B. Chiswell

Synthesis and complexes of unsymmetrical multidentate ligands. Part III. Quadridentate ligands

The synthesis and characterization of some new highly unsymmetrical quadridentates and their metal complexes are reported. The ligands are obtained by the stepwise condensation of: (A) one molecule of phenylhydrazine with one molecule of glyoxal, followed by a molecule ofo-phenylenediamine, and then a molecule of salicylaldehyde in the presence of Ni(II) ion: (B) one molecule of o-aminobenzaldehyde with one of 2-pyridylhydrazine, followed by a molecule of salicylaldehyde; (C) one molecule of o-aminobenzaldehyde with one ofo-phenylenediamine, followed by one of salicylaldehyde in the presence of Ni(II) ions. Mass spectral analysis has been used to establish the existence of these highly unsymmetrical ligands.

The multidentate chemistry of manganese(II). V. Non-charged complexes of salen-type ligands and their reaction with oxygen

The preparation of a series of manganese(II) compounds of the type [Mn(ligand)] (where ligand = salen, or ethylene-chain substituted salen) is reported. The interaction of oxygen with pyridine solutions of these manganese(II) complexes has been studied in some detail, and it has been shown that in boiling pyridine such reaction yields complexes only of stoichiometry [Mn(ligand)OH] together with a small amount of MnO2. Detailed oxygen uptake measurements indicate that each Mn atom reacts with one O atom. In pyridine solutions at -15°C, oxygen uptake has been shown to be approx. 0.6 O atoms to each Mn atom, and although [Mn(ligand)OH] is again the major reaction product, a large proportion of the manganese in the reaction is obtained in an inseparable mixture which appears to contain more than one manganese complex. Oxygenation of the similar [MnII(ligand)] complexes (where ligand = N,N′-bis(salicylaldehyde)-o-phenylenediamine and N,N′-bis(salicylaldehyde)1,3-propanediimine) have been studied for comparison purposes. Magnetic data are given for all complexes. A comprehensive statement of results of previous workers in the field is given.

The multidentate chemistry of manganese(II). III. Complexes of linear quadridentate nitrogenous ligands

Linear quadridentate nitrogenous ligands have been shown to yield three different types of Manganese(II) compound. Simple octahedral compounds of formulation Mn(quad)X2*(where X = Cl, Br, ClO4 or BPh4) are obtained with most ligands. However, with sterically rigid ligands, compounds of the type [Mn(quad)2]X2 (X = ClO4 or BPh4, possibly 8-coordinate) can also be prepared, while on the other hand with less rigid ligands, bridged dimers of the type [Mn2(quad)3]X4 (X = ClO4 or BPh4) are also obtained.

The multidentate chemistry of manganese(II). II. Six and eight coordinate compounds with bidentate ligands

Abstract The existence of colourless, pure manganese(II) complexes containing four molecules of 1:10-phenanthroline (phen) per manganese atom has been substantiated, and some new compounds of this type prepared to extend the range of known compounds to the following: Mn(phen)4X2.nH2O (where X = a weakly or non-coordinating anion such as BPh4, I or 2-bromocamphor-π-sulphonate; n = 2, 4 or 6 depending upon X). A number of yellow compounds possessing three or two molecules of phen per manganese atom have also been prepared for comparison with tetrakis-phen compounds, as have also the colourless complexes M(phen)4(ClO4)2.nH2O (where M = Sr, Ba or Pb; n = 0, 4 or 5). Two other bidentate ligands with rigid chelate rings, viz. o-phenylenediamine and 8-aminoquinoline, have also been shown to yield 8-coordinate tetrakis-ligand manganese(II) perchlorate complexes, as well as octahedral compounds of the types [Mn(ligand)3](ClO4)2 and [Mn(ligand)2X2], (where X = Cl or Br). On the other band, bidentate nitrogenous ligand with more flexible chelate rings have been shown to yield tris- and bis-ligand octahedral complexes of the types [Mn(ligand)3](ClO4)2 and [Mn(ligand)2X2] (where X = Cl or Br).

Deprotonation of metal complexes derived from ligands containing pyrrole, pyrazole and indene residues

The synthesis of several new planar nitrogenous tridentate ligands, specially designed to present their donor atoms at positions very close to the normal octahedral sites of a metal atom, are described. Each of these ligand moieties, when complexed to a metal atom, also possess the potential ability to lose a proton from the periphery of the ligand molecue to yield deprotonated non-charged metal complexes. The lack of change in colour and magnetic moment of complexes of these ligands, upon undergoing such deprotonation reactions, is compared with the marked increase in colour intensity and decrease in magnetic moment when charged complexes containing a 2-pyridylhydrazine entity in the ligand residue undergo similar deprotonation reactions.

