Organotransition‐Metal Complexes of Multidentate Ligands 3. The Unexpected Derivatives of Bis(3,5‐Dimethylpyrazol‐1‐YL)Methanetetracarbonylmolybdenlim(0) and‐Tungsten(0) Complexes

Thermolysis of (H 2 CPz′ 2 )M(CO) 4 (H 2 CPz′ 2 = bis(3,5‐dimethylpyrazol‐1‐yl)methane; M=Mo, W) in 1,2‐dimethoxyethane did not give the expected 16‐electron complexes, (H 2 CPz′ 2 )M(CO) 3 , but gave dinuclear compounds, [(H 2 CPz′ 2 )M(CO) 3 ] 2 , probably containing two linear carbonyl bridges and no metal‐metal interactions. The dimers reacted with CH 3 CN to give mononuclear compounds, (H 2 CPz′ 2 )M(CO) 3 (NCCH 3 ), identical to the substitution products between (H 2 CPz′ 2 )M(CO) 4 and CH 3 CN.