Synthesis of poly(3,5-dicarbomethoxypyrazolato)copper and its reactions with carbon monoxide and cyclohexyl isocyanide. Crystal structures of [Cu2(dcmpz)2(py)2(CO)] and [Cu(dcmpz)(RNC)]2 (Hdcmpz = 3,5-dicarbomethoxypyrazole, R = cyclohexyl)