Multinuclear magnetic resonance spectroscopy and crystal structures of iodo-bridged dinuclear Pt(II) complexes with amines

摘要

Complexes of the types cis-Pt(amine)(2)I-2 were transformed into the iodo-bridged dimers, which were characterized mainly by multinuclear ((195)pt, H-1 and C-13) magnetic resonance spectroscopy. For bulby amines, the dinuclear species were synthesized directly from K-2[PtI4]. Compounds with several primary aliphatic and cyclic amines and two secondary amines were studied. In (195)pt NMR, two signals were observed between -3899 and -4080 ppm in acetone. These species were assigned to the cis and trans dinuclear compounds I(amine)Pt(mu-I)(2)PtI(amine). We suggest that the most shielded compound is the trans isomer. The difference between the two isomers is 12-13 ppm for the primary amine system and 26-27 ppm for the two secondary amines. There seems to be a slight dependence of the proton affinity in the gas phase of the amine (linear amines) with the delta(Pt) chemical shifts of the dinuclear Pt(II) compounds. The (2)J(Pt-191-(HN)-H-1) coupling constants are slightly larger for the trans isomers (average 67 Hz, vs. 56 Hz). The (3)J(Pt-195-H-1) coupling constants were detected only for the dimethylamine compounds, 46 Hz (trans) and 44 Hz (cis). In C-13 NMR, the values of (2)J(Pt-195-C-13) and (3)J(Pt-195-C-13) were also found to be very slightly larger for the trans complexes (average 19 and 25 Hz vs. 15 and 18 Hz). The structures were confirmed by X-ray diffraction studies of the n-butylamine and diethylamine compounds. The two crystals were those of the trans dinuclear complexes. (c) 2005 Elsevier B.V. All rights reserved.