高尾（稲垣） 昭子

A series of 3,4-disubstituted (hex-3-ene-1,5-diyne-1,6-diyl) diron complexes with FeCp*(dppe) (Fe) end caps, Fe-C CC(R) C(R)C C-Fe (R = H, C C-SiMe3, C C-H, C6H5, p-C6H4CF3), and the related (octa-3,5-diene-1,7-diyne-1,8-diyl) diron complex, Fe-C C-C(H)=C(H)C(H)=C(H)C C-Fe, has been prepared, and their performance as molecular wires has been evaluated. The enyne complexes have been synthesized via vinylidene intermediates, [Fe=C=C(H)C(R)=C(R)C(H)=C=Fe](2+), derived from the corresponding terminal alkynes or the Me3Si-protected precursors (XC CCC(R)=C(R)C=C- X; X = H, SiMe3), and the products have been characterized spectroscopically and crystallographically. The performance of the obtained dinuclear enyne complexes as molecular wires has been evaluated on the basis of the comproportionation constants (K-C) obtained by electrochemical measurements and the V-ab values obtained from the spectral parameters of the intervalence charge transfer bands of the isolated monocationic radical species appearing in the near-IR region. As a result, the C-6-enediyne complexes turn out to be excellent molecular wires, with KC values larger than 108 as well as Vab values larger than 0.35, belonging to class III compounds according to the Robin and Day classification and being comparable to the related polyynediyl complexes as well. It is notable that, in the enyne system, the performance can be readily tuned by introduction of appropriate substituents onto the olefinic part. Thus, diiron complexes containing an enyne spacer can be regarded as tunable molecular wires.

Complexation of photochromic spirobenzopyran 1(SP-X) with the labile cationic ruthenium complex [Cp*Ru(NCMe)(3)]PF6 (2) furnishes two isomers of the 176-arene adducts, [Cp*Ru(eta(6)SP-X)]PF6 (3 and 4), i.e., one of the two diastereomeric adducts of the indoline part in the closed form of 1 (3) and the adduct of the dihydrobenzopyran part in the open transmerocyanine form of 1 (4). UV irradiation of the pale yellow adduct 3 does not cause an apparent color change, but H-1 NMR monitoring reveals formation of the diastereomer 3' with the inverted configuration of the chiral spiro carbon atom, which gradually reverts to 3 when left at ambient temperature in the dark over the course of a few days. The two diastereomers 3/3' are interconverted with each other through the open, merocyanine form III, which should result from photochemical C-O bond heterolysis of 3/3'. In the case of the SP-H complex 3b, photochromic behavior (3b <-> III'b (trans isomer of IIIb)) is noted but the amount of the colored species III'b formed is limited. On the other hand, irradiation of the deep red isomer 4 with visible light brings about trans to cis isomerization of the olefinic part to result in complete conversion to an equilibrated mixture of the two diastereomeric closed species 5 and 5', which are interconverted with each other at ambient temperature via the transient cis-open intermediate II. UV irradiation of the equilibrated mixture 5/5' reverses the ring-opening process to give a photoequilibrated mixture containing 4 in addition to 5/5'. Thus, 3 and 4 undergo interconversion of the diastereomers via photochemical C-O bond heterolysis and photochromic behavior is noted for 4.

A series of dinuclear complexes, [Tp(R)M--M'L(n)] [Tp(iPr(2) )M--Co(CO)(4) (1; M=Ni, Co, Fe, Mn); Tp(#)M--Co(CO)(4) (1'; M=Ni, Co); Tp(#)Ni--RuCp(CO)(2) (3')] (Tp(iPr(2) )=hydrotris(3,5-diisopropylpyrazolyl)borato; Tp(#) (Tp(Me(2),4-Br))=hydrotris(3,5-dimethyl-4-bromopyrazolyl)borato), has been prepared by treatment of the cationic complexes [Tp(iPr(2) )M(NCMe)(3)]PF(6) or the halo complexes [Tp(#)M--X] with the appropriate metalates. Spectroscopic and crystallographic characterization of 1-3' reveals that the tetrahedral, high-spin Tp(R)M fragment and the coordinatively saturated carbonyl-metal fragment (M'L(n)) are connected only by a metal-metal interaction and, thus, the dinuclear complexes belong to a unique class of xenophilic complexes. The metal-metal interaction in the xenophilic complexes is polarized, as revealed by their nu(CO) vibrations and structural features, which fall between those of reference complexes: covalently bonded species [R--M'L(n)] and ionic species [M'L(n)](-). Unrestricted DFT calculations for the model complexes [Tp(H(2) )Ni--Co(CO)(4)], [Tp(H(2) )Ni--Co(CO)(3)(PH(3))], and [Tp(H(2) )Ni--RuCp(CO)(2)] prove that the two metal centers are held together not by covalent interactions, but by electrostatic attractions. In other words, the obtained xenophilic complexes can be regarded as carbonylmetalates, in which the cationic counterpart interacts with the metal center rather than the oxygen atom of the carbonyl ligand. The xenophilic complexes show divergent reactivity dependent on the properties of donor molecules. Hard (N and O donors) and soft donors (P and C donors) attack the Tp(R)M part and the ML(n) moiety, respectively. The selectivity has been interpreted in terms of the hard-soft theory, and the reactions of the high-spin species 1-3' with singlet donor molecules should involve a spin-crossover process.

