The non-heteroatom-substituted manganese alkynyl carbene complexes (η5-MeC5H4)(CO)2MnC(R)CCR′
(3; 3a: R = R′
= Ph, 3b: R = Ph, R′
= Tol, 3c: R = Tol, R′
= Ph) have been synthesised in high yields upon treatment of the corresponding carbyne complexes [(η5-MeC5H4)(CO)2MnCR][BPh4]
([2][BPh4]) with the appropriate alkynyllithium reagents LiCCR′
(R′
= Ph, Tol). The use of tetraphenylborate as counter anion associated with the cationic carbyne complexes has been decisive. The X-ray structures of (η5-MeC5H4)(CO)2MnC(Tol)CCPh (3c), and its precursor [(η5-MeC5H4)(CO)2MnCTol][BPh4]
([2b](BPh4]) are reported. The reactivity of complexes 3 toward phosphines has been investigated. In the presence of PPh3, complexes 3 act as a Michael acceptor to afford the zwitterionic σ-allenylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R)CC(PPh3)R′
(5) resulting from nucleophilic attack by the phosphine on the remote alkynyl carbon atom. Complexes 5 exhibit a dynamic process in solution, which has been rationalized in terms of a fast [NMR time-scale] rotation of the allene substituents around the allene axis; metrical features within the X-ray structure of (η5-MeC5H4)(CO)2MnC(Ph)CC(PPh3)Tol (5b) support the proposal. In the presence of PMe3, complexes 3 undergo a nucleophilic attack on the carbene carbon atom to give zwitterionic σ-propargylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R)(PMe3)CCR′
(6). Complexes 6 readily isomerise in solution to give the σ-allenylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R′)CC(PMe3)R (7) through a 1,3 shift of the [(η5-MeC5H4)(CO)2Mn] fragment. The nucleophilic attack of PPh2Me on 3 is not selective and leads to a mixture of the σ-propargylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R)(PPh2Me)CCR′
(9) and the σ-allenylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R)CC(PPh2Me)R′
(10). Like complexes 6, complexes 9 readily isomerize to give the σ-allenylphosphonium complexes (η5-MeC5H4)(CO)2MnC(R′)CC(PPh2Me)R (10′). Upon gentle heating, complexes 7, and mixtures of 10 and 10′ cyclise to give the σ-dihydrophospholium complexes (η5-MeC5H4)(CO)2MnCC(R′)PMe2CH2CH(R)
(8), and mixtures of complexes (η5-MeC5H4)(CO)2MnCC(Ph)PPh2CH2CH(Tol)
(11) and (η5-MeC5H4)(CO)2MnCC(Tol)PMe2CH2CH(Ph)
(11′), respectively. The reactions of complexes 3 with secondary phosphines HPR12
(R1
= Ph, Cy) give a mixture of the η2-allene complexes (η5-MeC5H4)(CO)2Mn[η2-R12PC(R)CC(R′)H}]
(12), and the regioisomeric η4-vinylketene complexes (η5-MeC5H4)(CO)Mn[η4-R12PC(R)CHC(R′)CO}]
(13) and (η5-MeC5H4)(CO)Mn[η4-R12PC(R′)CHC(R)CO}]
(13′). The solid-state structure of (η5-MeC5H4)(CO)2Mn[η2-Ph2PC(Ph)CC(Tol)H}]
(12b) and (η5-MeC5H4)(CO)Mn[η4-Cy2PC(Ph)CHC(Ph)CO}]
(13d) are reported. Finally, a mechanism that may account for the formation of the species 12, 13 and 13′ is proposed.
非异位取代的碳化炔
锰络合物 (η5-MeC5H4)(CO)2MnC(R)CCR′ (3; 3a: R = R′ = Ph, 3b:R=Ph,R′=Tol,3c:R=Tol,R′=Ph),用适当的炔
锂试剂 LiCCR′(R′=Ph,Tol)处理相应的
炔烃络合物[(η5-MeC5H4)(CO)2MnCR][BPh4]([2][BPh4])后,以高产率合成。使用四苯基
硼酸盐作为与阳离子碳炔配合物相关的反阴离子具有决定性的意义。报告了 (η5-MeC5H4)(CO)2MnC(Tol)CCPh (3c) 及其前体 [(η5-MeC5H4)(CO)2MnCTol][BPh4]([2b](BPh4])的 X 射线结构。研究了复合物 3 对膦的反应性。在 PPh3 存在的情况下,络合物 3 充当迈克尔受体,在膦对远端炔基碳原子的亲核攻击作用下,产生了齐射离子型 σ- 烯基膦络合物 (η5-MeC5H4)(CO)2MnC(R)CC(PPh3)R′ (5)。络合物 5 在溶液中表现出一种动态过程,这种动态过程被合理地解释为烯取代基围绕烯轴的快速[核磁共振时间尺度]旋转;(η5-MeC5H4)(CO)2MnC(Ph)CC(PPh3)Tol (5b)的 X 射线结构中的计量特征支持这一提议。在 PMe3 的存在下,络合物 3 的碳碳原子发生亲核反应,生成齐聚物σ-
丙炔基膦络合物 (η5-MeC5H4)(CO)2MnC(R)(PMe3)CCR′ (6)。络合物 6 在溶液中很容易发生异构,通过[(η5-MeC5H4)(CO)2MnC(R′)CC(PMe3)R]片段的 1,3 移位,生成σ-烯基
磷鎓络合物 (η5-MeC5H4)(CO)2MnC(R′)CC(PMe3)R)(7)。PPh2Me 对 3 的亲核攻击不具有选择性,会导致 σ-
丙炔基膦络合物 (η5-MeC5H4)(CO)2MnC(R)(PPh2Me)CCR′ (9) 和 σ-烯基膦络合物 (η5-MeC5H4)(CO)2MnC(R)CC(PPh2Me)R′ (10) 的混合物。与络合物 6 一样,络合物 9 也很容易发生异构,生成 σ-烯基
磷鎓络合物 (η5-MeC5H4)(CO)2MnC(R′)CC(PPh2Me)R(10′)。缓和加热后,络合物 7 以及 10 和 10′ 的混合物环化,得到 σ-二氢
磷鎓络合物 (η5-MeC5H4)(CO)2MnCC(R′)PMe2CH2CH(R) (8)、以及络合物 (η5-MeC5H4)(CO)2MnCC(Ph)PPh2CH2CH(Tol) (11) 和 (η5-MeC5H4)(CO)2MnCC(Tol)PMe2CH2CH(Ph) (11′) 的混合物。络合物 3 与仲膦 HPR12(R1 = Ph、Cy)的反应得到了η2-烯络合物(η5-MeC5H4)(CO)2Mn[η2-R12PC(R)CC(R′)H}]的混合物(12)、以及η4-
乙烯酮络合物 (η5-MeC5H4)(CO)Mn[η4-R12PC(R)CHC(R′)CO}] (13) 和 (η5-MeC5H4)(CO)Mn[η4-R12PC(R′)CHC(R)CO}] (13′)。报告了 (η5-MeC5H4)(CO)2Mn[η2-Ph2PC(Ph)CC(Tol)H}] (12b) 和 (η5-MeC5H4)(CO)Mn[η4-Cy2PC(Ph)CHC(Ph)CO}] (13d) 的固态结构。最后,提出了一种可能解释物种 12、13 和 13′ 形成的机理。