Molecular weight determination of coordination and organometallic oligomers by T 1 and NOE constant measurements: concepts and challenges

This paper describes how to determine molecular weights of coordination and organometallic polymers (or rather oligomers) in solution using spin‐lattice relaxation time (T 1 ) and Nuclear Overhauser Enhancement constant (η NOE ) measurements. The methodology is explained using simple organometallic‐complexes such as M(CN‐t‐Bu) 4 + complexes (M = Cu, Ag). Very good results are obtained for oligomers that exhibit a rigid structure. Conversely, very poor results are extracted when the materials show flexible chains in the backbone. The typical examples for rigid and flexible oligomers are the {Ag(dmb) 2 + } n (dmb = 1,8‐diisocyano‐p‐menthane), and {Pd 2 (dmb) 2 (diphos) 2+ } n (diphos = dppa, dppb, dpppent, and dpph) as well as {Pd 2 (diphos) 2 (dmb) 2+ } n (diphos = dppe, dppr, and dppp R ; R = O(CH 2 ) 2 O‐naphthyl), respectively.