Pentagonal-bipyramid geometry and cadmium-113 NMR chemical shifts: crystal structures and solution and solid-state cadmium-113 NMR of bis(.mu.-o-hydroxybenzoato)bis(o-hydroxybenzoato)tetraaquodicadmium(II) and tris(pyridine)bis(o-hydroxybenzoato)cadmium(II)

Abstract

Bis(~-o-hydroxybenzoato)bis(o-hydroxybenzoato)tetraaquodicadmium(II) (I) and tris(pyridine)bis(o-hydroxybenzoat0)-cadmium(I1) (11) have been shown by X-ray diffraction to consist of pentagonal-bipyramidal seven-coordinate Cd(I1). In the former, the coordination sphere is made up of five carboxyl oxygen atoms in the equatorial plane (one bridging) and two oxygen atoms of water molecules in the axial positions. The latter has four carboxyl oxygen atoms and one pyridine nitrogen atom in the equatorial plane and two axial pyridine nitrogen atoms to complete the coordination sphere. The solid-state MAS '%d NMR chemical shifts of these compounds are -31 and +61 ppm, respectively. The lI3Cd NMR chemical shifts of these and other Cd-containing compounds are correlated with the number of lone pairs that are directed toward the Cd atom. The shielded chemical shifts of a number of Cd model compounds as well as Cd-containing macromolecules are discussed. Crystal data (I): a = 7.747 (3) A, b = 12.455 (3) A, c = 15.725 (7) A, p = 96.23 (3)", 2 = 4, P2Ja, pohd = 1.83 (2) g/cm3, pcald = 1.86 g/cm3, N O = 5058, NV = 208, R , = 0.028. Crystal data (11): a = g/cm3, N O = 4944, NV = 428, RF = 0.029. For both I and 11, structures were refined by full-matrix least squares with anisotropic temperature factors and absorption corrections. 10.187 (4) A, b = 14.846 (5) A, C = 17.965 (5) A, p = 93.79 (3)", z = 4, P2l/ll, pobsd = 1.54 (2) g/Cm3, pcalcd = 1.53

The structures and solid-state and solution 113Cd NMR of diaquabis(p-chlorobenzoato)cadmium(II), [Cd(C7H4ClO2)2(H2O)2] (A), diaquabis(p-nitrobenzoato)cadmium(II), [Cd(C7H4NO4)2(H2O)2] (B), and aquabis(p-chlorobenzoato)bis(pyridine)cadmium(II), [Cd(C7H4ClO2)2(C5H5N)2(H2O)] (C)

“…In all three of these structures, as well as other Cd 2+ structures previously reported by us (Charles et al, 1983;Griffith et al, 1982;Turner, Charles & Amma, 1982) and others (Mostad & Rosenqvish, 1971;Flook, Freeman, Moore & Scudder, 1973;Boman, 1974;Harrison & Trotter, 1972), it is interesting to note that the carboxylate ligands tend to form the four-membered chelate rings with Cd, in contrast to the behavior of transition-metal carboxylates.…”

“…Ultimately we would like to utilize results from single-crystal static a~aCd NMR individual shielding tensor elements to calculate the MAS results and compare them with the experiment. Recently, we reported a summary of ll3Cd NMR solution, crosspolarization magic-angle spinning (CP/MAS) solidstate 1~3Cd NMR results found for models of the $2 site of concanovalin A, the EF site of parvalbumin, troponin C and calmodulin (Rodesiler & Amma, 1982;Charles, Griffith, Rodesiler & Amma, 1983). We wish to report here the details of the crystal structure analyses referred to herein as well as the details of the solution and solid-state ~aCd NMR.…”

“…However, both adducts were suitable for NMR data and were filtered and washed by gravity filtration. The ~3Cd solid-state NMR data with magicangle spinning and with cross polarization were obtained at the Regional NMR Center at Colorado State University on a Nicolet NT-200 spectrometer with parameters discussed elsewhere (Charles et al, 1983). The ~13Cd NMR solution data were observed on either a highly modified Varian XL-100 or on a Bruker WP-400 at the University of South Carolina Regional NMR Center.…”

“…This is in marked contrast to the ~13Cd NMR CP/MAS results of-31p.p.m. (shielded) for the PBP seven-coordinate Cd 2+ in bis-/t-(o-hydroxybenzoato)bis(o-hydroxybenzoato)Cd n, [Cd(H20)2(CO2-C6H4OH)2] 2, (D) (Charles et al, 1983), -52 p.p.m, for the seven-coordinate PBP Cd 2+ in Cd(succinato).H20 (Griffith et al, 1982) (E) and -58 p.p.m. (Mennitt et al, 1981;Rodesiler & Amma, 1982) (F) for the irregular seven-coordinate Cd 2+ in Cd(CH3COE)v2H20 (Post & Trotter, 1974).…”

Structure of bis(cyclopentadienyl)bis(pyridine)cadmium(II)

“…The Cd-N and Cd-C distances for the four coordinating atoms are 2.307 (5), 2.309 (3), 2.353 (5) and 2.360 (3) A for C(6), N(1), C(1) and N(2) respectively. Comparable Cd--N distances have been found in other pyridine-containing Cd complexes such as trans-diiodotetrakis(pyridine)cadmium(II) with Cd-N distances of 2.368 (6) and 2.454 (9)A (Ito, Shibata & Saito, 1984), in bis(o-hydroxybenzoate)tris(pyridine)-cadmium(II) with Cd-N distances in the range 2.350 (2)-2.372 (2) A (Charles, Griffith, Rodesiler & Amma, 1983) and in bis(nitrato)tris(pyridine)-cadmium(II) with Cd-N distances of 2.301 (9) and 2.35 (1)A (Cameron, Taylor & Nuttal, 1972). The deviation of the Cd atom from the least-squares planes through the N(1) and N(2) pyridine rings are 0.50 (1) and 0.119 (4) A respectively.…”