Synthesis and reactivity of N,N-dialkylcarbamato complexes of manganese(II). Crystal and molecular structure of [Mn6(O2CNEt2)12], a hexamer with four five-co-ordinated manganese(II) atoms
Abstract
The compounds [{Mn(O2CNR2)2}n](R = Me, Et, or Pri) have been prepared by treating [Mn(cp)2](cp =η5-C5H5) with CO2–NHR2 in organic solvents. These reactions may possibly involve the addition compound [Mn(cp)2]·NHR2. In the case of R = Et, the adduct has been isolated and characterized, and the space group, crystal data, and metal connectivity established. The structure of the N,N-diethylcarbamato complex has been solved by X-ray diffraction. Crystal data: monoclinic, space group C2/c, a= 18.546(3), b= 19.287(3), c= 24.877(3)Å, β= 95.38(2)°, R= 0.078. It consists of hexameric units [Mn6(O2CNEt2)12], containing four five-co-ordinated Mn atoms, joined by bridging carbamato ligands. It was found to be unreactive towards nucleophiles, while by reaction with [{Ti(cp)2Cl}2] the new complex [Ti(cp)2(O2CNEt2)] has been obtained. Organic electrophiles react regioselectively at the oxygen or at the nitrogen atom of the carbamato ligand of the manganese complexes, and in the former case the CO2 fragment is retained in the reaction products.