MODELS FOR ORGANOMETALLIC POLYMERS - ZIGZAG CHAINS OF MO2(O2CCH3)4 UNITS LINKED BY DMPE AND TMED LIGANDS

Infinite zigzag chains of Mo2(O2CCH3)4 units linked by the bidentate ligands 1,2-bis(dimethylphosphino)ethane (dmpe) and tetramethylethylenediamine (tmed) crystallize from solutions of Mo2(O2CCH3)4 (1) dissolved in the respective neat ligand. Single-crystal X-ray structures of the light yellow polymers {formula-omited} (2) and {formula-omited} (3) showed that the compounds were isostructural. Compound 2 crystallizes in space group {formula-omited} (−135 °C) with a = 8.473 (2) Å, b = 9.562 (3) k,c = 7.654 (3) Å, α = 110.59 (2)°, β = 100.06 (2)°, γ = 69.26 (2)°, Z = 1, V= 541.9 (3) Å3, R = 0.058, and Rw = 0.058. Compound 3 crystallizes in space group {formula-omited} (20 °C) with a = 8.388 (1) Å, b = 8.445 (2) Å, c = 8.840 (2) Å, α = 105.95 (2)°, β = 115.62 (1)°, γ = 91.63 (2)°, Z = 1, K = 535.1 (2) Å3, R = 0.025, and Rw = 0.033. The ligands dmpe and tmed are coordinated axially through weak Mo-L bonds to relatively unperturbed Mo2(O2CCH3)4 centers. The solid-state Raman spectrum of 3 reveals a small decrease in the Mo-Mo stretching frequency (νMo-MO = 391 cm−1) relative to 1 (νMo-MO = 405 cm−1). TGA and powder X-ray diffraction studies involving 3 showed that solid-state thermolysis results in the expulsion of tmed at 92 °C and the formation of crystalline 1. © 1990, American Chemical Society. All rights reserved.