The reduction of CO2 to formate using sodium borohydride was originally investigated in the 1950s. Despite this clue from the chemical literature, many recent publications describe catalytic CO2 hydroboration methods leading to formate or methoxide with more expensive and less reactive boranes such as pinacolborane. Herein we describe the uptake of 3 equiv of CO2 by NaBH4, along with full spectroscopic and crystallographic characterization of the resulting triformatoborohydride, Na­[HB­(OCHO)3]. Conducting the synthesis in acetonitrile under 300 psi of CO2 constitutes a new preparative procedure for generating Na­[HB­(OCHO)3]. This reaction does not require the presence of a strongly coordinating alkali metal cation, as evidenced by the analogous reactivity of [NEt4]­[BH4]. Even at 1 atm pressure and without using rigorously dry solvent, treatment of NaBH4 with CO2 and subsequent quenching gave formic acid (1.5 equiv based on B).

The stereoselective synthesis of a family of cis-macrocyclic diphosphines was achieved in only three steps from white phosphorus and commercial materials. These new ligands showed activity in the nickel-catalyzed coupling of CO2 and ethylene.

Herein we report the finding that molybdate absorbs not just one but two equivalents of CO2 (the second, reversibly) together with complete characterization including single-crystal X-ray diffraction studies of the resulting mono- and dicarbonate complexes.

Metaphosphate acids cannot be thoroughly studied in aqueous media because their acidity is leveled by the solvent, and the resulting metaphosphates are susceptible to acid-catalyzed hydrolysis. Exploration of metaphosphate acid chemistry has now been made possible with the development of a general synthetic method for organic media soluble metaphosphate acids. Protonation of the [PPN](+) salts ([PPN](+) = [N(PPh3)2](+)) of tri-, tetra-, and hexametaphosphates results in five new metaphosphate acids, [PPN]2[P3O9H] (2), [PPN]4[(P4O12)3H8] (3), [PPN]4[P6O18H2]·2H2O (4), [PPN]3[P6O18H3] (5), and [PPN]2[P6O18H2(H3O)2] (6), obtained in yields of 80, 71, 66, 88, and 76%, respectively. Additionally, our synthetic method can be extended to pyrophosphate to produce [PPN][P2O7H3] (7) in 77% yield. The structural configurations of these oxoacids are dictated by strong hydrogen bonds and the anticooperative effect. Intramolecular hydrogen bonds are observed in 2, 4, and 5 and the previously reported [PPN]2[P4O12H2] (1), while intermolecular hydrogen bonds are observed in 3, 6, and 7. The hydrogen bonds in 3-7 possess short distances and are classified as low-barrier hydrogen bonds. Gas-phase acidity computations reveal that the parent tri- and tetrametaphosphoric acids are superacids. Their remarkable acidity is attributable to the stabilization of their corresponding conjugate bases via intramolecular hydrogen bonding.