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Organometallic Lewis Acids, LIV. - Mo(CO)2(PPh3)2(O3SCF3)2: A New Precursor for an Organometallic Dicationic Lewis Acid with Three Accessible Coordination Sites
Rosendorfer, Philipp,Beck, Wolfgang
, p. 729 - 734 (2007/10/03)
The reaction of Mo(CO)2(PPh3)2Br2 (1) with AgO3SCF3 gives the bis(triflate) complex Mo(CO)2(PPh3)2(O3SCF3)2 (3) which can be considered as a precursor for the 12-e(1-) system Mo(CO)2(PPh3)2(2+) .According to the spectroscopic data one of the two coordinated CF3SO3(1-) anions is acting as a chelate ligand.Treatment of 3 and of the in situ generated W(CO)2(PPh3)2(O3SCF3)2 (4) with H2O affords the dinuclear hydroxobridged complexes (5: M = Mo; 6: M = W).Acetonitrile replaces the CF3SO3(1-) ligands in 3 and 4 to afford the cationic complexes 2 (7: M = Mo; 8: M = W).The reaction of 3 with an excess of 2-butyne and 1-phenyl-1-propyne leads to the monoalkyne complexes Mo(CO)(MeCCR)(PPh3)2(O3SCF3)2 (9: R = Me; 10: R = Ph) in moderate yield.In contrast, the bisalkyne complexes (11: M = Mo; 12: M = W) are formed in high yield when a CH2Cl2 solution of 2-butyne is added to 1 and 2 in the presence of AgO3SCF3.At room temperature, 11 and 12 are highly fluxional in solution, while 9 and 10 are stereochemically rigid.Treatment of 11 with acetonitrile yields 2 (13).Compounds 3-13 (except 4) are characterized by IR, 1H-, 13C-, 19F-, and 31P-NMR spectroscopy. - Keywords: Lewis acids, organometallic; 12-e(1-) Systems; Alkyne complexes; Molybdenum complexes; Tungsten complexes
