Structure pyramidalization, ethyl

Figure 4.11 Molecular structures of typical crown-ether complexes with alkali metal cations (a) sodium-water-benzo-I5-crown-5 showing pentagonal-pyramidal coordination of Na by 6 oxygen atoms (b) 18-crown-6-potassium-ethyl acetoacetate enolate showing unsymmelrical coordination of K by 8 oxygen atoms and (c) the RbNCS ion pair coordinated by dibenzo-I8-crown-6 to give seven-fold coordination about Rb.

Methyl pyruvate thiosemicarbazone in the presence of zinc chloride or acetate resulted in the formation of complexes with the ligand hydrolyzed or transesterified. The complexes with pyruvate thiosemicarbazone, ZnL2, or ethyl pyruvate thiosemicarbazone, ZnLCl2 were structurally characterized by single-crystal X-ray crystallography showing respectively a distorted octahedral and distorted square pyramidal geometry.874... 

The amino acid complexes [TcNCl(L)(PPh3)] (HL=L-cysteine, L-cysteine ethyl ester, cysteamine) have been prepared from [TcNC PPlfj ] or ASPI14 [TcNCU]/PPh3 [88]. The crystal structure of the L-cysteine ethyl ester complex 21 shows a Tc=N bond length of 1.605(3) A and the Tc atom displaced by 0.594(1) A above the square basal plane [88]. Other structurally characterized examples are the square pyramidal 22 with ONSP coordination and Tc=N 1.611(3) A [81], and 23 with NSPC1 coordination and Tc=N 1.615(7) A [89],... 

Reaction of a methanolic solution of copper(II) acetate and enantiomerically pure (/ )/(S)-methyl( )-4ethyl-2-oxazolidinylidene)cyanoacetate 64 leads to the coordinatively unsaturated CVsymmetric intermediates (R,Rj-65 and (S,S)-65, which are sterically shielded at one side by two ethyl groups. Therefore, in contrast to the 2D- and 3D-coordination polymers, coordination of (R,R)/(S,S)-65 with only one cyano donor is possible, resulting in the formation of polymers (/>)-oc1[Cu(Li )2] (P-66) and (M)-J[Cu(L5)2] (M)-66) (Scheme 24) ([166, 169, 170] for other chiral lD-coordination polymers of our group, see [171, 172]). The X-ray crystal structure analysis of polymer (P)-66 clearly proves a well-ordered infinite onedimensional architecture. The central copper atoms in (P)- [Cu(L )2] CP-66) are almost tetragonal-pyramidally coordinated, and in contrast to the 2D- and... 

Fig. 12 Schematic drawing of the square pyramidal structure of the cardiac imaging agent 99mTcN- (N-ethoxy, N-ethyl)dithiocarbamato comprising two identical bidentate ligands coordinated to the same metal center...

Sulfoxides possess a non-planar pyramidal configuration consequently, chiral sulfoxides can exist as optical enantiomers (see Chapter 5, p. 63). This is illustrated by the structures (33a) and (33b) showing the optical isomers of ethyl methyl sulfoxide (Figure 2). 

Hogeveen, Heldeweg, and coworkers also prepared the ethyl and isopropyl derivatives of these pyramidal dications (235a-235d) and their bridged structures have been conhrmed by II and NMR spectra and quenching studies ... 

Imidazole and Related Donors. Structural models for the co-ordination geometries of a Cu-Cu" redox couple in copper enzymes suggest a mechanism for where both electrons and protons are involved a model has been characterized bis(imidazole) copper(ii) diacetate (102). Dark green crystals of [Cu(caffeine)Cl2,H20] in which copper is tetragonal pyramidal distorted towards trigonal bipyramidal have been characterized Cu—Ni = 1.98 A,Cu—0(H20) = 1.96 A, Cu—Cl = 2.32,2.25 A. Dinitrato-2,6-bis-[l-(phenylimino)ethyl]pyridinecopper(ii) (103) contains a planar... 

Another neutral diaminodithiolate complex, which showed high pulmonary accumulation in rodents, was synthesized by reduction of TCO4 with S2O4 in a basic medium in the presence of 4-N-ethyl-2,9-dimethyl-4,7-diaza-2,9-decanedithiol dihydrochloride. X-ray structure analysis of the pale-brown needle-shaped crystals confirm a distorted square pyramidal arrangement around Tc(V). ITie ethyl substituent... 

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