Stable cationic 17-electron [LM(CO)3]+ species (L = 1,4,7-tribenzyl-1,4,7-triazacyclononane; M = Cr, Mo, W): synthesis, spectroscopic properties, and reactivity. Crystal structure of [LMo(CO)3](PF6).cntdot.dmf

Abstract

The neutral 18-electron complexes LM(CO)3 (L = 1,4,7-tribenzyl-1,4,7-triazacyclononane; M = Cr, Mo, W) were prepd. from M(CO)6 and L in DMF at 150 Deg. Oxidn. of these diamagnetic complexes in CH2Cl2 with [FeCp2]PF6 (Cp = cyclopentadienyl) affords the 17-electron species [LM(CO)3]PF6 in good yields. Magnetic susceptibility measurements and ESR spectroscopy confirm the presence of 1 unpaired electron per cation in these materials. The crystal structure of [LMo(CO)3](PF6).DMF has been detd. by x-ray crystallog. (trigonal, space group R.hivin.3, a 18.299(4), c 24.852(7) .ANG., Z = 9, R = 0.085, Rw = 0.078). The Mo atom is in a pseudooctahedral environment of 3 facially coordinated amine N atoms and 3 carbonyl ligands. The cation possesses crystallog. imposed C3 symmetry. Cyclic voltammetry reveals a reversible one-electron oxidn. of LM(CO)3 species in DMF at -0.545 V vs [FeCp2]+/[FeCp2] for the Cr complex at -0.23 V for the Mo complex and at -0.305 V for the W complex. At more anodic potentials a second irreversible oxidn. wave has been obsd. The reactivity of the [LM(CO)3] species has been briefly investigated.