The preparation of H[H2O]3[Mo3O(OAc)Cl6] from MoCl3.3H2O and HOAc is reported. Its crystal structure was determine by x-ray single crystal structure anal.: a 17.468(4), b 9.948(2), c 13.035(2) ? b 148.83(2)? Z = 2, space group Pc, R = 0.057. The anion is a O-monocapped equilateral triangle of Mo atoms, average distance of Mo-Mo is 2.569 ? The assignment of vibrational spectra was carried out using normal coordinate anal. of [Mo3O(m-Cl)3Cl3]2+. The average error between observed and calculated frequencies of 10 IR bands is 1.15%. The assignment of main bands (including metal bond) and force constants is discussed.

Key words: INFRARED SPECTROPHOTOMETRY, WATER, CHLORIDE, CRYSTAL STRUCTURE, MOLECULAR STRUCTURE, ACETOXY GROUP, MOLYBDENUM COMPLEX, ACETIC ACID, CLUSTER COMPOUND, TRANSITION METAL COMPLEX