Alkoxides structure

Some characteristic features of the alkoxide structures can be identified for the monomers ... 

Priebsch, W. and D. Rehder. 1990. Oxovanadium alkoxides Structure, reactivity, and 51-V NMR characteristics. Crystal and molecular structures of VO(OCH2CH2Cl)3 and V0C12(THF)2H20. Inorg. Chem. 29 3013-3019. 

Fig. 33. Plots of the average terminal Ln-0(OR) distance for the different series of alkoxide structures ...

We showed that the four routes outlined below all led to one and the same crystalline compound, while route (d) proved the alkoxide structure of the magnesium derivative unambiguously (75). Hence the hypothesis of Grignard, not that of the German workers, is correct. 

The mixed valence dinuclear species U2(OBu )g was obtained from unstable K[U2(OBu )g]. The dimer crystallizes as a face-sharing bioctahedron Theoretical studies have been carried out to understand the lack of metal-metal bonding in these dinuclear uranium alkoxide structures. ... 

We also noted that the homoaldol diastereoselectivity was dependent npon the alkoxide structure (Table 20.4). Smaller alkoxide ligands yielded the homoaldol products 20 with higher diastereoselectivity. Thus, we were able to improve upon the diastereoselectivity simply by adjusting the alkoxide source used in the homologation and transmetallation steps. 

The transition state forms by a 1,4-dipolar addition to a polarized double bond. Coordination of the lithium atom to two oxygen atoms determines stereoregulation. Each new incoming monomer must approach from below the plane because the other side is blocked by an axial methyl group. This favors isotactic placement. There is doubt, however, whether it is correct to assume a rigid six-membered cyclic alkoxide structure for a propagating lithium enolate." ... 

The effects of lithium alkoxides on the rates of alkyllithium-initiation reactions depend on the solvent, the monomer, the alkoxide structure, the alkyllithium initiator, and the ratio of [RLi]/[LiOR l (49,50). For n-butyllithium initiation of styrene in cyclohexane, the rate of initiation is increased at low relative concentrations of added lithium alkoxide [ -C4H90Li]/[C4H9Li]< 0.5). At a ratio of 1/1, the rate is essentially the same as the control without alkoxide beyond this ratio, the rate decreases continuously with increasing relative concentration of lithium alkoxide. In aromatic solvents, the initiation rate decreases with increasing relative concentrations of lithium alkoxide. Lithium alkoxides generally accelerate the rate of initiation by alkyllithiums (n-butyllithium and sec-butyllithium) for isoprene in hexane. 

Alkoxide bridges are a characterisic feature of metal alkoxide structures and in principle are also affected by r-bonding supplementing the cr-bonds (4-IV-4-VII). 

Although some oxo alkoxides of technetium have been characterized there are no homoleptic alkoxide structures available. 

The first homoleptic Cu(i) alkoxide structure determined was the tetranuclear tert-butoxide [Cu4(/ti-OBu )4] which has a planar CU4O4 ring (Fig. 4.54) with linear two-coordinated copper rather than the cubane-like structure which might have been anticipated." Addition of PPhs produced the dimer [Cu2(ir-OBu )2(PPh3)2] with three-coordinated copper. The CU2P2O2 core is not coplanar owing to the dihedral... 

Although no oxo-alkoxide structures involving cobalt or nickel appear to have been reported there is an interesting octanuclear nickel antimony heterometallic compound [Ni5Sb3(/u.4-0)2(/u,3-OEt)3(/r-OEt)9(OEt)3(EtOH)4] in which the Ni(n) atoms are octa-hedraUy coordinated, one Sb is four-coordinated (lone pair in the vacant site of a... 

Priebsch W., Rehder D. Oxovanadium alkoxides structure, reactivity and vanadium-51 NMR characteristics. Crystal and molecular structures of tris(2-chloroethoxo)oxovanadium and aquadichlorooxobis(tetrahydrofuran) vanadium. Inorg. Chem. 1990 29 3013 Razuvaev GA., Drobotmko V.V. Synthesis and properties of alkoxy derivatives of vanadium R2V(0R )2, J. Organometal. Chem. 1977 131 43 Reuter H., Kremser M. Investigations into tin(IV) alkoxides 1. Crystal and molecular structure of tin(IV) isopropoxide-isopropanol solvate, Sn(0 Pr)4 PrOH. Z. Anorg. AUg. Chem. 1991 598 259... 

SEN (SrBi2Nb209) alkoxide structure, 54 crystals sublattices, 53 films orientation mechanism, 392 precursors molecular structure, 54 thin films, 53... 

Corresponding negative ion FABs do not provide any useful information as matrix interactions predominate obscuring all oAer peaks. Unfortunately, high resolution mass spectral analysis did not confirm the proposed structure. As shown in Table III, the exact mass analysis of the molecular ion peak corresponds to that of the disilicate structure with a potassium counterion, rather than the proposed protonated trimetallic double alkoxide structure. 

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