二茂鎂

二茂鎂
	IUPAC名; bis(η5-cyclopentadienyl)magnesium
識別
CAS號	1284-72-6
PubChem	11984632
ChemSpider	10628001
SMILES	[cH-]1cccc1.[cH-]1cccc1.[Mg+2];
InChI	1S/2C5H5.Mg/c21-2-4-5-3-1;/h21-5H;/q2*-1;+2;
EINECS	603-275-0
性質
化學式	C10H10Mg
摩爾質量	154.49 g·mol−1
外觀	無色晶體
熔點	176 °C（449 K）（）
沸點	290 °C（563 K）（）
溶解性	與水激烈反應，可溶於極性和非極性溶劑。
危險性
	GHS危險性符號;
GHS提示詞	Danger
H-術語	H228, H250, H261, H314
P-術語	P210, P231+232, P280, P303+361+353, P304+340+310, P305+351+338+310, P335+334, P422
	若非註明，所有數據均出自標準狀態（25 ℃，100 kPa）下。

二茂鎂，有時簡稱 MgCp₂，是一種有機鎂化合物，化學式 Mg(η⁵-C₅H₅)₂。它是一種主族夾心配合物，結構類似過渡金屬的茂金屬，由中心鎂原子和兩個環戊二烯配體組成。

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製備

二茂鎂是在1954年由恩斯特·奧托·菲舍爾和傑弗里·威爾金森獨立發現的。^[4]^[5]它可以由CpMgBr歧化或是金屬鎂和環戊二烯在500 °C 下反應而成。對於前者，茂基溴化鎂可以由乙基溴化鎂和環戊二烯反應而成，然後在220 °C 和10⁻⁴ mbar下分解成MgCp₂ 和MgBr₂：^[6]

\mathrm {Mg(C_{2}H_{5})Br\ {\xrightarrow[{-C_{2}H_{6}}]{+C_{5}H_{6},\ Et_{2}O}}\ Mg(C_{5}H_{5})Br{\xrightarrow[{-MgBr_{2}}]{x2,\ 220^{\circ }C,\ 10^{-4}mbar}}\ Mg(C_{5}H_{5})_{2}}

Et₂O = 乙醚

\mathrm {Mg\ +\ 2\ C_{5}H_{6}\ {\xrightarrow[{-H_{2}}]{500^{\circ }C}}\ Mg(C_{5}H_{5})_{2}\ }

在實驗室里，可以由二烷基鎂和環戊二烯反應得到二茂鎂：^[1]

\mathrm {Mg(C_{4}H_{9})_{2}\ +\ 2\ C_{5}H_{6}\ \rightarrow \ Mg(C_{5}H_{5})_{2}\ +\ 2\ C_{4}H_{10}\uparrow \ }

性質

室溫下，二茂鎂是一種白色固體。^[7]它的熔點為 176 °C，儘管在常壓下會在100 °C時升華。^[7]不像二茂鐵，二茂鎂會在極性、給電子溶劑中（例如醚和THF）會自耦電離：^[8]

{\ce {MgCp2 <=> MgCp+ + Cp-}}

{\ce {MgCp2 + MgCp+ <=> Mg2Cp3+}}

{\ce {MgCp2 + Cp- <=> MgCp3-}}

二茂鐵在標準情況下穩定，但二茂鎂在氧氣或濕氣中迅速分解，所以在惰性氣氛下製備和儲存。^[9]

結構和成鍵

通過X射線晶體學，固體二茂鎂的平均 Mg-C 和C-C鍵長分別為2.30 Å 和1.39 Å，兩個茂環是錯位的，點群D_5d。^[10]氣相電子衍射顯示出相似的鍵長，不過兩個茂環是重疊的，點群 D_5h。^[11]^[12]

關於Mg-Cp 的相互作用主要是離子鍵^[13]^[14]還是共價鍵^[11]^[12]^[15]一直存在激烈的爭論。

反應性和潛在用處

二茂鎂可以用來製備其它茂金屬：^[16]

{\ce {MgCp2 + MCl2 -> MCp2 + MgCl2}}

在四氫呋喃里，二茂鎂會和 MgX₂（X = 鹵素）交換配體，形成半夾心化合物CpMgX ：^[17]

{\ce {MgCp2 + MgX2 <=> 2 CpMgX}}

反應產生的半夾心化合物可作為從有機鹵化物合成取代茂基的原料。^[18]

