Barbara L. Ruhl

Axial additions in nickel(II) complexes of (5SR,7RS,12RS,14SR)-tetra-methyl-1,4,8,11-tetra-azacyclotetradecane (Lα) and crystal-structure analysis of the planar orange and octahedral violet perchlorate salts NiLα,(ClO4)2

Reduction of the nickel(II) complex of C-meso-5,7,12,14-tetramethyl-1,4,8,11-tetra-azacyclotetradeca-4,11-diene with NaBH4 gives predominantly the nickel(II) complex of the title ligand, Lα. Both orange (1) and violet (2) isomers of NiLα(ClO4)2 have been characterised and structures established by X-ray crystallography. Crystals of (1) are monoclinic, space group P21/c with two formula units in a unit cell of dimensions a= 8.244(1), b= 8.656(1), c= 16.701(1)A, and β= 110.28(1)°. Crystals of (2) are triclinic, space group P with two formula units in a cell of dimensions a= 10.645(1), b= 8.298(1), c= 14.198(2)A, α= 121.36(1), β= 94.61(1), and γ= 82.77(1)°. Both structures were solved by the heavy-atom method and refined by full-matrix least-squares calculations. For (1), R= 0.036 for 2 434 observed reflections; for (2). R= 0.043 for 1 924 observed reflections. Orange complex (1) contains ionic perchlorate with the closest Ni ⋯ O contact 2.808(5)A. In the centrosymmetric square-planar cation the Ni–N distances are 1.964(3) and 1.974(3)A. The purple complex (2) contains two independent discrete half molecules (2a) and (2b) lying on inversion centres in the asymmetric unit, both with axially bound perchlorate. Principal distances are Ni–O 2.235(3) and 2.221(2)A and Ni–N 2.063(2)–2.081 (2)A. The metal complexes have the trans III arrangement of the chiral nitrogen centres, with the four methyl groups equatorial. The complex [NiLα]2+ undergoes axial additions with unidentate ligands (H2O, Br–, Cl–, NCS–, N3–, NO2–, O2CMe–) and trans-[NiLX2]n+ have been prepared and characterised. Infrared and d–d spectra are reported. The equilibrium [NiLα]2++ 2H2O ⇌[NiLα(OH2)2]2+has been studied over a temperature range, yielding K= 5.06 at 25 °C with ΔH⊖=–22.1 kJ mol–1 and ΔS⊖=–60.6 J K–1 mol–1.

Synthesis, X-ray crystal structures, and cation transfer properties of alkyl calixaryl acetates, a new series of molecular receptors

Calix[4]-, [6]-, and [8]-arenes have been converted into a series of alkyl acetates which show significant phase-transfer activity and selectivity towards alkali metal picrates; the X-ray crystal structure of two members of the series, (1b) and (2d), have been determined.

Formation of η2-aroyl, η1-halogenocarbyne or sterically crowded aryldiazenide ligands in the reactions of ring-substituted tricarbonyl[hydrotris(pyrazolyl)borato]-molybdate and -tungstate anions with arenediazonium cations and related oxidants

Although the hydrotris(pyrazolyl)borato complex [Mo{HB(pz)3}(CO)3]– reacted with 3- or 4-substituted arenediazonium cations [R′N2]+ yielding carbonyl-substitution (i.e. aryldiazenido) products [Mo{HB(pz)3}(CO)2(N2R′)]. reaction of the methylsubstituted analogue [ML*(CO)3]–[L*= tris(3,5-dimethylpyrazolyl)hydroborate; M = Mo or W] led, via oxidative formation of aryl radicals and [ML*(CO)3]˙, to η2-aroyl complexes [ML*(CO)2(η2-COR′)][R′= C6H4X-4 (X = NO2, CN, COMe, CF3, H, Me, OMe or NMe2) or C6H4X-3 (X = NO2 or OMe)] in acetonitrile or to the halogenocarbyne complexes [ML*(CO)2(CX)](X = Cl, Br or I) in the presence of the halogenoalkanes CH2Cl2 or CHX3(X = Br or I). The complex [MoL*(CO)3]– reacted similarly with diphenyliodonium or triphenylsulfonium cations, but in the latter case anion–cation redox is very slow in the dark but rapid upon irradiation with sunlight. Comparison of these results with those obtained for [ML*(CO)3]– analogues with different substituents in the pyrazolyl rings demonstrates that oxidation of the former by arenediazonium cations occurs in response to the steric rather than the electronic effect of the 3-methyl substituents. However further steric crowding in either the hydrotris(pyrazolyl)borate ligand or the diazonium cation promotes a reversion to the carbonyl-substitution pathway. A mechanism to account for these observations is proposed. Attempts to extend the chlorocarbyne synthesis to systems other than [ML*(CO)3]– met with only limited success. Spectroscopic data for the new complexes are reported and discussed. Two aryldiazenido complexes, [MoL*(CO)2(N2R′)](R′= 2,6-Me2C6H3 or 2,3-dimethyl-5-oxo-1-phenyl-3-pyrazolin-4-yl) have been characterised by single-crystal X-ray diffraction studies and are found to differ in the manner in which the aryldiazenide ligand accommodates to steric crowding in the molybdenum co-ordination sphere.

