title: Octanuclear Heterobimetallic {Ni4Ln4} Assemblies Possessing Ln4 Square Grid [2 × 2] Motifs: Synthesis, Structure, and Magnetism.
abstract: Octanuclear heterobimetallic complexes, [Ln4Ni4(H3L)4(μ3-OH)4(μ2-OH)4]4Cl·xH2O·yCHCl3 (Dy(3+), x = 30.6, y = 2 (1); Tb(3+), x = 28, y = 0 (2) ; Gd(3+), x = 25.3, y = 0 (3); Ho(3+), x = 30.6, y = 3 (4)) (H5L = N1,N3-bis(6-formyl-2-(hydroxymethyl)-4-methylphenol)diethylenetriamine) are reported. These are assembled by the cumulative coordination action of four doubly deprotonated compartmental ligands, [H3L](2-), along with eight exogenous -OH ligands. Within the core of these complexes, four Ln(3+)'s are distributed to the four corners of a perfect square grid while four Ni(2+)'s are projected away from the plane of the Ln4 unit. Each of the four Ni(2+)'s possesses distorted octahedral geometry while all of the Ln(3+)'s are crystallographically equivalent and are present in an elongated square antiprism geometry. The magnetic properties of compound 3 are dominated by an easy-plane single-ion anisotropy of the Ni(2+) ions [DNi = 6.7(7) K] and dipolar interactions between Gd(3+) centers. Detailed ac magnetometry reveals the presence of distinct temperature-dependent out-of-phase signals for compounds 1 and 2, indicative of slow magnetic relaxation. Magnetochemical analysis of complex 1 implies the 3d and the 4f metal ions are engaged in ferromagnetic interactions with SMM behavior, while dc magnetometry of compound 2 is suggestive of an antiferromagnetic Ni-Tb spin-exchange with slow magnetic relaxation due to a field-induced level crossing. Compound 4 exhibits an easy-plane single-ion anisotropy for the Ho(3+) ions and weak interactions between spin centers.
authors: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur-208016, India.
authors: Sourav
authors: S
authors: Biswas
authors: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur-208016, India.
authors: Joydeb
authors: J
authors: Goura
authors: Department of Chemistry, Institute of Infrastructure Technology Research and Management , Near Khokhara Circle, Maninagar East, Ahmedabad-380026, India.
authors: Sourav
authors: S
authors: Das
authors: Clarendon Laboratory, University of Oxford , Parks Road, Oxford, OX1 3PU, United Kingdom.
authors: Craig V
authors: CV
authors: Topping
authors: Department of Physics, University of Warwick , Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom.
authors: Jamie
authors: J
authors: Brambleby
authors: Department of Physics, University of Warwick , Gibbet Hill Road, Coventry, CV4 7AL, United Kingdom.
authors: Paul A
authors: PA
authors: Goddard
authors: Department of Chemistry, Indian Institute of Technology Kanpur , Kanpur-208016, India.|National Institute of Science Education and Research , Institute of Physics Campus, Sachivalaya Marg, PO: Sainik School, Bhubaneswar - 751 005, Orissa, India.
authors: Vadapalli
authors: V
authors: Chandrasekhar