Formation of a trimethyldihydroperimidinium cation from proton sponge [1,8-bis(dimethylamino)naphthalene] during base-promoted reactions of rhodium and ruthenium complexes

Abstract

Proton sponge, in the presence of mer-RhCl3(dmso)3 or [RuCl(dppb)12(p-CI), (dmso = dimethyl sulphoxide, dppb = Ph2P[CH2I4PPh2), generates (via a net hydride loss from one methyl group) the 1 ,I ,3-trimethyl-2,3-dihydroperimidinium cation, which is isolated as the counter-ion in complexes containing the anions tran~-[RhCt~(dmso)~]and { [ Ru CI (d p p b) 12( p-C I )3} -.We reported recently1 on the facile dehydrogenation of triethylamine in the presence of rner-RhC13(dmso)3 (dmso = dimethyl sulphoxide) , with resulting formation of the ylidic enamine complex RhC13(dmso)2(a-CH2CH=NEt2). We now

Transition Metal Complexes with the Proton Sponge 4,9-Dichloroquino[7,8-h]quinoline: Highly Twisted Aromatic Systems and an Extreme “Out-of-Plane” Position of the Coordinated Transition Metal Atom

“…In analogy to related bithiazoles a syn-arrangement of the methyl and the methoxy group was likely. Following the above-mentioned concept we envisioned a Suzuki cross-coupling [6] of the building blocks 2 and 3 as a possible key step for the construction of the carbon skeleton of 1 (Scheme 1). While the vinyl boronic acid 2 was to be derived from the fragements 4 and 5 by a stereoselective aldol reaction, [7] the synthesis of bithiazole 3 was planned starting from 2,4-dibromothiazole (6).…”

“…While the vinyl boronic acid 2 was to be derived from the fragements 4 and 5 by a stereoselective aldol reaction, [7] the synthesis of bithiazole 3 was planned starting from 2,4-dibromothiazole (6). Initial attempts aimed at a cross-coupling of isopropyl zinc chloride with 2,4-dibromothiazole (6) were not promising and delivered only minor quantities of the desired product 7. In contrast, isopropenyl zinc chloride reacted smoothly (96 % yield, Scheme 2).…”

“…[6] Although 1,8-diaminonaphthalene [7,8] is not a proton sponge a few transition metal complexes are known.…”

On the Electronic Structure of NiII Complexes That Feature Chelating Bisguanidine Ligands

“…Indeed, to date just one complex [24] of the archetypical proton sponge 1,8-bis(dimethylamino)naphthalene [25] has been reported. [26] …”

Übergangsmetallkomplexe des Protonenschwammes 4,9-Dichlorchino[7,8-h]chinolin: ein stark gekrümmtes aromatisches System und extreme „Out-of-plane“-Position des Übergangsmetallzentrums

“…Der erste Protonenschwamm, 1,8‐Bis(dimethylamino)naphthalin 2 ,5 ist als Ligand für Metallkomplexe ungeeignet, da die Methylgruppen die Stickstoffatome so abschirmen, dass die zur Komplexbildung erforderliche thermodynamische Stabilität nicht gegeben ist 6. Obwohl 1,8‐Diaminonaphthalin7, 8 kein Protonenschwamm ist, sind hiermit nur wenige Übergangsmetallkomplexe bekannt.…”