S- and P-donor ligands

S- and P-donor ligands. The complexes [(YPPh2 CH PPh2Y)2Fe] (Y = S or Se) are prepared by treating (Ph2PY)2CH with Bu Li, followed by addition of an Fe halogeno-complex anion. The complexes are both tetrahedral and the Se complex is the first example of tetrahedral co-ordination of Se to Fe .  

Mixed donor ligands. The complex [FeL3]Cl3 (L = acetylhydrazine) contains the ligand in its bidentate form, bonded via the carbonyl and primary amino-groups.Pyridine-2-carboxaldehyde and l,l,l-tris(aminoethyl)ethane react with Fe via a template reaction to form [Fejlpyljltame) ], in which three molecules of carboxaldehyde have condensed with one molecule of triamine to produce (pyljltame). MeC(CH2N=CH-oc-py)3 the complex cation is octahedral. The complexes [FeL ] (L = l,10-phenanthroline-2-carboxamide, n = 1 or 2) have been isolated they are both six-co-ordinate. Very weak d-d bands have been identified in the spectra of complexes of ot-picolinic acid and quinaldic acid with Fe .  

The five-co-ordin ite complexes [Fe(cdpp).X]X (.X = Cl or Br cdpp = 8-quinoldiphenylphosphine) have been prepared. 

The complexes [FeX2L2] (X = Cl or Br L = thioamide or urea) all have distorted tetrahedral geometry. The complexes of diacetylmonoxime selenosemicarbazone. [Fe (Hdseo)2] and [FeCl2(H2dseo)2], both have octa- 

Iron(ii) complexes of ethylenedithiodiacetic acid, diethylenetrithioacetic acid, and ethylenetetrathiotetra-acetic acid have all been reported. Isonitrile and other complexes. Refluxing [Fe(CNMe) ](HSOj2 hh excess methylamine for 12 h in methanol gives the cation [Fe(CNMe)gNH2Me] which can be precipitated as its PF salt. The structure of this cation has been determined by X-ray methods and is shown in (52). The location of the protons was confirmed by n.m.r. and the suggested mechanism of formation is as shown. 

Charalambous, M. J. Frazer, and R. Sims, Inorg. Chim. Acta, 1976,18, 247. 

3-NO2 and 5-NO2, 5-Cl and 5-Me complexes are low spin, the others showing a spin equilibrium. The planar quinquedentate ligand, 2,6-diacetylpyridine bis-(semi-carbazone) (DAPSC) forms the complex [FeCl2(DAPSC)]Cl,2H20 in which the 

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Until comparatively recently only vanadium had a significant coordination chemistry and even so the majority of its compounds are easily oxidized and must be prepared with air rigorously excluded. The usual methods are to use VCI3 as the starting material, or to reduce solutions of vanadium(V) or (IV) electrolytically. However, the reduction of pentahalides of Nb and Ta by Na amalgam or Mg, has facilitated the expansion of Nb " and Ta " chemistry particularly with S-and P-donor ligands. 

The coordination of heteroditopic T -donor ligands on (r7 -arene)-ruthenium and osmium entities has been extensively investigated in the last few years, especially when X= O, N. Less extensive studies involving P,As-, P,S, and P, < -donor ligands have also been performed and the corresponding results are summarized in Sections 6.14.4.3.1 and 6.14.4.4.3, respectively. 

Few quantitative data are available on the relative nucleophilicities of L toward various alkyl carbonyls. The rates of the reaction of CpMo(CO)3Me with L in toluene (Table II) decrease as a function of the latter reactant P( -Bu)3 > P( -OBu)j > PPhj > P(OPh)j, but the spread is relatively small (<8). The above order is that customarily observed for 8 2 reactions of low-valent transition metal complexes (J, 214). Interestingly, neither CpMo(CO)3Me nor CpFe(CO)2Me reacts with 1 or N, S, and As donor ligands 28, 79). This is in direct contrast to the insertion reactions of MeMn(CO)5 which manifest much less selectivity toward various L (see Section VI,B,C,D for details). 

This oxidation state is dominated by amine complexes, and a large variety of complexes with N, 0, S, and P donors. Complexes with N-heterocyclic ligands tend to be strong oxidants. Invariably, Os(III) complexes are low spin and octahedral (2, 5, 6). 

S-donor and P-donor ligands. Fe(S2CNR2)2 and the new complexes. [Fe(S2CNR2)3]... 

In the case of reaction (j), the cationic product is converted to M(CO)2( >-triars)X2 by recrystallization from hot methanol (M = Mo, only). Other examples of halogen addition exist for Mo and W carbonyl complexes that contain N-donor ,P-donor " S and As-donor ligands. 

A gold complex auranofin has been developed for the treatment of rheumatoid arthritis. This is a typical linear two-coordinate complex of gold , with soft S and P donors to match the soft metal ion (Figure 9.4). The bulky ligands here promote compatibility in the bio-environment, and activity is influenced by the substituents on the RS and R3P ligands. Gold complexes have also been examined for antimicrobial, antimalarial and anti HIV (human immunodeficiency virus) activity. A copper(II) complex (Figure 9.4) is effective as a competitive inhibitor of HIV-1. 

S- and Se-Donor Ligands. Molybdenum(vi) and tungsten(vi) thio- and seleno-halide complexes are described on p. 153. 

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