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Calculation at density functional theory (DFT) levels helps determine the geometry parameters for zirconacycles produced from the stereoselective intramolecular diene cyclozirconation. Molecular mechanics calculations and semiempirical molecular orbital ZINDO calculations help predict the stereochemical outcome of these reactions. All three methods exactly predict the formation of stable trans isomer from 1,7-octadiene and N, N-diallylaniline. Theoretical study complements experimental approach in understanding the stereochemistry of intramolecular diene cyclozirconation.

Deuterated starting materials enable the synthesis of stable carbene perdeuterio-1,3,4, 5-tetramethylimidazol-2-ylidene. X-ray diffraction and neutral diffraction at 80 and 173 K enable the determination of electron distribution in these molecules. Experimental determination and density functional calculations show the molecule as a true carbene having negligible ylidic character.

Homochiral trialkanolamine ligands, present in early transition metal complexes, exhibit characteristic features of enantioselective catalysis. Trialkanolamines enable synthesis in enantiopure form and generate thermally- strong tetradentate complexes with early transition metals. Trialkanolamines form a highly-asymmetric environment near transition metals. The three similar O-C-H hydrogen atoms allow chirality initiation in the coordination sphere of the metal.

A tetrapeptide RGD-containing sequence, which was linked between the two semirigid linker ends, facilitated the preparation of a class of cyclic peptide antagonists of the glycoprotein IIb/IIIa adhesion molecule. These peptides, which included compounds that were highly active, exhibited certain features that influenced the peptide conformation. Such peptides, which bind to biological receptor molecules, may be useful to the pharmaceutical industry.

A newly developed class of chiral C2-symmetric bis(phospholane) ligands is used in rhodium catalyzed asymmetric hydrogenation reactions to establish a practical, one-pot process that uses enantioselective pure 1,4-diol cyclic sulfates in the synthesis of a homochiral series of 1,2-bis(phospholano)ethanes and 1,2-bis(phospholano)benzenes. Cationic rhodium complexes with these new ligands are very good catalyst precursors for the asymmetric hydrogenation of several alpha-(N-acylamino)acylate (enamide) substrates.

The synthesis through elimination reactions and the structural characterization of phosphato-bridged chlorotitanium, imidotitanium and oxotitanium compounds are presented. The imidotitanium compounds R'N-double bond-Ti(O2P)(OR)2 2 2, where R = tBu when R' = tBu, R = SiMe3 when R' = tBu and R = SiMe3 when R' = tert-amyl, are generated from Me2NSiMe3 elimination from OP(OSiMe3)(OR)2 and ((Me2N)2Ti(mu-NR'))2.

Crystallographic determination revealed that the compound (i-Pr 3 P)2(RhCl2) is monoclinic in the space group P2(sub 1)/c with a = 8.127(1) Angstrom (A), b = 8.953(2) A, c = 16.189(3) A, beta = 92.52(1) degrees, R = 0.020, R(sub w) = 0.020. (i-Pr 3 P)2(RhH2Cl) is triclinic in the space group P1 with a = 11.807(2) A, b = 14. 681(3) A, c = 14.743(3) A, alpha = 111.66(1) degrees, beta = 92.18(1) degrees, gamma = 93.29(1) degrees, R = 0.026, R(sub w) = 0.027, and (i-Pr 3 P)2(RhHCl2) is monoclinic in the space group P2(sub 1)/c with a = 8.092(1) A, b = 8.961(1) A, c = 16.27(3) A, beta = 92.56(1) degrees, R = 0.020, Rw = 0.026.

The structure of the ((t-Bu)3P)2Rh(CO)Cl complex was reinvestigated by usage of low-temperature, X-ray diffraction technique. Two crystalline forms obtained upon synthesis were each analyzed of their crystal system, space group and unit cell dimensions. The structures were subjected in different packing environments. A comparison of the two structures, solvated and unsolvated, showed that difference lies in the relative orientation in their two phosphine ligands.