由於其高反應性，二茂鎂是半導體研究中的一個有吸引力的目標，可作為化學氣相沉積和摻雜應用的起始材料。^[19]^[20]

二茂鎂在下一代的鎂離子電池中，有作為電解質的潛在用途。^[8]

參考資料

[1]
Anja Jaenschke: Basenaddukte des Magnesocens: Darstellung und Strukturuntersuchung von Cyclopentadienyl-, Pentamethylcyclopentadienyl- und Indenyl-Metallocenen des Magnesiums. Dissertation, Uni Hamburg, 2006 Template:URN.
[2]
W. A. Barber. Eugene G. Rochow , 編. Magnesium cyclopentadienide. McGraw-Hill Book Company, Inc. 1960: 11–15 （英語）.
[3]
{{{2}}}. www.chemicalbook.com.
[4]
E. O. Fischer, W. Hafner: Cyclopentadienyl-vanadin-tetracarbonyl. In: Zeitschrift für Naturforschung B. 9, 1954, S. 503–504 (online).
[5]
G. Wilkenson, F.A. Cotton, Chem. Ind.(London) 1954, 307–308
[6]
Christoph Elschenbroich: Organometallchemie. 6. Auflage, Teubner Wiesbaden, 2008, ISBN 978-3-8351-0167-8, S. 65 (《二茂鎂》在Google Books的內容。).
[7]
Barber, W. A.; Jolly, William L., Magnesium Cyclopentadienide, Inorganic Syntheses (John Wiley & Sons, Ltd), 1960: 11–15, ISBN 9780470132371, doi:10.1002/9780470132371.ch5
[8]
Schwarz, Rainer; Pejic, Marijana; Fischer, Philipp; Marinaro, Mario; Jörissen, Ludwig; Wachtler, Mario. Magnesocene-Based Electrolytes: A New Class of Electrolytes for Magnesium Batteries. Angewandte Chemie International Edition. 2016-11-21, 55 (48): 14958–14962. ISSN 1521-3773. PMID 27791301. doi:10.1002/anie.201606448.
[9]
Barber, W. A. A new preparation of magnesium cyclopentadienide. Journal of Inorganic and Nuclear Chemistry. 1957-01-01, 4 (5–6): 373–374. ISSN 0022-1902. doi:10.1016/0022-1902(57)80026-8.
[10]
Bünder, W.; Weiss, E. Verfeinerung der kristallstruktur von dicyclopentadienylmagnesium, (η-C5H5)2Mg [Refinement of the crystal structure of dicyclopentadienylmagnesium, (η5-C5H5)2Mg]. Journal of Organometallic Chemistry. 1975-06-10, 92 (1): 1–6. ISSN 0022-328X. doi:10.1016/S0022-328X(00)91094-5.
[11]
Starowieyski, Kazimir B.; Brunvoll, Jon; Novak, David P.; Lusztyk, Janusz; Haaland, Arne. Molecular structures of dicyclopentadienylmagnesium and dicyclopentadienylchromium by gas-phase electron diffraction. Journal of the Chemical Society, Chemical Communications. 1974-01-01, (2): 54–55. ISSN 0022-4936. doi:10.1039/C39740000054.
[12]
Haaland, A.; Lusztyk, J.; Brunvoll, J.; Starowieyski, K. B. On the molecular structure of dicyclopentadienylmagnesium. Journal of Organometallic Chemistry. 1975-02-11, 85 (3): 279–285. ISSN 0022-328X. doi:10.1016/S0022-328X(00)80301-0.
[13]
Cotton, F. A.; Reynolds, L. T. The Structure and Bonding of Cyclopentadienylthallium and Bis-cyclopentadienylmagnesium. Journal of the American Chemical Society. January 1958, 80 (2): 269–273. ISSN 0002-7863. doi:10.1021/ja01535a004.
[14]
Aleksanyan, V. T.; Garbuzova, I. A.; Gavrilenko, V. V.; Zakharkin, L. I. Vibrational spectra and structure of bis(cyclopentadienyl)magnesium. Journal of Organometallic Chemistry. 1977-04-12, 129 (2): 139–143. ISSN 0022-328X. doi:10.1016/S0022-328X(00)92483-5.
[15]
Lippincott, Ellis R.; Xavier, J.; Steele, D. The Vibrational Spectra and Structure of Bis-cyclopentadienylmagnesium. Journal of the American Chemical Society. 1961-05-01, 83 (10): 2262–2266. ISSN 0002-7863. doi:10.1021/ja01471a011.
[16]
Hull, H. S.; Reid, Allen Forrest; Turnbull, Alan G. Heat of formation and bond energy of bis(cyclopentadienyl)magnesium. Inorganic Chemistry. 1967-04-01, 6 (4): 805–807. ISSN 0020-1669. doi:10.1021/ic50050a032.
[17]
Ford, Warren T.; Grutzner, John B. Proton and carbon-13 nuclear magnetic resonance spectra of cyclopentadienylmagnesium compounds in tetrahydrofuran. The Journal of Organic Chemistry. 1972-08-01, 37 (16): 2561–2564. ISSN 0022-3263. doi:10.1021/jo00981a009.
[18]
Dzhemilev, U. M.; Ibragimov, A. G.; Tolstikov, G. A. Synthesis and transformations of "non-grignard" organomagnesium reagents obtained from 1,3-dienes. Journal of Organometallic Chemistry. 1991-03-26, 406 (1–2): 1–47. ISSN 0022-328X. doi:10.1016/0022-328X(91)83169-5.
[19]
Lundberg, Å; Andersson, S. G.; Landgren, G.; Rask, M. Abruptp- type doping transitions using bis-(cyclopentadienyl)-magnesium in metal-organic vapor phase epitaxy of GaAs. Journal of Electronic Materials. 1988-07-01, 17 (4): 311–314. Bibcode:1988JEMat..17..311R. ISSN 1543-186X. S2CID 97230793. doi:10.1007/BF02652111.
[20]
Kondo, M.; Anayama, C.; Sekiguchi, H.; Tanahashi, T. Mg-doping transients during metalorgic vapor phase epitaxy of GaAs and AlGaInP. Journal of Crystal Growth. 1994-08-01, 141 (1–2): 1–10. Bibcode:1994JCrGr.141....1K. ISSN 0022-0248. doi:10.1016/0022-0248(94)90085-X.

