Chromium complexes 2,2 :6 ,2"-terpyridyl

Since complexes of 2,2 -bipyridyl and 1,10-phenanthroline with chromium in oxidation states I and 0 can be obtained by reduction (Scheme 64) of the chromium(n) complexes, these oxidation states will be considered together. Oxidation, as shown in Schemes 65 and 68 of Section 35.4.2.5, gives chromium(III) complexes, which are often best prepared in this way. Earlier work has been extensively reviewed, and few complexes of 2,2 6, 2"-terpyridyl are known.32 A chromium(I) phthalocyanine derivative is mentioned in Section 35.4.9.3. 

Chromium(II) complexes of bipyridyls, terpyridyl and the phenanthrolines have been discussed in Section 35.2.2.1. Complexes of the ligands 2-aminomethylpyridine (pic, 2-picolyl-amine) and 8-aminoquinoline (amq), which have one heterocyclic and one amino nitrogen donor atom, have been prepared by methods similar to those in Scheme 10. The bis(amine) complexes are typical high-spin, distorted octahedral complexes, and the mono(amine) complexes, from their antiferromagnetic behaviour and reflectance spectra, are six-coordinate, halide-bridged polymers (Table 15).103 No tris(amine) complexes could be prepared so the attempt to find spin isomeric systems in octahedral chromium(II) systems was unsuccessful ([Cr(en)3]X2 are high-spin and [Cr(bipy)3]X3 and [CrX2(bipy)2] low-spin). 

Ferrocenyl ligands, via zinc reagents, 9, 120 Ferrocenylmethyl phosphonium salts, with gold(I), 2, 274 Ferrocenylmonophosphine, in styrene asymmetric hydrosilylation, 10, 817 Ferrocenyl oxazolines, synthesis, 6, 202 Ferrocenylphosphines with chromium carbonyls, 5, 219 in 1,3-diene asymmetric hydrosilylation, 10, 824-826 preparation, 6, 197 various complexes, 6, 201 Ferrocenylselenolates, preparation, 6, 188 Ferrocenyl-substituted anthracenes, preparation, 6, 189 Ferrocenyl terpyridyl compounds, phenyl-spaced, preparation 6, 188 Ferrocifens... 

Linkage isomerism has been the subject of several reviews. - Much recent work has dealt with nitro-nitrite isomerizationlO and thiocyanate-isothiocyanate isomerization.11 12 Examples of linkage isomerism involving cyanate, methanesulfinate, terpyridyl, alizarin, dihydroxybenzoate, and acetone complexes have been reported also. Some additional examples are discussed in paragraphs that follow. Thus, the rate of M-CN/M-NC linkage isomerization at chromium has been studied, Eq. 11.1. 

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