A NEW MODEL FOR DIOXYGEN BINDING IN HEMOCYANIN - SYNTHESIS, CHARACTERIZATION, AND MOLECULAR-STRUCTURE OF THE MU-ETA-2-ETA-2 PEROXO DINUCLEAR COPPER(II) COMPLEXES, [CU(HB(3,5-R2PZ)3)]2(O2) (R = ISO-PR AND PH)
A NEW MODEL FOR DIOXYGEN BINDING IN HEMOCYANIN - SYNTHESIS, CHARACTERIZATION, AND MOLECULAR-STRUCTURE OF THE MU-ETA-2-ETA-2 PEROXO DINUCLEAR COPPER(II) COMPLEXES, [CU(HB(3,5-R2PZ)3)]2(O2) (R = ISO-PR AND PH)
复制标题
DOI：
10.1021/ja00030a025
复制
发表时间：
1992-02-12
影响因子：
15
通讯作者：
NAKAMURA, A
中科院分区：
文献类型：
--
作者：
KITAJIMA, N;FUJISAWA, K;NAKAMURA, A
本文报道了在理化性质上与氧血红蛋白（或氧酪氨酸酶）相似的mu-eta-2:eta-2过氧双核铜（II）配合物的合成和表征。双mu-羟基铜（II）配合物[Cu(HB(3,5-i- pr2pz)3)]2(OH)2(8)与H2O2低温反应得到了mu-过氧配合物[Cu(HB(3,5-i- pr2pz)3)]2(O2)(6)。在铜(I)配合物Cu(HB(3,5- I - pr2pz)3)(9)的基础上，采用二氧加成法制备了配合物6。通过对铜(I)丙酮加合物Cu(Me2CO)(HB(3,5- ph2pz)3)（10）进行类似的双氧处理，制备了类似的过氧配合物[Cu(HB(3,5- ph2pz)3)]2(O2)(7)。6与CO或PPh3反应，释放出二氧，生成相应的铜(I)加合物Cu(CO)(HB(3,5- I - pr2pz)3)（11）或Cu(PPh3)(HB(3,5- I - pr2pz)3)（12）。对6-6（CH2Cl2）、8-1.5（CH2Cl2）和11进行晶体学分析。化合物6-6（CH2Cl2）在单斜空间群C2/c中结晶，a = 26.36(2)埃，b = 13.290(4)埃，c = 29.29(2)埃，β = 114.59(6)度，V = 7915(9)埃3，Z = 4。对于F大于或等于3-sigma（F(o)）的3003个反射，精细化收敛于最终R（R(w)）值0.101（0.148）。化合物8-1.5（CH2Cl2）在三斜空间群P1BAR中结晶，a = 16.466(4)埃，b = 16.904(5)埃，c = 14.077(3)埃，alpha = 112.92(2)度，beta = 99.21(2)度，gamma = 90.76(2)度，V = 3550(2)埃3，Z = 2，对于F大于等于3-sigma（F(o)）的7226次反射，最终R（R(w)）因子为0.083（0.105）。化合物11在单斜空间群中结晶，P2(1/a), a = 16.595(4)埃，b = 19.154(4)埃，c = 10.359(2)埃，β = 106.65(2)度，V = 3155(1)埃3，Z = 4，当F大于或等于3-sigma（F(o)）时，5356反射的最终R（R(w)）值为0.083（0.074）。6-6（CH2Cl2）的x射线分析首次明确地建立了过氧化物离子的mu-eta-2:eta-2配位结构。这种不寻常的侧面结构对于d块元素过渡金属-二氧配合物来说是完全新颖的。6号和7号都表现出与已知的氧血青素和氧酪氨酸酶非常相似的显著特征。配合物6：抗磁性；nu(O-O), 741 cm-1；UV-vis, 349nm (epsilon, 21000), 551nm (epsilon, 790)；Cu-Cu， 3.56埃。配合物7：抗磁性，nu(O-O), 759 cm-1；UV-vis, 355nm (epsilon, 18000), 542 nm （epsilon, 1040）。这些性质都与类似的配合物[Cu(HB(3,5- me2pz)3)]2(O2)(5)的性质一致，其表征和反应性已经被报道过（Kitajima， N., et al.）。j。化学。社会科学。1990,112,6402；1991, 113, 5664)。详细讨论了5-7的磁性和光谱特征及其生物学意义。此外，基于扩展的Huckel MO计算提供了N3Cu(O22-)CuN3发色团电子态的简单解释。由于-eta-2:eta-2过氧配合物5-7与氧血青素的性质非常相似，我们提出了一种新的血青素双氧结合模型；二氧在两个铜离子之间以mu-eta-2:eta-2模式结合。有了这个结构模型；内源性桥接配体的存在，通常被认为是氧血青素抗磁性的原因，不再是必要的。
The synthesis and characterization of mu-eta-2:eta-2 peroxo dinuclear copper(II) complexes which show many similarities to oxyhemocyanin (or oxytyrosinase) in their physicochemical properties are presented. The low-temperature reaction of a di-mu-hydroxo copper(II) complex [Cu(HB(3,5-i-Pr2pz)3)]2(OH)2 (8) with H2O2 gave a mu-peroxo complex [Cu(HB(3,5-i-Pr2pz)3)]2(O2) (6). Complex 6 was also prepared by dioxygen addition to a copper(I) complex Cu(HB(3,5-i-Pr2pz)3) (9). The preparation of an analogous peroxo complex [Cu(HB(3,5-Ph2pz)3)]2(O2) (7) was accomplished by the similar dioxygen treatment of a copper(I) acetone adduct Cu(Me2CO)(HB(3,5-Ph2pz)3) (10). The reaction