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Bendix J, Bogevig A: Synthesis and Characterization of a Stable trans-Dioxo Tungsten (IV) Complex and Series of Mono-Oxo Molybdenum (IV) and Tungsten (IV) Complexes. Inorg Chem. 1998 Nov 16;37(23):5992-6001.
Structural and Electronic Effects of pi-Bonding in trans-[M (O)(X)(dppe)(2)](+/0) Systems.. trans-[W (O)(F)(dppe)(2)](BF (4)) (dppe = Ph (2) PCH (2) CH (2) PPh (2), 1,2-bis (diphenylphosphino) ethane) (10) has been synthesized. From this, the neutral trans-[W (O)(2)(dppe)(2)].2CH (3) OH (11) was prepared by a hydrolysis and deprotonation reaction with Et (4) NOH in methanol/water. Together with the analogous molybdenum compound (2) this compound afforded by substitution under acid conditions salts of trans-[M (O)(X)(dppe)(2)](+) ions (M = Mo, W; X = OH, OCH (3), Cl, Br, I, NCS) and trans-[Mo (O)(N (3))(dppe)(2)](CF (3) SO (3)) (9). All the compounds have low-spin d (2) electronic configuration. The compounds were characterized by (31) P{(1) H} NMR, positive FAB-ionization mass spectrometry, UV-vis spectroscopy, and vibrational spectroscopy. X-ray crystallographic studies were carried out on compounds 10, 11, trans-[W (O)(OH)(dppe)(2)](ClO (4)) (12), and trans-[W (O)(NCS)(dppe)(2)](BPh (4)) (16). The electronic spectra of the mono-oxo species are consistent with the lowest energy transitions being of d (xy)() --> {d (zx)(), d (yz)()} character. No ligand-field transitions are observed for the dioxo tungsten complex. Identical pi-spectrochemical series were found for the two metals. The shielding of the phosphorus nuclei determined by (31) P{(1) H} NMR is significantly influenced by the nature of the axial ligands. |
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