Diphenylacetylen‐Komplexe von Molybdän: [MoCl 4 (PhCCPh)(POCl 3 )] und die Kristallstruktur von [MoCl 4 (PhCCPh)] 2

Diphenylacetylene Complexes of Molybdenum: [MoCl 4 (PhCCPh)(POCl 3 )] and the Crystal Structure of [MoCl 4 (PhCCPh)] 2 The monomeric alkyne molybdenum(IV) complex [MoCl 4 ‐(PhCCPh)(POCl 3 )] ( 1 ) is prepared by the reaction of MoCl 5 with diphenylacetylene in CH 2 Cl 2 solution in the presence of POCl 3 . According to spectroscopic results, the alkyne ligand in 1 forms a metallacyclopropene structure. In diluted CH 2 Cl 2 solutions, 1 dissociates forming [MoCl 4 (PhCCPh)] 2 ( 2 ) and POCl 3 . The crystal structure determination of 2 leads to the space group p 2 1 / n . 2 forms centrosymmetric dimeric molecules with MoCl 2 Mo bridges.