[Jaenschke-1] [1]
Anja Jaenschke: Basenaddukte des Magnesocens: Darstellung und Strukturuntersuchung von Cyclopentadienyl-, Pentamethylcyclopentadienyl- und Indenyl-Metallocenen des Magnesiums. Dissertation, Uni Hamburg, 2006 Template:URN.

[IS6-2] [2]
W. A. Barber. Eugene G. Rochow , 編. Magnesium cyclopentadienide. McGraw-Hill Book Company, Inc. 1960: 11–15 （英語）.

[Chemicalbook-3] [3]
{{{2}}}. www.chemicalbook.com.

[4] [4]
E. O. Fischer, W. Hafner: Cyclopentadienyl-vanadin-tetracarbonyl. In: Zeitschrift für Naturforschung B. 9, 1954, S. 503–504 (online).

[5] [5]
G. Wilkenson, F.A. Cotton, Chem. Ind.(London) 1954, 307–308

[Elschenbroich_65-6] [6]
Christoph Elschenbroich: Organometallchemie. 6. Auflage, Teubner Wiesbaden, 2008, ISBN 978-3-8351-0167-8, S. 65 (《二茂鎂》在Google Books的內容。).

[Barber_1960-7] [7]
Barber, W. A.; Jolly, William L., Magnesium Cyclopentadienide, Inorganic Syntheses (John Wiley & Sons, Ltd), 1960: 11–15, ISBN 9780470132371, doi:10.1002/9780470132371.ch5

[Schwarz_2016-8] [8]
Schwarz, Rainer; Pejic, Marijana; Fischer, Philipp; Marinaro, Mario; Jörissen, Ludwig; Wachtler, Mario. Magnesocene-Based Electrolytes: A New Class of Electrolytes for Magnesium Batteries. Angewandte Chemie International Edition. 2016-11-21, 55 (48): 14958–14962. ISSN 1521-3773. PMID 27791301. doi:10.1002/anie.201606448.

[9] [9]
Barber, W. A. A new preparation of magnesium cyclopentadienide. Journal of Inorganic and Nuclear Chemistry. 1957-01-01, 4 (5–6): 373–374. ISSN 0022-1902. doi:10.1016/0022-1902(57)80026-8.

