Nitrosyl complexes of chromium, molybdenum and

A. DICARBONYL(t -CYCLOPENTADIENYL)NITROSYL complexes of CHROMIUM, MOLYBDENUM, AND TUNGSTEN... 

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. 

Chromium, Molybdenum, and Tungsten. Neutron diffraction studies on [Crj-(CO)io(a -D)] at 17 K provide evidence for a four-fold site distribution of the deuterium. A more simple preparation of homo- and hetero-dinuclear complexes from the combination of 17-e species [M(CO)3Cp, (M=Cr, Mo, W) Mn(CO)s Fe(CO)2Cp Co(CO)4 Ni(CO)Cp] has been described. Heating [Cr(CO)2( -C6He)(NCMe)] results in the formation of the Cr Cr complex, [Cr2( -C6H6)2(/M-CO)3], and the antiferromagnetic complexes, [CraCpgCw-S)-(jM-EPh)2], (E = S, Se), have been reported. The preparation of a variety of nitrosyl dimers of chromium, molybdenum, and tungsten has been reported ... 

Figures 7,8 shows plots of data for chromium and molybdenum nitrosyl species the slope with El(L) is essentially the same as for non-NO species. Thus, in Figure 7,8 [data from 10,31,32], a value for El(NO) is used which will cause the nitrosyl complexes to fit the correlation line. This yields El(NO + ) = 2.55 - 2.57 for both metal ions. Values in the range 1.2 -1.8, for El(NO" "), have been described by Clarke [33] for some technetium nitrosyl derivatives. This area would benefit from a detailed analysis.

Chromium nitrosyl complexes, [Cr(S2CNR2)3(NO)], are somewhat less thermally stable than their molybdenum and tungsten counterparts heating [Cr(S2CNMc2)3(NO)] in toluene for 3 h leads to the formation of cis-[Cr(NO)2(S2CNMe2)2] and [Cr(S2CNMe2)3] (752). Somewhat contradictory reports siuround the electrochemical behavior of [Cr(S2CNR2)3(NO)]. Connelly and co-workers (752) report that they show no redox chemistry between 1.5 V,... 

The nitrosyl carbonyls CpM(NO)(CO)2 [M=Cr (21, 7S), Mo (57), W (19)) can be made by the action of nitric oxide on [CpCr(CO)3]2, [CpMo(CO)3] , or [CpW(CO)3] , respectively. The chromium complex undergoes a Friedel-Crafts acetylation to give (CsH4COCH3)Cr(NO)(CO)2 (21). A series of molybdenum complexes CpMo(NO)l2L [L = PPh3, P(OPh)3, py, and bipy] has been made from L and [CpMo(NO)l2]2 (57). The cationic manganese species [CpMn(NO)(CO)2], obtained by the action of nitrite and acid on CpMn(CO)3, can be precipitated as the yellow hexafluorophosphate salt (51). With sodium borohydride this affords [CpMn(NO)(CO)]2 which probably contains bridging NO groups (see below) (58). The complex [CpMn(NO)S2] is probably similar in structure... 

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