Cationic triruthenium hexahydrido complexes, [(Ru(C5Me5)}(3)(mu-H)(6)](Y) (Y = BF4, CF3SO3, 1/2(SO4), C6H5CO2, CH3CO2), have been synthesized by the reaction of diruthenium tetrabydride [(Ru(C5Me5)}(2)(mu-H)(4)] with the corresponding acid, HBF4, CF3CO2H, H2SO4, C6H5CO2H, and CH3CO2H. The trimeric structure of these complexes has been confirmed by a crystallographic study of [(RU(C5Me5)}(3)(mu-H)(6)](PF6). The treatment of [[Ru(C5Me5)}(3)(mu-H)(6)(Y) with CH3ONa in methanol selectively afforded a neutral trinuclear pentahydrido complex, [(Ru(C5Me5)}(3)(mu-H)(3)(mu(3)-H)(2)], which underwent an intermolecular H/D exchange reaction with benzene-d(6), toluene-d(8), or o-xylene-d(10) to give [{Ru(C5Me5)}(3)(mu-D)(3)(mu(3)-D)(2)] as the result of arene C-H bond activation via an eta(2)-arene intermediate complex. A cationic hydrido complex, [{RU(C5Me5)}(3)(mu-H)(6)](Y), having a carboxylate as a counter anion was equilibrated with [{Ru(C5Me5)}(3)(mu-H)(3)(mu(3)-H)(2)] in solution, and the equilibrium constant depended on the counter anion. An X-ray diffraction study showed that [{Ru(C5Me5)(3)(mu-H)(3)(mu(3)-H-2] has a triangular reaction field surrounded by three C5Me5 ligands. The reaction of [{Ru(C5Me5)}(3)(mu-H)(3)(mu(3)-H)(2)] with 1 equiv Of O-2 proceeded with the retention of the RU3 framework to yield an 80/20 mixture of a mono-mu(3)-oxo complex [{Ru(C5Me5)}(3)(mu-H)(3)(mu(3)-O)] and a di-mu(3)-oxo complex [{Ru(C5Me5)(3)(mu-H)(3)(mu(3)-O)(2)]. A novel trinuclear mu(3)-iodo-tetra-mu-hydrido complex, [{Ru(C5Me5)}(3)(mu(3)-H)(mu-H)(3)(mu(3)-I)] was formed upon the treatment of [{RU(C5Me5)}(3)(mu-H)(3)(mu(3)-H)(2)] with 1 equiv of CH3I in tetrahydrofuran. The treatment of [{Ru(C5Me5)}(3)(mu-H)(3)(mu(3)-H)(2)] with carbon monoxide generated a paramagnetic trinuclear tctracarbonyl complex, [{Ru(C5Me5)}(3)(mu-CO)(3)(mu(3)-CO)].

