J. Keijsper

Comparison of free and metal coordinated 1,4-disubstituted-1,4-diaza-1,3-butadienes : Crystal and molecular structures of 1,4-dicyclohexyl-1,4-diaza-1,3-butadiene and trans-[dichloro(triphenylphosphine)(1,4-di-tert-butyl- 1,4-diaza-1,3-butadiene)palladium(II)]

Abstract The crystal and molecular structures of c-Hex-DAB (c-hexyl-NC(H)C(H)N-c-hexyl; DAB = 1,4-diaza-1,3-butadiene) and of trans-[PdCl2(PPh3)(t-Bu-DAB)] are reported. Crystals of c-Hex-DAB are monoclinic with space group C2/c and cell constants: a = 24.70(1), b = 4.660(2), c = 12.268(3)A, β = 107.66(4)°, Z = 4. The molecule has a flat E-s-trans-E structure with bond lengths of 1.258(3)A for the CN double bond and 1.457(3)A for the central CC′ bond. These bond lengths and the NC-C′ angle of 120.8(2)° indicate that the C- and N-atoms are purely sp2-hybridized and that there is little or no conjugation within the central DAB skeleton. Crystals of trans-[PdCl2(PPh3)(t-Bu-DAB)] are triclinic with space group P-1 and cell constants: a = 17.122(3), b = 18.279(3), c = 10.008(5)A, α = 96.77(2), β = 95.29(3), γ = 109.79(2). Z = 4. The t-Bu-DAB ligand is coordinated to the metal via one lone pair only. In this 2e; σ-N coordination mode the E-s-trans-E conformation of the free DAB-ligand is still present and the bonding distances within the DAB-ligand are hardly affected. [CN: 1.261(10)A; CC′: 1.479(10)A (mean).] The PdN-, NC- and central CC′-bond lengths are compared with those found in other metal -R-DAB complexes.

Ruthenium carbonyl 1,4-diaza-1,3-butadiene (R-DAB) complexes. Reactivity of Ru2(CO)6(R-DAB) towards hetero-allenes L (L = carbodiimide, sulphine), resulting in C-C bond formation. X-ray molecular structure of Ru2(CO)5(t-BuN=CHC(H)(Nt-Bu)-C(N-p-Tol)=N-p-Tol) and of Ru2(CO)5(i-PrN=CHC(H)(Ni-Pr)C(S)C12H8)

Abstract Ru2(CO)6(R-DAB)(R-DAB = 1,4-disubstituted-1, 4-diaza-1,3-butadiene = RNCHCHNR) (R-DAB) stands for RNCHCHNR: DAB = 1,4-diaza-1,3-butadiene, see. ref. 1) reacts with hetero-allenes L (L=carbodiimide = RŃCNR′, R′ = p-Tol, i-Pr, c-Hex, R = t-Bu; L = thiofluorenone-S-oxide=C12H8CSO, R = i-Pr, t-Bu, c-Hex) to yield C(R-DAB)C(L) coupled products. From the reaction of Ru2(CO)6(t-Bu-DAB) with R′NCNR′, Ru2(CO)5(t-BuN CHC(H)(Nt-Bu)C(NR′)(Ru2(CO)5(AIP{t-Bu,R′}), AIP = 1,2-di-amino-2,3-di-imino-propane) is obtained. The AIP-moiety is bonded to the two Ru atoms via three of the four N-atoms, while the R′N-imine atom is not coordinated. This was proven by an X-ray crystal structure determination for R′ = p-Tol. Crystals of Ru2(CO)5(AIP{t-Bu, p-Tol}) are triclinic, space group P 1 and cell constants: a = 16.69(2), b = 19.65(2) and c = 12.46(2) A, α = 102.83(6), β = 108.24 and γ = 64.53(10)°; Z = 4.6546. Reflections were used in the refinement, resulting in a final R = 0.056. There are two independent molecules in the unit cell, having only slightly different geometries. The single Ru(1)Ru(2) bond of 2.779(1) A (mean) (throughout this paper, standard deviations of mean values are calculated by σ = {χi(χi – χ)2/N(N –1} 1 2 ) is spanned by a slightly asymmetrically bridging carbonyl group (C(3)O(3)). Each Ru-atom is coordinated by two terminal CO-groups. The organic t-Bu-N(1)C(6)C(7)(t-BuN(2))C(8) (p-Tol-N(4))p-Tol-N(3) fragment is σ-N bonded via N(1) to Ru(2) while the amino N(2)- and N(4)-atoms are both symmetrically bridging the Ru(1)(2) bond. N(3) is in non-bonding position with respect to both Ru-atoms. The intra-ligand bond distances are in accord with a reduction of one imine bond of the former t-Bu-DAB ligand: C(7)N(2) = 1.50(1) A (mean). The new C(7)C(8) bond has a bond length of 1.53(1) A (mean). During the reaction of Ru2(CO)6(R-DAB) with the sulphine C12H8CSO, CO2 gas evolved and the product, i.e. Ru2(CO)5(RNCHC(H)(NR)C(S)C12H8) no longer contains the sulphines oxygen, as was proven by an X-ray crystal structure determination for R = i-Pr. Crystals of Ru2(CO)5(i-PrNCHC(H)(N-i-Pr)C(S) C12H8) are orthorhombic: space groups P2,12121 and cell constants a = 14.822(5), b = 16.951(28) and c = 25.413(16) A; Z = 8.1304. Reflections were used in the refinement, resulting in a final R = 0.047. There are two independent molecules in the unit cell having non-significant differences in geometry. The single Ru(1)Ru(2) bond of 2.811(1) A (mean) is bridged by one carbonyl group (C(22)O(1)). Furthermore, each Ru-atom is coordinated by two terminal CO groups. The organic i-Pr(N(2)C(2) C(1)(i-PrN(1)C(3)(S)C12H8 moiety is σ-N(2) bonded to Ru(2). The N(1) symmetrically bridges the Ru(1)Ru(2) bond, while S does so asymmetrically: Ru(1)S = 2.43(1), Ru(2)S = 2.54(1) A (mean). All complexes were characterized by IR-,FD-mass-and 1H NMR-spectroscopy.

