A copper precursor composition comprising: a first copper complex comprising an imine or a first cyclic amine coordinated to a first copper precursor compound, the imine comprising a compound of Formula (I) where R 1 , R 2 and R 3 are the same or different and are H, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 alkynyl, C 3-8 cycloalkyl, C 6-14 aryl, C 7-20 alkaryl, C 7-20 aralkyl, OH, O-C 1-8 alkyl, O-C 7-20 aralkyl, O-C 7-20 alkaryl, CO 2 -(C 1-8 alkyl), SO 2 -(C 1-8 alkyl) or SO-(C 1-8 alkyl) or R 1 and R 2 taken together form a C 3 -C 8 ring, with the proviso that at least one of R 1 , R 2 and R 3 is not H, the first cyclic amine comprising a 5-membered, 6-membered or 7-membered ring structure, 1 to 30 carbon atoms and 1 to 3 nitrogen atoms where at least one nitrogen atom is in the ring structure and available for coordination to copper; and, a second copper complex comprising a primary amine or a second cyclic amine coordinated to a second copper precursor compound, the primary amine comprising formula R-NH 2 , where R is a C 3 -C 20 organic group, the second cyclic amine comprising a 5-membered, 6-membered or 7-membered ring structure, 1 to 30 carbon atoms and 1 to 3 nitrogen atoms where at least one nitrogen atom is in the ring structure and available for coordination to copper, the first and second copper complexes being different complexes, wherein the copper precursor composition is thermally degradable at a temperature lower than a comparable composition comprising only the second copper complex under otherwise the same conditions to produce a metallic copper film having a resistivity of about 200 μΩ•cm or less. a first copper complex comprising an imine or a first cyclic amine coordinated to a first copper precursor compound, the imine comprising a compound of Formula (I) where R 1 , R 2 and R 3 are the same or different and are H, C 1-8 alkyl, C 2-8 alkenyl, C 2-8 alkynyl, C 3-8 cycloalkyl, C 6-14 aryl, C 7-20 alkaryl, C 7-20 aralkyl, OH, O-C 1-8 alkyl, O-C 7-20 aralkyl, O-C 7-20 alkaryl, CO 2 -(C 1-8 alkyl), SO 2 -(C 1-8 alkyl) or SO-(C 1-8 alkyl) or R 1 and R 2 taken together form a C 3 -C 8 ring, with the proviso that at least one of R 1 , R 2 and R 3 is not H, the first cyclic amine comprising a 5-membered, 6-membered or 7-membered ring structure, 1 to 30 carbon atoms and 1 to 3 nitrogen atoms where at least one nitrogen atom is in the ring structure and available for coordination to copper; and, a second copper complex comprising a primary amine or a second cyclic amine coordinated to a second copper precursor compound, the primary amine comprising formula R-NH 2 , where R is a C 3 -C 20 organic group, the second cyclic amine comprising a 5-membered, 6-membered or 7-membered ring structure, 1 to 30 carbon atoms and 1 to 3 nitrogen atoms where at least one nitrogen atom is in the ring structure and available for coordination to copper, the first and second copper complexes being different complexes, wherein the copper precursor composition is thermally degradable at a temperature lower than a comparable composition comprising only the second copper complex under otherwise the same conditions to produce a metallic copper film having a resistivity of about 200 μΩ•cm or less. <EOS>