Conformational fluctuation in palladium(II)–methyl aldopentopyranoside complexes

Carbohydrate Chelation in Neutral Aqueous Solution: The threo‐Tetritolato‐Pd4 Butterfly Motif

“… [a] Signals may be interchanged. [b] 50 % free glycoside, 30 % of [Pd(en)(Me‐β‐ D ‐Ara p 3,4H −2 )], the major species of strongly alkaline solutions 12. [c] 10 % free glycoside, 60 % of [Pd(en)(Me‐α‐ D ‐Lyx p 2,3H −2 )], the major species of strongly alkaline solutions 12.…”

“…[b] 50 % free glycoside, 30 % of [Pd(en)(Me‐β‐ D ‐Ara p 3,4H −2 )], the major species of strongly alkaline solutions 12. [c] 10 % free glycoside, 60 % of [Pd(en)(Me‐α‐ D ‐Lyx p 2,3H −2 )], the major species of strongly alkaline solutions 12. [d] 20 % free glycoside, 25 % of [Pd(en)( neo ‐Ins2,3H −2 )], 20 % of [Pd(en)( neo ‐Ins3,4H −2 )] the major species of strongly alkaline solutions.…”

“…Specifically, the H3‐C3‐C4‐H4 unit of the [Pd 2 (en) 2 ( neo ‐Ins2,3,4H −3 )] + species, which is close to a diaxial arrangement (Scheme ; H3‐C3‐C4‐H4 torsion angle about 170° derived from a typical O3‐C3‐C4‐O4 torsion angle of 50°), showed a 3 J 3,4 coupling constant of 10.1 Hz. More data were provided by two monometallated xylopyranoside chelates of the general formula [Pd{( R , R )‐chxn}(Me‐β‐ D ‐Xyl p H −2 )]: 3 J 2,3 for the κ O 2,3 chelate: 9.3 Hz; 3 J 3,4 for the κ O 3,4 chelate: 9.1 Hz 12…”

“…for the kO 2,3 chelate: 9.3 Hz; 3 J 3,4 for the kO 3,4 chelate: 9.1 Hz. [12] To analyse the bonding situation in an open-chain m-triolato species, these reference values may be compared with the coupling constants of glycerol and its Pd II complexes. If, for example, the [Pd(en)(Glyc1,2H À2 )] species C in Scheme 3 were a rigid chelate, one of the two H-C1-C2-H angles should be, for the same reasons as cited above, about 1708 and, accordingly, one of the coupling constants should exceed the 9 Hz limit.…”

Metal‐binding Sites of N‐Acetylneuraminic Acid

“…By using 13 C NMR spectroscopy we were now able to identify the actual binding sites at NANA. To probe the metal‐binding sites, Pd II N 2 ‐type fragments (N 2 = bidentate nitrogen ligand) which we recently introduced as tools for the analysis of carbohydrates and carbohydrate derivatives in aqueous solution were employed in this work 11,12. For the investigation of the NANA binding sites, Pd‐tmen, an aqueous solution of [Pd(tmen)(OH) 2 ] (tmen = N , N , N ', N '‐tetramethylethane‐1, 2‐diamine), and Pd‐chxn, an aqueous solution of [Pd(chxn)(OH) 2 ] (chxn = (1 R ,2 R )‐cyclohexane‐1, 2‐diamine) were used.…”