Tetra-aza macrocyclic complexes containing a pendant amino group. Copper(II), nickel(II), and cobalt(III) complexes of 5-aminomethyl-2,5,10,12-tetramethyl-1,4,8,1 1-tetra-azacyclotetradecane (L) and X-ray structural characterisation of the cobalt(III) complex [Co(L)Cl][ClO4]Cl·EtOH

The macrocycle 5-aminomethyl-2,5,10,12-tetramethyl-1,4,8,11-tetra-azacyclotetradecane (L) containing a pendant amino group has been prepared. A variety of copper(II), nickel(II), and cobalt(III) complexes have been characterised. Octahedral [NiL(H2O)]2+ complexes are readily protonated to give yellow or orange planar [Ni(HL)]3+ species. Analogous copper(II) complexes have also been prepared. X-ray crystallographic investigation of the complex [Co(L)Cl][ClO4]Cl·EtOH confirms the ligand stereochemistry and establishes a trans III (2 N–H bonds up, 2 N–H bonds down) stereochemistry for the chiral NH centres. The pendant amino group acts as a donor in one of the axial sites and lies trans to the chloride ligand. Rapid base hydrolysis of the Cl– ligand occurs with kOH= 2.2 × 104 dm3 mol–1 s–1 and kaq= 3.5 × 10–5 s–1 at 25 °C and I= 0.1 mol dm–3.

Transition metal derivatives of arenediazonium ions: XIII. Indirect synthesis of a bis(arenediazo) derivative of the hydrotris(1-pyrazolyl)boratotricarbonylmolybdenum anion: The crystal and molecular structure of hydrotris(1-pyrazolyl)boratobis(p-toluenediazo)fluoromolybdenum(0) MoF(N2C6H4Me-p)2[HB(C3H3N2)3]☆

Abstract Although the anion [Mo(CO) 3 (η-C 5 H 5 )] − reacts readily with excess [ArN 2 ] + to give a cationic bis-arenediazo derivative [Mo(N 2 Ar) 2 (L)(η-C 5 H 5 )] + (L= CO or solvent) the analagous hydrotris(1-pyrazolyl)borato complexes are not accessible via the reaction of either [Mo(CO) 3 {HB(C 3 H 3 N 2 ) 3 }] − or Mo(N 2 Ar)(CO) 2 [HB(C 3 H 3 N 2 ) 3 ) with [ArN 2 ] + . This reactivity difference can be ascribed to the reluctance of molybdenum poly(1-pyrazolyl)borato complexes to form 7-coordinate intermediates. However the bis(arenediazo) complex MoF(N 2 C 6 H 4 Me- p ) 2 [HB(C 3 H 3 N 2 ) 3 ] (I) is accessible via an indirect route involving reaction of the kinetically labile complex [Mo(N 2 C 6 H 4 Me- p ) 2 PPh 3 )(η-C 5 H 5 )][BP 4 ] (XI) with T1[HB(C 3 H 3 N 2 ) 3 ]. Crystals of I are monoclinic, space group P 2 1 / n with four molecules in a unit-cell of dimensions a 10.354(4), b 8.289((1), c 30.402(7) A and β 99.78(3)°. The structure was solved by the heavy-atom method and refined by full-matrix least squares calculations. All hydrogen atoms were located from difference syntheses. Final R = 0.030 for 3812 reflections with I > 3σ(I). Complex I has octahedral geometry and approximate mirror symmetry with the two arenediazo ligands bound to Mo in the “singly-bent” (formal [ArN 2 ] + ) coordination mode (MoNN 176.1(2), 175.2(2); NNC both 118.2°; MoN both 1.832(3), NN 1.217(4), 1.226(3) A) and the MoF bond length is 1.965(2) A. The orientation of the bending of the two arenediazo ligands is ascribed to steric crowding within the molybdenum coordination sphere. The MoN (pyrazolyl) bond lengths show a pronounced trans -effect (MoN trans to F = 2.173(2), MoN trans to [N 2 C 6 H 4 Me- p ] 2.211, 2.210(3) A].

