TUngsten complexes alkyne, structures

The chemistry which has developed for molybdenum(II) and tung-sten(II) alkyne monomers encompasses syntheses, structures, spectra, molecular orbital descriptions, and reactions. The sheer volume of literature reports germane to this seemingly narrow topic is surprising. The Mo(II) and W(II) complexes addressed here are not unique in terms of alkyne 7rx donation. Related alkyne chemistry is appearing for d4 metals other than molybdenum and tungsten, as well as for d2 complexes in general. 

X-Ray Crystal Structure Determinations of Molybdenum(II) and Tungsten(II) Halocarbonyl Alkyne Complexes Reported since 1987... 

Ring-closing metathesis (RCM) is not restricted to alkenes similar reactions are also known for alkynes. The tungsten alkylidyne complex W(=CCMe3)(OCMc3)3 has been used to catalyze such reactions. Predict the structures of the cyclic products for metathesis of... 

The carbene complex starting materials mentioned above include an enamine structure which is coupled with an alkyne. Vice versa, the coupling of alkynylcarbene complexes with enamines leads to cyclopentanoid products as well. The complementary reaction of tungsten alkynylcarbene complex 59 with enamine... 

The NMR characterisation of fBA adducts formed in the reaction of tungsten and molybdenum seven-coordinate compounds leaves little doubt concerning their formulation. However, we were unable to separate such compounds and to prepare a crystalline sample. To obtain a more stable terminal alkyne compound, we introduced two phosphine ligands into the coordination sphere of tungsten(II). In this way a cationic complex of tungsten(II), [WCl(CO)( BuC=CH)(NCMe)(PPh3)2]2[SnCl6], was prepared [45]. The crystal structure of this compound consists of two independent cations and a... 

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