Stereoselective synthesis and reactivity of cis- and trans- dimolybdenum nitrosyl derivatives with the bridging bis(dimethylsilanediyl)di(η 5 -cyclopentadienyl) ligand. X-ray molecular structures of cis-[{Mo(CO) 2 (NO)} 2 {μ-(η 5 -C 5 H 3 ) 2 (SiMe 2 ) 2 }], trans-[{Mo(CO)(NO)(CN t Bu)} 2 {μ-(η 5 -C 5 H 3 ) 2 (SiMe 2 ) 2 }], cis-[{Mo 2 (CO) 3 (NO) 2 (PMe 3 )}{μ-(η 5 -C 5 H 3 ) 2 (SiMe 2 ) 2 }] and trans-[{Mo(NO)(CN t Bu) 2 } 2 {μ-(η 5 -C 5 H 3 ) 2 (SiMe 2 ) 2 }]