An unusual effect of ligand methyl-substitution in the reaction of tricarbonyl (Group 6A metal)[hydrotris(3,5-R2-1-pyrazolyl)borato]anions (R = H, Me) with arenediazonium cations: X-ray crystallographic characterisation of a MoIIη2-aroyl complex, [Mo(η2-COC6H4Me-p)(CO)2{HB(3,5-Me2C3HN2)3}] and of an η2-hexahydrobenzoyl analogue, [Mo(η2-COC6H11)(CO)2{HB(3,5-Me2C3HN2)3}]

An X-ray crystallographic study has shown that the intensely-coloured products which result from the anomalous reaction of arenediazonium cations with [Mo(CO)3{HB(3,5-Me2C3HN2)}3]– are η2-aroyl dicarbonyl derivatives of MoII, [Mo(η2-COAr)(CO)2{HB(3,5-Me2C3HN2)3}] rather than η1-aryl tricarbonyl complexes as originally proposed: a by-product formed when the reaction is carried out in the presence of cyclohexane has been identified by X-ray crystallographic methods as the η2-hexahydrobenzoyl complex [Mo(η2-COC6H11)(CO)2{HB(3,5-Me2C3HN2)3}] the formation of which has been interpreted in terms of a free-radical mechanism for the reaction.

Transition metal derivatives of arenediazonium ions XV. The synthesis, chemistry and X-ray crystallographic characterisation of molybdenum(0) and tungsten(0) complexes containing the cis-[M(NO)(N2Ar)]2+ structural unit☆

Abstract Synthetic procedures and preliminary chemical studies are described for four new types of Group VIa nitrosyl-arenediazo complex: (η-C 5 H 5 )M(NO)(N 2 Ar)Cl (VII), (HBpz 3 )M(NO)(N 2 Ar)Cl (VIII). [(HCpz 3 )M(NO)(N 2 Ar)Cl] + (IX) and [(η-C 5 H 5 )M(NO)(N 2 Ar)(PPh 3 )] + (XIII). These complexes complete the homologous series containing the isoelectronic and quasi-isostructural fragments [M(NO) 2 ] 2+ , [M(NO)(N 2 Ar)] 2+ and [M(N 2 Ar) 2 ] 2+ (M = Group VIa metal). IR spectroscopic studies of VII and VIII suggest that the hydrotris-(1-pyrazolyl)borato ligand in these complexes is a better π-acceptor than cyclopentadienide. Two of the new complexes have been characterised by X-ray crystallographic methods. Crystals of (HBpz 3 )Mo(NO)(N 2 C 6 H 4 F- p )Cl (VIIIb) are triclinic, space group P 1 with four molecules in a unit cell of dimensions a = 13.053(3), b = 18.275(3), c = 8.954(2) A, α = 97.18(2), β = 106.50(2), γ = 88.53(2)°. Crystals of [(η-C 5 H 5 )Mo(NO)(N 2 C 6 H 4 F- p )(PPh 3 )]PF 6 , [(XIIIc)]PF 6 , are also triclinic, space group P 1 , with two formula units in a unit cell of dimensions a = 11.526(1), b = 13.875(2), c = 10.873(2) A, α = 108.37(2), β = 105.82(10, γ = 103.00(1)°. Both structures were determined by the heavy-atom method and refined to final R values of 0.030 (for 3812 observed reflections, VIIb) and 0.028 (for 3560 observed reflections [(XIIIc)]PF 6 ). There are two independent molecules of VIIIb in the asymmetric unit. Principal bond lengths are: VIIIb: MoN(nitrosyl) 1.767(4) and 1.789(4), MoN(arenediazo) 1.857(3) and 1.877(3), MoN(Pz) 2.158–2.200(4), MoCl 2.424(1) and 2.428(1) A; [(XIIIc)]PF 6 : MoN(nitrosyl) 1.802(3), MoN(arenediazo) 1.876(3), MoP 2.487(1), MoC(C 5 H 5 ) 2.318–2.371(4) A.