The dirhodium-tetracarbonyl complex with the PNNP ligand, [Rh-2(PNNP)(CO)(4)]BF4, 1(.)BF(4) [PNNP = 3,5-bis(diphenylphosphinomethyl)pyrazolato], serves as a precursor for the active species [Rh-2(PNNP)(CO)(2)](+), A, with cis-divacant coordination sites, which can accommodate a donor species with up to four donor electrons. Interaction of 1(.)BF(4) with Li-CdropC-R, Li-CH=CH2, PPN[M(CO)(n)], CN-Cy, SMe2, and Et-CdropC-Et leads to the formation of the corresponding dinuclear adducts [(X)Rh-2(PNNP)(CO)(2)](n+) (BF4)(n) [X/n = mu-eta(1):eta(2)-CdropC R/0 (2), mu-eta(1):eta(2) -CH=CH2/0 (3), mu-Co(CO)(4)/0 (4a), mu-Mn(CO)(5)/0 (4b), (eta(1)-CdropN-Cy)(2)/1 (5(.)BF(4)), mu-eta(1):eta(1)-SMe2/1 (6(.)BF(4)), mu-eta(2):eta(2)-Et-CdropC-Et/1 (7(.)BF(4))], respectively. Selective replacement of the inner CO ligands trans to the P atoms is verified by spectroscopic and crystallographic characterizations of the adducts. The mu-acetylide (2) and mu-vinyl complexes (3) show dynamic behavior via the conventional windshield wiper motion of the unsaturated hydrocarbyl ligand. Systematic structural analysis of a series of the mu-acetylide complexes 2 (R = H, SiMe3, n-Bu, Ph, p-tol) reveals three typical conformations for the Rh-2(PNNP)(CO)(2) backbone: C-s-(type I), C-2- (type II), and C-2v-symmetrical ones (type III). On the other hand, interaction of 1(.)BF(4) with 1-alkyne, hydrosilanes, and hydroxo anion produces tetranuclear adducts resulting from 1 (donor):2 [Rh-2(PNNP)(CO)(2)] coupling reactions. The mu(4)-eta(1)(C-alpha):eta(2)(C(alpha)dropC(beta))-acetylide complexes, [(mu(4)-CdropC-R)Rh-4(PNNP)(2)(CO)(4)]BF4, 8(.)BF4, consisting of an acyclic, folded Z-shaped Rh-4 linkage are fluxional via a combination of windshield wiper-like motions between the wingtip Rh centers and between the wingtip and hinge Rh centers, which involve reversible M-M bond scission and recombination processes. The ethynyl complex 8a(.)BF(4) (R = H) is readily deprotonated by the action of a base to give the mu(4)-dicarbide complex (mu-eta(1):eta(1):eta(2):eta(2)-CdropC)Rh-4(PNNP)(CO)(4), 9, via cleavage of three Rh-Rh bonds, and this process is reversed upon protonation of 9 with HBF4. The reaction of 1(.)BF(4) with hydrosilanes and hydroxo anion furnishes the isostructural tetranuclear complexes [(mu(4)-X)Rh-4(PNNP)(CO)(4)](n+)-(BF4)(n) [X/n = H/1 (10(.)BF(4)), 0/0 (11)], in which the four Rh atoms arranged in a tetrahedral array are connected by the mu(4)-bridging ligand (X), as characterized by X-ray crystallography. The tetranuclear structures are retained mainly by Rh-X interactions even in the case of the electron-deficient hydride complex 10(.)BF4 with 58 valence electrons (cf. 64e for a coordinatively saturated species), where the filled, spherically distributed ls orbital of the hydride ligand interacts with the four Rh centers arranged in a tetrahedral array. Depending on the size of the bridging ligand X, the structure of the tetranuclear complexes varies from the encapsulated structure (10(.)BF(4) and 11) to the one with a folded Z-shaped metal linkage (8(.)BF4). The present study reveals (i)the high reactivity (electrophilicity) of the active species A with cis-divacant coordination sites, (ii) M-M bonds being not always essential for a polynuclear system, (iii) dynamic behavior via reversible M-M bond cleavage and recombination processes, and (iv) flexible coordination properties of the Rh-2(PNNP) system.

The reaction of the monocationic triruthenium hexahydride [(Cp'Ru)(3)(mu-H)(6)]X (1; X = 1/2 SO4, BF4, PF6, BPh4) with hydrazine leads to the formation of the mono(mu(3)-imido) complex (Cp'Ru)(3)(mu(3)-NH)(mu-H)(3) (3) and the triruthenium pentahydride complex (Cp'Ru)(3)(mu(3)-H)(2)(muH)(3) (2). Complex 1 is in equilibrium with 2 in the presence of NH4X or N2H5X, and complex 1 is regenerated upon treatment of 2 with such a protic salt. Complex 3 further reacts with hydrazine to yield the bis(mu(3)-imido) complex (Cp'Ru)(3)(mu(3)-NH)(2)(mu-H) (4) as a result of cleavage of the nitrogen-nitrogen bond, which is formally catalyzed by a proton. Both 3 and 4 undergo hydrogenation to generate 2 together with ammonia. Thus, reductive cleavage of the nitrogen-nitrogen bond of hydrazine leading to ammonia is achieved by the use of the monocationic trinuclear hexahydride complex 1 and dihydrogen under conditions without any added proton source and a reducing agent.

Pairs of isomeric heterodinuclear complexes, [(cod) Ir(mu-PNNN) M(L)] BF4 and [(L) M(mu-PNNN) Ir(cod)] BF4, with switched metal arrangements are prepared in a specific manner by simply changing the addition order of the reagents.