Metal complexes of some hybrid bidentate ligands containing tertiary arsine and primary amine donor groups. II. Compounds of nickel and copper

Some first transition series metal complexes of the three new tertiary arsine-primary amine bidentate ligands, o-dimethylarsinoaniline (MAA), o-diphenylarsinoaniline (PAA), and 1-amino-2-(diphenylarsino)ethane (APE), have been prepared, and their structures elucidated by physico-chemical studies. Octahedral high spin complexes of the type Ni(ligand)2X2 (where X = halogen, NCS or NO3) were obtained for all three ligands. Only in the case of the weakly coordinating perchlorate ion were low spin four-coordinate compounds of formula [Ni(ligand)2](ClO4)2 isolated. The products from the reactions of the ligands with copper(II) salts were (i) complexes of copper(II); (ii) complexes of copper(I); (iii) complexes of the corresponding arsine oxide with copper(II). In the case of MAA, examples of each of the three types of product were obtained. The complexes, [Cu(ligand)2](ClO4)2 (where ligand = MAA or PAA), which are stable as solids, apear to be the first known examples of complexes of tertiary arsines with copper(II).

Syntheses and complexes of unsymmetrical multidentate ligands. Part I. Bidentate glyoxalanil(1)-phenylhydrazone-(2) ligands

Abstract The synthesis of a series of new unsymmetrical bidentate ligands is described. they are obtained by stepwise condensation of the two carbonyl groups of glyoxal with firstly phenylhydrazine, and secondly a primary amine. The non-charged complexes of these ligands of the type [M(LH)2]° (where LH = deprotonated ligand residue) for M = Cu(II), Ni(II) and Co(II) have been isolated and studied. A series of copper compounds of formula CunligX((n+1)) (where n = 2, 3 or 4 and X = Cl or Br) have also been obtained, and are postulated as mixed Cu(I) and Cu(II) compounds.

The multidentate chemistry of Manganese(II).I. Hybrid tridentate ligand complexes

The complex compounds obtained from the interaction of manganese(II) salts and four new tridentate ligands, each possessing the donor set NNAs, and prepared by the Schiff-base condensation of σ-dimethyl or σ-diethylarsinoaniline, are described. Three types of complex were obtained: (i) [Mn ligand X2] (where X = Cl. Br, or I); ii, [Mn(ligand)2]Y2 (where Y = ClO4 or BPh4); (iii) Mn Ligand (NCS)2. Physical measurements have been used to demonstrate that in each case the ligands act as tridentates, and that type (i) complexes are five-coordinate, type (ii) complexes are octahedral, and type (iii) complexes are polymeric octahedral species. Attempts to obtain manganese(II) complexes of various other ligands with the donor sets NNAs and ONAs were unsuccessful.

The multidentate chemistry of manganese(II). Part VI. Tridentate Nitrogenous Ligands Complexes

A large number of manganese(II) complexes of formulation [Mn(ligand)X2] (where ligand = linear tridentate, quadridentate or quinquidentate nitrogenous ligand; X = Cl, Br, I or NCS) are described. The tridentate ligand compounds, in which X = Cl or NCS have been shown, in general, to be five coordinate on the basis of conductivity measurements, X-ray powder data and infrared spectral analysis; but in some cases the compounds may possess a polymeric octahedral structure. The quadridentate ligand compounds are octahedral, as are a series of complexes of formulation [Mn(NNN)2](ClO4)2.

The multidentate chemistry of manganese(II). IV. Non-charged complexes of linear quadridentate nitrogenous ligands and their reaction with oxygen

The preparation and properties of the non-charged manganese(II) compounds of formula [Mn(N4 ligand)], in which (N4ligand) is any one of twelve linear quadridentate nitrogeneous ligands derived from the interaction of α-diketones and 2-pyridylhydrazones, are described. The structures of the compounds have been elucidated by reference to similar nickel(II) compounds and to magnetic moment studies. The reaction of these compounds with oxygen in cold pyridine solution has been studied in detail and it has been shown that each manganese atom combines with approx. 1.3 oxygen atoms. Reaction rates have been measured in some cases. This odd manganese to oxygen ratio is explained by the isolation from the oxygenation reactions of four products: (i) MnO2; (ii) Mn(N4ligand)(py)OH; (iii) Mn(N4ligand)(py)O2); (iv) Mn(N4ligand)(pyO or Mn(N4ligand)(py)O12;