Chemistry of (Carbonyl)(nitrosyl)[bis(phosphorus donor)]rhenium Complexes

The chemistry of [Re(CO)(NO)L 2 ] fragments (L phosphorus donor) was explored. Starting from [Re(CO) 5 Cl] the synthesis of [Re 2 Cl 2 (μ‐Cl) 2 (CO) 4 (NO) 2 ] ( 1 ) was accomplished via the preparation of [Et 4 N] 2 [Re 2 Cl 2 (μ‐Cl) 2 (CO) 6 ] and nitrosylation of this compound with [NO][BF 4 ]. Complex 1 was converted to [RecL 2 (CO)(NO)L 2 ] complexes 2 ( a L = (MeO) 3 P; b L = (EtO) 3 P; c L = (i‐PrO) 3 P; d L Me 3 P; e L Et 3 P; f L Cy 3 P) by heating with L in MeCN. In the case of the reaction of L = (MeO) 3 P, a trisubstitued compound mer ‐{ReCl 2 (NO)[P(OMe) 3 ] 3 } 3 was also obtained. Replacement of the Cl ligands in 2a–e with Me groups was achieved by reacting them with MeLi in Et 2 O yielding cis , trans ‐[Re(CO)(NO)Me 2 L 2 ]complexes 4a–e . Reaction of 2a–e with Li[BHEt 3 ] led to substitution of one Cl by an H ligand with formation of [ReCl(CO)H(NO)L 2 ] compounds 5a–;e , displaying trans ‐H,NO geometries. The hydride‐transfer agent Na[AlH 2 (OCH 2 CH 2 OCH 3 ) 2 ] transformed 2 into the cis ‐dihydride systems [Re(CO)H 2 (NO)L 2 ] 6a–f . Reductive carbonylation of 2a–d in the presence of Na/Hg and CO gave pentacoordinate [Re(CO) 2 (NO)L 2 ] complexes 7b–d , and under comparable conditions the Cl substituents of 2b–f were replaced by tolane using Mg or t ‐BuLi giving trigonal bipyramidal [Re(CO)(NO)L 2 (PhCCPh)] compounds 8b–f . Complexes 5c , 6a , and 8d were characterized by X‐ray crystal‐structure analysis.