skip to main content

Explore Research Products in the NSF-PAR

Title: Correlating magnetic anisotropy with [Mo(CN) 7 ] 4− geometry of Mn II –Mo III magnetic frameworks
Four new three-dimensional (3-D) coordination frameworks based on the heptacyanomolybdate( iii ) anion were prepared and characterised by magnetic measurements: {[Mn II (imH) 2 ] 2 [Mn II (H 2 O)(imH) 3 ][Mn II (imH) 4 ] [Mo III (CN) 7 ] 2 ·6H 2 O} n ( 1 ) (imH = imidazole), {[Mn II (H 2 O) 2 (imH)] 3 [Mn II (H 2 O)(imH) 2 ][Mo III (CN) 7 ] 2 ·5H 2 O} n ( 2 ), {[Mn II (Htrz)(H 2 O) 2 ][Mn II (Htrz) 0.7 (H 2 O) 2.3 ][Mo III (CN) 7 ]·5.6H 2 O} n ( 3 ) (Htrz = 1,2,4-triazole) and {[Mn II (H 2 O) 2 ] 3 [Mn II (H 2 O) 4 ][Mo III (CN) 7 ] 2 ·6H 2 O·2urea} n ( 4 ). All four compounds exhibit long-range ferrimagnetic ordering and exhibit an opening of their magnetic hysteresis loops at 1.8 K; 1 and 2 exhibit the highest coercive fields among all known [Mo III (CN) 7 ]-based assemblies, 5000 and 4500 Oe respectively. The coercivity of 1–4 is correlated with the geometry of the heptacyanomolybdate( iii ) anion and the cyanide bridging pattern. A paramagnetic analogue of compound 1 , {[Mn II (imH) 2 ] 2 [Mn II (H 2 O)(imH) 3 ][Mn II (imH) 4 ][Re III (CN) 7 ] 2 ·6H 2 O} n ( 1Re ), where the heptacyanomolybdate( iii ) anion is substituted by the diamagnetic heptacyanorhenate( iii ) anion is also reported which constitutes the first example of a coordination framework based on [Re III (CN) 7 ] 4− .  more » « less
Award ID(s):
1808779
NSF-PAR ID:
10108460
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Dalton Transactions
ISSN:
1477-9226
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ( , Acta Crystallographica Section E Crystallographic Communications)
    The investigation of the coordination chemistry of rare-earth metal complexes with cyanide ligands led to the isolation and crystallographic characterization of the Ln III cyanotriphenylborate complexes dichlorido(cyanotriphenylborato-κ N )tetrakis(tetrahydrofuran-κ O )lanthanide(III), [ Ln Cl 2 (C 19 H 15 BN)(C 4 H 8 O) 4 ] [lanthanide ( Ln ) = dysprosium (Dy) and yttrium Y)] from reactions of LnCl 3 , KCN, and NaBPh 4 . Attempts to independently synthesize the tetraethylammonium salt of (NCBPh 3 ) − from BPh 3 and [NEt 4 ][CN] in THF yielded crystals of the phenyl-substituted cyclic borate, tetraethylazanium 2,2,4,6-tetraphenyl-1,3,5,2λ 4 ,4,6-trioxatriborinan-2-ide, C 8 H 20 N + ·C 24 H 20 B 3 O 3 − or [NEt 4 ][B 3 (μ-O) 3 (C 6 H 5 ) 4 ]. The mechanochemical reaction of BPh 3 and [NEt 4 ][CN] without solvent produced crystals of tetraethylazanium cyanodiphenyl-λ 4 -boranyl diphenylborinate, C 8 H 20 N + ·C 25 H 20 B 2 NO − or [NEt 4 ][NCBPh 2 (μ-O)BPh 2 ]. Reaction of BPh 3 and KCN in THF in the presence of 2.2.2-cryptand (crypt) led to a crystal of bis[(2.2.2-cryptand)potassium] 2,2,4,6-tetraphenyl-1,3,5,2λ 4 ,4,6-trioxatriborinan-2-ide cyanomethyldiphenylborate tetrahydrofuran disolvate, 2C 18 H 36 KN 2 O 6 + ·C 24 H 20 B 3 O 3 − ·C 14 H 13 BN − ·2C 4 H 8 O or [K(crypt)] 2 [B 3 (μ-O) 3 (C 6 H 5 ) 4 ][NCBPh 2 Me]·2THF. The [NCBPh 2 (μ-O)BPh 2 ] 1− and (NCBPh 2 Me) 1− anions have not been structurally characterized previously. The structure of 1-Y was refined as a two-component twin with occupancy factors 0.513 (1) and 0.487 (1). In 4 , one solvent molecule was disordered and included using multiple components with partial site-occupancy factors. 
