Eric J. Gabe

Binuclear copper(II) complexes of tetradentate (Ne) diazine ligands. Crystal structures of [μ-1,4-Bis(4,6-dimethyl-2-pyridylamino)phthalazine-N,μ-N3,μN3,N]-(μ-Dichloro)dichlorodicopper(II), [μ-3,6-Bis(2-pyridylthio)pyridazine-N,μ-N1,μ-N2,N] (μ-dichloro)dichlorodicopper(II) ethanol, and 3,6-Bis(2-pyridylthio)-pyridazine

Abstract The X-ray structures of two binuclear copper(II) chloride complexes of the tetradentate ligands 1,4- bis(4,6-dimethyl-2-pyridylamino)phthalazine (PAP46Me) and 3,6-bis(2-pyridylthio)pyridazine are reported. [Cu2(PAP46Me)Cl4] (1) and [Cu2(PTP)Cl4]· CH3CH2OH (2) contain triply bridged binuclear centres involving a diazine (Nue5f8N) and two chlorobridges with copper-copper separations in the fange 3.19–3.25 A and distorted square pyramidal copper stereochemistry. The reduced room temperature magnetic moments indicate antiferromagnetically coupled binuclear copper(II) centres. Complex 1 forms green crystals with a= 15.795(3), b=10.661(3), c=16.155(4) A, β= 113.82(3)°, C2/c, Z = 4, Rf=0.031. Complex (2) forms green crystals with a=33.9022(8), b= 9.1626(5), c= 15.7885(5) A,β= 114.853(2)°, C2/c, Z=8, Rf=0.047. The structure of the ligand PTP is also reported and compared with that of 2.

Assemblage of multimetal complexes using the diphosphoxane (POP) linkage

Abstract Heterobimetallic complexes can be prepared using the monodentate diphosphoxane ligand in Mo(CO)5PPh2OPPh2. Reactions with Cr(CO)5CH3CN and Fe2(CO)9 yielded the corresponding bimetallic products. The structure of Mo(CO)5PPh2OPPh2Fe(CO)4 was established by a single-crystal X-ray study. Cell data: Space group P 1 , monoclinic, a 10.533(2), b 10.993(2), c 16.439(3) A; α 97.86(2), β 92.34(1), γ 116.20(1)°; Z = 2, Dc 1.561 g cm−3 RF is 0.037 for 3830 observed reflections. The diphosphoxane ligand was found to bridge an octahedral Mo and the axial site of a trigonal bipyramidal Fe. Reaction of two equivalents of Mo(CO)5PPh2OPPh2 with (PhCN)2PdCl2 produced the trimetallic complex trans-PdCl2[PPh2OPPh2Mo(CO)5]2. The trimetallic complexes P[OPR2Mo(CO)5]3 were prepared from the reaction of PCl3 with Na[OPR2Mo(CO)5] (R = Ph, OEt). Similarly, a bimetallic complex PhP[OP(OEt)2Mo(CO)5]2 can be prepared from PhPCl2. These products illustrate the usefulness of the diphosphoxane linkage in the synthesis of multimetal complexes.

Binuclear copper(II) complexes of some tetradentate (N4) diazine ligands with benzimidazole donor groups. Crystal structure of [μ-3,6-bis(N-ethyl-2-benzimidazolylthio)pyridazine-N, μ-N5, μ-N6, N]-(μ-hydroxo)(μ-chloro)dichlorodicopper(II) DMF

Abstract Binuclear copper(II) and copper(I) complexes and mononuclear copper(II) complexes of a series of N - alkyl substituted derivatives of the tetradentate ligand 3,6-bis(2-benzimidazolylthio)pyridazine (BITP) are reported. The complex [Cu 2 (EtBITP(OH)Cl 3 ]·DMF ( II ) contains a triply bridged binuclear centre with a diazine (N-N), a hydroxide and a chloride bridge. The two trigonal-bipyramidal copper(II) centres are separated by 3.017 A with a Cuue5f8O(H)ue5f8Cu bridge angle of 104.7° and are antiferromagnetically coupled (−2 J =260 cm −1 ). Cyclic voltammetric studies on several binuclear copper(II) complexes show quasi- reversible or essentially non-reversible redox waves at positive potentials (0.41-0.46 V versus SCE) associated with two electron reduction. Complex II forms green crystals with a=8.9198- (5), b =13.5738(8), c =13.7178(7) A,α=105.318- (5)°, β=105.255(5)°, γ=99.461(5)°, P 1 , Z=2, R f = 0.028.

