Triangular Trinuclear Molybdenum(IV) Cluster Compounds with Two Capping Oxygen Atoms

Michael Ardon, Avi Bino*, F. Albert Cotton, Zvi Dori, Menachem Kaftory, George Reisner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

45 Scopus citations

Abstract

The preparation and structural characterization of two trinuclear molybdenum(IV) cluster compounds with capping oxygen atoms are reported. Reaction of Mo(CO)6 with acetic acid under O2 allows the isolation, after suitable workup by cation-exchange resin chromatography of 1, [Mo3O2(OAc)6(H2O)3]Br2-H2O. This forms rhombohedral crystals in space group R3̄m with unit cell dimensions a = 11.784 (5) Å, a = 106.34 (5)°, V= 1386.6 (1) Å3, and Z = 2. The structure consists of [Mo3O2(O2CCH3)6(H2O)3]2+ ions having effectively D3h symmetry residing on crystallographic positions of C3v symmetry. The metal atoms form an equilateral triangle capped above and below by oxygen atoms. The edges of the triangle are each bridged by two acetate ions, and there is a water molecule coordinated to each metal atom with the Mo-OH2 bond direction intersecting the center of the opposite Mo-Mo bond. The bromide ions and the additional H2O are disordered over several positions in the rhombohedral cell. Reaction of Mo2(O2CCH3)4 with a mixture of propionic acid and propionic anhydride followed by cation column chromatography using CF3SO3H to elute gives [Mo3O2(O2C-C2H5)6(H2O)3](CF3SO3)2(CF3SO3H)(H2O)4. This forms triclinic crystals in space group P1̄ with a = 15.760 (5) Å, b = 14.848 (5) Å, c = 13.632 (4) Å, α = 70.4 (2)°, β = 118.5 (2)°, γ = 123.1 (2)°, V= 2336.6 (1) Å3, and Z = 2. The trinuclear cation resides on a general position but is very similar to the one in the acetate and has essentially D3h symmetry. The important dimensions within the [Mo3O2(O2CR)6(H2O)3]2+ ions are virtually identical in the two cases, with Mo-Mo = 2.766 (2) Å in the acetate and averaging 2.752 (3) Å in the propionate. This type of trinuclear cation can be formulated electronically as having six electrons for Mo-Mo bonding and bond orders of 1. They are very similar to the analogous [W3O2(02CR)6(H2O)3]2+ cations described earlier.

Original languageEnglish
Pages (from-to)1912-1917
Number of pages6
JournalInorganic Chemistry
Volume21
Issue number5
DOIs
StatePublished - 1982

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