Hydrazido complex

A general approach to rhenium hydrazido complexes is the reaction of oxo or chloro compounds with organohydrazines as has been demonstrated in an early report with the synthesis of [Re NNC(Ph)0 Cl2(PPh3)2] (310), " the molecular structure of which was solved in 1988. A detailed study on [Re(NNR)Cl2(PPh3)2] complexes with R = COPh or phthalazine shows that the course of subsequent reactions is governed both by the nature of the donor group R responsible for chelate closure and by the type of donor ligand introduced. No simple substitution chemistry has been observed for R = phthalazine. The benzoyl compound... 

Osmium(VI) hydrazido complexes can be generated by electrochemical oxidation of the corresponding osmium(V) hydrazido complexes (Section 5.6.5.3.1). The complex trans-[0s (tpy)(Cl)2(NN(CH2)40)] " (83) is able to oxidize benzyl alcohol to benzaldehyde. It also oxidizes PPhs to PPh30, and R2S to give R2SO the source of O atoms is presumably H2O in the solvent. 

Table 14 Summary of bond distances, angles, and stretching frequencies for osmium hydrazido complexes.

Eligh oxidation state hydrazido complexes have been proposed as key intermediates in biological... 

The bis[hydrazido(2-)] complex Mo(NNMePh)2(Me2dtc)2 reacts with one equivalent of HC1 to produce the cationic complex Mo(NNMePh)(NHNMePh)(Me2dtc) which contains one near-linear hydrazido(2-) and one hydrazido(l-) ligand bound to Mo through both N atoms.279 The side-on bound hydrazido(l-) ligand has Mo—N = 2.069(8) and 2.185(9) and N—N = 1.388(12) A. Other side-on bound hydrazido complexes are known.262... 

The chemical and structural relationships between hydrazine and hydrazido complexes and between hydroxylamine and hydroxylamido complexes have been recently reviewed.510... 

There is only one reported mononuclear hydrazido(2—) complex for the titanium group, [Ti(r/5-CjHj)2(NNSiMe3)2].498 Other hydrazido complexes are known but involve bridging hydrazido groups (see below). For reasons not yet fully understood, titanium is apparently reluctant to form four electron metal-nitrogen multiple bonds. 

Hydrazido(2 —) complexes are most prevalent within group VI although there are to date no reported hydrazido complexes of chromium. Representative examples of known structure are shown in Table 16. Sulfur coligands predominate reflecting the metal-sulfur coordination in nitrogenase and the participation of hydrazide ligands in dinitrogen chemistry. 

The reaction of cis- [PtCl2(PMexPh3 x)] (x = 1—3) with either dibenzoyl- or diacetyl-hydrazine in EtOH has yielded new hydrazido-complexes 150 1H n.m.r. and also unpublished X-ray data reveal the hydrazide to be in the enolized form (41). 

Hydrazido-complexes [WCl2(NNH2)(L)(PMe2Ph)2] (L = CO, C2H4) react with 2,4,6-trisubstituted pyrilium tetrafluoroborate salts to form (1 -pyr-idinio)imido-complexes 26 (L = CO, C2F14, R2 = R4 = R6 = Me L = CO, C2H4, R2 = R6 = COOEt, R4 = Ph) (96IC5118). 

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