12129-68-9Relevant articles and documents
Electronic absorption spectra of molybdenum(0) bisarene complexes, (η6-Arene)2Mo(0)
Ketkov, S. Yu.,Domrachev, G. A.
, p. 187 - 195 (1990)
The UV and visible absorption spectra of (ν6-Arene)2Mo0 (Arene = benzene (I), toluene (II), m-xylene (III), mesitylene (IV)) in the vapor phase and in the pentane solution have been investigated.Rydberg series converging to the ioniz
Synthesis and characterization of aluminum- and gallium-bridged [1.1]chromarenophanes and [1.1]molybdarenophanes
Lund, Clinton L.,Schachner, Joerg A.,Burgess, Ian J.,Quail, J. Wilson,Schatte, Gabriele,Mueller, Jens
, p. 5992 - 6000 (2009/02/05)
The synthesis and structural characterization of the first [1.1]chromarenophanes and the first [1.1]molybdarenophanes are described. A salt-metathesis reaction of [2-(Me2NCH2)C 6H4]AlCl2 with freshly prepared [Cr(LiC 6H5)2]·TMEDA (TMEDA = N,N,N′,N′-tetramethylethylenediamine) resulted in the dialumina[1.1]chromarenophane [{2-(Me2NCH2)-C 6H4}Al(η6-C6H5) 2Cr]2 (2a). The poor solubility of 2a in organic solvents prompted us to synthesize the new intramolecularly coordinated aluminum- and gallium dichlorides [5-tBu-2-(Me2NCH2)C6H 3]ECl2 [E = Al (3a), Ga (3b)] in which the phenyl group was equipped with a tert-butyl group. Salt-metathesis reactions of 3a and 3b, respectively, with freshly prepared [M(LiC6H5) 2]·TMEDA (M = Cr, Mo) resulted in four new [1.1]metallarenophanes of the general type [{5-tBu-2-(Me2NCH 2)C6H3}E(η6-C6H 5)2M]2 [E = Al, M = Cr (4a); E = Ga, M = Cr (4b); E = Al, M = Mo (5a); E = Ga, M = Mo (5b)]. 2a, 4a,b, and 5a,b have been structurally characterized by single-crystal analysis [2a·1/2C 6H12: C48H56Al2Cr 2N2, monoclinic, P21/c, a = 9.9117(9) A, b = 19.9361(16) A, c = 10.638(2) A, α = 90°, β = 112.322(5)°, γ = 90°, Z = 2; 4a·2C6H 6: C62H72Al2Cr2N 2, monoclinic, P21/c, a = 10.9626(9) A, b = 19.3350(18) A, c = 12.4626(9) A, α = 90°, β = 100.756(5)°, γ = 90°, Z = 2; 4b·2C6H 6: C62H72Cr2Ga2N 2, monoclinic, P21/c, a = 10.8428(2) A, b = 19.4844(4) A, c = 12.4958(2) A, α = 90°, β = 100.6187°, γ = 90°, Z = 2; 5a·2C6H6: C62H72Al2Mo2N2, triclinic, P1, a = 10.4377(4) A, b = 11.6510(4) A, c = 11.6514(4) A, α = 73.545(3)°, β = 89.318(2)°, γ = 76.120(2)°, Z = 1; 5b·2C6H6: C 62H72Ga2Mo2N2, triclinic, P1, a = 10.3451(5) A, b = 11.6752(6) A, c = 11.6900(5) A, α = 73.917(3)°, β = 89.550(3)°, γ = 76.774(2)°, Z = 1]. All five [1.1]metallarenophanes 2a, 4a,b, and 5a,b crystallize as anti isomers with both Me2N donor groups in exo positions (Ci point group symmetry). The new [1.1]metallarenophanes show NMR spectra that can be interpreted as being caused by time-averaged C2h symmetrical species, which is consistent with the findings of their molecular structures in the solid state. Variable-temperature 1H NMR measurements for 4a,b and 5a,b (500 MHz; -90 to 90 °C) revealed only peak broadening in the lower temperature range of -70 to -90 °C. 1H NMR saturation transfer difference experiments did not show an expected anti-to-anti isomerization, rendering the new [1.1]metallacyclophanes rigid on the NMR time scale. Electrochemical measurements were performed for 4a,b and 5a,b. However, reproducible cyclic voltammograms could only be obtained for the two gallium species 4b and 5b, revealing the expected weak communication between the two transition-metal atoms in both compounds (class II).
