Butterick Robert, Ramachandran Bhaskar M, Carroll Patrick J, Sneddon Larry G
Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323, USA.
J Am Chem Soc. 2006 Jul 5;128(26):8626-37. doi: 10.1021/ja062201u.
The reaction of the tricarbadecaboranyl anion, 6-Ph-nido-5,6,9-C(3)B(7)H(9)(-), with M(CO)(5)Br [M = Mn, Re] or [(eta(6)-C(10)H(8))Mn(CO)(3)(+)]BF(4)(-) yielded the half-sandwich metallatricarbadecaboranyl analogues of (eta(5)-C(5)H(5))M(CO)(3) [M = Mn, Re]. For both 1,1,1-(CO)(3)-2-Ph-closo-1,2,3,4-MC(3)B(7)H(9) [M = Mn (2) and Re (3)], the metal is eta(6)-coordinated to the puckered six-membered open face of the tricarbadecaboranyl cage. Reactions of 2 and 3 with isocyanide at room temperature produced complexes 8-(CNBu(t))-8,8,8-(CO)(3)-9-Ph-nido-8,7,9,10-MC(3)B(7)H(9) [M = Mn (4), Re (5)], having the cage eta(4)-coordinated to the metal. Photolysis of 4 and 5 then resulted in the loss of CO and the formation of 1-(CNBu(t))-1,1-(CO)(2)-2-Ph-closo-1,2,3,4-MC(3)B(7)H(9) [M = Mn, Re (6)], where the cage is again eta(6)-coordinated to the metal. Reaction of 2 and 3 with 1 equiv of phosphine at room temperature produced the eta(6)-coordinated monosubstituted complexes 1,1-(CO)(2)-1-P(CH(3))(3)-2-Ph-closo-1,2,3,4-MC(3)B(7)H(9) [M = Mn (7), Re (9)] and 1,1-(CO)(2)-1-P(C(6)H(5))(3)-2-Ph-closo-1,2,3,4-MC(3)B(7)H(9) [M = Mn (8), Re (10)]. NMR studies of these reactions at -40 degrees C showed that substitution occurs by an associative mechanism involving the initial formation of intermediates having structures similar to those of the eta(4)-complexes 4 and 5. The observed eta(6)-eta(4) cage-slippage is analogous to the eta(5)-eta(3) ring-slippage that has been proposed to take place in related substitution reactions of cyclopentadienyl-metal complexes. Reaction of 9 with an additional equivalent of P(CH(3))(3) gave 8,8-(CO)(2)-8,8-(P(CH(3))(3))(2)-9-Ph-nido-8,7,9,10-ReC(3)B(7)H(9) (11), where the cage is eta(4)-coordinated to the metal. Photolysis of 11 resulted in the loss of CO and the formation of the disubstituted eta(6)-complex 1-CO-1,1-(P(CH(3))(3))(2)-2-Ph-closo-1,2,3,4-ReC(3)B(7)H(9) (12).
三碳十硼烷阴离子6-Ph-巢式-5,6,9-C(3)B(7)H(9)(-)与M(CO)(5)Br [M = Mn, Re] 或[(η⁶-C₁₀H₈)Mn(CO)₃⁺]BF₄⁻反应，生成了(η⁵-C₅H₅)M(CO)₃ [M = Mn, Re]的半夹心金属三碳十硼烷类似物。对于1,1,1-(CO)₃-2-Ph-闭壳型-1,2,3,4-MC(3)B(7)H(9) [M = Mn (2) 和Re (3)]，金属以η⁶配位方式与三碳十硼烷笼状结构的褶皱六元开口面相连。2和3在室温下与异腈反应生成配合物8-(CNBuⁱ)-8,8,8-(CO)₃-9-Ph-巢式-8,7,9,10-MC(3)B(7)H(9) [M = Mn (4), Re (5)]，其中笼状结构以η⁴配位方式与金属相连。然后对4和5进行光解导致CO的损失并形成1-(CNBuⁱ)-1,1-(CO)₂-2-Ph-闭壳型-1,2,3,4-MC(3)B(7)H(9) [M = Mn, Re (6)]，此时笼状结构再次以η⁶配位方式与金属相连。2和3在室温下与1当量的膦反应生成η⁶配位的单取代配合物1,1-(CO)₂-1-P(CH₃)₃-2-Ph-闭壳型-1,2,3,4-MC(3)B(7)H(9) [M = Mn (7), Re (9)] 和1,1-(CO)₂-1-P(C₆H₅)₃-2-Ph-闭壳型-1,2,3,4-MC(3)B(7)H(9) [M = Mn (8), Re (10)]。在-40℃下对这些反应进行核磁共振研究表明，取代反应通过缔合机制发生，涉及最初形成结构与η⁴配合物4和5类似的中间体。观察到的η⁶-η⁴笼状结构滑移类似于在环戊二烯基金属配合物相关取代反应中提出的η⁵-η³环滑移。9与额外当量的P(CH₃)₃反应生成8,8-(CO)₂-8,8-(P(CH₃)₃)₂-9-Ph-巢式-8,7,9,10-ReC(3)B(7)H(9) (11)，其中笼状结构以η⁴配位方式与金属相连。对11进行光解导致CO的损失并形成二取代的η⁶配合物1-CO-1,1-(P(CH₃)₃)₂-2-Ph-闭壳型-1,2,3,4-ReC(3)B(7)H(9) (12)。
