An Investigation Of Π-Complexes From Disubstituted Acetylenes And Copper (I) Compounds

ABSTRACT

1-bromo-3-methylbut-1-yn-3-ol, 1-bromo-3-methypent-1-yn-3-ol, 4-hydroxy-4-methyhex-2-yn-nitrile, 1-chloro-3-mrthylpent-1-yn-3-ol, 1-chloro-3-methybut-1-yn-3-ol, 4-methylhex-2-yn-4-ol, 4-methylhexa-2, 3-dienenitrile and 4-methoxy-4-methylhex-2.yn were separately prepared and then each of them was used as the disubstituted acetylene for complexation with copper(I), cyanide, copper(I) bromide and copper(I) chloride respectively in dimethyl form amide (d.m.f) and then in dimethyl sulphide (d.m.s.o), as the solvent in each case.

E.D.T.A analysis for copper(I) in each couples and the G.L.C of the hydrolysis products have been used to elucidate the stoichiometry and structures of the complexes prepared. Results indicate that in D.M.F., the stoichometry of the complexes is of the form; (CuX)4 . (D.M.F.)2 RRC(OH)C=C-Y (X=CN, Br, or Cl.) (Y=Br, Cl CN, or Me). And in d.m.d.o. the stoichiometry have been postulated as; (CuCN)2 (D.M.S.O.)2 RRC(OH)C=C-Y and CuX1(DMSO)2 RRRC(OH) C=C-Y (C1=Br, or Cl).

With 4-methoxy-4-methylhex-2-yn as the disubstituted acetylene it has been shown that Π-bonding did not occur.

This emphasises the fact that the hydroxyl group was very crucial for Π-bonding to copper(I) by the disubstituted acetylenes.

With allenic nitriles Π-bonding to copper(I) was not observed, rather, d.m.f and d.m.s.o. were ligand anions to the copper(I) in a coordination number of 3 in each case.