Reactions of CO 2 with tetrahydroborato copper(I) complexes in moist solvents: Synthesis and reactions of [(phen) 2Cu] [(HO) 3B(O 2CH)] and (phen)(Ph 3P)Cu(O 2COH) (phen = 1,10-phenanthroline)

Abstract

Carbon dioxide reacts with the tetrahydroborato copper(I) complex, (phen)(Ph 3P)Cu(BH 4) (phen = 1,10-phenanthroline) ( 1) in moist tetrahydrofuran and in the presence of free phen affording the ionic derivative [(phen) 2Cu] [(HO) 3B(O 2CH)] ( 3). The same complex 3 can be obtained from 1 and aqueous formic acid in the presence of phen; from the new tetrahydroborato copper( I) complex, (phen) 2Cu(BH 4) ( 2), and aqueous formic acid; and from 2 with CO 2 in moist tetrahydrofuran. The reaction of (phen)(Ph 3P)Cu(BH 4) ( 1) with CO 2 in moist methanol gives the bicarbonato derivative, (phen)(Ph 3P)Cu(O 2COH) ( 4). The action of alcohols, ROH, on 3 causes the formation of the ionic formato complex [(phen) 2Cu](O 2CH) ( 5), the boron atom being eliminated as the alkyl boric ester, (RO) 3B. Complex 3 reacts with an alcoholic triphenylphosphine solution giving the already reported covalent formato derivative, (phen)(Ph 3P)Cu(O 2CH). The reaction of 3 with PhCH 2Br gives the benzyl formic ester HCO 2CH 2Ph. The reactivity of 4 toward neutral ligands such as phen and CyNC has been investigated, the ionic bicarbonato derivatives, [(phen) 2Cu](HCO 3) ( 8) and [(phen)(CyNC) 2Cu](HCO 3) ( 9), being obtained respectively.