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Characterization of the {Ag(dmb)2+}n Oligomers (dmb = 1,8-Diisocyano-p-menthane) in Solution

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journal contribution
posted on 2002-05-07, 00:00 authored by Martin Turcotte, Pierre D. Harvey
The crystallographically characterized polymers {[Ag(dmb)2]Y}n (Y = BF4-, NO3-, ClO4-) extensively dissociate in solution, contrarily to the Cu analogue, and common molecular weight determination techniques such as light scattering, osmometric, and intrinsic viscosity measurements fail to provide data allowing full characterization. Using pulsed NMR experiments, notably 13C NMR T1 (spin lattice relaxation time) and NOE (nuclear Overhauser enhancement) measurements on various ionic [{Ag(dmb)2]Y}n materials (Y = BF4-, NO3-, ClO4-) and their related mononuclear [Ag (CN-t-Bu)4]Y salts in acetonitrile-d3 (as comparative standards), the dipole−dipole spin lattice relaxation times (T1DD) of a selected quaternary 13C probe are measured. These data allow us to extract the correlation times (τc), which in turn permit us to estimate the volume of the tumbling species in solution. The comparison of the data between the {Ag(dmb)2+}n and Ag(CN-t-Bu)4+ species indicates the oligomeric nature of the former species, where the average number of Ag(dmb)2+ ∼ 8 (Mn ∼ 4000−5000).

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