Über Metallalkyl‐ und ‐aryl‐Verbindungen, 44 Darstellung und Struktur von Methylnatrium. Strukturbestimmung an NaCD₃‐Pulvern bei 1.5 und 300 K durch Neutronen‐ und Synchrotronstrahlenbeugung

Abstract

Metal Alkyl and Aryl Compounds, 44 1) – Preparation and Structure of Methylsodium. Structure Determination using NaCD, Powders at 1.5 and 300 K by Neutron and Synchrotron Radiation Diffraction [D 3 ]Methylsodium (NaCD 3 ) has been obtained by the reaction of [D 3 ]methyllithium with sodium tert ‐butoxide. Its crystal structure has been determined from NaCD 3 powder samples using the combination of neutron and synchrotron radiation diffraction techniques. Studies at 1.5 and 300 K show a new structure type (orthorhombic, space group I 222, Z 16). Na and C atomic positions have been obtained from synchrotron radiation data and subsequently D positions by neutron diffraction. The complete structure has been refined using Rietveld methods. – Half of the ions are arranged in tetramers, (NaCD 3 ) 4 , similar to those in methyllithium. The orientation of the methanide ions with respect to the three next Na ions is staggered. The remaining 8 Na and 8 methanide ions interconnect the tetramers by Na‐C contacts; their Na ions are arranged in zigzag chains. Thus, the structure of methylsodium shows elements of the methyllithium and methylpotassium structure. All methanide ions are trigonal‐pyramidal with C‐D 109 pm and D‐C‐D angles of 106° (1.5 K). Na‐C distances vary from 253 to 291 pm, depending upon the methyl‐Na orientation. IR data of NaCD 3 are given.