Thermally stable lead(II) amidinates and guanidinates

The reactions of lithium amidinates and guanidinates [Li(Fiso)] (Fiso = N, N'-bis(2,6-diisopropylphenyl) formamidinate), [Li(Piso)] (Piso = N, N'-bis(2,6-diisopropylphenyl)( tert-butyl) amidinate), [Li(CyG)] (CyG = N, N ''-bis(2,6-diisopropylphenyl)-N', N'-dicyclohexylguanidinate) and [Li(HDG)] (HDG = N, N ''-bis(2,6-diisopropylphenyl)-N'-(2,6diisopropylphenyl) guanidinate) with anhydrous PbCl(2) in THF afforded the amidinate complexes [Pb(Fiso)(2)] 1, and [Pb(Piso)Cl](2) 2, and the guanidinate complexes [Pb(CyG)Cl](2) 3, and [Pb(HDG)Cl](2) 4 in moderate yields. The complexes are thermally stable, 2, 3 and 4 decompose between 163-202 degrees C whilst 1 melts with decomposition to lead metal at 310 degrees C. 2, 3 and 4 are unsymmetrical dimers in the solid state but their NMR data suggested fluxional behaviour in solution. Storing the yellow crystals of [Pb(CyG)Cl](2) 3 for one week in the perfluorinated crystallography oil under air resulted in oxygen incorporation into one isopropyl group of the CyG ligand giving a mixed amidinate-alkoxide dianion (CyGO) and afforded some new colourless crystals of [(CyGO) Pb](2) 5 that were characterised by a X-ray single crystal structure determination

Synthesis and characterisation of bulky guanidines and phosphaguanidines: precursors for low oxidation state metallacycles

Reactions of alkali metal amides or phosphides with the bulky carbodiimide, ArN[double bond, length as m-dash]C[double bond, length as m-dash]NAr (Ar = C6H3Pri2-2,6), followed by aqueous work-ups, have yielded several guanidines, ArNC(NR2)N(H)Ar (R = cyclohexyl (GisoH) or Pri (PrisoH); NR2 = cis-NC5H8Me2-2,6 (PipisoH)), a bifunctional guanidine, {ArNCN(H)Ar}2{µ-N(C2H4)2N} (Pip(GisoH)2), and two phosphaguanidines, ArNC(PR2)N(H)Ar (R = cyclohexyl (CyP-GisoH) or Ph (PhP-GisoH)). A very bulky guanidine, ArNC{N(Ar)SiMe3}N(H)Ar (ArSi-Giso), and an aryl coupled bifunctional guanidine, {ArN(H)C(NPri2)NC6H2Pri2-2,6-}2 (PrisoH)2, have been prepared by other routes. All compounds have been crystallographically characterised and shown to exist in a number of isomeric forms in the solid state. These appear to be largely retained in solution. The deprotonation of GisoH with BunLi in either hexane or THF led to crystallographically characterised dimeric and monomeric complexes respectively, viz. [Li{Li(κ2-N,N'-Giso)2}] and [Li(THF)(η1-N,η3-Ar-Giso)]. Deprotonation of PrisoH and Pip(GisoH)2 with K[N(SiMe3)2] gave the unsolvated polymer, [{K(η1-N,η6-Ar-Priso)}∞], and the solvated complex, [{K(THF)2}{Pip(Giso)2}{K(THF)3}], respectively

Charge-separated and molecular heterobimetallic rare earth-rare earth and alkaline earth-rare earth aryloxo complexes featuring intramolecular metal-pi-arene interactions

A new family in town! Treatment of a rare-earth metal (Ln) and either a potential divalent rare-earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200–250 °C) afforded heterobimetallic aryloxo complexes (see figure). Both a charge-separated species, [(Ln'/Ae)2(Odpp)3][Ln(Odpp)4], and a neutral species, [AeEu(Odpp)4], were obtained and crystallographically characterised. Treatment of a rare earth metal (Ln) and a potential divalent rare earth metal (Ln') or an alkaline earth metal (Ae) with 2,6-diphenylphenol (HOdpp) at elevated temperatures (200–250 °C) afforded heterobimetallic aryloxo complexes, which were structurally characterised. A charge-separated species [(Ln'/Ae)2(Odpp)3][Ln(Odpp)4] was obtained for a range of metals, demonstrating the similarities between the chemistry of the divalent rare earth metals and the alkaline earth metals. The [(Ln'/Ae)2(Odpp)3]+ cation in the heterobimetallic structures is unusual in that it consists solely of bridging aryloxide ligands. A molecular heterobimetallic species [AeEu(Odpp)4] (Ae=Ca, Sr, Ba) was obtained by treating an alkaline earth metal and Eu metal with HOdpp at elevated temperatures. Similarly, [BaSr(Odpp)4] was prepared by treating Ba metal and Sr metal with HOdpp. Treatment of [Ba2(Odpp)4] with [Mg(Odpp)2(thf)2] in toluene afforded [Ba2(Odpp)3][Mg(Odpp)3(thf)]. Analogous solution-based syntheses were not possible for [(Ln'/Ae)2(Odpp)3][Ln(Odpp)4] complexes, for which the free-metal route was essential. As a result of the absence of additional donor ligands, the crystal structures of the heterobimetallic complexes feature extensive π-Ph–metal interactions involving the pendant phenyl groups of the Odpp ligands, thus enabling the large electropositive metal atoms to attain coordination saturation. The charge-separated heterobimetallic species were purified by extraction with toluene/thf mixtures at ambient temperature (Ba-containing compounds) or by extraction with toluene under pressure above the boiling point of the solvent (other products). In donor solvents, heterobimetallic complexes other than those containing barium were found to fragment into homometallic species

Aluminum and indium complexes derived from guanidines, triazenes, and amidines (dataset)

CCDC 882991-883001 CCDC 1406713-140671