TRANSITION METAL COORDINATION COMPOUNDS CONTAINING A NOVEL TRIDENTATE PYRAZOLE CHELATING LIGAND. X‐RAY CRYSTAL STRUCTURE OF (N,N‐BIS(3,5‐DIMETHYLPYRAZOL‐1‐YLMETHYL)AMINOETHANE)(NITRATO‐O)(NITRATO‐O,O′)NICKEL(II)