Structure-Reactivity Studies in Copper(II)-Catalyzed Phosphodiester Hydrolysis

摘要: We have investigated the ability of a series three related copper complexes Cu([9-11]aneN(3))X(2) to hydrolyze activated phosphodiesters bis(4-nitrophenyl) phosphate (BNPP) and ethyl 4-nitrophenyl (ENPP). The compound Cu([10]aneN(3))Br(2) crystallizes in monoclinic space group C2/c, = 20.693(4) A, b 11.429(2) c 20.138(4) beta 104.78(3) degrees, V 4605(2) A(3), Z 16. Cu([11]aneN(3))Br(2) orthorhombic Pnma, 13.7621(10) 8.7492(13) 10.0073(10) 1205.0(2) 4. structure Cu([9]aneN(3))Cl(2) was previously reported (Inorg. Chem. 1980, 19, 1379). crystal structures show progression geometry from square pyramidal distorted trigonal bipyramidal as size macrocycle increases. Larger macrocycles also result ion being pulled closer plane defined by ligand nitrogens, which turn results an increase sum N-Cu-N angles 249 degrees 257 278 along with concomitant decrease X-Cu-X angle. Significantly, rate constant for hydrolysis BNPP increases nearly order magnitude nine-membered 11-membered ring. Correlations been made between catalytic structural electronic properties complexes. All catalysts exist monomer-dimer equilibrium solution, monomer catalytically active species. As increases, dimer formation (K(f)) decreases due steric constraint, thereby increasing concentration species hence hydrolysis. contributions Lewis acidity constraint on both substrate binding (K(2)) P-O bond cleavage (k(3) or k(cat)) are less important than dimerization determining reaction.