReNClaCPPhsla. "... 

The binuclear complex [Mo2Cl2N2o] features a terminal nitrido ligand, N=, as well as terminal and bridging azido ligands, i.e. [ (MoCl(N)(t, -N,)2(/t,t -Nt)l2] Concatenations larger than N3 are rare. The planar bridging N4... 

Nitridotechnetium phthalocyanine (PcTcN) is prepared in a melt of phthalonitrile and ammonium pertechnetate (NH4Tc04). The axial nitrido ligand has its origins from the ammonium ion.250... 

TcvN]2+ complexes may be prepared by the reaction of TcO /ligand with NH2NH2 HC1 as the reducing agent and source of the nitrido ligand [2,3], Two... 

Crystallography has shown that the product of the reaction of [TcNBr4] With 2,2 -bipyridine in ethanol is cA-[TcvNBr(bpy )2] 2 [Ten Br4], This remarkable and unprecedented reaction involves loss of a nitrido ligand and reduction of TeVI to Tc11 under mild conditions to yield the previously unknown [TcBr4]2. With methanol as the solvent the product is [9]BPh4 [56,57],... 

Complex 10 is prepared by substitution of [TcNBr2(PPh3 )2]. The Tc-N bond length of the tertiary amine N atom coordinated trans to the nitrido ligand is 2.47(1) A and of the pyridine N atoms coordinated cis is 2.141 av. A. The thioether sulfur atom is not coordinated in the solid, but the H NMR spectrum shows that in solution there is an equilibrium between the dibromo form and one in which Br is expelled and the thioether sulfur is coordinated [62]. 

The ability of the nitrido ligand to stabilize the Tc(VI) oxidation state is apparent in the stability of the [TcN]3+ core to hydrolysis and disproportionation. This is in marked contrast to the [TcviO]4+ core, which is highly susceptible to oxidation and to disproportionation according to 3TcVI — TcIV + 2Tcvn and is not readily stabilized by coordination [4]. A characteristic feature is the formation of dimeric [NTcOTcN]4+ and [NTc(/i-0)2TcN]2+ complexes, which have no ana-... 

The structure of the bpy and phen complexes is also most probably pentagonal bipyramidal with the nitrido ligand in an axial position and the heterocyclic ligand spanning axial and equatorial positions [178]. In the IR spectra of the nitridoperoxo complexes v(TcN) occurs at 1069-1035, v(O-O) at 912-894 and vSym(Tc02) at 665-647 cm-1 [177]. 

The behavior of the nitrido ligand seems rather complex while the reaction of complex [Mo(=N)(CH2Me3)3] with silica leads to the well-defined species [( SiO) Mo(=NH)(=CHCMe3)(CH2CMe3)j [29, 30], protonation of the nitrido ligand is not observed in the case of [Mo(=N)(0- Bu)3] [31]. 

Nitrido complexes of Mn with porphyrin ligands were first prepared by Hill and Hollander and independantly by Buchler et al. in 1982 " . These are described in Section 5.1.7.1.1. Nitrido Mn complexes with Schiff base ligands were first reported in 1996. The nitrido ligand... 

The values for the corresponding chloro complexes are +0.21 V and +1.84V, respectively. It was concluded that these dramatic differences are a result of greater interaction of the nitrido ligand with the technetium center in comparison to the oxo ligand. This leads to stronger destabilization of the axial ligands for the nitrido species and hence to an increased susceptibility for an oxidation process. Thus, the oxidation is easier for [TcNCU]" than for [TcOC ], and even a... 

The formation of complexes with the [NTc(/u-0)2TcN] central structural unit has parallels in molybdenum chemistry, where isostructural complexes such as [ MoO(S2CNEt2) 2(M 0)2] are well established. In the MoO system, the differences for the 0x0 ligand compared to the nitrido ligand are again obvious, since the Mo sites about 0.73 A above the basal plane of the square pyramid, compared to 0.65 A in the technetium case. ... 

The [Tc=N] core is second only to the [Tc=0] core in its importance for the coordination chemistry of technetium in the context of radiopharmaceutical applications. The nitrido ligand N is isoelectronic with the 0x0 o ligand and with the imido R—ligand. The highly negative charge makes the nitrido ligand a very powerful rr-donor, well able to stabilize the... 

---