For an octahedral coordination with six positions, the possible arrangements of a linear pentadentate ligand are designated by ffms ffma fff fmf fmama fmsma fmsms fmams where each letter f or s represents three consecutive donor atoms: f represents facial fac arrangement, m is meridianal mer a is "anti" and s is "syn" for positioning of the mer arrangement relative to other donors.
The pattern can use parenthesis: () to indicate a side chain, eg NNM(N)N. For octahedral coordination there are four arrangements designated: f(m)m f(f)f f(f)ma and f(f)ms where the parenthesis ow indicate how the side chain participates in coordination.
[1] The metal may be five-coordinate with arrangements being square-pyramidal or trigonal-bipyramidal, or somewhere between the two.
2,2':6',2'':6'',2''':6''',2''''-Quinquepyridine is fairly rigid, and tries to be in a plane, so coordination will be pentagonal planar.
For silver it is planar, but for rhenium it slightly twists to a helix.