Vincent R. Magnuson

Reactions of FeIII with LiAlH4 and LiBH4 in the presence of bis(diphenylphosphino)methane (dppm) and CO. The crystal and molecular structures of trans-[Fe(Cl)(CO)(η2-dppm)2] [FeCl4], trans-Fe(H)2(η2-dppm)2 and cis-[Fe(η2-S2CH(η2-dppm)2]BF4

Abstract Reactions between FeIII, dppm, CO as appropriate and LiAlH4 produce the FeII complexes trans-[Fe(Cl)(CO)(η2-dppm)2] [FeCl4]. (1a) trans-[Fe(H)2(η2-dppm)2] (2) and trans-[Fe(H)(Cl)(η2-dppm)2] (3), depending upon the reaction conditions. The trans octahedral structures, with chelating dppm ligands, of 1a and 2 have been established by X-ray crystallography. Compound 2 reacts with CO to produce the Fe0 complex Fe(CO)3(η1-dppm)2 (4), identified by NMR spectrometry, and with H2HBF4·Et2O to give the dihydrogen complex trans-[Fe(H)(η2-H2)(η2-dppm)2]BF4 (5). The dihydrogen can be replaced with, for example, CO and CH3CN to give trans-[Fe(H)(L)(η2-dppm)2]BF4 (L = CO, 6, and L = CH3CN, 7, respectively). With CS2, insertion into the Fe—bond of 5 occurs to produce the dithioformato complex cis-[Fe(η2-S2CH)(γ2-dppm)2]BF4 (8), the structure of which is also reported.

A convenient synthetic route to bi- and tri-nuclear palladium and platinum complexes. The crystal structures of [M3(μ3-CO)(Cl) (μ-dppm)3]Cl, MPd, Pt, dppm = bis(diphenylphosphino)methane

Abstract Simple new one-pot syntheses from metal salts, CO, dppm and NaBH 4 and the crystal structures of [M 3 ( μ 3 -CO)Cl)( μ -dppm) 3 ]Cl (M Pd, Pt) are reported. The structure of the triangulo Pd 3 -containing cation is very similar to that already reported with a CF 3 COO − anion, including the disorder at the CO and Cl ligands. There is no disorder in the Pt cation. The CO asymmetrically caps one side of the Pt 3 face and the Cl − ligand on the other side is weakly associated with only one of the Pt atoms. Convenient, high-yield syntheses of additional Pt-dppm and Pt-dppm-CO complexes are also reported.

New bis(diphenylphosphino)methane-bridged d10-d10 heterobinuclear complexes derived from Ni(Co)2(η1-Ph2PCH2 PPH2)2 and Ni2(μ-CO)(CO)2(μ-Ph2PCH2PPH2)2: The crystal structure of NiCu(CO)2(μ-Ph2PCH2PPh2) 2(BH3CN)

Abstract Syntheses of the d 10 - d 10 ionic complexes [NiCu(CO) 2 (μ-dppm) 2 (MeCN) 2 ]X (dppm = Ph 2 PCH 2 PPh 2 , X = ClO 4 , BPh 4 or PF 6 ), containing four-coordinate copper, and the related complex NiCu(CO) 2 (μ-dppm) 2 (BH 3 CN) from reactions of Ni(CO) 2 (η 1 -dppm) 2 with copper(I) species are reported as is the crystal structure of the second of these compounds. This shows a tetrahedral arrangement about nickel(O), a slightly distorted trigonal planar arrangement about copper(II), a Ni—Cu distance [3.171(4) A] which is too great for significant metal-metal interaction, and a cradle type of arrangement for the Ni—Cu-dppm framework in the solid state. Attempts to prepare related d 10 - d 10 Ni(O)—M(I or II) (M = Ag, Au, Zn or Hg) complexes by similar methods were not successful but a Ni—Au complex of limited stability can be identified in related reactions involving Ni 2 (μ-CO) (CO) 2 (μ-dppm) 2 .

Some reaction chemistry of trans-[Fe(H)(η2-H2)(η2-dppm)2] [BF4]. The crystal and molecular structure of trans-[Fe(H)(CH3CN)(η2-dppm)2] [BF4], dppm=bis(diphenylphosphino)methane

Substitution of H 2 by ligands (L) in either pure trans -[Fe(H)( η 2 -H 2 )( η 2 -dppm) 2 ] [BF 4 ], 1, or solutions of [Fe(H) 2 (dppm) 2 ] 2, L and HBF 4 .Et 2 O in which 1 is made in situ , produce the compounds trans -[Fe(H)(L)( η 2 -dppm) 2 ] [BF 4 ] (LCH 3 CN, 3; succinonitrile, 4; pyridine, 5; C 2 H 4 , 6; and N 2 , 7). The order of H 2 replacement from 1 appears to be CH 3 CN>N 2 >C 2 H 4 ∼pyridine. Evidence is presented for the protonation of the hydride ligands of 1 or 2 to produce [Fe(H 2 ) 2 ( η 2 -dppm) 2 ] [BF 4 ] 2 , 8, although 8 could not be fully characterized nor could it be obtained in the solid state. Trans -[Fe(CH 3 CN) 2 ( η 2 -dppm) 2 ] [BF 4 ] 2 , 9, was obtained from solutions of 8 treated with acetonitrile. The coordination geometries of 3, 9 and 4 (monodentate succinonitrile) have been confirmed by X-ray crystallography (only the gross structural features of 4 were obtained due to a poor data set from a very small crystal).

