Sulfuranes. 22. Stereochemical course of an associative displacement at tetracoordinate sulfur(IV) in a sulfurane of known absolute configuration. A proposed system of nomenclature for optically active pentacoordinate species

Xanthine Dehydrogenase Active Site: Chiral Switching and Substrate Coordination

“…[50] So I resorted to the early works delineating an extension of the CIP rules [51,52] and the current rules for the structure and nomenclature of inorganic complexes, given in the so-called "Red Book 2005", [53] referred to as "Recommendations" in this text. Given the possible broader didactic benefits I present the procedure applied here in full detail, Step #1 through Step #6.…”

“…[51,52] Step #6: The preceding Mo-pterin coordination is that of the oxidized, reaction-ready Mo(VI) center in the active site of xanthine and aldehyde oxidoreductive enzymes, XDH, AOXA, XO, XOR. Following the metathetic exchange with substrate, Scheme 3, the Mo(VI)-center loses the O(H) ligand to the substrate to become a twoelectron-reduced Mo(IV) tetrahedral complex, [31,41] (a), or, as invoked in early mechanistic considerations and suggested by some x-ray structural studies [43] a 5-coordinated aquaMo(IV) complex (b):…”

Stereomutation of a diastereomeric pair of 10‐P‐5 hydroxyphosphoranes

“…Thus, for 4, the activation energy should correspond to the energy of the least stable state 10S* [16] of which severe ring strain and steric strain are present in addition to slightly unfavorable apicophilicity. Here, 7R* is slightly more stable than 10S* due to the presence of an additional electronegative CF 3 group attached to the tertiary carbon bonded to the apical oxygen atom.…”

Syntheses and Characterization of Novel trans‐Bis(phosphoranido)platinum(II) Complexes: Reactions of Lithium Bis(naphth‐1,8‐diyl‐8‐oxy)phosphoranide with cis‐PtCl2(PR3)2 (R = OPh, OMe, Me)

“…[8] The 31 P NMR spectrum of meso-6a, in which the relative stereochemistry at the two pentacoordinate phosphorus atoms is RS(SR), [13] is shown in Figure 3. Similar to the case of trans-5, the 1 J P,Pt value for the phosphoranide diminishes as the π-acidity of the phosphane ligand increases (Table 3).…”