Theoretical studies of magnetic interactions in Mn(II)(hfac)(2)[di(4-pyridyl)phenylcarbene] and Cu(II)(hfac)(2)[di(4-pyridyl)phenylcarbene].
Theoretical studies of magnetic interactions in Mn(II)(hfac)(2)[di(4-pyridyl)phenylcarbene] and Cu(II)(hfac)(2)[di(4-pyridyl)phenylcarbene].
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DOI：
10.1021/ja015967x
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发表时间：
2002-01
影响因子：
15
通讯作者：
Y. Takano;Y. Kitagawa;T. Onishi;Y. Yoshioka;K. Yamaguchi;N. Koga;H. Iwamura
中科院分区：
文献类型：
--
作者：
Y. Takano;Y. Kitagawa;T. Onishi;Y. Yoshioka;K. Yamaguchi;N. Koga;H. Iwamura
双（六氟乙酰丙酮（hfac））锰（II）与二（4-吡啶基）苯基卡宾配位，Mn(II)(hfac)(2)[二（4-吡啶基）苯基卡宾]（1a）及其铜类似物Cu(II)(hfac)(2)[二（4-吡啶基）苯基卡宾]（2a）从光致磁学的角度引起了人们的极大兴趣。以过渡金属离子和碳烯为自旋源的配合物1a和2a为新的d-pi-p共轭体系。磁性测量分别证明了1a和2a的反铁磁和铁磁有效交换相互作用。在这里，我们进行了UHF和UHF加DFT混合计算（UB3LYP）来阐明Mn(II)（或Cu(II)）离子与1a（或2a）及其模型配合物中的三重态碳位点之间的通过键有效交换相互作用的性质。对UHF和UB3LYP溶液进行了自然轨道分析，并对1a和2a的最简单模型进行了CASCI计算，以阐明自旋极化（SP）和自旋离域（SD）（或超交换（SE））相互作用对确定J（ab）值符号的相对贡献。Mn（II）卡宾配合物1a由于π型反铁磁SE效应和π型SP效应而表现出反铁磁相互作用，而Cu（II）卡宾配合物2a的正J（ab）值可以解释为由于轨道正交性导致的铁磁SE和SP相互作用比sigma型反铁磁SE相互作用更有效。4-pyridylcarbene和hfac的配体配位效应对J（ab）值的测定都起着至关重要的作用，但hfac的配体配位效应对电荷或自旋密度分布的主动控制比4-pyridylcarbene的更重要。1a和2a的自旋排列机制确实符合SE + SP规则，这与自然轨道的形状和对称性以及电荷和自旋密度分布都得到了证实。
Bis(hexafluoroacetylacetonato(hfac))manganese(II) coordinated with di(4-pyridyl)phenylcarbene, Mn(II)(hfac)(2)[di(4-pyridyl)phenylcarbene] (1a) and its copper analogue Cu(II)(hfac)(2)[di(4-pyridyl)phenylcarbene] (2a) have attracted great interest from the viewpoint of photoinduced magnetism. The complexes 1a and 2a are regarded as the new d-pi-p conjugated systems containing transition metal ion and carbene as spin sources. The magnetic measurements demonstrated antiferromagnetic and ferromagnetic effective exchange interactions for 1a and 2a, respectively. Here, we have performed UHF and UHF plus DFT hybrid calculations (UB3LYP) to elucidate the nature of the through-bond effective exchange interaction between Mn(II) (or Cu(II)) ion and triplet carbene sites in 1a (or 2a) and their model complexes. The natural orbital analysis of the UHF and UB3LYP solutions and CASCI calculations for the simplest models of 1a and 2a are performed to elucidate relative contributions of spin polarization (SP) and spin delocalization (SD) (or superexchange (SE)) interactions for determination of the sign of J(ab) values. Mn(II) carbene complex 1a shows an antiferromagnetic interaction because of the pi-type antiferromagnetic SE effect and the pi-type SP effect, while the positive J(ab) value for Cu(II) carbene complex 2a can be explained by the fact that ferromagnetic SE and SP interactions due to orbital orthogonality are more effective than the sigma-type antiferromagnetic SE interaction. The ligand coordination effects of both 4-pyridylcarbene and hfac play crucial roles for determination of the J(ab) values, but the ligand coordination effect of hfac is more important for the active control of charge or spin density distributions than that of 4-pyridylcarbene. The spin alignment mechanisms of 1a and 2a are indeed consistent with SE plus SP rule, which is confirmed with the shape and symmetry of natural orbitals, together with charge and spin density distributions.