Diolato complexes

The reactions of olefins with non-organometallic Tc(VII) compounds behaved similarly. In a recent study, [Tc03C1(AaA)] (86a) (in which AA stands for aromatic diamine derivatives) was shown to react quantitatively with olefins, and produce the corresponding Tc(V) diolato-complex [TcOC1(OaO)(AaA)] (87a). The process could not be run catalytically, as Tc(V) complexes tend to undergo disproportionation rather than reoxidation in the presence of water [97]. These alkene-glycol interconversions could not be performed with the analog Re(VII) compound. Rhenium displays completely contrary behaviour, in that alkenes can... 

It is known that five-membered Cr(V) chelates are favored over six-membered ones.19,50,61 For Cr(V)-diolato complexes formed with linear diols, it was observed that all of the protons are equivalent in the isotropic EPR spectra,62 although the strain of a six-membered ring imparts inequivalence to the magnetic environment of the protons in the second coordination sphere.63 This observation at room temperature again points to rotational flexibility in the chelate ring (namely, puckering in the 8 or X configuration),20 similar to that observed for 1. 

While palladium(II) and copper(II) build solely 1,2-diolato complexes with erythritol which leads to five-membered chelate rings, boron(III) is involved in the six-membered rings as in the bis(phenylboronic acid ester) 13 (O Fig. 2). Erythritol adopts a zigzag conformation similar to that in 9 but the oxygen atoms are grouped alternatively on opposite sites of the C4-chain. The six-membered chelate rings in half-chair conformation provide a suitable bond pattern for a boron center involved in the delocalized jr-hond system of the phenyl suhstituent. 

Studies with palladium(II) revealed that in [Pd(en)(OH)2]/ribitol solutions with a molar ratio of 3 1 or 2 1 the dimetallated complex [Pd2(en)2(Ribtl,2 3,4H 4)] is formed as main species. The remaining terminal hydroxyl function is employed in an intramolecular S hydrogen bond to 02 causing the enhanced stability compared to the minor, bis(terminal) species [Pd2(en)2(Ribtl,2 4,5H 4)]. The monometallated terminal complex [Pd(en)(Ribtl,2H 2)] is the main species in equimolar solutions. The detection of the isomeric complex [Pd(en) (Ribt2,3H 2)] as a minor species gives reason to state that terminal chelation in erythro polyols is more favorable than a chelation with two adjacent secondary hydroxyl functions [19]. This is confirmed by the observation that (dppp)Pt " forms the terminal 1,2-diolato complex with ribitol with marked excess compared to the 2,3-erythro bound isomer (molar ratio 83 17, respectively) [22]. 

The reaction of cyrtidine 126 with [wrer-(dien)(NO)RuCl2]PF6 in an aqueous solution of a pH of 12.5 leads to two isomers of diolato complexes similar to those descrihed above with 118 while guanosine and uridine—both providing deprotonated amide functions under these conditions—are bonded to the mthenium center by their nucleobases [81]. 

The acyl product shows a carbonyl stretching vibration at 1490cm", suggestive of bonding. With an excess of carbon monoxide, the intermediate acyl reacts to the enedione diolato complex 1, characterized by X-ray diffraction methods. Thus, the Lu uses carbon-carbon coupling to mediate a tetramerization of carbon monoxide. 

The reactivity of the dialkyl complexes TiR2(LL)2 (LL = N,N -dimethylaminotroponiminato) has been widely studied. Reactions with CO and aldehydes or ketones afford unsymmetrical diolato complexes that convert to the corresponding vicinal diols after hydrolysis. CO and acetylene react to form the oxametallacyclopentene complex. Treatment with RNC yields the free imine and low-valent titanium species (Scheme 131). In the reaction with BucNC, free ButN=CMe2 is formed and the addition of benzaldehyde or benzyl reagents affords titanium diolato or enediolato complexes. Thiolato-alkoxo or amido-alkoxo titanium complexes can also be similarly prepared (Scheme 132).123-125... 

Hydrosilylation of unsaturated organic molecules is an attractive organic reaction. Asymmetric hydrosilylation of prochiral ketones or imines provides effective routes to optically active secondary alcohols or chiral amines (Scheme 756). These asymmetric processes can be catalyzed by titanium derivatives. The ( A ebthi difluoro titanium complex has been synthesized from the corresponding chloro compound.1659 This compound results in a very active system for the highly enantioselective hydrosilylation of acyclic and cyclic imines and asymmetric hydrosilylation reactions of ketones including aromatic ketones.1661,1666,1926-1929 An analogous l,l -binaphth-2,2 -diolato complex catalyzes the enantioselective hydrosilylation of ketones.1... 

Reductive cyclocondensation of alkane-1,2-dithiols or alkane-1-thio-l,2-diols with [Re(0)3(Tp )] and PPI13 has been investigated and [Re(0)(Tp )(SCH2CH2S)] has also been structurally characterized. The 1,2-diolato complexes are less thermally stable than the sulfur analogs, stable in hydrocarbon solvents for more than one week at 120°C. DFT calculations have been performed on selected derivatives.208... 

Cycloreversion of 4-methoxystyrene from [Re(0)(OCH2CHPhO)-(Tp )] has been investigated and it has been proposed that the reaction proceeds via a significantly asynchronous but concerted transition state. Computation modeling studies as also a Hammett study on cycloreversions of substituted styrene from a series of different [Re(0)(Tp )(diolato)] complexes have also been reported.214... 

C. Reactivity of Tris(benzene-l,2-diolato) Complexes of Silicon. 1271... 

Edwards D.A., Mahon M.F., Molloy K.C., Ogrodnik V. Silver(I) aryloxide-triphenylphosphine complexes. An assessment of their potential as CVD precursors and the structure of [Ag(OC6H4Me-2)(PPh3)3]-2-MeC6H40H.C6H5Me. Inorg. Chim. Acta 2003, 349 37 Edwards P.G., Jokela J., Lehtonen A., Sillanpaa R. Preparation and reactions of rhenium(VII) trioxo hydrogendiolato complexes and rhenium(VI) oxo bis(diolato) complexes. J. Chem. Soc., Dalton Trans. 1998 3287... 

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