Toshikatsu Yoshida

Liquid-crystalline (lsonitrile)gold(I) acetylide complexes

The mesomorphic properties of three types of gold(i) acetylide complexes, [(ArNC)Au-CCAr, (ArNC)Au-CCR and (RNC)Au-CCAr, where R and Ar represent alkyl and aryl groups, respectively] were systematically examined and it was found that of the three, (RNC)Au-CCAr (complex C) is the choice for liquid-crystalline materials, and that introduction of an appropriate lateral group on the isonitrile and/or acetylene ligands led to the formation of nematic and smectic A phases without any decomposition of the complexes. The linear geometry around the central gold atom was confirmed by X-ray crystallographic analysis of complex C-5b. The relation between the thermal behaviour and the molecular structure of the complexes is discussed.

Cationic rhodium(I) complexes of 1,4,8,11-tetrathiacyclotetradecane ([14]aneS4) and the 6,6,13,13-tetramethyl analogue (Me4[14]aneS4). Preparation of two conformers, X-ray crystal structure of {Rh[14]aneS4}2Cl2·MeCN, and conformational effect on the nucleophilicity of the rhodium(I) ion

Two conformers for the cationic rhodium(I) complexes of the title 14-membered cyclic tetrasulphides have been prepared and the conformational effect upon the nucleophilicity of rhodium(I) ion is shown by the oxidative addition reaction of CH2Cl2; {Rh[14]aneS4}Cl (1), in which the Rh atom lies 0.1332(2)A above the plane of four S atoms, forms a dimer through a Rh ⋯ Rh [3.313(1)A] and four Rh ···S [3.697(9)–3.822(3)A] intermolecular non-bonded interactions as established by an X-ray crystal structure determination.

Insertion reaction of isocyanide into the PtC bonds of 2,5-thienylene-bridged diplatinum complexes and 2-thienyl platinum complexes: molecular structure of Cl(Et3P)2PtC(NC6H4OMe-p)C4H2SC (NC6H4OMe-p)Pt(PEt3)2Cl·CH2Cl2

Abstract Treatments of 2,5-thienylene-bridged diplatinum complexes Cl(R 3 P) 2 PtC 4 H 2 SPt(PR 3 ) 2 Cl ( 1 ) with two equivalents of isocyanide cause the insertion of isocyanide into each of the two PtC bonds to produce Cl(R 3 P) 2 PtC(NAr)C 4 H 2 SC(NAr)-Pt(PR 3 ) 2 Cl ( 2 ). 2-Thienyl platinum complexes C 4 H 3 SPt(PR 3 ) 2 Cl ( 4 ) also react with isocyanide to give iminoacyl complexes C 4 H 3 SC(NAr)Pt(PR 3 ) 2 Cl ( 5 ). Further insertion of isocyanide into PtC bonds of 2 and 5 was not observed even in the reaction with excess isocyanide. When 1a was treated with an equimolar amount of p -tolyl isocyanide, a single-insertion product Cl(Et 3 P) 2 PtC(NC 6 H 4 Me- p )C 4 H 2 SPt(PEt 3 ) 2 Cl ( 3b ) was obtained altogether with the mixture of 1a and 2a . The molecular structure of Cl(Et 3 P) 2 PtC(NC 6 H 4 OMe- p )C 4 H 2 SC(NC 6 H 4 OMe- p )Pt(PEt 3 ) 2 Cl·CH 2 Cl 2 ( 2b ) was determined by an X-ray crystallographic analysis and the crystallographic data are as follows: space group, P 2 1 / n ; a = 11.044(2), b = 28.086(3) and c = 18.396(3) A ; β = 93.96°; V = 5692(2) A 3 ; Z = 4 .

Preparation and characterization of μ-alkyne-hexacarbonyldicobalt complexes derived from 1,1′-dialkynylferrocene. Molecular structures of {(η5-C5H4CPh)2Fe}{Co2(CO)6}2 and {(η5--C5H4CCPh)2Fe} Co2(CO)6

Abstract The reaction of 1,1′-dialkynylferrocene (η5-C5H4CCR)2Fe (1) R  Ph, SiMe3, Me, Fc; Fc = ferrocenyl) with excess octacarbonyldicobalt (2) results in the formation of dark green complexes {(η5-C5H4CCR)2Fe}{Co2(CO)6}2 (3) (R  Ph, SiMe3, Me, Fc), in which a CO2(CO)6 group coordinates to each of the two CC bonds of 1. When 1,1′-di(phenylethynyl)ferrocene (1a) was treated with an equimolar amount of 2, {(η5-C5H4CCPh)2Fe}CO2(CO)6 (4), as well as 3a, was obtained. In the thermal reaction of 4 intermolecular Co2(CO)6 group migration to give 3a was observed. Molecular structures of {(η5-C5H4CCPh)2Fe}{Co2(CO)6}2 (3a) and {(η5C5H4CCPh)2Fe}Co2(CO)6 (4) have been determined by single-crystal X-ray analyses.

