A general synthetic route to fully N-alkylated azamacrocycles, and an uncommon geometry for a six-coordinate nickel(II) complex of 1,4,8,11-tetrapropyl-1,4,8,11-tetraazacyclotetradecane (L1). Crystal structure of trans-(R,S,R,S)-[Ni(L1)(NCS)2]

Abstract

A two-step route to a range of fully N-alkylated azamacrocycles has been developed; the crystal structure of tran~-[Ni(Ll)(NCS)~] (L1 = 1,4,8,1 l-tetrapropyl-l,4,8,1 I -tetraazacyclotetradecane) shows the nickel(ii) to be sixcoordinate, but with the uncommon (R,S,R,S)-or trans-(1)-set of N-configurations.Although a few tetra-N-alkyl derivatives of 1,4,8,11-tetraazacyclotetradecane (cyclam) such as L2-L4 have been known for some time,1-4 a convenient synthetic route to a wider range of simple N-alkylated azamacrocycles (e.g. cyclam with R = ethyl, propyl, butyl . . .) has not been reported. Such ligands

Structure, Magnetic Properties and Magnetic Phase Diagram of a Layered, Bimetallic, Cyanide-Bridged CrIII-NiII Metamagnet

“…Indeed, the apical NiϪN bond lengths are shorter for trans-[Ni(tetrapropylcyclam)(NCS) 2 ] than for trans-[Ni(cylam)(NCS). [38,39] The same tendency is observed when comparing the data of the present compound to those of the previously reported cyclam analogue. The shortest NiϪN bond length is found for nitrogen atoms belonging to the organic macrocycle [NiϪN ϭ 2.06(2) Å ] for the cyclam analogue, while for the present compound the apical NiϪN bond length is found to be the shortest.…”

A New Robust and Versatile Tetradentate Linker for Amides To be Cleaved under Mild Conditions by Unusual Complexation of the Amide Nitrogen to Cu++

“…[10] Reductive amination with N-Boc-ethylenediamine and sodium triacetoxyborohydride in 1,2-dichloroethane (DCE) gave secondary amine 17 in a yield of 73 %. [7] This was transformed into compound 18 in 75 % yield by alkylation with 1-bromopropane and DIEA in CH 3 CN. Boc deprotection with TFA/CH 2 Cl 2 (1:1) to free amine 19 was followed by reductive amination with pyridine-2-carboxaldehyde under the conditions that were applied to the first reductive amination procedure.…”

“…Such over-alkylations of the secondary amino groups in azamacrocycles are already reported in the literature. [7] A reductive amination with propionaldehyde and sodium triacetoxy borohydride [8] resulted in desired product 9b although only in a moderate yield of 37 %. An alternative alkylation with npropyl bromide in the presence of N,N-diisopropylethyl-amine (DIEA) afforded desired product 9b in a yield of 69 %.…”

Metal Complexes with Macrocyclic Ligands. PartXLV Axial coordination tendency in reinforced tetraazamacrocyclic complexes

“…SMe, (Scheme). This method has previously proved to be superior than the direct alkylation in the synthesis of tetra-N-alkylated derivates of 1,4,8,1l-tetraazacyclotetradecane [8] [19]. Mixing the ligands with the corresponding Cu2+ and Ni2+ salts gives the metal complexes, except for 2 and 3 which do not or only partially react with Ni2+.…”