Coordinated tautomers of a bis-(phosphoryl)-phosphine: assemblage of group VIB metal complexes containing diphosphoxane (POP) linkages

Abstract Reactions of the hydrogen-bridged chelates cis-(CO)4M(PPh2O-)2H− (M ue5fb Cr, Mo, W) with Cl2PPh yield complexes of the type cis-(CO)4 M(-P Ph2-P(O)Ph-O-PPh2) containing five-membered chelate rings. X-ray structural determination of the Mo complex confirmed the formation of the heterocycle. Crystal data: space group C2/c; a 16.477(3), b 19.845(3), c 20.512(4) A; β 106.61(2)°; Z = 8, Dcalc 1.421 Mg m−3. The final residual is 0.027 for 4737 observed reflections. The five-membered chelate ring is nonplanar with the phosphoryl P 0.888(2) A out of an approximate plane containing the other four atoms. For the tungsten analogue, 31P NMR data are consistent with the initial formation of a six-membered heterocyclic intermediate: cis-(CO)4W(PPh2-O)2PPh, which tautomerizes readily to give the final product. Six-membered chelate rings containing the (PPh2O)2PPh ligand can be assembled by the reaction of cis-(CO)4Mo(PPh2Cl)2 with (CO)5M-PPhO2H− (M = Cr, Mo). Complexes of the type cis-(CO)4Mo(PPh2O-)2PPh-M(CO)5 (M = Cr, Mo) were isolated. Reaction of Cl2PPh with two equivalents of (CO)5Mo-PPh2O− yields PhP(-OPPh2-Mo(CO)5)2. The above complexes represent coordination-stabilized PhP(-OPPh2)2 and (Ph2P-)-

Binuclear copper(II) complexes of some sexadentate phthalazine-hydrazone ligands with strong antiferromagnetic exchange

Abstract Sexadentate phthalazine-hydrazone ligands (N6), involving pyridine and N-methylimidazole as peripheral donor groups, form binuclear hydroxo-bridged copper(II) complexes which exhibit very strong antiferromagnetic exchange (−2J=885−1211 cm−1), which is propagated via a superexchange mechanism through the bridging diazine (Nue5f8N) and hydroxide groups. When the hydroxide bridge in [Cu2(APHPue5f8H)(OH)(H2O)2](ClO4)2·H2O (APHP=1,4-dihydrazinophalazine-bis(2-pyridine) acetaldimine) (−2J=988 cm−1) is replaced by a pyrazolide bridge, a dramatic decrease in exchange is observed (−2J=521 cm−1) indicating the importance of hydroxide as a dominant superexchange bridge. The complexes are highly colored, exhibiting very intense visible absorptions (16 400–16 700 cm−1) associated with charge transfer transitions. The crystal and molecular structure of [Cu2(APHPue5f8H)(OH)(H2O)2](ClO4)2·H2O (VI) is reported. VI crystallized in the monoclinic system, space group P21/n, with a=8.0110(20), b=24.100(5), c=15.6750(20) A, β=100.240(20)° and four formula units per unit cell. Refinement by full-matrix least-squares gave final residuals of R=0.076 and Rw=0.038. This complex has a hydroxo-bridged suare-pyramidal structure with a Cuue5f8Cu separation of 3.296(2) A and a Cuue5f8O(H)ue5f8Cu angle of 117.8(3)°.

A binuclear zirconium fulvalene tetraallyl complex. The preparation and the molecular structure of [η5 : η5-C10H8][CpZr(η1-CH2CHCH2)(η3-CH2CHCH2)]2

Abstract Reaction of [η 5 : η 5 -C 10 H 8 ][CpZrX 2 ] 2 (X = halide) with (η 3 -C 3 H 5 )MgCl in THF at room temperature allowed the isolation and characterization of anti -[η 5 : η 5 -C 10 H 8 ][CpZr(η 1 -CH 2 CHCH 2 (η 3 -CH 2 CHCH 2 )] 2 ( 4b ) in good yield and crystalline form. Crystal data for 4b are as follows: monoclinic, P 2 1 / c , a = 7.990(1), b = 18.522(3), c = 18.272(1) A, β = 93.76(1)°, V = 2698.2(6) A 3 , Z = 4; least-squares refinement of 268 parameters and 2417 out of 3504 reflections converged to R = 0.056 and R w = 0.070. NMR features suggest that occurrence in solution of rapid intramolecular rearrangements between two possible conformations of the allyl groups observed in the solid state structure.

Diphosphine monoxide ligands: Complexes of tetraphenyldiphosphine oxide with group VIB metal carbonyls

Abstract Tetraphenyldiphosphine monoxide forms complexes of the type(CO)5M[PPh2P(O)Ph2] with Group VIB metals (M = Cr, Mo, W). The crystal and molecular structure of the Mo-complex has been determined:MoP2O6C29H20, Monoclinic Space Group P21/n,a 13.776(1),b 16.811(2),c12.162(1)A, β 90.36(1)°;Z = 4 and Dc 1.47 Mg m−3. RF is 0.038 for 5006observed reflections. The Mo atom is found to be coordinated to the originally trivalent phosphorusatom while the ligand P P bond remains intact and the oxygen atom isuncomplexed. The overall conformation around the P P bond is staggered. Heating of these complexes in diglyme resulted in loss of CO and tautomerization of the diphosphine oxide ligand into the chelatingdiphosphaxane in products identified as c i s − ( C O ) 4 M ( P P h 2 O ︹ P P h 2 ) . Reaction of excess OP2Ph4 with cis-(CO)4M(NHC5H10)2 yielded H-bonded heterocycles of the type c i s − ( C O ) 4 M [ P P h 2 O ( P P h 2 ) O ... H ︹ N C 5 H 10 ] which are inert towards displacement of the remaining piperidine ligand.

