Half-Sandwich Ruthenium-Phosphine Complexes with Pentadienyl and Oxo- and Azapentadienyl Ligands
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Treatment of RuCl2(PPh3)3 and RuHCl(PPh3)3 with the tin compound CH2C(Me)CHC(Me)CH2SnMe3 gives the corresponding acyclic pentadienyl half-sandwich (η5-CH2C(Me)CHC(Me)CH2)RuX(PPh3)2 [X = Cl, (2); H, (3)]. The steric congestion in 2 is most effectively relieved by formation of the cyclometalated complex (η5-CH2C(Me)CHC(Me)CH2)Ru(C6H4PPh2)(PPh3) (4). Addition of 1 equiv of PHPh2 to (η5-CH2CHCHCHCH2)RuCl(PPh3)2 (1) affords the chiral complex (η5-CH2CHCHCHCH2)RuCl(PPh3)(PHPh2) (5), while compound (η5-CH2C(Me)CHC(Me)CH2)RuCl(PPh3)(PHPh2)] (6) is directly obtained from the reaction of RuCl2(PPh3)3 with CH2C(Me)CHC(Me)CH2Sn(Me)3 and PHPh2. Treatment of RuCl2(PPh3)3 with the corresponding Me3SnCH2CHCHCHNR (R = Cy, t-Bu) affords (1-3,5-η-CH2CHCHCHNCy)RuCl(PPh3)2 (7) and [1-3,5-η-CH2CHCHCHN(t-Bu)]RuCl(PPh3)2 (8). The hydrolysis of 7, on a silica gel chromatography column, allows the isolation of RuCl(η5-CH2CHCHCHO)(PPh3)2 (9). The azapentadienyl complex 7 reacts with 1 equiv of PHPh2 to afford [1-3,5-η-CH2CHCHCHN(Cy)]RuCl(PPh3)(PHPh2) (10), while the corresponding product [1-3,5-η-CH2CHCHCHN(t-Bu)]RuCl(PPh3)(PHPh2) (11) from 8 is only observed through 1H and 31P NMR spectroscopy as a mixture of isomers. Two equivalents of PHPh2 gives spectroscopic evidence of [η3-CH2CHCHCHN(t-Bu)]RuCl(PHPh2)3. A mixture of products [η5-CH2C(Me)CHC(Me)O]RuCl(PPh3)2 (12) and [η5-CH2C(Me)CHC(Me)O]RuH(PPh3)2 (13) is obtained from reaction of RuCl2(PPh3)3 with Li[CH2C(Me)CHC(Me)O]. In contrast, the oxopentadienyl compound 13 is cleanly formed from RuHCl(PPh3)3 and Li[CH2C(Me)CHC(Me)O]. An attempt to separate compounds 12 and 13 by crystallization gives an orthometalated product [η5-CH2C(Me)CHC(Me)O]Ru(C6H4PPh2)(PPh3) (14), which is the oxopentadienyl analogue to 4. The bulky [1-3,5-η-CH2C(t-Bu)CHC(t-Bu)O]RuH(PPh3)2 (15) analogue to 13 has also been prepared from RuHCl(PPh3)3 and Li[CH2C(t-Bu)CHC(t-Bu)O]. Compounds 3, 5, 6, 7, and 12–15 have been structurally characterized. The preferred heteropentadienyl orientations and the relative positions of the H, Cl, PPh3, and PHPh2 ligands have been established in the piano-stool structures for all compounds, and it can be definitively surmised that the chemistry involved in the heteropentadienyl half-sandwich compounds studied is dominated by steric effects.
将三(三苯基膦)二氯化钌(II) (RuCl₂(PPh₃)₃)与三(三苯基膦)氯化氢化钌(II) (RuHCl(PPh₃)₃)分别与锡化合物CH₂=C(Me)CH=C(Me)CH₂SnMe₃反应，可得到对应的无环戊二烯基半三明治配合物(η⁵-CH₂=C(Me)CH=C(Me)CH₂)RuX(PPh₃)₂ [X=Cl对应产物2，X=H对应产物3]。配合物2中的空间位阻拥挤可通过生成环金属化配合物(η⁵-CH₂=C(Me)CH=C(Me)CH₂)Ru(C₆H₄PPh₂)(PPh₃)（产物4）得到最有效的缓解。向(η⁵-CH₂CHCHCHCH₂)RuCl(PPh₃)₂（产物1）中加入1当量二苯基膦(PHPh₂)，可得到手性配合物(η⁵-CH₂CHCHCHCH₂)RuCl(PPh₃)(PHPh₂)（产物5）；而配合物(η⁵-CH₂=C(Me)CH=C(Me)CH₂)RuCl(PPh₃)(PHPh₂)（产物6）可直接由RuCl₂(PPh₃)₃与CH₂=C(Me)CH=C(Me)CH₂SnMe₃及二苯基膦(PHPh₂)的反应制得。将RuCl₂(PPh₃)₃与相应的Me₃SnCH₂CH=CHCH=NR（R=环己基(Cy)、叔丁基(t-Bu)）反应，可得到(1-3,5-η-CH₂CHCHCHNCy)RuCl(PPh₃)₂（产物7）与[1-3,5-η-CH₂CHCHCHN(t-Bu)]RuCl(PPh₃)₂（产物8）。配合物7在硅胶色谱柱上发生水解反应，可分离得到RuCl(η⁵-CH₂CHCHCHO)(PPh₃)₂（产物9）。氮杂戊二烯基配合物7与1当量二苯基膦(PHPh₂)反应，可得到[1-3,5-η-CH₂CHCHCHN(Cy)]RuCl(PPh₃)(PHPh₂)（产物10）；而由产物8得到的对应产物[1-3,5-η-CH₂CHCHCHN(t-Bu)]RuCl(PPh₃)(PHPh₂)（产物11）仅通过氢核磁共振谱(¹H NMR)与磷核磁共振谱(³¹P NMR)观测到，为异构体混合物。加入2当量二苯基膦(PHPh₂)后，可通过光谱学证据证实生成了[η³-CH₂CHCHCHN(t-Bu)]RuCl(PHPh₂)₃。由RuCl₂(PPh₃)₃与Li[CH₂=C(Me)CH=C(Me)O]反应，可得到产物混合物[η⁵-CH₂=C(Me)CH=C(Me)O]RuCl(PPh₃)₂（产物12）与[η⁵-CH₂=C(Me)CH=C(Me)O]RuH(PPh₃)₂（产物13）。与之相反，氧杂戊二烯基配合物13可由三(三苯基膦)氯化氢化钌(II) (RuHCl(PPh₃)₃)与Li[CH₂=C(Me)CH=C(Me)O]干净地合成。尝试通过结晶法分离产物12与13，得到了邻位金属化产物[η⁵-CH₂=C(Me)CH=C(Me)O]Ru(C₆H₄PPh₂)(PPh₃)（产物14），其为产物4的氧杂戊二烯基类似物。位阻较大的[1-3,5-η-CH₂C(t-Bu)CH=C(t-Bu)O]RuH(PPh₃)₂（产物15），即产物13的类似物，也可由RuHCl(PPh₃)₃与Li[CH₂=C(t-Bu)CH=C(t-Bu)O]制得。配合物3、5、6、7及12~15均已完成结构表征。所有配合物的钢琴凳构型中，杂戊二烯基的优势取向以及H、Cl、三苯基膦与二苯基膦配体的相对位置均已确定；可以明确推断，所研究的杂戊二烯基半三明治配合物的化学行为主要由位阻效应主导。
