Source of materialToasuspension of dichlorocyclooctatetraeneplatinum(II)(0.5053 g, 1.37 mmol) in ether (30 ml) was added slowly methyllithium (1.6 Msolutioninether, 5.07 ml, 8.11 mmol), and stirred for4hat -5°C.After methanolysiswith 1mlMeOH,the resulting mixture was diluted with pentane (20 ml), and then filtered directly through aplug of Al 2 O 3 (3 cm ×2cm) and eluted with pentane. The solvent was removedinvacuo, the dark brown residue was dissolved in pentane, and filtered once more through anew plug of Al 2 O 3 (3 cm ×2cm). Evaporation of the solvent gave ayellow powder (0.2601 g).1 HNMR analysis reveals that the productisa mixture, containing mono-and dinuclear Pt(II)c ompounds, [Pt(CH 3
Experimental detailsThree Hatoms (H1, H2, H4) were located from Fourier difference maps and refined isotropically.The H3atom was also found and refined, but the C3-H3bond distance was restrained to the averaged value of the other bond lengths and an estimated standard deviation to achieve reasonable bond data. The methyl Hatoms at C5w ere positioned using AFIX 137 instruction ( d (C-H)= 0.97 Åand U iso (H)=1.5 U eq (C)) [1]. The other methyl group with C6appears to be disordered. Its Hatoms were modeled as disordered over two sites rotated by 60°from one another using AFIX 123 instruction [1], with an occupancy ratio of 0.6(1)/0.4.
DiscussionThe titlecompound was previously prepared by the reaction of cyclooctatetraenediiodoplatinum(II)w ith Grignard reagent, CH 3 MgI [2]. The NMR spectrum of the compound was examined for potential long-range coupling by the 195 Ptnuclei [3], and Xray structure analysis was also carried out [4]. The published and our crystal structuresare essentially the same, however, the geometric properties and parameters here presented are slightly different and more accurate, respectively. The complex consists of two dimethylplatinum groups bridged by an 1,3,5,7-cyclooctatetraene (cot) ligand, and is disposed about atwofold axis passing throughthe two Ptatoms and the center of the ligand along the b axis. Each Ptatom is essentially in asquareplanar environment defined by the two Catoms of methyl groups and the two midpoints of the p -coordinated double bonds of the cot ligand.The Pt, Catoms and the midpoints form two coordination planes with the largest deviations 0.022 Å(C5) and 0.006 Å (C6), respectively, from the least-squares planes andwith approx-
