54935-70-5Relevant articles and documents
Studies of monosubstituted compounds of formula M2(NMe2)5X (M≡M), where M = Mo and W and X = I, alkyl, aryl, and diphenylphosphido, and the bridged-1,1′-ferrocenyl complex W2(NMe2)4(μ-(C5H 4)2Fe)
Schulz, Hartmut,Folting, Kirsten,Huffman, John C.,Streib, William E.,Chisholm, Malcolm H.
, p. 6056 - 6066 (2008/10/08)
The reaction between M2(NMe2)6 and Me3SiI (1 equiv) in toluene at 22°C leads to an equilibrium mixture of M2(NMe2)6, M2(NMe2)5I, and M2(NMe2)4I2(Ca. 1:5:1), where M = Mo and W. The reactions between M2(NMe2)6 and Me2SiI (2 equiv) in toluene yield the compound M2(NMe2)4I2 in ca. 85% isolated yield. The monoiodo compounds are also formed by the reactions between M2(NMe2)6 and M2(NMe2)4I2 in toluene. In solution the M2(NMe2)4I2 compounds exist as a mixture of gauche and anti isomers in a ca. 1:2 ratio. We have characterized by single-crystal X-ray crystallography (i) anti-W2(NMe2)4I2, (ii) a crystalline sample containing a solid solution of Mo2(NMe2)5I (90%) and anti- and gauche-Mo2(NMe2)4I2; and (iii) W2(NMe2)5I which contains a 5% disorder. Crystal data: for W2(NMe2)4I2 at -179°C, a = 7.838(3) A?, b = 7.706(2) A?, c = 15.010(5) A?, β = 103.48(1)°, Z = 2, dcalcd = 3.05 gem-3, and space group P21/n; for Mo2(NMe2)5I at-178°C, a = 14.251(2) A?, b = 18.031(2) A?, c = 7.477(1) A?, Z = a, dcalcd = 1.86 g cm-3, and space group Pmnb; for W2(NMe2)5I at -171°C, a = 14.220(2) A?, b= 18.179(2) A?, c = 7.449(1) A?, Z = 4, dcalcd = 2.47 g cm-3, and space group Pmnb. In each of the above there is a staggered ethane-like M2N5I or M2N4I2 core with W≡W distances = 2.29(1) A?, and W-I = 2.69(1) A? (average) and Mo≡Mo distances = 2.21(1) A? and Mo-I = 2.70(1) A?, with M-N in the range 1.92-1.97 A?. The substitution behavior of the M2(NMe2)5I compounds has been investigated by metathetic reactions involving ClMgCH2Ph, LiCH2SiMe3, LiMe, KCH2C6H4-3-Me, LiPPh2, (LiC5H4)2Fe, vinyl lithium, LiC≡CR, where R = But and Ph, SnMe4, Sn(vinyl)4, and AlMe3. The monosubstituted compounds M2(NMe2)5R were isolated and characterized for R = Me, CH2Ph, m-CH2C6H4Me, and PPh2. Substitution of the M-I bond in reactions involving organolithium compounds requires the addition of Me2NCH2CH2NMe2 (TMEDA). Reactions employing alkynyl- and vinyllithium reagents gave intractable products. The compound W2(NMe2)5(PPh2) was crystallographically characterized and shown to contain an ethane-like W2N5P core [W-W = 2.304(1) A?, W-N = 1.95 A? (average), and W-P = 2.43 A] and a pyramidal phosphide ligand. Crystal data for W2(NMe2)5(PPh2) at -174°C: a = 20.653(3) A?, b = 46.774(5) A?, c= 11.223(3) A?, Z = 16, dcalcd = 1.895 g cm-3, and space group Fdd2. Reactions employing (LiC5H4)2Fe and M2(NMe2)5I did not yield tetranuclear ferrocenyl linked compounds but gave the bridged dinuclear complexes M2(NMe2)4(μ-(C5H 4)2Fe). Crystal data for W2(NMe2)4(μ-C5H4) 2Fe) at-155°C: a= 15.426(3) A?, b = 16.664(3) A?, c = 9.727(2) A?, a = 90.34(1)°, β = 107.52(1)°, γ = 65.24(1)°, Z = 4, dcalcd = 2.263 g cm-3, and space group P1. Selected distances for the two independent molecules in the unit cell (averaged): W-W = 2.28(1) A?, W-C = 2.11-2.18 A?, W-N = 1.88-1.98 A? for the ethane-like gauche W2C2N4 core, and Fe-C = 1.98-2.12 A? for the ferrocenyl group. The compounds M2(NMe2)5R, where M = Mo and R = CH2Ph and M = W and R = CH2SiMe3, react with Me3SiI (1 equiv) in toluene at 22°C to give the respective M2(NMe2)4(R)(I) compounds which exist mostly in the gauche 1,2-disubstituted form in solution. The compound Mo2(NMe2)4(CH2Ph)I reacted with LiCH2SiMe3 in hexane/THF at 22°C to give the mixed 1,2-diorganodimolybdenum compound Mo2(NMe2)4(CH2Ph)(CH 2SiMe3).
