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

Abstract

The syntheses and characterizations of the novel platinum(II) mono-1,2-dithiolenes (COD)Pt(dddt) (1), (Ph3P)2Pt(dddt) (2), (COD)Pt(edt) (3), (Ph3P)2Pt(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. 195Pt NMR spectral analysis was performed on the above-mentioned compounds along with the previously reported compounds (COD)Pt(dmid) (7), (Ph3P)2Pt(dmid) (8), (Ph3P)2Pt(dmit) (9), (COD)Pt(mnt) (10), (Ph3P)2Pt(mnt) (11), (COD)Pt(dt) (12), and (Ph3P)2Pt(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-1,2-dithiolate). 195Pt NMR results show that, depending on the nature of L2 in L2Pt(1,2-dithiolene) complexes, the 1,2-dithiolene ligands behave as either π donors or acceptors toward the Pt metal center. 195Pt 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 L2. Support is also provided by electrochemistry, UV−vis spectroscopy, and 13C NMR. X-ray structural analysis results are given for 1, monoclinic, P21/a, a = 10.2420(10) Å, b = 10.7510(10) Å, c = 13.2890(20) Å, β = 102.870(10), Z = 4, and for 5, monoclinic, I2/a, a = 7.2294(2) Å, b = 11.4574(4) Å, c = 14.9103(6) Å, β = 89.380(15), Z = 4.