Tungsten hexacarbonyl complexes

C H, 1,3-Cydopentadiene, l-methyl-, chromium, molybdenum, and tungsten hexacarbonyl complexes, 28 148 preparation and purification of, 27 52 titanium complex, 27 52 vanadium complex, 27 54... 

Another class of complexes involves rj (N)-coordinated species of the Nl-unsubstituted pyrazoles. Chromium hexacarbcMiyl and pyrazole or 3,5-dimethyl-pyrazole form [(Hpz)Cr(CO)5] ot [(Hpz )Cr(CO)5] irrespective of the ratio of reactants. In similar circumstances, tungsten hexacarbonyl yields both [(Hpz)W(CO)5]... 

Molybdenum and tungsten hexacarbonyls are able to form anionic complexes (AsPli4)2[(OC)4M( -pz)2M(CO)4] upon reaction with sodium pyrazolate and PluAsCl (72CB3203). The cationic complexes [(rj -Cp)2Mo(/Lt-pz)2Mo(rj -Cp)2] " (n = 2, 3) are known as well (74HCA1988). The other representatives of the complexes containing an exobidentate ligand (26) are derived from 4//-pyrazoles [70ZAAC(379)169]. 

Nucleophilic acyl complexes can be 0-alkylated with hard electrophiles to yield the corresponding alkoxy- or (acyloxy)carbene complexes. The first carbene complex ever isolated [61] was prepared by this route the intermediate, anionic acyl complex was generated by addition of phenyllithium to tungsten hexacarbonyl (Figure 2.3). 

The heat of formation of [MolCOlg] has been determined as -960 + 12 kJ mol by measuring its heat of decomposition. The Mossbauer parameters for the 100 keV transition of in [W(CO)g] and some tungsten(vi) complexes have been measured and discussed in terms of known bonding and structure. Secondary ions [M (CO) ] (M = Mo, m = I or 2 M = W, m = 1—4 n = 0—14) formed by ion-molecule reactions have been observed in the mass spectra of the hexacarbonyls. A mixt u re of [Cr(CO) ] and [MolCO) ] vapours affords [CrMo(CO) ] ( = 5—7). [MofCOl ] and [WICO) ] catalyse the condensation of isocyanates with aldehydes to give imines in high yields. ... 

Diene complexes of the type [W(CO)4(diene)l (VI M = W) are formed by cyclo-octa-1,5-diene (79, 151), hexa-1,5-diene (151), and dimethyldi-vinylsilane (158) on heating with tungsten hexacarbonyl. Cycloheptatriene (158) displaces cyclo-octa-1,5-diene and 1 mol. of carbon monoxide from its tungsten complex ... 

Treatment of tungsten hexacarbonyl with a mixture of cyclo-octa-1,3,5-and -1,3,6-triene gives the complex [W(OO iCslIiohJ (85). The hydrocarbon is believed to be the 1,3,6-triene, acting as a diene, but for the reasons mentioned (see Section III,H) it is possible that the ligand is bicyclo[4,2,0]-octa-2,4-diene (XV). 

Tungsten hexacarbonyl on treatment with bicyclo-[4,3,0Jnona-2,4,8-triene(C9Hio) gives a brick red complex [W(CO)3(C9Hi0)J which appears to be completely analogous to the molybdenum complex [Mo(CO).i(CaH,t))] of structure (VIII) (142). 

Tungsten hexacarbonyl is reported to form a number of stable complexes with acetylenes (116, 118), but no details have been published. 

These complexes decompose slowly in solution at 20°. When the complex (R = diethylamino) in diethyl ether is treated with carbon monoxide at 100 bar and 60° for 18 hours, tellurium, tungsten hexacarbonyl, and 3-diethylamino-l,l-diphenylpropene (77% yield) were formed3. 

Complexes of N6P6(NMe2)12 with other metal chlorides and nitrates have essentially similar structures as indicated by infrared and electronic spectroscopic data (98). Compounds N4P4Me8 and N5P5Me10(L ) react with molybdenum and tungsten hexacarbonyls... 

Most of the work is done with carbonyl complexes of group-VIA metals. Tungsten hexacarbonyl reacts at RT with methyllithium in solvents such as diethylether or THF almost quantitatively with addition of the carbanion to the carbon atom of a coordinated CO to give the lithium salt of acetylpentacarbonyl tungstate. This complex can be converted by aqueous tetramethylammonium bromide into the more stable tetramethyl-ammonium salt ... 

If an excess of chloride is added to the tungsten hexacarbonyl, a bridged complex XX is formed (cf. XVIII), which also is well-suited for oxidative addition ... 

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