The 195Pt NMR of L2Pt(1,2-dithiolene) complexes

The syntheses and characterizations of the novel platinum(II) mono-1,2-dithiolenes (COD)Pt(dddt) (1), (Ph3P)(2)- Pt(dddt) (2), (COD)Pt(edt) (3), (Ph3P)(2)Pt(edt) (4), (bipy)Pt(edt) (5), and (Ph3P)(CO)Pt(dddt) (6) (COD = 1,5-cyclooctadiene; dddt = 5,6-dihydro-1,4-dithiin-2,3-dithiolate; edt = ethylene-1,2-dithiolate, bipy = 2,2'-bipyridyl) are reported. Pt-195 NMR spectral analysis was performed on the above-mentioned compounds along with the previously reported compounds (COD)Pt(dmid) (7), (Ph3P)(2)Pt(dmid) (8), (Ph3P)(2)Pt(dmit) (9), (COD)Pt(mnt) (10), (Ph3P)(2)Pt(mnt) (11), (COD)Pt(dt) (12), and (Ph3P)(2)Pt(dt) (13) (dmid = 1,3-dithiole-2-oxo-4,5-dithiolate; dmit = 1,3-dithiole-2-thione-4,5-dithiolate; mnt = maleonitrile-1,2-dithiolate; dt = ethane-1,3,-dithiolate). Pt-195 NMR results show that, depending on the nature of L-2 in L2Pt(1,2-dithiolene) complexes, the 1,2-dithiolene ligands behave as either pi donors or accepters toward the Pt metal center. Pt-195 NMR is also sensitive to the relative electron-withdrawing ability of the substituents on the 1,2-dithiolene backbone which results in an ordering of chemical shifts into a series independent of L-2. Support is also provided by electrochemistry, UV-vis spectroscopy, and C-13 NMR. X-ray structural analysis results are given for 1, monoclinic, P2(1)/a, a = 10.2420(10) Angstrom, b = 10.7510(10) Angstrom, c = 13.2890(20) Angstrom, beta = 102.870(10), Z = 4, and for 5, monoclinic, I2/a, a = 7.2294(2) Angstrom, b = 11.4574(4) Angstrom, c = 14.9103(6) Angstrom, beta = 89.380(15), Z = 4.