Budzichowski, Theodore A. and Chisholm, Malcolm H. and Folting, Kirsten and Streib, William E. and Scheer, Manfred (1996) Tetranuclear Phosphinidine, Phosphide, Arsenide, and Oxide Anionic Clusters of Molybdenum and Tungsten Supported by Neopentoxide Ligands: Na(18-crown-6)[M4(μ3-PSiMe3)(OCH2tBu)11], K(18-crown-6)[M4(μ3-E)(OCH2tBu)10] (E = P, As), K(18-crown-6)2[Mo4(μ3-O)(OCH2tBu)11]. Inorganic Chemistry 35 (12), pp. 3659-3666.
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From the reactions between M2(OCH2tBu)6 (2 equiv) and NaP(SiMe3)2 (1 equiv) in benzene and 18-crown-6 the phosphinidine clusters [M4(μ3-PSiMe3)(OCH2tBu)11]-, compounds 1 (M = Mo) and 2 (M = W) are formed and are reactive intermediates in the formation of [M4(μ3-P)(OCH2tBu)10]- cluster anions, compounds 3 (M = Mo) and 4 (M = W), respectively, which have been isolated and characterized as their Na(18-crown-6)+ salts. Crystals of Na(18-crown-6)+[Mo4(μ3-P)(OCH2tBu)10]-·C6H6 were examined by single crystal X-ray crystallography at −110 °C in the space group Pn with a = 13.000(2) Å, b = 17.501(3) Å, c = 18.703(2) Å, and β = 93.11(1)° with Z = 2 and at −173 °C in the space group Cc with a = 22.118(4) Å, b = 17.480(3) Å, c = 23.250(4) Å, and β = 110.82(1)° with Z = 4. At the lower temperature, there is higher symmetry and no disorder of the 18-crown-6 molecule. The cluster anion has a Mo4 butterfly with a μ3-P ligand and virtual mirror symmetry. One wing-tip Mo atom is five-coordinate and bonded to the μ3-P atom and shows longer Mo-to-Mo distances (2.68(1) and 2.71(1) Å) relative to its counterpart (2.48(1) and 2.50(1) Å); the backbone Mo−Mo distance is 2.53(1) Å. The cluster anion in 3 but not 4 is also accessible from the reaction between Mo2(OCH2tBu)6 (2 equiv), PH3, and KOCH2tBu (1 equiv) in THF/18-crown-6 (THF = tetrahydrofuran). A similar approach involving AsH3, Mo2(OCH2tBu)6, and KOCH2tBu gave the μ3-arsenide cluster complex K(18-crown-6)+[Mo4(μ3-As)(OCH2tBu)10]-, compound 5, which by NMR spectroscopy is analogous in structure to 3. The reaction between Mo2(OCH2tBu)6 (2 equiv) and KOH in THF/18-crown-6 gave K(18-crown-6)2+[Mo4(μ3-O)(OCH2tBu)11]-, compound 6, which is proposed to be isostructural with the phosphinidine complexes 1 and 2 on the basis of NMR data. Crystal data for K(η6-C12H24O6)(η2-C12H24O6)+[Mo4(μ3-O)(OCH2tBu)11]- at −165 °C: a = 17.595(2) Å, b = 28.044(3) Å, c = 20.443(2) Å, β = 97.61(1)° with Z = 4, and space group P21/n. The cluster anion in 6 contains a 12-electron Mo4 butterfly with 12 M−M bonding electrons, as in 3, but the shortest Mo−Mo distance 2.42(1) Å involves the backbone metal atoms. The Mo−Mo distances involving the oxo-capped triangle (2.61(1) and 2.62(1) Å) are notably longer than those in the other triangle (2.48(1) Å).
|Institutions:||Chemistry and Pharmacy > Institut für Anorganische Chemie > Chair Prof. Dr. Manfred Scheer|
|Subjects:||500 Science > 540 Chemistry & allied sciences|
|Created at the University of Regensburg:||Unknown|
|Deposited On:||21 Jun 2010 12:49|
|Last Modified:||20 Jul 2011 22:31|