[Morphic flip]

Other than x-ray crystallography, what other methods are there for determining between cis and trans isomers.
And how would you tell if the isomer was cis or trans using the methods.

[lemonoman]

Depending on the compound, melting point may be useful.  Each isomer will probably have a different melting point

And if you have access to one, an NMR might do it.  cis- and trans- coupling constants are different, and so different splitting patterns may occur.

[Morphic flip]

Compounds are PtpyCl₂I^- and PtpyBr₂I^-
Thank`s.

[Albert]

Compounds are PtpyCl₂I^- and PtpyBr₂I^-

Could you type their name?  Sorry but I'm not used to these abbreviations.

[AWK]

Compounds should be neutral - cations are missing (eg - Me4N+) . py - probably means  pyridine.
I doubt in possibility of avoiding X-ray.

[Morphic flip]

With vibrational spectroscopy, how would it determine different isomers, what would be the obvious thing`s to look for?