NITRILOTRIPROPIONIC ACID (NTP) AND OTHER POLYAMINO CARBOXYLIC-ACIDS AS SEQUESTERING AGENTS FOR BERYLLIUM(II) - X-RAY CRYSTAL-STRUCTURE OF SODIUM (NITRILOTRIPROPIONATO)BERYLLATE(II) TRIHYDRATE, NA[BE(NTP)]CENTER-DOT-3H(2)O

Potentiometric studies in aqueous solution at 25 degrees C and ionic s trength 0.5 mol dm(-3) in NaClO4 show that beryllium(II) with differen t polyamino carboxylic acids forms the following complexes: EDTA (ethy lenediaminetetraacetic), -PDTA(1,2-propylenediamine-N,N,N',N'-tetraace tic), and CDTA rans-1,2-cyclohexanediamine-N,N,N',N'-tetraacetic) (lig ands, H(4)L), [BeHL](-), [BeL](2-), and [Be-3(OH)(3)(HL)]; EDDADP (eth ylenediamine-N,N'-diacetic-N,N'-dipropionic) and EDTP (ethylenediamine -N,N,N',N'-tetrapropionic) (ligands, H(4)L), [BeH(2)L], [BeHL](-), [Be L](2-), and [Be-3(OH)(3)(HL)]; o-PhDTA o-phenylenediamine-N,N,N',N'-te traacetic),3,4-TDTA (3,4-toluenediamine-N,N,N',N'-tetraacetic) and 4-C l-o-PhDTA 4-chloro-o-phenylenediamine-N,N,N',N'-tetraacetic) (ligands, H(4)L), [BeHL](-) and [BeL](2-); NTA (nitrilotriacetic) (ligand H(3)L ), [BeL](-) and [Be-3(OH)(3)(HL)](+); NDAP (nitrilodiaceticpropionic) (ligand H(3)L), [BeH(2)L](+), [BeHL], [BeL](-), [Be-3(OH)(3)(HL)](+), and [Be-3(OH)(3)L]; NADP (nitriloaceticdipropionic) (ligand, H(3)L), [ BeHL] and [BeL](-); NTP (nitrilotripropionic) (ligand, H(3)L), [BeL](- ). The following complexes are formed analogously for magnesium(II): o -PhDTA, 3,4-TDTA, and 4-Cl-o-PhDTA, [MgHL](-) and [MgL](2-); NADP and NTP, [MgHL] and [MgL](-). The stability constants were determined. Fro m an aqueous solution of Be(OH)(2) and NTP (ratio 1:1), boiled until t he Be(OH)(2) was completely dissolved, crystals of the complex sodium (nitrilotripropionato)beryllate(II) trihydrate, Na[Be(NC9H12O6)]. 3H(2 )O were obtained. X-ray diffraction structural analysis revealed that, in the chelate complex [Be(NTP)](-) (hexagonal), P6(3), a = 11.4768(7 ) Angstrom, b = 11.4768(7) Angstrom, c = 6.2807(3) Angstrom, V = 716.4 4(7) Angstrom(3), Z = 2, R1 = 0.0433, wR2 = 0.1110), the tetrahedron B eNO3 is almost regular with a very slight distortion toward the symmet ry C-3v, H-1, C-13, Be-9 NMR, IR spectra, and thermal analyses are stu died. The selective uptake of beryllium(II), a very toxic cation, was analyzed by means of the chemical speciation diagrams as well as the s o-called conditional or effective formation constants K-BeL(eff). With respect to H+, the order 3,4-TDTA greater than or equal to o-PhDTA > 4-Cl-o-PhDTA greater than or equal to NADP greater than or equal to NT P much greater than> NDAP > EDTA > EDTP > EDDADP is found for K-BeL(ef f). This result indicates that, in competition with H+, o-PhDTA, 3,4-T DTA, 4-Cl-o-PhDTA, NADP, and NTP are good sequestering agents at pH 4. 5-6 for beryllium(II), and analogously to o-PhDTA, these ligands can p otentially be used for the analytical determination of beryllium(II). In the presence of Mg(2+)and H+ (Be2+ inhibits numerous enzymes that c ompete with Mg2+), the order NTP approximate to NADP much greater than o-PhDTA approximate to 3,4-TDTA > 4-Cl-o-PhDTA is found. In the prese nce of Mg2+, at pH 4-6, NTP and NADP practically only sequester Be2+! The advantages of NTP and NADP acids to sequester specifically berylli um(II) are evident. H-1, C-13, and Be-9 NMR studies confirm the potent iometric studies.