Isolation and X-ray characterization of a new crystal modification of Pd6(μ2-CO)6(μ-dppm)3 during the synthesis of the novel fluxional triangulo Pd(0) complex [Pd3(μ2-CO)3(dppm)2]n (n = 1 or 2)

Abstract The one-step synthesis of a new type of fluxional Pd0CObis(diphenylphosphino)methane (dppm) cluster from PdII acetate is reported and the complex has been identified as [Pd3(μ2-CO)3(μ-dppm)2]n ( n = 1 or 2, 8 ) on the basis of microanalytical and spectroscopic data. During repeated attempts to grow suitable crystals of this complex for X-ray analysis, a second crystal modification (7) of Pd6(μ6-CO)3(μ-dppm)3 molecules in the was isolated as a 0.5 toluene solvate. This modification contains two Pd6(μ2-CO)3(μ-dppm)3 molecules in the asymmetric unit cell each showing minor structural differences from each other as well as from the previously characterized Pd6(μ2-CO)6(μ-dppm)3 · CH2Cl2 (6).

The crystal structure of trans-CrBr2(pyridine)4 · 2pyridine

Abstract The structure of CrBr2 · 6(py) (py = pyridine) consists of a Cr atom at the intersection of three 2-fold axes in the space group Ccca. The Cr is coordinated to 4 N atoms of py ligands [CrAN distances of 2.135(4) and 2.164(5) A] and interacts weakly with 2 Br ions [CrBr distance 2.998(1) A] giving the CrN4Br2 unit D2h symmetry. There are two py molecules per Cr centre trapped in the lattice.

Tandem sequence of ArSCl initiated AdE reactions resulting in formation of two C–C bonds

A one-pot procedure for the sequence of reactions between arylsulfanyl chloride, vinyl ether-I, vinyl ether-II and organomagnesium reagents has been developed for assembling polyfunctional compounds from simple precursors. 2,3-Dihydropyran and various vinyl ethers have been used as VE-I and/or VE-II. The dependence of the stereochemical course of the carbon–carbon bond formation step upon the Lewis acid has been studied. In the case of the sequence p-toiylsulfanyl chloride, 2,3-dihydropyran, 1-methoxy-2-methylpropene and Grignard reagent the reaction initiated with TiCl4 takes place with a very high diastereoselectivity ( > 95%).

Synthesis and X-ray crystal structure of bis(tetrahydroborato)bis[1,5-bis(diphenylphosphino)pentane]dicobalt(I), Co2(BH4)2(Ph2P[CH2]5PPh2)2·0.5C6H6: a novel mode of tetrahydroborate co-ordination

The title compound, obtained as one of several intermediates in a complex sequence of reactions involving CoII, NaBH4, and α,ω-bis(diphenylphosphino)alkanes, is isolated as a phosphine-bridged binuclear species in which each of two tetrahydroborato groups also bridges the two CoI units via the previously unknown M–H–BH2–H–M type of linkage; an additional and unexpected feature of the X-ray crystal structure is that one hydrogen atom of each of the two central BH2 groups also acts as a bridging ligand.

Bis(diphenylphosphino)Alkane / Co(II)/Tetrahydroborate and Cyanotrihydroborate Reactions: Formation of Unusual Bis(diphenylphosphino)methane Complexes and the Influence of Carbon Monoxide

Abstract Reactions between Co(II), bis(diphenylphosphino)methane (dppm) and either NaBH4 or NaBH3CN have been studied. They follow pathways which are in marked contrast to those followed by Ph2P(CH2)nPPh2 (n=2−6) in the presence of NaBH4 in which the final product is normally CoH(phosphine)2 although binuclear BH4-bridged complexes may sometimes be obtained. The products obtained with dppm are Co2X3(dppm)2 (X=Cl,Br) (I), CoCl(dppm)3 (II), {CoHX(dppm)2}Y (X=Cl, Br, I, BH3CN; Y=Cl,BH3CN,BPh4,Clo4) (III), and Co2H2(dppm)3 (IV). While a binuclear A-frame structure can be proposed for the Co(I)-Co(II) species (I), crystal twinning has so far prevented an X-ray determination. However, X-ray studies on (II) and (IV) have shown that (II) contains tetrahedral Co(I) to which one chloro and three monodentate dppm ligands are attracted while (IV) is a binuclear species containing bridging dppm ligands and two terminal hydrides. The compounds (III) are octahedral Co(III) complexes. Possible mechanisms for the formatio...