Search for: All records

The 2.2.2-cryptand ligand (crypt) that is heavily used in reductions of rare-earth metal complexes to encapsulate alkali metals has been found to function as a bidentate ligand to rare-earth metal ions in some cases. The X-ray crystal structures of the reduced dinitrogen metal complex, [{(R 2 N) 2 Ce(crypt-κ 2 -O,O′)} 2 (μ–η 2 :η 2 -N 2 )] (R = SiMe 3 ), and the ytterbium metallocene, (C 5 Me 5 ) 2 Yb(crypt-κ 2 -O,O′), are presented to demonstrate this binding mode. The implications of this available binding mode in rare-earth metal cryptand chemistry are discussed.

N , N ′-Di- tert -butylcarbodiimide, Me 3 CN=C=NCMe 3 , undergoes reductive cleavage in the presence of the Gd II complex, [K(18-crown-6) 2 ][Gd II (N R 2 ) 3 ] ( R = SiMe 3 ), to form a new type of ligand, the tert -butylcyanamide anion, (Me 3 CNCN) − . This new ligand can bind metals with one or two donor atoms as demonstrated by the isolation of a single crystal containing potassium salts of both end-on and side-on bound tert -butylcyanamide anions, (Me 3 CNCN) − . The crystal contains [K(18-crown-6)(H 2 O)][NCNCMe 3 - kN ], in which one ( t BuNCN) − anion is coordinated end-on to potassium ligated by 18-crown-6 and water, as well as [K(18-crown-6)][η 2 -NCNCMe 3 ], in which an 18-crown-6 potassium is coordinated side-on to the terminal N—C linkage. This single crystal also contains one equivalent of 1,3-di- tert -butyl urea, (C 9 H 20 N 2 O), which is involved in hydrogen bonding that may stabilize the whole assembly, namely, aqua( tert -butylcyanamidato)(1,4,7,10,13,16-hexaoxacyclooctadecane)potassium(I)–( tert -butylcyanamidato)(1,4,7,10,13,16-hexaoxacyclooctadecane)potassium(I)– N , N ′-di- tert -butylcarbodiimide (1/1/1) [K(C 5 H 9 N 2 )(C 12 H 24 O 6 )]·[K(C 5 Hmore »9 N 2 )(C 12 H 24 O 6 )(H 2 O)]·C 9 H 20 N 2 .« less