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

The chemistry of [Re(CO)(NO)L2] fragments (L  phosphorus donor) was explored. Starting from [Re(CO)5Cl] the synthesis of [Re2Cl2(μ‐Cl)2(CO)4(NO)2] (1) was accomplished via the preparation of [Et4N]2[Re2Cl2(μ‐Cl)2(CO)6] and nitrosylation of this compound with [NO][BF4]. Complex 1 was converted to [RecL2(CO)(NO)L2] complexes 2 (a L = (MeO)3P; b L = (EtO)3P; c L = (i‐PrO)3P; d L  Me3P; e L  Et3P; f L  Cy3P) by heating with L in MeCN. In the case of the reaction of L = (MeO)3P, a trisubstitued compound mer‐{ReCl2(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 Et2O yielding cis, trans‐[Re(CO)(NO)Me2L2]complexes 4a–e. Reaction of 2a–e with Li[BHEt3] led to substitution of one Cl by an H ligand with formation of [ReCl(CO)H(NO)L2] compounds 5a–;e, displaying trans‐H,NO geometries. The hydride‐transfer agent Na[AlH2(OCH2CH2OCH3)2] transformed 2 into the cis‐dihydride systems [Re(CO)H2(NO)L2] 6a–f. Reductive carbonylation of 2a–d in the presence of Na/Hg and CO gave pentacoordinate [Re(CO)2(NO)L2] 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)L2(PhCCPh)] compounds 8b–f. Complexes 5c, 6a, and 8d were characterized by X‐ray crystal‐structure analysis.