Preparation of trans-RuH(η1-BH4)L (L = Me6[15]aneS4, Me8[16]aneS4) and oxidation in alcohols to give trans-{Ru(OR)2(anti-Me8[16]aneS4)}+ R = Me, Et). Crystal structures of the hydrido and ethoxo complexes of Me8[16]aneS4

Abstract Reaction of cis-RuCl2L (L = Me8[16]aneS4, Me6[15]aneS4) with an excess of NaBH4 in EtOH gave trans-RuH(η1-BH4)L(L = Me8[16]aneS4 (1); Me6[15]ane S4 (2)). The monodentate coordination of the BH4− ligand in 1 was confirmed by a single crystal X-ray diffraction study. It crystallizes in monoclinic space group P21/c, with Z = 4, a = 13.720(5), b = 17.975(6), c = 13.033(3) A , β = 113.86(3)°, R (R w ) = 0.070 (0.070) for 2258 reflections (|FO|⩾4σ(Fo)) and 272 parameters. Reaction 1 with O2 and subsequent treatment with alcohols produced trans-{Ru(OR)2(ani-Me8[16]aneS4)}+ (if(R = Me (3), Et (4)). The diethoxo complex was fully characterized by X-ray crystallography: monoclinic, space group C2/c, c = 16.627(5), b = 11.917(4), c = 18.418(9) A , β = 102.80(3)°, Z = 4, R (Rw = 0.036 (0.040) for 3491 reflections (|Fo|⩾3σ(FO)) and 312 parameters.

Ruthenium(II) hydrido complexes of quadridentate crown thioethers, trans-RuH(Cl)(syn-L) (L Me4[14]aneS4, Me6[15]aneS4, Me8[16]aneS4) and {Ru2H(μ-H)Cl(syn-Me4[14]aneS4)2} Cl containing a linear RuHRu bond. Novel characteristics of syn-crown thioethers affecting discrimination of axial ligands and geometry of the unsupported RuHWRu linkage

Abstract A series of ruthenium(II) hydrido complexes containing crown thioethers, trans -RuH(Cl)( syn -L) ( 4 , L  Me 4 [l4]aneS 4 ; 5 , L  Me 6 [15]aneS 4 ; 6 , L Me 8 [l6]aneS 4 ), were prepared in good yields by treating the corresponding dichlorides cis -RuCl 2 L ( 1 , L  Me 4 [4]aneS 4 ; 2 , L  Me 6 [15]aneS 4 ; 3 , L  Me 8 [16]aneS 4 ) with NaBH 4 in MeOH for 4 and in EtOH for 5 and 6 . The structures of 4 and 5 were elucidated by an X-ray diffraction study: 4 , orthorhombic, space group Pna 2 1 (No 33), a = 14.683(13), b = 12.605(2), c = 10.284(7)A, Z = 4, R ( R w ) = 0.030(0.033) for 2303 reflections (| F o | ⩾5σ( F o )); 5 , orthorhombic, Pbca (No. 61), a = 14.976(3), b = 13.877(3), c = 21.079(27)/rA, Z = 8, R ( R w ) = 0.043(0.051) for 3011 reflections (|F o |⩾ 5σ(F o )). The hydrido ligand in 4 and the chloro anion in 5 coordinate specifically at the congested axial site surrounded by the ring carbon atoms of the syn -crown thioethers. By contrast, the stereochemically different axial sites of the Ru( syn -Me 8 [16]aneS 4 ) moiety in 6 failed to discriminate between the two axial ligands and 6 exists as a mixture of two geometrical isomers. A similar reaction of 1 with NaBH 4 in EtOH gave an unsupported bridging hydride {Ru 2 H(μ-H)Cl( syn -Me 4 [14]aneS 4 ) 2 }Cl ( 7 ) as the major product together with 4 . Compound 7 crystallizes in the trigonal, space group, R 3 c (No. 167), with a = 18.615(6), c = 64.937(13) A, Z = 18. Least-squares refinement of 1975 reflections (| F o |⩾6σ( F o )) gave a final R ( Rw ) = 0.055(0.063). The cation of 7 possesses crystallographically C 2 symmetry with a face to face disposition of the RuH( syn -Me 4 [14]aneS 4 ) and RuCl( syn -Me 4 [14]aneS 4 ) moieties which are connected through a μ-hydride. The μ-hydride is completely surrounded by the lone pair orbitals of eight S atoms of the two moieties in a staggered conformation. The rotational barrier of the two moieties about the RuHRu bond assessed by extended Huckel MO calculations on the model compound {Ru 2 H(μ-H)Cl[ syn -(SH 2 ) 4 ] 2 } + of C 4 V symmetry is 0.82 eV. The calculations also indicated that the linear RuHRu geometry is more stable than the bent one; the elevation in total energy on bending the RuHRu linkage by 20° from linearity is 0.78 eV. Structural flexibility of syn -Me 4 [14]aneS 4 was proved from the molecular structure of 7 where a bulky chloro ligand is accommodated at the congested axial site of the Ru( syn -Me 4 [14]aneS 4 ) moiety. In sharp contrast to the facile displacement of all PPh 3 ligands in RuCl 2 (PPh 3 ) 3 by the crown thioethers employed here to give 1–3 , an attempt to prepare 4 by treating RuHCl(PPh 3 ) 3 with Me 4 [l4]aneS 4 failed and RuH(Cl 2 )(PPh 3 )2Me 4 [14]aneS 4 ( 9 ) was obtained. The chloride and one of two PPh 3 ligands of 9 readily dissociate in MeOH affording cis -{RuH(PPh 3 ) Me 4 [14]aneS 4 }Cl 2 ( 10 ).

