Thermal Decarbonylation of Molybdenium(II) Carbonyl-Iodide Complexes. Molecular and Electronic Structures of the Mixed-Valence Trinuclear Clusters Mo3HI7L3 (L=Tetrahydrofuran, Acetonitrile, Benzonitrile) and Molecular Structures of MoI3(EtCN)3 and Mo2I4(PhCN)4

Article abstract of DOI:10.1021/ja00211a023

Trinuclear cluster compounds of the type Mo3HI7L3 (L=THF,CH3CN,C6H5CN) can be obtained by decarbonylation of carbonyl-iodide complexes of molybdenum(II) in the presence of hard-donor ligands.In tetrahydrofuran (THF) an oligonuclear compound of stoichiometry x (1) is formed as the main product.The trinuclear cluster Mo3HI7(THF)3*THF (2) is obtained from the same reaction in low yields.When MeCN and EtCN are used as solvents, solutions containing the quadruply bonded dimers Mo2I4(RCN)4 are obtained, together with other minor insoluble products.Interaction of compound 1 with RCN also gives Mo2I4(RCN)4, which is unstable toward loss of the nitrile and cannot be isolated for R=Me and Et.A ligand-exchange reaction with PhCN affords Mo2I4(PhCN)4 (6), which is stable in the solid state.Other compounds that are produced in smaller yields in these reactions have been isolated and characterized, namely Mo3HI7(MeCN)3*MeCN (3), MoI3(EtCN)3 (4), and Mo3HI7(PhCN)3*C6H5CH3 (5).Compound 1 also reacts with PMe3 to afford Mo2I4(PMe3)4 and with I^- to produce the ^- anion.A different form of the trinuclear cluster with coordinated THF has also been obtained, Mo3HI7(THF)3 (7).Crystal data are the following.Compound 2: orthorhombic; space group Pcam; a=21.216(3), b=8.459(1), c=18.477(2) Angstroem; V=3316(1) Angstroem³; Z=4; d_calcd=2.933 g*cm^-3; R=0.0461, R_w=0.0743 for 148 parameters and 1716 observed data 0² > 3?(F₀²)>.Compound 3: orthorhombic; space group Pcmb; a=7.703(1), b=17.903(2), c=20.179(2) Angstoem; V=2783 (1) Angstroem³; Z=4; d_calcd=3.199 g*cm^-3; R=0.0355, R_w=0.0478 for 103 parameters and 1661 observations with F₀² > 3?(F₀²).Compound 4: monoclinic; space group P2₁/n; a=11.065(5), b=13.174(3), c=12.974(5) Angstroem; β=103.70 (3)deg; V=1836 (2) Angstroem³; Z=4; d_calcd=2.321 g*cm^-3; R=0.0570, R_w=0.0680 for 145 parameters and 1379 observations with F₀² > 3?(F₀²).Coumpound 5: monoclinic; space group P2₁/m; a=8.606(3), b=18.471(10), c=12.628(6) Angstroem; β=96.38(4)deg; V=1995(3) Angstroem³; Z=2; d_calcd=2.626 g*cm^-3; R=0.0495, R_w=0.0728 for 144 parameters and 1594 observations with F₀² > 3?(F₀²).Coumpound 6: orthorhombic; space group Fddd; a=22.941(2), b=39.516(12),c=17.336(8) Angstroem; V=15715(15) Angsroem³; Z=16; d_calcd=1.879 g*cm^-3; R=0.0664, R_w=0.0827 for 92 parameters and 851 observations with F₀² > 3?(F₀²).Coumpond 7: trigonal; space group R3m; a=17.112(4), c=8.599(2) Angstroem; V=2180.5(14) Angstroem³; Z=3; d_calcd=4.158 g*cm^-3; R=0.0428, R_w=0.0583 for 43 parameters and 321 observations with F₀² > 3?(F₀²).The structure of the Mo3HI7L3 (L=THF,MeCN, PhCN) clusters consists of an equilateral-triangular arrangement of the metals with strong metal-metal bonding interactions.The faces of the triangle are capped by an iodide and a hydride ligand,and a bridging iodide ion spans each edge.The sructure is completed by three terminal iodide ions and three terminal ligands L.The Mo3I7 core of the molecules can ...