Chromium, nitrosyl

Several chromium nitrosyls, and complexes of quinones which are members of redox series, can be considered to contain chromium(O) or chromium(I) (see Sections 35.4.2.6 and 35.4.4.8). 

Table 64 Some Properties of Macrocyclic-chromium Nitrosyl Complexes1...

Some cyclopentadienyl-/x-mercapto-, -alkoxo-, and /a-dialkylamido-chromium nitrosyl complexes (VI)-(X) have been studied by Preston and Reed 167). 

A direct, quantitative, and convenient method for the preparation of [Cr(H20)5N0] has been achieved by the slow, dropwise addition of an aqueous solution of Cr° (10 ml, 0.5 mol 1" ) to a stirred solution of HCIO4 (200 ml, 0.1 mol 1" ) which was continuously saturated with NO. This reaction is rapid and produces only [Cr(H20)5N0] , provided that NO is in excess. This study also confirmedthe previously reported d-d spectrum of this ion. Several e.s.r. studies of chromium nitrosyl complexes containing a variety of other ligands have been reported. The i.r.-polarized spectra of K3[Cr(CN)5N0],2H20 have been determined and the results strongly support the suggestion that the orientation of the anions is disordered. The salts K4[M(CN)5N0] (M = Cr or Mo) appear to be isomorphous and the assignment of the vibrational modes in these ° and related compounds has been discussed. ... 

The condensation chemistry of 2, and is quite similar in that in all systems fragment ions wTll react with the parent neutral to form more complex ions. In the CpMn(C0)3, 1, system, these condensation reactions stop after the formation oT tertiary ions. In contrast, in the chromium nitrosyl,, and thionitrosyl, systems, the tertiary ions are reactive. 

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,... 

Compared to the more extensively studied metal clusters of NO, there are only a handful of examples of monomeric or dimeric nitrosyl complexes undergoing N-O bond dissociation. Cummins and coworkers [117] reported novel in-termolecular NO reductive cleavage reactions of chromium nitrosyl complexes utilizing a highly reactive low-coordinate V htriaryl complex (THF)V(Mes)3 (Mes = 2,4,6-C6H2Me3) as the 0-atom acceptor (Scheme 2.4). 

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