Coordination compounds hydrazide ligands

A slightly different situation is observed in coordination compounds formed by hydrazides of carbonic acids [112]. In this case, together with complexes 419 and 420 which are closely related to 417 and 418, the structure 421 is formed, which for the examined compounds has been found to behave as a monodentate N-donor ligand [112] ... 

The presence of two (or more) noninnocent ligands in a coordination compound requires a very careful analysis of the electronic situation (16,29.a). For instance, claims postulating a RuNO situation for [Ru(NO)L(PPh3)Cl], L = 1 -phenyl-1 -(pyridine-2-yl)-2-(pyridine-2-ylmethylene)hydrazide (45), may well be reformulated as a RuNO case with an oxidized L ligand. 

A rich coordination chemistry of aromatic diazine (N-N), especially pyridazine and phthalazine related ligands has emerged over the last three decades,1-72 and recently open-chain diazine (N-N) coordination chemistry has been well developed, especially by Thompson and others.62-113 Many types of aromatic heterocyclic compounds contain a 1,2-diazine (N-N) moiety, e.g., pyridazine and its 3,6-disubstituted derivatives (Scheme 1, Type 1), phthalazine, condensed phthalazines and their substituted derivatives (Scheme 1, Type 2), and other compounds such as pyrazole, triazole, thiadiazole, tetrazole, indazole, 1,2,4-triazine, 1,2,4,5-tetrazine, and thiadiazepines. Alternatively, the 1,2-diazine (N-N) moiety also exists as an open-chain entity in some related compounds, e.g., A-substituted-amide hydrazonimidates (Scheme 1, Type 3), A-substituted-amide hydrazonidates (Scheme 1, Type 4), A-substituted hydrazides (Scheme 1, Type 5), A-substituted amidrazones (Scheme 1, Type 6), and A-sub-stituted hydrazidates (Scheme 1, Type 7). 

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