School of Chemistry, University of Bristol, Bristol, UK BS8 1TS.
Dalton Trans. 2010 Dec 28;39(48):11616-27. doi: 10.1039/c0dt00774a. Epub 2010 Nov 1.
The heteroscorpionate ligands HB(taz)(2)(pz(R)) (pz(R) = pz, pz(Me2), pz(Ph)) and HB(taz)(pz)(2), synthesised from the appropriate potassium hydrotris(pyrazolyl)borate salt and 4-ethyl-3-methyl-5-thioxo-1,2,4-triazole (Htaz), react with [{Rh(cod)(μ-Cl)}(2)] to give [Rh(cod)Tx] {Tx = HB(taz)(2)(pz), HB(taz)(2)(pz(Me2)), HB(taz)(2)(pz(Ph)), HB(taz)(pz)(2)}; the heteroscorpionate rhodaboratrane [Rh{B(taz)(2)(pz(Me2))}{HB(taz)(2)(pz(Me2))}] is the only isolable product from the reaction of [{Rh(nbd)(μ-Cl)}(2)] with K[HB(taz)(2)(pz(Me2))]. Carbonylation of the cod complexes gave a mixture of [Rh(CO)(2)Tx] and [(RhTx)(2)(μ-CO)(3)] which reacts with PR(3) to give [Rh(CO)(PR(3))Tx] (R = Cy, NMe(2), Ph, OPh). In the solid state the complexes are square planar with the particular structure dependent on the steric and/or electronic properties of the scorpionate and ancillary ligands. The complex [Rh(cod){HB(taz)(pz)(2)}] has the heteroscorpionate κ(2)[N(2)]-coordinated to rhodium with the B-H bond directed away from the rhodium square plane while [Rh(cod){HB(taz)(2)(pz(Me2))}] is κ(2)[SN]-coordinated, with the B-H bond directed towards the metal. The complexes [Rh(CO)(PPh(3)){HB(taz)(2)(pz)}] and [Rh(CO)(PPh(3)){HB(taz)(2)(pz(Me2))}] are also κ(2)[SN]-coordinated but with the pyrazolyl ring cis to PPh(3); in the former the B-H bond is directed towards rhodium while in the latter the ring is pseudo-parallel to the rhodium square plane, as also found for [Rh(CO)(2){HB(taz)(2)(pz(Me2))}]. The analogues [Rh(CO)(PR(3)){HB(taz)(2)(pz(Me2))}] (R = Cy, NMe(2)) have the phosphines trans to the pyrazolyl ring. Uniquely, [Rh(CO)(PPh(3)){HB(taz)(2)(pz(Ph))}] is κ(2)[S(2)]-coordinated. A qualitative mechanism is given for the rapid ring-exchange, and hence isomerisation, observed in solution.
偕二唑螺环配体HB(taz)(2)(pz(R))（pz(R)=pz，pz(Me2)，pz(Ph)）和[HB(taz)(pz)(2)]-，由相应的钾六氢三（吡唑基）硼酸盐盐和 4-乙基-3-甲基-5-硫代-1,2,4-三唑（Htaz）合成，与[{Rh(cod)(μ-Cl)}(2)]反应得到[Rh(cod)Tx] {Tx=HB(taz)(2)(pz)，HB(taz)(2)(pz(Me2))，HB(taz)(2)(pz(Ph))，HB(taz)(pz)(2)};偕二唑硼烷[Rh{B(taz)(2)(pz(Me2))}{HB(taz)(2)(pz(Me2))}]是[{Rh(nbd)(μ-Cl)}(2)]与 K[HB(taz)(2)(pz(Me2))]反应的唯一可分离产物。 cod 配合物的羰基化反应得到[Rh(CO)(2)Tx]和[(RhTx)(2)(μ-CO)(3)]的混合物，该混合物与 PR(3)反应得到[Rh(CO)(PR(3))Tx]（R=Cy，NMe(2)，Ph，OPh）。在固态中，这些配合物为平面正方形，其特定结构取决于螺环配体和辅助配体的空间和/或电子性质。配合物[Rh(cod){HB(taz)(pz)(2)}]具有异螺环κ(2)[N(2)]配位的铑，B-H 键指向远离铑正方形平面，而[Rh(cod){HB(taz)(2)(pz(Me2))}]为κ(2)[SN]-配位，B-H 键指向金属。配合物[Rh(CO)(PPh(3)){HB(taz)(2)(pz)}]和[Rh(CO)(PPh(3)){HB(taz)(2)(pz(Me2))}]也是κ(2)[SN]-配位，但吡唑环顺式与 PPh(3)配位；在前者中，B-H 键指向铑，而在后者中，吡唑环与铑正方形平面近似平行，这与[Rh(CO)(2){HB(taz)(2)(pz(Me2))}]相同。类似物[Rh(CO)(PR(3)){HB(taz)(2)(pz(Me2))}]（R=Cy，NMe(2)）具有磷原子与吡唑环反式配位。独特的是，[Rh(CO)(PPh(3)){HB(taz)(2)(pz(Ph))}]为κ(2)[S(2)]配位。给出了在溶液中观察到的快速环交换（因此是异构化）的定性机制。
