Divalent derivatives

Carbenes are neutral divalent derivatives of carbon. Carbenes can be included with carbanions, carbocations, and carbon-centered radicals as among the fundamental intermediates in the reactions of carbon compounds. Depending on whether the nonbonding electrons are of the same of opposite spin, they can be triplet or singlet species. 

Molybdenum trioxide, intercalation into, 12, 823 Molybdocenes, as anticancer agents, 1, 892 MOMNs, see Metal-organometallic coordination networks Monisocyanides, with silver(I) complexes, 2, 223 Monitoring methods, kinetic studies, 1, 513 Mono(acetylacetonate) complexes, with Ru and Os halfsandwich rf-arenes, 6, 523 tj2-Monoalkene monodentate ligands, with platinum divalent derivatives, 8, 617 tetravalent derivatives, 8, 625 theoretical studies, 8, 625 zerovalent derivatives, 8, 612... 

The carborane derivatives MC2B9Hn (M = Ge, Sn, Pb) (63), and bis(2-phenyl-l,2-dicarba-c/oso-dodecaborane(12-l-yl)tin(II) (64) were the first bona fide divalent derivatives of tin and lead containing tr-bonds to carbon. The proposed structures for the former compounds are shown in Fig. 7. 

Phenylselenosilanes reduce the oxides Ph2MO (M = S, Se, Te) and other functionally substituted sulphoxides to the divalent derivatives and are oxidised by halogens (equation 64). They substitute the trichlorides MC13 (M = B, P, As), readily substitute ally acetate in the presence of Znl2 and bromoethane with 18-crown-6 and KF (equation 65)58,59. 

In addition to the usual divalent molecules and solids, for example, Ca(OH)2, and the monovalent molecules, for example, CaOH, a third type of molecule has been predicted by Kong and Boyd [13], They calculate that the H—Ca—O isomer of CaOH is a minimum on the potential energy surface, The H—Ca—O molecule is, in fact, a divalent derivative of Ca with an ionic electron distribution, H Ca2 + 0. Perhaps the ultraviolet (UV) photochemical isomerization of CaOH in a rare gas matrix will yield HCaO. 

This section refers to mononuclear complexes with ligands having, in addition to a single 77 -alkene interaction, one (or more) additional donor atoms linked to the metal center. Most of the complexes reported are divalent derivatives. 

Samarium(II) in Sml2(THF)2 is oxidized to Sm(III) when reacts with Co2(CO)g yielding l2SmCo(CO)4(THF)5 [54]. However, the reactions of Sml2 and Ybl2 with T1[Co(CO) 4] result in the divalent derivatives ILnCo(CO)4 [47]. 

Since these early times many new preparations of Yb " and Sm + derivatives have been devised. The main techniques involve the reduction of a trivalent salt by any of several kinds of reagents including the lanthanide metal. Another class of syntheses involves metathesis which allows the transformation of one divalent compound into another. Some methods require quite vigorous conditions but gentle techniques are also available. The reaction conditions are important to define because some divalent derivatives are stable only for a given set of experimental conditions. 

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