of 6 with CO or PPh3 causes release of dioxygen, resulting in formation of the corresponding copper(I) adduct, Cu(CO)(HB(3,5-i-Pr2pz)3) (11) or Cu(PPh3)(HB(3,5-i-Pr2pz)3) (12). Crystallography was performed for 6-6(CH2Cl2), 8-1.5(CH2Cl2), and 11. Compound 6-6(CH2Cl2) crystallizes in the monoclinic space group C2/c with a = 26.36 (2) angstrom, b = 13.290 (4) angstrom, c = 29.29 (2) angstrom, beta = 114.59 (6)-degrees, V = 7915 (9) angstrom 3, and Z = 4. The refinement converged with the final R (R(w)) value, 0.101 (0.148), for 3003 reflections with F greater-than-or-equal-to 3-sigma(F(o)). Compound 8-1.5(CH2Cl2) crystallizes in the triclinic space group P1BAR with a = 16.466 (4) angstrom, b = 16.904 (5) angstrom, c = 14.077 (3) angstrom, alpha = 112.92 (2)-degrees, beta = 99.21 (2)-degrees, gamma = 90.76 (2)-degrees, V = 3550 (2) angstrom 3, Z = 2, and the final R (R(w)) factor, 0.083 (0.105), for 7226 reflections with F greater-than-or-equal-to 3-sigma(F(o)). Compound 11 crystallizes in the monoclinic space group, P2(1/a) with a = 16.595 (4) angstrom, b = 19.154 (4) angstrom, c = 10.359 (2) angstrom, beta = 106.65 (2)-degrees, V = 3155 (1) angstrom 3, Z = 4, and the final R (R(w)) value 0.083 (0.074) for 5356 reflections with F greater-than-or-equal-to 3-sigma(F(o)). The X-ray analysis of 6-6(CH2Cl2) definitely established the mu-eta-2:eta-2 coordination structure of the peroxide ion for the first time. This unusual side-on structure is entirely novel for a d-block element transition-metal-dioxygen complex. Both 6 and 7 show remarkable characteristics which are very similar to those known for oxyhemocyanin and oxytyrosinase. Complex 6: diamagnetic; nu(O-O), 741 cm-1; UV-vis, 349 nm (epsilon, 21 000), 551 nm (epsilon, 790); Cu-Cu, 3.56 angstrom. Complex 7: diamagnetic, nu(O-O), 759 cm-1; UV-vis, 355 nm (epsilon, 18 000), 542 nm (epsilon, 1040). These properties are all consistent with those of an analogous complex, [Cu(HB(3,5-Me2pz)3)]2(O2) (5), of which the characterization and reactivities were reported already (Kitajima, N., et al. J. Am. Chem. Soc. 1990, 112, 6402; 1991, 113, 5664). The magnetic and spectroscopic features of 5-7 and their biological relevance are discussed in detail. Furthermore, simple interpretation of the electronic state of the N3Cu(O22-)CuN3 chromophore is provided based on extended Huckel MO calculations. The close resemblance between the properties of mu-eta-2:eta-2 peroxo complexes 5-7 and oxyhemocyanin led us to propose a new model for dioxygen binding in hemocyanin; dioxygen is simply bound between the two copper ions in the mu-eta-2:eta-2 mode. With this structural model; the existence of an endogenous bridging ligand, which has been generally supposed to account for the diamagnetism of oxyhemocyanin, is no longer necessary.