Single and unsupported RuHRu bond: Preparation and crystal structure of {Ru2H(μ-H)Cl(syn-Me4[14]aneS4)2}Cl (Me4[14]aneS4 = 1,4,8,11-tetrathiacyclotetradecane)

Abstract Treatment of cis -RuCl 2 Me 4 [14]aneS 4 with an excess of NaBH 4 in ETOH gave {Ru 2 H(μ-H)-Cl(Me 4 [14]aneS 4 ) 2 }Cl ( 1 ) together with trans -RuH(Cl)( syn -Me 4 [14]aneS 4 )( 2 ). Compound 1 represents a novel example of a single μ 2 -hydrido complex of crown thioether without any supporting bridged ligands or metalmetal bond. The molecular structure of 1 was elucidated by an X-ray diffraction study.

Novel optically active 7,7′-bridged-1,1′-biisoquinolines and their chelation to rhodium (I) ion

Optically pure 7,7′-ethylenedioxy-1,1′-biisoquinoline 2and the 7,7′-(5-methoxy-m-xylylenedioxy) analogue 3 are prepared; their chelation to rhodium(I) takes place with complete retention when (R)-(–)-3 is treated with [RhCl(cod)]2 to give [Rh{(R)-(–)-3}(cod)]+, while a similar reaction of (+)-2gives a racemic complex [Rh(2)(cod)]+; both RhIcomplexes are structurally characterized by an X-ray diffraction study.

Chemistry of crown thioether complexes of low- valent second-row transition metals

- Preparation, structures, and reactions of 14- and 16-membered quadri dentate crown thioethers complexes , trans-Mo( N2)2Me8[ 161 aneS4, cisand trans-RuC12Ly and RhL’ (L=R4[141aneSq, R8[16]aneSq; R=H, Me) are described emphasizing the novel features of crown thioethers vs. phosphines. The most prominent electronic property of the crown thioethers is pT donor ability. The factors determining the reactivities of these complexes such as ring size and conformational effects of the macrocycles and geometrical effect of the complexes are discussed.

Preparation of a novel optically active 8,8′-bi-isoquinolyl and its co-ordination as a bridging ligand in rhodium(I) complexes

A novel optically active 7,7′-dimethoxy-8,8′-bi-isoquinolyl (5) with known absolute configuration has been prepared and has been found to co-ordinate to RhI as a bridging ligand in [RhCl(cod)]2[µ-(±)-(5)](6) and {Rh2(cod)2[µ-(+)-(5)]2}(CIO4)2(8)(cod = cyclo-octa-1,5-diene).