REACTION OF ORGANOISOTHIOCYANATES WITH [CO(ETA-C5H5)(PPH3)2] - PREPARATION, STRUCTURE, AND REACTIVITY OF TRINUCLEAR COBALT COMPLEXES CONTAINING A TRIPLY BRIDGING, 2-ELECTRON-DONOR CNR LIGAND

The slow addition of RNCS to [Co(η-C5H5)(PPh3)2] in benzene at room temperature gives a good yield of green [Co3(η-C5H5)3(µ3-S)(µ3-CNR)] (1) where R = alkyl or aryl. A crystal structure determination (R = Et; monoclinic, space group P21/c with a = 14.405 (4) Å, b = 9.221 (3) Å, c = 15.040 (5) Å, β = 117.9 (3)°, and Z = 4) shows that these complexes contain a planar Co3(η-C5H5)3 triangle (Co–Co = 2.447, 2.452, and 2.483 (1) Å) capped on one side by a µ3-S atom and on the other by a µ3-CNR ligand acting as a two-electron donor through C. The CNEt ligand is bent at N so that the N–Et bond lies above the center of one Co–Co bond with a C–N–Et angle of 129°. The N atoms of 1 are basic, but the basicity is a function of R. When R = Me or Et (1) reacts with [Ph3C]BF4 to give [Co3(η-C5H5)3(µ3-S){µ3-CN(H)R}]BF4, [2]BF4, although the source of the protons is unclear, and with MeI or RʹSO3CF3 to give [Co3(η-C5H5)3(µ3-S){µ3-CN(Rʹ)R}]X, [3]X; both [2]BF4 and [3]X react with excess HBF4·OEt2 to give [CO3(η-C5H5)3(µ3-S){µ3-CN(H)2R}][BF4]2, [4][BF4]2, and [Co3(η-C5H5)3(µ3-S){µ3-CN(H)(Rʹ)R}][BF4]2, [5][BF4]2salts, respectively. In contrast, when R = aryl, both [Ph3C]BF4 and excess HBF4·OEt2 convert 1 to [2][BF4] only, and some 1 molecules are not alkylated to [3] I by MeI, but all are alkylated by MeSO3CF3. Infrared and NMR spectroscopic data are reported and discussed. © 1990, American Chemical Society. All rights reserved.