    more » « less
  2. ; ; ; ; ; ; ; ; ; ; et al ( , New Journal of Chemistry)
    Reactions of the bicompartmental bis(phenolato) compound 6,6′-methylenebis(2-((bis(pyridin-2-ylmethyl)amino)methyl)-4-chlorophenol)hemihydrate (H 2 L ½H 2 O) with 3d metal( ii ) ions afforded novel fully structurally characterized bridged acetato dinuclear complexes [Mn 2 (HL)(μ 1,2 -OAc) 2 ]PF 6 (1) [Zn 2 (HL)(μ 1,2 -OAc)(H 2 O) 0.75 (MeOH) 0.25 ](PF 6 ) 2 ·0.45(H 2 O) (5) and [Cd 2 (HL)(μ 1,1,2 -OAc)(OAc)(H 2 O)]PF 6 ·H 2 O (6) as well as the polymeric bridged-azido tetranuclear catena -[Cu 4 (HL) 2 (μ 1,1 -N 3 ) 2 (μ 1,3 -N 3 ) 2 ](NO 3 ) 2 ·5H 2 O (4). The complex [Cu 4 (HL) 2 (ClO 4 ) 3 (H 2 O) 5 ](ClO 4 ) 3 ·5H 2 O (2) was partially characterized. In addition, three more dinuclear complexes [Cu 2 (H 2 L)(NO 3 ) 2 (H 2 O) 2 ](NO 3 ) 2 (3), [Cu 2 (HL)(OAc)(CH 3 OH)](PF 6 ) 2 (7) and [Cu 2 (HL)(NCS) 2 ]NO 3 ·2H 2 O (8) were also isolated. All complexes were characterized by CHN elemental analysis, IR and UV-Vis spectroscopy, ESI-MS, conductivity measurements and X-ray single crystal crystallography for compounds 1, 4, 5 and 6, where the bis(phenolato) ligand displayed different deprotonation (H 2 L, HL − and L 2− ). The magnetic susceptibility measurements over the temperature range 2–300 K revealed very weak antiferromagnetic coupling in dimanganese( ii ) 1 ( J = −1.64(1) cm −1 ) and almost negligible magnetic interaction in dicopper( ii ) 2 ( J = 0(3) cm −1 ). In the azido catena -[Cu 4 (HL) 2 (μ 1,1 -N 3 ) 2 (μ 1,3 -N 3 ) 2 ](NO 3 ) 2 ·5H 2 O (4) complex, the J value of −133(3) cm −1 was obtained upon moderate-to-strong antiferromagnetic coupling through the di-μ 1,3 -N 3 -bridged dicopper( ii ) unit with no magnetic interaction between the two copper( ii ) ions in the di-μ 1,1 -N 3 -bridged unit. 
    more » « less
  3. ; ; ; ; ; ( , Dalton Transactions)
    We report the syntheses and magnetic property characterizations of four mononuclear cobalt( ii ) complex salts featuring a tripodal iminopyridine ligand with external anion receptor groups, [CoL 5-ONHtBu ]X 2 (X = Cl ( 1 ), Br ( 2 ), I ( 3 ) and ClO 4 ( 4 )). While all four salts exhibit anion binding through pendant amide moieties, only in the case of 1 is field-induced slow relaxation of magnetisation observed, whereas in the other salts this phenomenon is absent at the limits of our instrumentation. The effect of chloride inducing a seventh Co–N interaction and concomitant structural distortion is hypothesized as the origin of the observed dynamic magnetic properties observed in 1 . Ab initio computational studies carried out on a 7-coordinate Co( ii ) model species survey the complex interplay of coordination number and trigonal twisting on the sign and magnitude of the axial anisotropy parameter ( D ), and identify structural features whose distortions can trigger large switches in the sign and magnitude of magnetic anisotropy. 
    more » « less
  4. ; ; ( , Acta Crystallographica Section E Crystallographic Communications)
    null (Ed.)
    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 H 9 N 2 )(C 12 H 24 O 6 )(H 2 O)]·C 9 H 20 N 2 . 
    more » « less
  5. ; ; ; ; ; ; ; ( , Journal of Materials Chemistry C)
    Planar MO 3 (M = B, C, N) units have frequently been considered important structural components of novel birefringent crystal materials. An efficient approach for constructing new functional crystals is to simultaneously assemble multiple structural motifs together. Two compounds, Na 3 Rb 6 (CO 3 ) 3 (NO 3 ) 2 X·6H 2 O (X = Br and Cl), were synthesized by the integration of three kinds of anionic groups. More interestingly, the [CO 3 ] 2− and [NO 3 ] − groups in Na 3 Rb 6 (CO 3 ) 3 (NO 3 ) 2 X·6H 2 O are all coplanar with the aid of [NaO 7 ] 13− polyhedra, which can enhance the anisotropic polarizability. Na 3 Rb 6 (CO 3 ) 3 (NO 3 ) 2 X·6H 2 O have a large theoretical birefringence of ∼0.165 at 1064 nm and possess a short UV cut-off edge of ∼230 nm. Additionally, the two compounds exhibit good crystal growth habits. These properties illustrate that Na 3 Rb 6 (CO 3 ) 3 (NO 3 ) 2 X·6H 2 O are promising UV birefringent crystals. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email