Tungsten complexes with nitrosyl

The chemistry of the dicarbonyl(7 -cyclopentadienyl)nitrosyl and the chloro-(i7 -cyclopentadienyl)dinitrosyl complexes of chromium, molybdenum, and tungsten [i.e., fT -CsHs)M(CO)j(NO)] and [(i7 -CsHs)M(NO)2Cl] has not been studied extensively, partly because of the various difficulties associated with their preparation. The procedures described below are of general applicability to all three metals and lead to the desired compounds in high yields. The carbonyl nitrosyl complexes are the synthetic precursors of the chloro nitrosyl complexes and so their preparation is described first. 

The reaction between PySeSePy (2,2 -dipyridyl diselenide) and [W(C7H8)(CO)4] (CvHg = norbornadiene) yielded the seven-coordinate complex [Wn CsI I4N(2-Se)-A-,SV 2(CO) ,].2 Oxidative addition of 2,2 -pyridine disulfide to [L3W(CO)3] (L3 = (pyridine)3, cycloheptatriene) in dichloromethane gave the seven-coordinate [W( 72-mp)2(CO)3] (mpH = 2-mercaptopyridine). This complex reacted with NO in the presence of additional pyridine disulfide to yield the seven-coordinate tungsten I) nitrosyl complex [Wn( 72-mp)3(NO)], as well as [W(rf-mp) 2 (N O) 2] and a trace amount of [Wiv(f72-mp)4].208... 

Neutral and cationic homoleptic see Homoleptic Compound) tungsten-isocyanide complexes W(CNR)6 and [W(CNR)7] + (R = alkyl, aryl) are known, and W(CO)6-n(CNR) (n=l-3) complexes may be prepared from W(CO)6 and excess isocyanide in the presence of catalytic amounts of C0CI2 or PdO. Isocyanides are isoelectronic with CO and also insert into the W-R bonds of alkyl complexes see Alkyl Complexei). For instance, the alkyl-nitrosyl complexes Cp"W(NO)(X)(CH2BuO (X = NHBuC OBu ) react with CNBu to afford -iminoacyl complexes, and the isocyanide complexes, Cp W(CO)2(Me)(CNR) (10, R = alkyl), rearrange to afford either jj -iminoacyl Cp W(CO)2( -MeCNR) (11) or Li azaallyl Cp"W(CO)2(/ 3-CH2CHNR) (12) derivatives, depending upon the reaction conditions (equation 4). ... 

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