Molybdenum tricarbonyl complexes of tricyclic trisaminomethane derivatives; synthesis and structural studies

Abstract Reactions of the trisaminomethanes, 1 (R = H) and 2 (R = Me), with cycloheptatrienyl molybdenum tricarbonyl afforded their respective molybdenum tricarbonyl complexes; 3 and 4. Structures of these products have been determined by X-ray diffraction studies. Complex 3 crystallizes in the monoclinic space group P21/m with a = 7.7364(6), b = 12.505(1), c = 7.774(1) A, β = 107.70(1)°, Z = 2, μ(Mo-Kα) = 0.90 mm−1. Its molybdenum coordination sphere features unusually small ligand bite angles (Nue5f8Moue5f8N) of 57.7(1)–58.0(1)°. The unique bridgehead methinyl hydrogen was not located, but its existence has been confirmed by IR and solid-state NMR spectroscopy. Complex 4 crystallizes in the orthorhombic space group Pcmn with a = 7.7537(2), b = 12.3176(4), c = 15.6563(7) A, Z = 4, μ(Mo-Kα) = 0.87 mm−1. Similarly, pinched Nue5f8MOue5f8N angles of 58.8(1)° are observed. Significantly, the methyl to bridgehead carbon bond is shortened by 0.04 A relative to the free ligand value, consistent with a reduced negative hyperconjugation upon complexation.

Molecular structure and dynamical behavior of seven-coordinate Mo(CO)3X2(Ar2POPAr2) complexes

Abstract Direct reaction of elemental halogens with Mo(CO)4(R2POPR2) yielded seven-coordinate Mo(II) complexes of type Mo(CO)3X2(R2POPR2) (R = phenyl or p-tolyl, X = I or Br). The structures of Mo(CO)3I2(Ph2POPPh2) (I) and Mo(CO)3Br2(tolyl2POPtolyl2) (II) have been determined by X-ray diffraction methods. Crystal data: MoI2P2O4 C27H2O·C2H2Cl4, complexI, triclinic space group P 1 - ; a = 10.019(1), b = 11.876(1), c = 15.342(2)A; α = 73.96(1)°, β = 79.12(1)°, γ = 78.19(1)°, Zcalc. = 1.88 Mg m−3· The structure was solved by MULTAN on the basis of 5169 reflections to a final R value of 0.035. Crystal data: MoBr2P2O4C31H28, complexII, monoclinic space group P21/c, a = 15.932(2), b = 9.847(1), c = 21.360(2)A, β = 106.58(1)°, Z = 4, Dcalc. = 1.62 Mg m−3· The structure was solved using MULTAN on the basis of 1588 reflections to a final R value of 0.097. Both structures approximate a pentagonal bipyramidal coordination geometry around the metal center. This stereochemistry is in accord with Keperts prediction for chelate normalized bites of less than 1.1 (1.03 and 1.05, respectively, for the POP ligands). The equatorial plane contains both halides, the two phosphorus donors, and a carbonyl. The axial carbonyls are distorted from linearity by 8.5(2) and 13(2)°, respectively. Variable-temperature31P NMR studies of these and the related MO(CO)3I2(Ph2PCH2PPh2) Complex confirmed fluxional behavior. Furthermore, for each of the iodo complexes, equilibration with a second solution isomer was observed.

Crystal, molecular and electronic structure of methyltin triiodide

The crystal structure of methyltin triiodide (CH 3 SnI 3 ) has been determined by single crystal X-ray diffraction. It belongs to the orthorhombic space group Cmc 2 1 , with a 10.3421(15), b 13.1403(15) and c 6.5700(8) A. The CH 3 SnI 3 molecules are found to be discrete and loosely packed in the crystalline state. This observation is contrary to most methyltin halide structures in which the geometry at the tin atom is distorted from the ideal tetrahedron due to intermolecular coordination. The average Snue5f8I bond length of 2.6692(11) A is shorter than those reported in similar compounds. Theoretical molecular orbital calculations show a small back-donation from the iodine atoms to the tin atom. The failure of the point charge model to predict the 119 Sn Mossbauer quadrupole splitting of CH 3 SnI 3 is attributed to the partial double bond character of the Snue5f8I bonds.