REACTIVITY PATTERNS FOR MULTISITE-BOUND ACETYLIDES - NUCLEOPHILIC-ATTACK AT THE ALPHA-CARBON IN MU-2-ETA-2-ACETYLIDES - BRIDGING 2-AMINO-1-METALLAPHENETHYLIDENE COMPLEXES VIA ADDITION OF PRIMARY AMINES TO FE2(CO)6(MU-2-ETA-2-C=CPH)(MU-PPH2), RU2(CO)6(MU-2-ETA-2-C=CPH)(MU-PPH2, OS2(CO)6(MU-2-ETA-2-C=CPH(MU-PPH2)

The binuclear σ-π-acetylides M2(CO)6(µ2-η2-C≡CPh)(µ-PPh2) (1a, M = Fe; lb, M = Ru; 1c, M = Os) react with cyclohexylamine to form the two-carbon-bridged iminium complexes M2(CO)6[µ2-C{NHR}CH-(Ph)](μ-PPh2) (3a‒c, R = c-C6H11) in all three cases by attack at the α-carbon of the acetylide of 1 and proton transfer across the acetylide triple bond. The new ligands in 3a‒c are 2-(cyclohexylamino)-1-metallaphenethylidene derivatives with a carbene-like carbon atom coordinated to one metal and an sp3 carbon atom, derived from Cβ of the acetylide attached to the second metal. Analogous complexes M2(CO)6[µ2-C{NH(i-Pr)}CH(Ph)](µ-PPh2) (M = Ru, 5b; M = Os, 5c) have been characterized from the reactions of 1b and 1c with isopropylamine. Complex 1a only also forms the product of β-acetylide addition M2(CO)6[µ2-CHC(NRH)Ph](µ-PPh2). The entire triad of two-carbon-bridged products from 1a‒c with cyclohexylamine, M2(CO)6[µ2-C{NH(Cy)}CH(Ph)](µ-PPh2) (3a‒c), have been characterized by IR and1H,13C{1H}, and31P{1H} NMR spectroscopy and by single-crystal X-ray diffraction. Crystals of 3b,c are monoclinic space group P21/c with the following unit cell dimensions: 3b, a = 10.076 (3), b = 17.290 (4), c = 20.807 (4) Å, β = 102.18 (2)°, Z = 4; 3c, a = 10.164 (2), b = 17.126 (5), c = 20.691 (5) Å, β = 99.44 (2)°, Z = 4. The two structures were solved by the heavy-atom method and refined to the following R and Rw values: 3b, R = 0.030, Rw = 0.035 on 4372 observed diffractometer data; 3c, R = 0.035, Rw = 0.038 on 4051 observed data. Comparison with the structure of 3a determined earlier shows that all three molecules are isostructural, with M‒M bond lengths of 2.628 (1) Å for 3a, 2.7896 (4) Å for 3b, and 2.8197 (5) Å for 3c. Changes in the metal‒hydrocarbyl interactions down the triad are discussed. © 1990, American Chemical Society. All rights reserved.