Amino‐Substituted Ferra‐bis(tricarbollides) − Metallatricarbaboranes Designed for Linear Molecular Constructions

Abstract

Abstract Reactions between high purity FeCl 2 and the anion [ nido ‐7‐( t BuHN)‐7,8,9‐C 3 B 8 H 10 )] − ( 1 − ) have been used for efficient syntheses of the twelve‐vertex double‐cluster metallatricarbollide complexes of the para , para ( p , p ) type [ closo ‐9,9′(RHN) 2 ‐ commo ‐2,2′‐Fe II ‐1,7,9‐(C 3 B 8 H 10 )‐1′,7′,9′‐(C 3 B 8 H 10 )] ( 2 ) ( 2a , R = t Bu and 2b , R = H) (yields 42−45% for 2a ). Compound 2b , which contains two reactive amino substituents conveniently attached to the tricarbollide subclusters in p ‐positions with respect to the metal center, was prepared via facile cleavage of the t Bu substituent in 2a either by AlCl 3 or by thermal means. The structure of 2b constitutes a good setting for the synthesis of building blocks for constructing linear metallatricarbollide rods of high stability. Two isomeric compounds of the para , meta ( p , m ) type 3 , [ closo ‐9,10′‐(RHN) 2 ‐ commo ‐2,2′‐Fe‐1,7,9‐(C 3 B 8 H 10 )‐1′,7′,10′‐(C 3 B 8 H 10 )] (where R = t Bu 3a and/or H 3b ), were isolated in smaller yields from reactions of high purity FeCl 2 with 1 − at higher temperatures. Also reported is the characterization of the m , m ‐type complex, [ closo ‐10,10′‐( t BuHN) 2 ‐ commo ‐2,2′‐Fe II ‐1,7,10‐(C 3 B 8 H 10 )‐1′,7′,10′‐(C 3 B 8 H 10 )] ( 4a ), and the two zwitterionic species of the new 7‐L‐7,8,10‐C 3 B 8 H 10 type ( 6 ) [L = Me 3 N 6a and t Bu(Me)HN 6b ] isolated in moderate yields from the reaction of reagent grade FeCl 2 with 1 − . The molecular structures of 2b , 3a , and 6b were determined by single‐crystal X‐ray diffraction studies. Multinuclear ( 1 H and 11 B), two‐dimensional [ 11 B‐ 11 B]‐COSY, and 1 H{ 11 B(selective)} magnetic resonance measurements enabled complete assignments of all resonances for all compounds and are in excellent agreement with the structures proposed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)