Due to disorder, [K(crypt‐222)]+ CF 3 − (1) is crystallographically indistinguishable from its isomer, a 1:1 fluoroform clathrate of deprotonated [K(crypt‐222)]+, [K(crypt‐222{‐H+})]·CHF3 (2). In our preceding publications, 1 was characterized on the basis of combined X‐ray diffraction, NMR, reactivity, labeling, acid‐base, and DFT studies. Herein we report that neither incorporation of deuterium nor any other transformation of [K(crypt‐222)]+ is observed in the presence of CD3OD/CD3OK at 70 °C or CD3S(O)CD2K/(D6)DMSO at 23 °C over hours and even days. Since fluoroform is easily and quickly deprotonated under such conditions, the demonstrated greater acidity of CHF3 relative to [K(crypt‐222)]+ provides additional evidence in favor of 1 and against 2. Likewise, crystal packing analysis and DFT calculations support 1, which has now been refined in the ultimately correct space group R32. Our previously drawn conclusions regarding [K(crypt‐222)]+ CF 3 − and the existence of a ‘naked’ trifluoromethyl anion in a condensed phase remain valid. The recent alternative refinement (Becker and Müller, Chem. Eur. J. 2017, 23, 7081 – 7086) of our raw diffraction data has been improperly performed in the wrong space group to yield a non‐charge‐balanced model [K(crypt‐222)]+·CHF3, which is hereby repudiated. Becker and Müller's attempts to resolve the charge balance issue have produced models that are inadequate from the perspective of both crystallography and chemistry. [ABSTRACT FROM AUTHOR]

Due to disorder, [K(crypt‐222)]+ CF 3 − (1) is crystallographically indistinguishable from its isomer, a 1:1 fluoroform clathrate of deprotonated [K(crypt‐222)]+, [K(crypt‐222{‐H+})]·CHF3 (2). In our preceding publications, 1 was characterized on the basis of combined X‐ray diffraction, NMR, reactivity, labeling, acid‐base, and DFT studies. Herein we report that neither incorporation of deuterium nor any other transformation of [K(crypt‐222)]+ is observed in the presence of CD3OD/CD3OK at 70 °C or CD3S(O)CD2K/(D6)DMSO at 23 °C over hours and even days. Since fluoroform is easily and quickly deprotonated under such conditions, the demonstrated greater acidity of CHF3 relative to [K(crypt‐222)]+ provides additional evidence in favor of 1 and against 2. Likewise, crystal packing analysis and DFT calculations support 1, which has now been refined in the ultimately correct space group R32. Our previously drawn conclusions regarding [K(crypt‐222)]+ CF 3 − and the existence of a ‘naked’ trifluoromethyl anion in a condensed phase remain valid. The recent alternative refinement (Becker and Müller, Chem. Eur. J. 2017, 23, 7081 – 7086) of our raw diffraction data has been improperly performed in the wrong space group to yield a non‐charge‐balanced model [K(crypt‐222)]+·CHF3, which is hereby repudiated. Becker and Müller's attempts to resolve the charge balance issue have produced models that are inadequate from the perspective of both crystallography and chemistry. [ABSTRACT FROM AUTHOR]

A novel method of synthesizing single molecular cluster precursor species to vanadyl pyrophosphate and vanadyl phosphite was established through decomposition by pyrolysis. The design featured cluster synthetic and thermal chemistry that provide 'slosh and burn' pathway to maleic anhydride catalysts using vanadyl (IV) sulfate as starting material. Crystal structure analysis have demonstrated that the clusters tetra-anions were conserved with the same metrics.

The synthesis and characterization of the new diethyl phosphato compound (dipic)V(=O)O2P(OEt)2 , where dipic = pyridine-2,6-dicarboxylic acid, are presented. The scheme involves the removal of the alcohol from mixtures of diethyl hydrogen phosphate and the alkoxy compound (dipic)V(=O)(OiPr)(sub2).HOiPr. Structural analysis showed a dimeric structure in the solid state with each diethyl phosphato group bridging two vanadium centers.

The structural facets of the numerous water molecules which cocrystallize with the cyclic (D-valyl-(N2-methyl-L-arginyl)glycyl-L-aspartyl-3-(aminomethyl)-benzoic acid), are examined as part of an investigation of RGD peptides. These water molecules use the peptide structure as a template to assemble into a completely ordered, infinite hydrogen-bonded network. Energy hydrogen atom is refined at 193 kelvin.

The cation salt of the tetrafluoroaluminate anion was investigated because of the lack of evidence to support the existence of such a salt. The structure was determined to be a simple (AlF4-) anion associated with a (PSH+) cation. The anion is tetrahedral and 2-folded disordered around the Al-F(1) axis with average Al-F distances of 1.62 Angstrom and F-Al-F distance of 109 Angstrom. The closest contact between the coordinated fluoride and the chelated proton of the (PSH+) cation was 2.77 Angstrom, indicating that the anion exists with only van der Waals contacts to either cations or anions of the lattice.