An efficient approach to the ammoxidation of alcohols to nitriles and the aerobic oxidation of alcohols to aldehydes in water using Cu( ii )/pypzacac complexes as catalysts

Reactions of 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetic acid (pypzacacH) ligand with Cu(OAc) sub(2), Cu(NO sub(3)) sub(2), CuSO sub(4), Cu(ClO sub(4)) sub(2) or CuCl sub(2) produced four dinuclear Cu(ii) complexes [{(MeOH)Cu(OAc)}( mu - Kappa super(2): Kappa super(1)-pypzacac)] sub(2).0.5H sub(2)O (1.0.5H sub(2)O), [{Cu(pypzacac)}( mu - Kappa super(2): Kappa super(1)-pypzacac) sub(2){Cu (H sub(2)O) sub(2)}](NO sub( 3)).2(MeOH) sub(0.5).6H sub(2)O (2.2(MeOH) sub(0.5).6H sub(2)O), [{(MeOH)Cu(mpypzacac)}( mu -SO sub(4))] sub(2).2MeOH (3.2MeOH; mpypzacac = methyl 2-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)acetate), [{Cu(mpypzacac) sub(2)}( mu - Kappa super(2): Kappa super(1)-pypzacac){C u(mpypzacac)}](ClO sub(4)) sub(3).MeOH (4.MeOH) and one polymeric Cu(ii) complex [(CuCl)( mu - Kappa super(3): Kappa super(1)-pypzacac)] sub()n(5), respectively. The mpypzacac ligand in 3 and 4 was in situgenerated viathe Cu super(2+)-catalyzed dehydrative esterification of acetic acid of the pypzacacH ligand. Complexes 1-5 are characterized by elemental analysis, IR and single-crystal X-ray diffraction. Complex 1 contains two {(MeOH)Cu(OAc)} fragments that are interconnected by two mu - Kappa super(2): Kappa super( 1)-pypzacac super(-) ligands, forming a dimeric structure. In 2, {Cu(pypzacac)} and {Cu(H sub(2)O) sub(2)} units are bridged by a pair of mu - Kappa super(2): Kappa super( 1)-pypzacac super(-) ligands. In 3, two {Cu(mpypzacac)} fragments are linked by two mu - Kappa super(1): Kappa super( 1)-SO sub(4) super(2-) ions to form a dinuclear structure. Complex 4 also adopts a dimeric structure in which {Cu(mpypzacac) sub(2)} and {Cu(mpypzacac)} units are interconnected by one mu - Kappa super(3): Kappa super( 1)-pypzacac super(-) ligand. Complex 5 contains a 1D chain in which (CuCl) fragments are interlinked by mu - Kappa super(3): Kappa super( 1)-pypzacac super(-) ligands. Complexes 1-5 exhibited excellent catalytic performance in the ammoxidation of alcohol to nitrile and the aerobic oxidation of alcohol to aldehyde in water. The catalytic aqueous solution was easily separated and could be reused for several cycles without any obvious decay of catalytic efficiency.