Mr=1164, space group C2/c, a=14.954(13)A,b=22.323(6)A,c=27.003(18)A,β=98.23(7)°,V=8920 A3, Z=8. Final R=0.069 for 2818 unique diffraction data with I≥30(I). The title cluster compound is of Ml configuration with a triple bridging atom O and with a ’loosely coordinated site’ occupied by an imidazole ligand. Three Mo-Mo bond lengths are 2.657 (2), 2.649(2),and 2.646(2)A,respectively. The average bond length of Mo-(μ3-O) bonds is 2.052 A.