Email Record: Tetra­kis(6-methyl-2,2′-bipyridine)-1κ(2) N,N′;2κ(2) N,N′;3κ(2) N,N′;4κ(2) N,N′-tetra-μ-nitrato-1:2κ(2) O:O′;2:3κ(3) O:O′,O′′;2:3κ(3) O,O′:O′′;3:4κ(2) O:O′-tetra­nitrato-1κ(4) O,O′;4κ(2) O,O′-tetra­lead(II)