Gravar-mail: {μ-2-[(3-Amino-2,2-dimethyl­prop­yl)imino­meth­yl]-6-meth­oxy­phenolato-1:2κ(5) O (1),O (6):N,N′,O (1)}{2-[(3-amino-2,2-dimethyl­prop­yl)imino­meth­yl]-6-meth­oxy­phenolato-1κ(3) N,N′,O (1)}-μ-azido-1:2κ(2) N:N-azido-2κN-methanol-2κO-dinickel(II)