Synthesis and spectroscopic properties of N-acetyl-DL-phenyl-glycinato complexes of cobalt(II), nickel(II) and copper(II). Crystal structures of bis(N-acetyl-DL-phenyl-glycinato)diaquobis-(N-methylimidazole)cobalt(II), bis(N-acetyl-DL-phenylglycinato)diaquobis (imidazole)cobalt(II) and nickel(II)