Synthesis and reactivity of naphthalene sandwich complexes of molybdenum. X‐ray structure of [Mo(η 6 ‐naphthalene) {P(OMe) 3 } 3 ] and [Mo(H)(η 6 ‐naphthalene){P(OMe) 3 } 3 ][BF 4 ]

The sandwich complexes bis(η 6 ‐naphthalene)molybdenum(0) ( 1 ), bis(η 6 ‐1‐methylnaphthalene)molybdenum(0) ( 2 ), and bis(η 6 ‐1,4‐dimethylnaphthalene)molybdenum(0) ( 3 ) are synthesized by cocondensation of Mo‐atoms with the naphthalene ligands. Complexes 1–3 are also obtained by reduction of MoCl 5 or MoCl 4 . 2THF with highly activated Mg in the presence of the naphthalene ligands. Mg was activated by sublimation of the metal in a simple rotating solution reactor. Complex 2 exists as a mixture of regio‐ and stereoisomers. Three regioisomers, 3a–c , are formed in reactions of Mo‐atoms with 1,4‐dimethylnaphthalene, whereas 3a , the isomer with the Mo‐atom coordinated to the unsubstituted rings, is formed selectively via the reductive method. The ligands in 1–3 are highly labile. CO displaces both naphthalene rings in 2 and 3 to give [Mo(CO) 6 ], while PF 3 , P(OMe) 3 , and PMe 3 displace only one coordinated naphthalene in 1 to yield the [Mo(η 6 ‐naphthalene)L 3 ] complexes 4–6 . In toluene, arene exchange is a competitive process in reactions of 1 with PF 3 . Complexes 5 (L = P(OMe) 3 ) and 6 (L = PMe 3 ) react with HBF 4 to give the cationic metal hydride complexes 8 and 9 . The X‐ray crystal structures of [Mo(η 6 ‐naphthalene) {P(OMe) 3 } 3 ] ( 5 ) and [Mo(H)(η 6 ‐naphthalene) {P(OMe) 3 } 3 ][BF 4 ] ( 8 ) are reported.