Nuclear magnetic resonance study of the .beta.-cis-ethylenediamine-N,N'-diacetatocobalt(III) chelate system

Proton nuclear magnetic resonance studies of several polyaminocarboxylic acid complexes of vanadium(V)

“…The structures proposed for the [V02EDDA]_ chelates are illustrated in Figure 3. Isomerization of metal-EDDA complexes between the -cis and /3-cis conformations has been observed by Legg,et al,5,7,18 fot the [Com(L)EDDA] system, where L represents ethylenediamine, oxalate, malonate, and carbonate. The bidentate ligands, L, can complex only in the cis configuration and are analogous to the cis V02 oxygens in the present study.…”

“…where Ai and A2 are constants. Using the projected H-C-H geminal angle, , and the smaller vicinal angle, , the Karpins relations can be rewritten for the EDTA backbone pattern as /cc,BDTA = Ai cos2 ( + ) (4) Jcd'bdta = Ai cos2 (5) /dd'edta = Ai cos2 ( -) (6) Similarly, for the EDDA analog ( -cis isomer) /cc'BDDA = Ai cos2 (fc + ) (7) /cd-bdda = Ai cos2 (8) /dd'EDDA = Ai cos2 ( ß -o>d) (9) These relations have been used to calculate the values of , , , and , where the subscripts T and D refer to the backbone structures of the EDTA and EDDA complexes, respectively. The resulting values are , 52; , 95; , 50; andSn, 113°.…”

Zirconium(IV) and hafnium(IV) complexes of .alpha.-hydroxy carboxylates, lactates, mandelates, and isopropylmandelates. Stereospecificity in eight-coordinate complexes

“…The nature of the ligand conformations in such coordination number six species was first examined by Corey and Bailar4 567and refined by others. [5][6][7] Considerable thought8•9 has gone into the nature of the coordination polyhedra suitable for species of higher coordination number and the dimensional restraints of the ligand bite, but little attention Has been given to the stereospecific effects of ligands. It is of interest, therefore, to look for stereospecific effects of optically active ligands in potential coordination number eight complexes.…”

Crystal and molecular structure of .DELTA..DELTA..DELTA..LAMBDA.-cis, trans(N-O)-uns-cis-ethylenediamine-N,N'-diacetato((R)-1,2-diaminopropane)cobalt(III) chloride monohydrate. Effect of denticity on chelate ring strain

“…The needle axis was found to be parallel to b*. The unit cell dimensions were obtained by least squares refinement16 of 12 high-angle reflections centered on a Picker four-circle automated diffractometer using Mo Ka radiation ( 0.7107 Á) and are a = 9.260 (8) k,b = 7.255 (9) A,c= 12.253 (13) A, ß = 111.05(6)°. With Z = 2 and a molecular weight of 360.69 amu, the calculated density is 1.559 g cm™3 compared with a measured density of 1.56 g cm™3 obtained by flotation in a benzene-carbon tetrachloride mixture.…”