679398-07-3Relevant academic research and scientific papers
Systematic Preparation of Mo24+ Building Blocks for Supramolecular Assemblies
Cotton, F. Albert,Liu, Chun Y.,Murillo, Carlos A.
, p. 2267 - 2276 (2004)
The preparation of additional and useful building blocks for the construction of supramolecular entities with quadruply bonded Mo 24+ units has been explored, and five new mixed-ligand complexes with three types of ligands and various basicities are reported. The ligands used were the DAniF (N,N′-di-p-anisylformamidinate) anion, the acetate anion, and neutral acetonitrile molecules. The formamidinate ligands are the least labile, and the acetonitrile molecules are the most labile. This difference as well as a relatively strong trans directing influence by the formamidinate anions in ligand substitution reactions allows designed synthesis of various mixed-ligand building blocks, including rare pairs of cis and trans isomers, The new compounds are cis-Mo2(DAniF)2(O 2CCH3)2 (1), trans-Mo2(DAniF) 2(O2CCH3)2 (2), trans-[Mo 2(DAniF)2(O2CCH3)(CH 3CNeq)2]BF4 (3), trans-[Mo 2(DAniF)2(CH3CNeq)4](BF 4)2 (4), and [Mo2(O2CH 3)(CH3CNeq)6(CH3CN ax)](BF4)3 (5), where eq and ax designate equatorial and axial ligands, respectively. A comparison with some previously synthesized complexes is given along with a discussion of the overall reactivity of all compounds.
Redox Potential Tuning of Dimolybdenum Systems through Systematic Substitution by Guanidinate Ligands
Metta, Nathalie,Metta-Magana, Alejandro J.,Rodríguez-López, Nancy,Villagrán, Dino
, (2020/03/04)
We report the synthesis and characterization of a series of dimolybdenum paddlewheel complexes of the type Mo2(DAniF)4-n(hpp)n (n = 1-3), where DAniF is the anion of N,N′-di-p-anisyl-formamidine and hpp is the anion of 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine. The effect on the electronic structure of these tetragonal paddlewheel dimolybdenum compounds was studied upon systematic substitution of formamidinate ligands by the more basic guanidinates. Mo-Mo distances in the paddlewheel structures decreased upon guanidinate ligand substitution, and were found to be 2.0844(6) and 2.0784(6), for Mo2(DAniF)3(hpp) (1) and trans-Mo2(DAniF)2(hpp)2 (2), respectively. Electrochemical studies show that the half-wave potential of the Mo25+/Mo24+ couple shifts cathodically upon ancillary ligand substitution ranging from -0.286 V for the tetraformamidinate complex to -1.795 V for the tetraguanidinate analogue and with redox potentials of -0.75, -1.07, and -1.14 V for 1, 2, and 3 (Mo2(DAniF)(hpp)3), respectively. The presence of a second redox event assigned to the Mo26+/Mo25+ couple was not observed until two guanidinate ligands were introduced. Raman spectroscopy shows that the v(M-M) stretch gets systematically strengthened upon formamidinate ligand substitution by the guanidinate ligand hpp. The induced delta bond destabilization by the basic hpp ligand was measured using DFT calculations by tracking the energy of the frontier orbitals. The decrease in the HOMO-LUMO energy gap was supported by the red shift in the UV-vis spectra of the compounds: 412, 442, and 450 nm for 1, 2, and 3, respectively.
Synthesis, X-ray Structure Analysis and Spectroscopic Characterization of trans-Aquabis(μ-benzoato-κ2 O:O′) bis[μ-N,N′-bis(4-methoxyphenyl) formamidinato-κ2 N:N′] dimolybdenum(II)
Kong, Ya-Jie,Han, Li-Juan
, p. 208 - 214 (2017/09/06)
Abstract: The title compound, trans-Mo2(DAniF)2(OOCC6H5)2(H2O) (I) has a quadruply bonded Mo2 4+ unit equatorially coordinated by two N,N′-bis(4-methoxyphenyl)formamidinate (referred as DAniF) ligands and two benzoate (OOCC6H5) groups in transverse, and axially coordinated by one aqua oxygen atom. The compound crystallizes in the space group C2/c with one molecule in the asymmetric unit and features a Mo–Mo bond length of 2.0983(4) ?, which is typical for dimolybdenum quadruple bonds. In the crystal, the offsetstacking between pairs of phenyl rings creating a one-dimensional linear chain perpendicular to the Mo–Mo directions, with a distance between phenyl rings of 3.44?? and the center-to-center distance of 3.83??. The coordinated water oxygen atoms act as donors and uncoordinated methoxyl group oxygen atoms act as acceptors in intermolecular O–H?O hydrogen bonds.stacking between phenyl rings assemble the molecules into a three-dimensional framework. Graphical Abstract: The offsetstacking between phenyl rings of quadruply bonded Mo2 4+ paddle-wheel molecules create a one-dimensional linear chain. [Figure not available: see fulltext.].
