Recent advances in crystalline hydrated borates with non-metal or transition-metal complex cations

Abstract

Structural aspects of crystalline hydrated polyborate salts containing polyborate anions partnered with either cationic transition-metal complexes or non-metal (organic) cations are documented. The structures are described in terms of Christ and Clark's and Burns' descriptors. The review, which concentrates on the period 2000-2015, also describes synthetic approaches (hydrothermal, solvothermal, flux methods) and physical and spectroscopic properties of the polyborate salts.

Crystal structure of pyridinium bis(naphthalane-2,3-diolato-κ2 O,O′)borate monohydrate, C25H20BNO5

“…The non-shared oxygen atoms will either bear a further negative charge (anhydrous borates) or will be protonated (hydrated borates). Hydrated borates are typically further hydrated by water molecules [8]. Most borates synthesized and studied to date have been prepared under the templating e ect of cations, such as alkali-metal, alkaline-earth metal, transition metal, main group metal, rare earth metal, and inorganic-organic hybrid borates.…”

Pentaborate(1-) Salts and a Tetraborate(2-) Salt Derived from C2- or C3-Linked Bis(alkylammonium) Dications: Synthesis, Characterization, and Structural (XRD) Studies

“…Synthetic strategies to prepare pentaborate(1-) salts partnered with organic cations include the reaction of a free base amine with B(OH) 3 in aqueous solution or use of OHactivated ion-exchange resins with quaternary ammonium halide salts [5]. Schubert and co-workers [19] have successfully applied the former method to α,ω-diaminoalkanes and have isolated a number of pentaborate(1-) salts containing a +2 diammonium cations of composition [H 3 N(CH 2 ) x NH 3 ][B 5 O 6 (OH) 4 ] 2 (x = 5, 6, [8][9][10][11][12].…”

“…Compounds 2, 3, 5 and 6 are previously unreported. Compound 1 has recently been prepared serendipitously in low yield (~10%) as a by-product from the reaction of a fluorinated borane CF 3 (CF 2 ) 5 [20]. Likewise, 4 has been previously obtained in very low yield (a few crystals) as a by-product of a reaction of B(OH) 3 with B 2 (NMe 2 ) 4 followed by crystallization from water [21].…”

“…Salts and neutral species containing polyoxidoborate (polyborate) anions occur as minerals and many synthetic derivatives have now also been prepared [1][2][3][4][5]. These compounds are structurally diverse, with the polyborate anions generally comprised of trigonal planar 3-coordinate and tetrahedral 4-coordinate boron centres, linked via oxygen bridges with as many terminal OH or O − groups as is necessary to complete the required geometry at boron [6][7][8][9][10][11].…”

“…These compounds are structurally diverse, with the polyborate anions generally comprised of trigonal planar 3-coordinate and tetrahedral 4-coordinate boron centres, linked via oxygen bridges with as many terminal OH or O − groups as is necessary to complete the required geometry at boron [6][7][8][9][10][11]. Some polyborate salts are sold as bulk chemicals for use in the glass/vitreous, fire retardant, and agricultural industries [12][13][14], whilst other synthetic polyborates have interesting and specialized physical e.g., semiconducting, luminescent, non-linear optical (NLO) properties [5,15]. We are interested in synthetic polyborate chemistry and recently have started to investigate non-metal cation stabilized silicate/borate solutions as potential…”