BINUCLEAR BIS(ETA-5-METHYLCYCLOPENTADIENYL)TITANIUM(III) COMPLEXES BRIDGED BY THE DIANION OF 2,4-DITHIOPYRIMIDINE AND RELATED DIANIONS - PREPARATION OF COMPLEXES AND MOLECULAR-STRUCTURE OF (2,4-DITHIOPYRIMIDINATO)BIS[BIS(ETA-5-METHYLCYCLOPENTADIENYL)TITANIUM(III)]

The preparation of six binuclear titanium(III) metallocenes of the composition [(η5-CH3C5H4)2Ti]2B, where bridge B is variously the dianion of 2, 4-dithiopyrimidine, 2, 4-diselenopyrimidine, 2-thiouracil, 4-thiouracil, 4, 6-dihydroxypyrimidine, or 4, 6-dithiopyrimidine, is reported. The preparations of an analogous trinuclear titanium(III) complex with the trianion of trithiocyanuric acid as a bridge and the mononuclear titanium(III) complex with the anion of 2-mercaptopyridine are also given. Analytical, mass spectral, and, in the following paper, magnetic susceptibility and EPR data are presented to establish the binuclear (trinuclear) structure of these complexes. The crystal and molecular structure of (2, 4-dithiopyrimidinato)bis[bis(η5-methylcyclopentadienyl)titanium(III)], C4H2N2S2[(η)5-CH3C5H4)2Ti]2, has been determined by using direct X-ray methods for 1444 reflections measured on a computer-automated four-circle diffractometer. The complex crystallizes as dark green plates belonging to the space group Pbca with eight molecules in a unit cell with a = 16.91 (2) Å, b = 22.22 (2) Å, c = 13.93 (1) Å, pobsd = 1.37 (1) g/cm3, and pcalcd = 1.41 g/cm3. The structure was refined to final discrepancy indices of = 0.085 and R2 = 0.056. The compound C4H2N2[(η5-CH3C5H4)2Ti]2 consists of asymmetric binuclear titanium(III) complexes, each with the dianion of 2,4-dithiopyrimidine acting as a bis-bidentate bridge between two (η5-CH3C5H4)2Ti moieties. The 2, 4-dithiopyrimidine dianionic bridge interacts with each titanium ion by means of one nitrogen and one sulfur atom [average distances of Ti-N = 2.21 ± 0.01 A and Ti-S = 2.594 ± 0.04 Å], A comparison of bond angles in the bridging group with those found for the uncoordinated 2,4-dithiopyrimidine confirms that both the sulfur and nitrogen atoms are coordinated to the titanium ion. The bridging dianion is essentially planar with the two titanium ions lying close to the plane (metal ion distances from the least-squares plane of 0.033 and 0.109 Å). The Ti-Ti distance in the binuclear complex is 6.075 (2) Å. © 1979, American Chemical Society. All rights reserved.