[10] [10]
Bünder, W.; Weiss, E. Verfeinerung der kristallstruktur von dicyclopentadienylmagnesium, (η-C5H5)2Mg [Refinement of the crystal structure of dicyclopentadienylmagnesium, (η5-C5H5)2Mg]. Journal of Organometallic Chemistry. 1975-06-10, 92 (1): 1–6. ISSN 0022-328X. doi:10.1016/S0022-328X(00)91094-5.

[Starowieyski_1974-11] [11]
Starowieyski, Kazimir B.; Brunvoll, Jon; Novak, David P.; Lusztyk, Janusz; Haaland, Arne. Molecular structures of dicyclopentadienylmagnesium and dicyclopentadienylchromium by gas-phase electron diffraction. Journal of the Chemical Society, Chemical Communications. 1974-01-01, (2): 54–55. ISSN 0022-4936. doi:10.1039/C39740000054.

[Haaland_1975-12] [12]
Haaland, A.; Lusztyk, J.; Brunvoll, J.; Starowieyski, K. B. On the molecular structure of dicyclopentadienylmagnesium. Journal of Organometallic Chemistry. 1975-02-11, 85 (3): 279–285. ISSN 0022-328X. doi:10.1016/S0022-328X(00)80301-0.

[13] [13]
Cotton, F. A.; Reynolds, L. T. The Structure and Bonding of Cyclopentadienylthallium and Bis-cyclopentadienylmagnesium. Journal of the American Chemical Society. January 1958, 80 (2): 269–273. ISSN 0002-7863. doi:10.1021/ja01535a004.

[14] [14]
Aleksanyan, V. T.; Garbuzova, I. A.; Gavrilenko, V. V.; Zakharkin, L. I. Vibrational spectra and structure of bis(cyclopentadienyl)magnesium. Journal of Organometallic Chemistry. 1977-04-12, 129 (2): 139–143. ISSN 0022-328X. doi:10.1016/S0022-328X(00)92483-5.

[15] [15]
Lippincott, Ellis R.; Xavier, J.; Steele, D. The Vibrational Spectra and Structure of Bis-cyclopentadienylmagnesium. Journal of the American Chemical Society. 1961-05-01, 83 (10): 2262–2266. ISSN 0002-7863. doi:10.1021/ja01471a011.

[16] [16]
Hull, H. S.; Reid, Allen Forrest; Turnbull, Alan G. Heat of formation and bond energy of bis(cyclopentadienyl)magnesium. Inorganic Chemistry. 1967-04-01, 6 (4): 805–807. ISSN 0020-1669. doi:10.1021/ic50050a032.

[17] [17]
Ford, Warren T.; Grutzner, John B. Proton and carbon-13 nuclear magnetic resonance spectra of cyclopentadienylmagnesium compounds in tetrahydrofuran. The Journal of Organic Chemistry. 1972-08-01, 37 (16): 2561–2564. ISSN 0022-3263. doi:10.1021/jo00981a009.

[Dzhemilev_1991-18] [18]
Dzhemilev, U. M.; Ibragimov, A. G.; Tolstikov, G. A. Synthesis and transformations of "non-grignard" organomagnesium reagents obtained from 1,3-dienes. Journal of Organometallic Chemistry. 1991-03-26, 406 (1–2): 1–47. ISSN 0022-328X. doi:10.1016/0022-328X(91)83169-5.

[19] [19]
Lundberg, Å; Andersson, S. G.; Landgren, G.; Rask, M. Abruptp- type doping transitions using bis-(cyclopentadienyl)-magnesium in metal-organic vapor phase epitaxy of GaAs. Journal of Electronic Materials. 1988-07-01, 17 (4): 311–314. Bibcode:1988JEMat..17..311R. ISSN 1543-186X. S2CID 97230793. doi:10.1007/BF02652111.

[20] [20]
Kondo, M.; Anayama, C.; Sekiguchi, H.; Tanahashi, T. Mg-doping transients during metalorgic vapor phase epitaxy of GaAs and AlGaInP. Journal of Crystal Growth. 1994-08-01, 141 (1–2): 1–10. Bibcode:1994JCrGr.141....1K. ISSN 0022-0248. doi:10.1016/0022-0248(94)90085-X.

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