Dilithiation of bis(benzene)molybdenum and subsequent isolation of a molybdenum-containing paracyclophane
Braunschweig, Holger,Buggisch, Nele,Englert, Ulli,Homberger, Melanie,Kupfer, Thomas,Leusser, Dirk,Lutz, Matthias,Radacki, Krzysztof
, p. 4840 - 4846 (2008/01/27)
The homoleptic sandwich complex bis(benzene)molybdenum, [Mo(η6-C6H6)2], was successfully dilithiated by employing an excess of BuLi in the presence of N,N,N,′,N′-tetramethylethylenediamine (up to 6 equiv each) at slightly elevated temperatures furnishing the highly reactive, ring metalated species [Mo-(η6-C6H5Li)2] ·tmeda in high yields. Alternatively, this compound was synthesized upon prolonged sonication with 5 equiv of tBuLi/tmeda without heating. An X-ray crystal structure determination revealed a symmetrical, dimeric composition in the solid state, i.e., a formula of [Mo(η6-C 6H5Li)2]2·(thf)6, where the six-membered rings are connected by two pairs of bridging lithium atoms. The synthesis of an elusive ansa-bridged complex failed in the case of a [1]bora and a [1]sila bridge due to the thermal lability of the resulting compounds. Instead, reverse addition of the dilithio precursor to an excess of the appropriate element dihalide facilitated the isolation of several unstrained, 1,1′-disubstituted derivatives, namely, [Mo{η6- C6H5(BN(SiMe3)2X)}2] (X = Cl, Br) and [Mo{η6-C6H5(Si iPr2Cl)}2], respectively. However, the incorporation of a less congesting [2]-sila bridge was accomplished. In addition to the formation of [Mo{ (η6-C6H5) 2Si2Me4}], a molybdenum-containing paracylophane complex was isolated and characterized by means of crystal structure analysis. The ancillary formation of 1 equiv of bis(benzene)molybdenum strongly suggests that this species is generated by deprotonation of the ansa-bridged complex by the dilithiated precursor and subsequent reaction with a second equivalent of the disilane.
[1]Molybdarenophanes: Strained metallarenophanes with aluminum, gallium, and silicon in bridging positions
Lund, Clinton L.,Schachner, Joerg A.,Quail, J. Wilson,Mueller, Jens
, p. 9313 - 9320 (2008/02/08)
The first [1]molybdarenophanes were synthesized and structurally characterized. The aluminum and gallium compounds [(Me2Ntsi) Al(η6-C6H5)2Mo] (2a) and [(Me2Ntsi)Ga(η6-C6H5) 2Mo] (2b) [Me2Ntsi = C(SiMe3) 2(SiMe2NMe2)] were obtained from [Mo(LiC 6H5)2]·TMEDA and (Me2Ntsi) ECl2 [E = Al, Ga] in analytical pure form with isolated yields of 74% (2a) and 52% (2b). The silicon-bridged species [Ph2Si- (η6-C6H5)2Mo] (2c) was synthesized from [Mo(LiC6H5)2]·TMEDA and Ph2SiCl2. Compound 2c was isolated as a crystalline material in an approximately 90% overall purity, from which a single crystal was used for X-ray analysis. The molecular structures of all three [1]molybdarenophanes 2a-c were determined by single-crystal X-ray analysis. The ring-tilt angle a was found to be 18.28(17), 21.24(10), and 20.23(29)° for 2a, 2b, and 2c, respectively. Variable temperature NMR measurements of 2a and 2b (-80 to 80°C; 500 MHz) showed a dynamic behavior of the gallium species 2b but not of compound 2a. The dynamic behavior of 2b was rationalized by assuming that the Ga-N donor bond breaks, inversion at the nitrogen atom occurs, and a rotation of the Me2Ntsi ligand takes place followed by a re-formation of the Ga-N bond on the other side of the gallium atom. The analysis of the signals of meta and ortho protons of 2b gave approximate values of ΔG ≠ of 59.6 and 59.1 kJ mol-1, respectively. Compound 2b reacted with [Pt(PEt3)3] to give the ring-open product [(η6-C6H6)Mo{η6-C 6H5[GaPh(Me2Ntsi)]}] (3b). The molecular structure of 3b was deduced from a single-crystal X-ray determination. The formation of the unexpected platinum-free product 3b can be rationalized by assuming that benzene reacted with 2b in a 1:1 ratio. Through a series of 1H NMR experiments with 2b it was shown that small amounts of donor molecules (e.g., THF) in benzene are needed to form 3b; in the absence of a donor molecule, 2b is thermally stable.