Preparation and crystal structure analysis of a vinyl ether chelate, dichloro[4-methoxy-2,2,N,N-tetramethylbut-(Z)-3-enylamine]palladium(II), and its conversion into di-µ-chloro-bis[3-(dimethylamino)-1-formyl-2,2-dimethylpropyl-C,N]dipalladium(II)

Reaction of either cis-(1a) or trans-4-methoxy-2,2,N,N-tetramethylbut-3-enylamine (1b) with PdCl2·2PhCN afforded only the cis-vinyl ether chelate [PdCl2(NMe2CH2CMe2CHCHOMe)], (6). Crystals of (6) are monoclinic, space group P21/n, with eight molecules in a unit cell of dimensions a= 14.241 (3), b 14.744(2), c= 13.508(1)A, and β= 111.53(1)°. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations to R= 0.024 8 for 3 981 reflections with I > 3σ(I). The two independent molecules have essentially the same conformation and dimensions. In each molecule, the Pd co-ordination is close to square planar with cis Cl atoms. The five-membered chelate rings have envelope conformations with quaternary carbon C(2) at the flap. The olefin configuration is cis. Principal bond lengths are Pd–Cl (trans to olefin) 2.321(1) and 2.330(1), Pd–Cl (cis to olefin) 2.298(1) and 2.296(1), Pd–N 2.082(2) and 2.089(2), Pd–C(3) 2.135(3) and 2.139(3), Pd–C(4) 2.266(3) and 2.249(3), CC 1.363(5) and 1.378(4), C(sp2)–O 1.336(4) and 1.341(4), O–CH3 1.436(5) and 1.442(4)A. It has been shown that (6) is also formed, along with di-µ-chloro-bis[4-(dimethylamino)-3,3-dimethylbut-2-yl-C,N]dipalladium(II)(3), when dichloro[2,2,N,N-tetramethylbut-3-enylamine]palladium(II)(2) is allowed to react with di-µ-chloro-bis[4-(dimethylamino)-3,3-dimethyl-1 -methoxybut-2-yl-C,N]dipalladium(II)(9). The last, (9) was generated by reaction of (2) with sodium methoxide. The conversion of (6) into di-µ-chloro-bis[3-(dimethylamino)-1-formyl-2,2-dimethylpropyl-C,N]dipalladium(II)(4) was investigated and found to proceed via a vinyl alcohol complex (8).

Preparation and crystal structure analysis of dichloro[4-(dimethylamino)-3,3-dimethyl-(z)-but-1-en-1-ol] palladium(II), the first η2-vinyl alcohol complex of palladium

Abstract The first η2-vinyl alcohol complex of palladium, PdCl2[Me2NCH2C(Me2)CHCHOH], has been prepared and characterized by single crystal X-ray dif- fraction. Crystals are triclinic, space group P 1 with a 8.410(3), b 15.105(5), c 9.810(3) A, α 90.88(1), β 102.89(1) and γ 95.62(1)°, Z = 4. The structure was solved by the heavy atom method and refined by full-matrix least-square calculations; R = 0.052 for 2531 reflexions with I> σ(I). The two independent molecules have essentially the same conformations and dimensions; the only difference between them being in the orientation of the hydroxyl hydrogen. In each molecule the Pd coordination is close to square planar with cis-Cl atoms, and the CC bond almost perpendicular to the plane. The five-membered chelate rings have envelope conformations with quaternary carbon C(2) at the flap; the configuration at the olefin bond is cis. There is a considerable trans-influence on the PdCl bond lengths. Principal bond lengths are: PdCl (trans to olefin) 2.342 and 2.357(3), PdCl (trans to N) 2.292 and 2.296(3), PdN 2.069 and 2.072(8), PdC(3) 2.10 and 2.12(1), PdC(4) 2.26 and 2.27(1), CC 1.37 and 1.41(2), CO 1.31 and 1.32(1) A.

The first nickel(II) allogon of a ditertiary phosphine ligand: Preparation, spectral and crystallographic characterization of square-planar bis(diphenylphosphinomethyl)dimethylsilanedinitratonickel(II)

Abstract The reaction of nickel(II) nitrate with bis(diphenylphosphinomethyl)dimethylsilane in ethanol solution gives Ni(NO3)2 · (Ph2PCH2)2SiMe2, recrystallized as orange and violet crystals from dichloromethane. Vibrational, electronic spectral and magnetic measurements of the initial product indicate the presence of allogons, the first case involving nitrate anions or a ditertiary phosphine ligand. The structure of the orange crystals 1 was determined by single-crystal X-ray diffraction analysis. The crystals are monoclinic, space group P21/c with four molecules in a unit cell of dimensions a = 10.512(2), b = 15.821(5), c = 18.948(8) A, β = 104.87(4)°. The structure was solved by the heavy-atom method and refined by full-matrix least-squares calculations to R = 0.029 for 2563 observed data. In the monomeric molecule the Ni atoms are square planar, with monodentate nitrate groups [NiO = 1.926(2) and 1.933(2) A]. The bidentate phosphine ligand has a bite angle of 94.81(3)° and the NiP bond distances are 2.166(1) and 2.170(1) A. The six-membered NiP2C2Si ring adopts a boat conformation.