Binuclear metal carbonyl R-DAB complexes. Part XIII. Reduction of coordinated 1,4-diaza-1,3-butadiene to dianionic 1,2-diaminoethane by [HFe(CO)4]−. Molecular structure of [(μ-H)FeMn(CO)6{μ,μ′-N(p-Tol)CH2CH2N(p-Tol)}], a pseudo-symmetrical hetero-dinuclear species

Abstract Reaction of [MnBr(CO) 3 ( p -Tol-DAB)] ( p -Tol-DAB = ( p -Tol)NCHN( p -Tol); DAB = 1,4-diaza-1,3-butadiene) with excess [HFe(CO) 4 − and subsequent protonation yielded the heterodinuclear species [(μ-H)FeMn(CO) 6 {μ,μ′-N( p -Tol)CH 2 CH 2 N-( p -Tol)}]. During the reaction neutral, 4e-bonded p -Tol-DAB is reduced to formally dianionic, 8e-bonded 1,2-di- para -tolylaminoethane, as evidenced by an X-ray structure determination. Crystal of C 22 H 19 FeMnN 2 O 6 are monoclinic, space group P 2 1/ a and cell constants: a = 21.996(2), b = 6.858(1), c = 15.546(5) » and β = 110.20(1)°; Z = 4.2514 reflections have been used in the refinement resulting in a final R -value of 0.042. Despite the presence of two different metal atoms in this heterodinuclear compounds, the structure exhibits a nearly perfect C 2 v-mm 2 symmetry with the Mn and Fe atoms being indistinguishable by crystallographic means. Each metal atom is almost ideally octahedrally surrounded by N(1), N(2) and H(30) in bridging positions and by three terminally bonded carbonyl groups. The MnFe distance of 2.5393(9) » is the shortest MnFe distance yet reported. This bond is bridged by the hydride H(30) with normal and not significantly different bond lengths of 1.83(6) and 1.70(6) ». The metalmetal bond is also bridged by the formally dianionic, 8e-donating 1,2-di- para -tolylamino ethane ligand, through both nitrogen atoms with four almost equal metal nitrogen bond lengths of 2.029 ». All 18 atoms of the C,N,-backbone of this ligands are in one plane, which is perpendicular to the FeH(30)Mn plane. The intraligands bond lengths and angles are consistent with a reduction of both CN double bonds of the α diimine. Spectroscopic ( 1 H and 13 c NMR, FD mass and IR) and analytical data are consistent with a structure as found in the solid state. The bridging hydride resonates ( 1 H NMR) at rather low field:−10.02 ppm. Reaction of [MnBr(CO) 3 ( p -Tol-DAB)] with [DFe-(CO) 4 ] − and subsequent protonation yielded [(μ-H)FeMn(CO) 6 {μ,μ,′N( p -Tol)C(H)(D)C(D)(H)N( p -Tol)}], containing the two D-atoms in a trans geometry as evidenced by 1 H NMR spectroscopy. A possible reaction mechanism is discussed.