Oximato-complexes

Methylglyoximate (MH) forms the complexes [Co(MH)2(tu)2]Cl, [Co-(MH)2(tu)X], and [Co(MH)2(tu)H20]X (X = halogen, tu = thiourea). In contrast to the corresponding dimethylglyoximato-complexes, both thiourea molecules in the bis-complex can be replaced by water. The complexes trans-[Co(Hdf)2L2]X (Hdf = a-benzildioximate L = cyclohexylcyanide X — CIO4, Cl, Br, NO3, or IO4) have been reported. Treatment of the perchlorate complex with strong base in methanol gives [Co(Hdf)(df)L2]H20.  

N- and S-bonded isomers of [Co(dmg)2(4-Bu -py)(thiocyanate)] undergo Co -catalysed equilibration in DMF or DMSO to approximately equal amounts. This is similar to the results obtained by Norbury et al. for [Co(dmg)2(CNS)py] (see Vol. 1, p. 18l). 

The Schiff base, HON=CMeCMe=N(CH2)2NH(CH2)2NH(CH2)2N= CMeCMe=NOH (L) reacts with Co salts to give [CoL]X (X = Br, I, or CIO Reaction of this complex with HBr or HCIO gives [Co(H2L)]Br3,3H20 and [Co(H2L)](C10J3, respectively. 

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Complexes involving oxime ligands display a variety of reactivity modes that lead to unusual types of chemical compounds. As far as the oxime chemistry of platinum is concerned, these complexes are involved in facile deprotonation of the OH group with formation of oximato complexes, reduction of Pt(IV) species, Pt(II)-assisted reactions with coordinated allene," alkylation by ketones, oxime-ligand-supported stabilization of Pt(III)—Pt(III) compounds, oxidative conversion into rare nitrosoalkane platinum(II) species, and coupling with organocyanamides. ... 

R CN (Table 2) [86]. The molecular structure of the 2,2-dimethylpropanonitrile derivative contains unsymmetrically bridging alkylidene amide ligands. Reaction of the yttrium and erbium hydride species with isonitrile results in the formation of a formidoyl moiety (Table 2) [87], Surprisingly the Ln-N interaction is in the range of the nitrile product A similar molecular structure was found in the oximato complex [Cp2Gd(/i-t/2-ONCMe2)]2 (Gd-Nav 2.42(1) A) [88]. 

A comparison of the activation parameters determined by two different methods is indicative of their satisfactory agreement. For example, the values of the free activation energy (AG ) are virtually the same within the deviations found. This is not surprising, however, since is slightly affected by the systematic errors in contrastto AS and A/7 [16, p. 108]. Analysis of our data shows that both methods ( F DNMR and DNMR) lead to comparable results and can be used independently of one another when studying the dynamic behavior of fluoro oximato complexes. 

An analysis of the experimental values of the activation parameters of isomerization of the oximato complexes (Table 3.5) indicates that the barrier to the hindered rotation of the ligand in the compound containing the oximato ion in anti conformation is higher than this barrier in the complex with syn conformation. 

To draw a conclusion about the isomerization mechanism of the oximato complexes, one should consider the problem of the effect of the ligand coordination mode in a transition state on the and ls.S values. 

Therefore, the isomerization of the oximato complexes of d transition metals proceeds via an internal rotation of the ni -coordinated ligand with bond cleavage and following formation of the metal-nitrogen bond. In the transition state, an open-structure complex is formed [46, 57] ... 

This conclusion is supported by the fact that the entropy of activation of all studied molybdenum and tungsten oximato complexes is positive (Table 3.5). 

The macrocyclic bis(oximato)borates 130-131 and its tetramethylene analogue 132 are derivatives of the bisborylated dioxime complexes discussed above, in which one of the OBR2O groups has been substituted by a trimethylene or tetramethylene unit, respectively (Fig. 35). 

Tetramminenickel(n) nitrite reacts with acetylacetone in refluxing ethanol to form (4-iminopentane-2,4-dione 3-oximato)(4-aminopent-3-en-2-onato)nickel(n). XH n.m.r. spectra of this and several related complexes confirmed the composition and structure (124), with a five-membered chelate ring of the 4R-iminopentane-2,4-dione 3-oximato... 

The reaction of Cp3Ln (Ln = Dy, Yb) with alcohols, ROH in THF produces dimers [Cp2Ln(/r-OR)]2 with symmetrical alkoxide bridges [90] (A) while with acetoxime dimeric complexes of the type [Cp2Ln()U- 2-ONCMe)]2 (Ln = Pr, Gd, Dy, Yb) are obtained. In the latter complex we have Gd-O-N-Gd(B) bonding (oximato bridge) [91]. 

Costes, J.P., Dahan, F., Dupuis, A., and Larrrent, J.P. (2000) Is ferromagnetism an intrinsic property of the Cu"/Gd " couple 1. Structures and magnetic properties of two novel dinuclear complexes with a p-phenolato-p,-oximato (Cu,Gd) core. Inorganic Chemistry, 39, 169-173. 

The hydrolysis of adenosine 5 -triphosphate (ATP) in the presence of various cobalt(III) complexes has been studied. Complexes such as [Co(en)3] which have no available sites for coordination of the substrate display no catalytic activity. Complexes having one site or two sites in a trans configuration such as tetraethylenepentaminecobalt(III) or bis(dimethylgly-oximato)cobalt III) slightly enhance ATP hydrolysis. However, complexes with two available sites in a cis configuration such as cis-a- or crs-jS-Co(trien) exhibit considerable activity. Both the reactions ATP+HjO- ADP+Pj and ATP+H20- AMP+PPi occur with these systems. The complex [Co(dien)] effectively enhances the hydrolysis of ATP to ADP+Pj. At pH 4.0 the uncatalyzed hydrolysis rate constant for ATP hydrolysis is 1.18xl0 s at 50 °C. For ATP UxlO M) and [Co (dien)] "" (2xlO M) at pH 4.0, = 1.75X 10 at 50°C, a rate... 

Since the publication of Comprehensive Coordination Chemistry CCC (1987), many publications on oxime complexes have appeared, namely in areas of general inorganic and coordination chemistries1-8 and unconventional methods for their synthesis have been reviewed.8 Oxime and oximato species can bind a metal in different coordination modes (see Scheme 1) and exhibit versatile reactivity. Their reactions, for a systematic purpose, can be classified according to the extent of involvement of the C=NO moiety and to the bond at which the reaction is centered, as shown below. 

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