Mixed Chloride/Amine Complexes of Dimolybdenum(II). 1. Preparation, Characterization, and Crystal Structure of Mo₂Cl₄(NHEt₂)₄:  A Quadruply-Bonded Dimolybdenum Compound with Diethylamine Ligands

Abstract

Reaction of the molybdenum(III) complex Mo2Cl6(THF)3 with diethylamine at room temperature causes reduction of the starting compound to produce the dimolybdenum(II) complex Mo2Cl4(NHEt2)4 (1). It was shown that the Cl- anions released by the substitution with amine can react with more of the starting material to give side products of molybdenum(III). Four such products were isolated and characterized: [NH2Et2][MoCl4(NHEt2)2] (2), [NH2Et2][Mo2Cl7(NHEt2)2] (3), [NH2Et2]2[MoCl5(NHEt2)] (4), and [NH2Et2]3[Mo2Cl8(NEt2)] (5). The crystal structures of all complexes 1−5 have been investigated by X-ray diffraction. The structure of 1 consists of two trans-MoCl2(NHEt2)2 units joined by a quadruple Mo−Mo bond (2.1330(6) Å). The crystallographic parameters for compounds 1−5 are as follows: for 1, monoclinic space group C2/c with a = 20.846(1) Å, b = 7.044(1) Å, c = 19.868(3) Å, β = 118.72(2)°, and Z = 4; for 2, triclinic space group P1̄ with a = 9.820(3) Å, b = 10.305(1) Å, c = 11.510(1) Å, α = 95.779(8)°, β = 97.80(2)°, γ = 111.17(1)°, and Z = 2; for 3, monoclinic space group P21/n with a = 13.847(5) Å, b = 10.448(4) Å, c = 22.091(4) Å, β = 96.68(2)°, and Z = 4; for 4, monoclinic space group P21/c with a = 11.710(2) Å, b = 12.363(2) Å, c = 30.272(7) Å, β = 95.87(2)°, and Z = 8; for 5, monoclinic space group P21/n with a = 10.335(1) Å, b = 18.061(1) Å, c = 16.775(1) Å, β = 95.558(8)°, and Z = 4.

Carbonyl and nitrosyl diruthenium compounds: Crystal structure of [Ru2(O2CMe)(DPhF)3(CO)]BF4·CH2Cl2 and its isomorphous nitrosyl analogue

“…Presumably, the solvent is involved in this reduction process and it could be related to the stabilization of the p * orbitals upon coordination of NO + , which makes the complex more oxidizing. The reduction of dimetallic compounds in THF has been previously pointed out [14].…”

Mixed Chloride/Amine Complexes of Dimolybdenum(II,II). 3. Preparation, Characterization, and Crystal Structure of Mo2Cl4(NH2R)4(R = Et, Prn, But, Cy): First Quadruply-Bonded Dimolybdenum Compounds with Primary Amine Ligands

“…The infrared spectra of the complexes 1 − 4 (Table ) exhibit two absorptions due to N−H stretching between 3193 and 3287 cm -1 , and one absorption for N−H bending between 1473 and 1448 cm -1 . Corresponding bands appear at 3219 and 1460 cm -1 , respectively, for Mo 2 Cl 4 (NHEt 2 ) 4 . The electronic spectra of the complexes with primary amines show the maximum of the δ − δ * transition absorption band between 538 and 528 nm (Table ).…”

“…It has recently been found that the reaction of the molybdenum(III) complex Mo 2 Cl 6 (THF) 3 with the secondary amine NHEt 2 at room temperature causes reduction of the starting material to produce the dimolybdenum(II) complex Mo 2 Cl 4 (NHEt 2 ) 4 . The yield of the product can be significantly improved by assisted reduction with sodium amalgam.…”

Mixed Chloride/Amine Complexes of Dimolybdenum(II,II). 5. Experimental and Theoretical Study of the Rotation Conformational Preferences of Mo2Cl4(R-py)4 (R-py = Substituted Pyridine) Molecules

“…Deuterated solvents were provided by Cambridge Isotope Laboratories, Inc. Compounds Mo 2 Cl 4 (amine) 4 (amine = 4-pic, 3,5-lut, 4-Bu t -py, NHEt 2 , NH 2 Et, NH 2 Pr n , NH 2 Cy 4 ) were synthesized according to published procedures. The new rotamer of Mo 2 Cl 4 (4-Bu t -py) 4 was crystallized by cooling to −30 °C a concentrated solution of the compound in acetone…”