Related Derivatives of the Group

Diheteroferrocenes and Related Derivatives of the Group 15 Elements Arsenic, Antimony, and Bismuth... 

A. J. Ashe III, and S. Al-Ahmad, Diheteroferrocenes and Related Derivatives of the Group 15 Elements Arsenic, Antimony, and Bismuth, Adv. Organomet. Chem. 39, 325-353 (1996). 

Neopentyl and related derivatives of the group-VIII transition metals in low oxidation states favor such a rearrangement (sometimes called y elimination), affording 3,3 -disubstituted metallacyclobutanes the reaction is less available earlier transition-metal analogsThis is an important route to metallacyclobutane, isolable examples of which are still relatively rare, but which are of great interest as reaction intermediates... 

Tetracycline antibiotics are closely related derivatives of the polycyclic naphtha-cenecarboxamide. They are amphoteric compounds with characteristic dissociation constants corresponding to the acidic hydroxyl group at position 3 (pK about 3.3), die dimethylamino group at position 4 (pK, about 7.5), and the hydroxyl group at position 12 (pK about 9.4). In aqueous solutions of pH 4-7, tetracyclines exist as dipolar ions, but as the pH increases to 8-9 marked dissociation of the dimethylamine cation occurs. They are soluble in acids, bases, and alcohols but are quite insoluble in organic solvents such as chloroform. Their ultraviolet spectra show strong absorption at around 270 and 360 nm in neutral and acidic solutions. Tetracyclines are readily transformed into fluorescent products in the presence of metal ions or under alkaline conditions. 

It is perhaps inopportune to elaborate on the nomenclature, but some of the data reported for the tantalum ylide indicate that there may be a fundamental difference between this transition metal compound and the formally related ylides of the Group Yb elements. The most significant discrepancy is found with the 13C NMR shift of the carbene/ylide carbon atoms, which typically is downfield for the Va element, but upheld for the Vb element derivatives. Ylidic carbon atoms may, therefore, possibly bear a much higher negative charge. 

In this chapter substitution, dissociation, and association reactions of compounds of the non-metals will be covered. Such intramolecular processes - inversion, restricted rotation about bonds - as are of inorganic rather than primarily of organic interest will also be mentioned. Simple compounds and organometallic derivatives of the Group III and Group IV metals are also included here rather than in Chapters 2—4 since their chemistry is so closely related to the non-metallic members of these Groups. Elements are arranged in Periodic Table order. 

Intramolecular chalcogen interactions may also stabilize reactive functional groups enabling the isolation of otherwise unstable species or their use as transient intermediates, especially in the case of selenium and tellurium. For example, tellurium(II) compounds of the type ArTeCl are unstable with respect to disproportionation in the absence of such interactions. The diazene derivative 15.23 is stabilized by a Te N interaction. Presumably, intramolecular coordination hinders the disproportionation process. Other derivatives of the type RTeX that are stabilized by a Te N interaction include 8-(dimethylamino)-l-(naphthyl)tellurium bromide, 2-(bromotelluro)-A-(p-tolyl)benzylamine, and 2-[(dimethylammo)methyl]phenyltellunum iodide. Intramolecular donation from a nitrogen donor can also be used to stabilize the Se-I functionality in related compounds." ... 

In the Lossen reaction a hydroxamic acid derivative (usually an 0-acyl derivative) is deprotonated by base, and rearranges via migration of the group R to give an isocyanate 2. Under the usual reaction conditions—i.e. aqueous alkaline solution—the isocyanate reacts further to yield the amine 3. The Lossen reaction is closely related to the Hofmann rearrangement and the Curtins reaction. 

X-Ray structures have been determined for at least one derivative for each of the group 15 1,1 -diheteroferrocenes. These compounds include dibismaferrocene 3212 distibaferrocenes 29,10 48,19 and 5521a diarsaferro-cenes 2625 and 4419 and diphosphaferrocene 79.28 In addition, structures29 have been determined for the closely related bismaferrocene 70,30 phos-phaferrocenes 80 and 81,31 arsacymantrene 74,32 and phosphacymantrene... 

By using combinations of hydrogenation and dehydrogenation reactions it has been possible to obtain nickel derivatives of the Curtis macrocycle containing from zero to four imine groups (Curtis, 1968 1974). Related reactions in the presence of a variety of other central metal ions have been described. The electrochemical oxidation of the Cu(ii) complex of the reduced Curtis ligand proceeds initially via a two-electron step to yield the monoimine complex (296) (Olson Vasilevskis, 1971). 

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