Methanediide complexes

Scheme 25 Synthesis of the Sm methanediide complex 38. Reproduced from [87] with permission of American Chemical Society...

As no reactivity studies of 38 were reported, facile and general routes to [Ln(BIPM ) (R)] complexes were required and this was addressed by the syntheses of [Y(BIPM ) (CH SiMejjCTHF)] (39), [Y(BlPMrws)(CHjPh)(THF)] (40) and [Y(BIPM s)(I)(THF)J (41) from yttrium alkyl precursors at room temperature (Scheme 27) [90], It was shown that 41 could alternatively be synthesized by deprotonation of [Y(BIPM H) (IfjfTHF)] with benzyl potassium [91]. These synthetic techniques have since been employed to synthesize a wide range of Ln methanediide complexes and this area has been reviewed thoroughly [85]. Computational studies on 39-41 revealed as expected localized electron density at the methanediide centers corresponding to approximately two lone pairs of electrons in frontier orbitals that do not interact appreciably with vacant Y orbitals (<5 % Y orbital contribution) [90]. The Y—C distances in... 

Scheme 6 Synthesis of calcium and barium methanediide complexes...

Both routes A and B have been used. Route A was mostly used for bis (thiophosphinoyl)methanediide complexes (ligand 7 ), whereas route B was... 

Reactivity studies on other rare earth methanediide complexes are scarce. Complex [(8a)Nd(8aH)] showed some activity in ring-opening polymerization of rac-lactide [69]. Scandium carbene complex [(7)ScCl(Py)2] has been used as a ligand transfer reagent for the synthesis of a new dimeric, dimetalhc iron complex featuring two bridging methanediide ligands (Scheme 18) [70]. 

Scheme 26 Reactivity studies performed on bis(iminophosphoranyl)methanediide and bis (thiophosphinoyl)methanediide complexes of U(IV), U(V), and U(VI)...

Scheme 28 Group 4 metal complexes synthesized following route B and various titanium bis (thiophosphinoyl)methanediide complexes obtained following route A...

Chart 5 Two gem-dialuminum methanediide complexes obtained from the reaction of diphenyl(N-tert-butyl)... 

It is worth to notice that those complexes are the first group 13 methanediide complex featuring a dianionic carbon interacting with one sole metal atom and the first indium and gallium methanediide complexes. 

Two kinds of reactivity have been explored to date, essentially by Cavell on spirocyclic dimetallic bis(diphenyliminophosphoranyl)methanediide complexes [(6)(AIR2)2]. BimetalUc compound [( XAIMe ] was proved to react stoechiome-tricaUy with heteroaUenes to afford the bimetallic bicyclic compounds [ ALJ and [AI5] [105] (Eq. (4)). 

Most classical hypervalent phosphoms-stabilized methanediide complexes of germanium [111, 112], tin, and lead [113] in their (+11) oxidation state are usually synthesized following either route B or intermediate route C. Most of the tin and lead complexes resulting from either route are dimeric, cyclic dimetalacyclobutanes, regardless of the steric bulkiness of the ligand (Scheme 35). 

Despite potential undesired redox reactivity, route A was used for the successful synthesis of the first 2-germaallene or bis-methanediide complex by So et al. [121] starting from the high-valent GeCl4 precursor and 7Li2, generated in situ (Eq. (7)). 

Scheme 38 Reactivity of dimeric tin l,3-benzobis(thiophosphinoyI)methanediide complex toward group 12, 13, and 14 compounds...

Leung W-P, Wan C-L, Mak TCW (2010) Synthesis and structure of magnesium and group 13 metal bis(thiophosphinoyl)methanediide complexes. Organranetallics 29 1622-1628. doi 10.1021/oml00019c... 

Wooles AJ, Cooper OJ, Mcmaster J, Lewis W, Blake AJ, Liddle ST (2010) Synthesis and characterization of dysprosium and lanthanum bis (iminophosphorano) methanide and -methanediide complexes. Organometallics 29 2315-2321. doi 10.1021/oml00104s... 

Kamalesh Babu RP, McDonald R, Cavell RG (2000) Nucleophilic reactivity of the multiply bonded carbon center in group 4 — pincer bis(iminophosphorano)methanediide complexes. Organometallics 19 3462-3465. doi 10.1021/om(X)0181d... 

Apama K, Mcdonald R, Ferguson M, Cavell RG (1999) Novel dialkyl aluminum bis (iminophosphorano) methanide and methanediide complexes. Organometallics 18 4241-4243. doi 10.1021/om990486w... 

Guo J-Y, Li Y, Ganguly R, So C-W (2012) Reactivity of a Tin(II) (iminophosphinoyl) (thiophosphinoyl)methanediide complex toward isocyanates and rhodium(I) chloride. Organ-ometallics 31 3888-3893. doi 10.1021/om300062n... 

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