Reaction of M3(CO)10 (M=Ru or Os) with but-2-yne. Crystal and molecular structures of M33-CH2CHC(H)CH3>(CO)8 (M=Ru or Os) and Ru22-CMe=CHMe>-<μ-O=CNMe2)(CO)5

Article abstract of DOI:10.1016/0022-328X(88)89039-9

The complexes M3<μ-H,μ-O=CR>(CO)10 (R=NMe2, M=Ru (1a) or Os (1b)) are observed to react with dimethylacetylene (2) under varying conditions.The reaction of 2 is observed with 1a at 23 deg C requiring 12 h for completion in hexane.Three isolable products are obtained along with a trace of Ru3(CO)12: Ru3<η³-CH2CHC(H)CH3><μ-(CO),μ-)=CNMe2>(CO)8 (3a, 35percent), Ru2(CO)6 (4a,14percent), and Ru2<μ-O=CCMe=CMe-(η²-CMe=CHMe><μ-O=CNMe2)(CO)5 (5a, 9percent).For reaction of the tri-osmium complex 1b with 2, heating to 140 deg C is required using excess 2 as its own solvent under autoclave conditions; only the η³-allyl derivative 3b is obtained (28percent conversion; 98percent yield).Structures of three of the new products have been determined using Picker (FACS-1) or Syntex P1 four circle automated diffractometers and graphite-monochromatized Mo-Kα radiation.Complex 3a crystallizes in the monoclinic space group P2₁/n; cell dimensions a 10.4734(13) Anstroem, b 15.3589(19) Angstroem, C 13.7645(17) Angstroem, and β 99.041(3) deg; calculated density 2.07 g cm^-2; 3831 unique reflections with I>?(I) were used in the refinement; final discrepancy indices, R=0.042 and Rw=0.055.This is one of three different crystallographic modifications with essentially the same molecular parameters.Complex 3b crystallizes in the monoclinic space group P2₁/n; cell dimensions a 15.3496(13) Angstroem, b 28.9195(22) Angstroem, and C 9.9116(8) Angstroem, and β 98.114(3) deg; calculated density 3.05 g cm^-3; 5897 unique reflections with I>3?(I) were used in the refinement; final discrepancy indices, R=0.047 and R_w=0.062.Complex 5a crystallizes in the monoclinic space group P1; cell dimensions a 7886(2) Angstroem, b 10.987(3) Angstroem, c 12.337(3) Angstroem, α 96.88(2) deg, β 87.18(2) deg, and χ 104.36(2) deg; calculated density 1.78 g cm^-3; 3872 unique reflections with I>3?(I) were used in the refinement; final discrepancy indices, R=0.035 and R_w=0.060.Metal atoms in all three structures were located by direct methods (MULTAN80).All othe r nonhydrogen atoms were then located by difference maps.Hydrogen atoms in the organic groups were included in structure factor calculations in calculated positions.Each of the crystals studied consists of discrete molecules of the complex; crystals of 3a and 3b each consist of a triangle of metal atoms containing and η³-methallyl fragment attached to one of the atoms along an edge also bridged by a CO group and a dimethylcarboxamido group.For 5a, a dinuclear unit is observed which is bridged by a <μ-O=CCMe=CMe-(η²-CMe=CHMe> group as well as a dimethylcarboxamido group.The metal-metal separations in the three structures are summarized as follows, Angstroem, respectively: unbridged Ru-Ru (in 3a) 2.867(1) and 2.829(1); bridged Ru-Ru separations 2.783(1) (in 3a) and 2.681(1) (in 5a).In 3b the Os-Os separations for the two independent molecules of the unit cell are, respectively, Angstroem: 2.848(1(, 2,846(1) and 2.833(1), 2.871(1) (unbridged) and 2.814(1), 2.786(1) bridged.