96413-44-4Relevant academic research and scientific papers
The molybdenum-molybdenum triple bond. 16. Bis[(trimethylsilyl)methylidene]tetrakis(trimethylphosphine)- dibromodimolybdenum(M≡M). An example of a nonbridged dinuclear bis(carbene) complex
Ahmed, Kazi J.,Chisholm, Malcolm H.,Huffman, John C.
, p. 1168 - 1174 (2008/10/08)
Hydrocarbon solutions of 1,2-Mo2Br2(CH2SiMe3) 4(M≡M) react rapidly with PMe3 (≥4 equiv) to yield Mo2Br2(=CHSiMe3)2(PMe 3)4(M≡M), I, and Me4Si (2 equiv). I reacts further in hydrocarbon solvents to give Mo2Br4(PMe3)4(M-4M), II, and MoBr(≡CSiMe3)(PMe3)4 along with Me4Si and trans-Me3SiCH=CHSiMe3. The mononuclear carbyne complex reacts with diphos (Ph2PCH2CH2PPh2) to give MoBr(≡CSiMe3)(diphos)2, III. Compounds I, II, and III have been characterized by NMR spectroscopy and single-crystal X-ray crystallography. I provides the first example of a nonbridged dinuclear bis(carbene) complex and the first example of the attachment of a divalent monodentate ligand to the (Mo≡Mo)6+ unit. Pertinent bond distances (?) and angles (deg) are as follows: Mo-Mo = 2.276 (1), Mo-Br = 2.636 (1), Mo-P = 2.534 (2) and 2.535 (2), Mo-C = 1.949 (5), Mo-Mo-C = 109.0 (2), Mo-Mo-Br = 116.54 (3), Mo-Mo-P = 101.54 (4) and 97.98 (4). Molecules of II belong to the symmetry group C2v. There is a central Mo2Br4P4 unit typical of that seen for compounds of formula Mo2X4L4(M-4M): Mo-Mo = 2.131 (2) ?, Mo-Br = 2.553 (2) and 2.549 (1) ?, Mo-P = 2.554 (3) and 2.549 (3) ?; Mo-Mo-Br = 114 (1)°, and Mo-Mo-P = 102 (1)°. III contains a central MoP4(C)(Br) octahedral unit with the carbyne and bromide ligands occupying trans positions: Mo-C = 1.82 (1) ?, Mo-Br = 2.731 (3) ?, Mo-P = 2.50 (3) ? (averaged), and Br-Mo-C = 176.5 (1)°. Reactions between 1,2-Mo2Br2(CH2SiMe3)4 and the monodentate phosphines proceed similarly to give Mo2Br4L4 and MoBr(≡CSiMe3)L4 compounds, where L = PMe2Ph and PEt3, via Mo2Br2(=CHSiMe3)2L4 compounds which may be detected spectroscopically but not isolated because of their more rapid decomposition. The reaction between dmpm (Me2PCH2PMe2) and 1,2-Mo2Br2-(CH2SiMe3) 4(M≡M) yields a thermally more stable compound Mo2Br2(=CHSiMe3)2(dmpm)2 which, based on NMR spectroscopic data, is formulated as an analogue of I. Crystal data for I at -165°C: a = 20.461 (11) ?, b = 9.918 (4) ?, c = 20.468 (11) ?, β = 120.67 (2)°, Z = 4, dcalcd = 1.540 g cm-3, and space group A2/a. Crystal data for II at -171°C: a = 17.384 (7) ?, b = 9.298 (3) ?, c = 18.297 (7) ?, β = 114.63 (2)°, Z = 4, dcalcd = 2.016 g cm-3, and space group A2/a. Crystal data for III at -160°C: a = 16.133 (12) ?, b = 16.571 (12) ?, c = 10.546 (7) ?, α = 92.17 (3)°, β = 103.13 (3)°, γ = 95.47 (3)°, Z = 2, dcalcd = 1.400 g cm-3, and space group P1.
