N,N-Di-iso-propylcarbamato Complexes of Boron

N,N-di-iso-propylcarbamato derivatives of boron(III) have been synthesized from di-iso-propylamine and boron trichloride in the presence of carbon dioxide. With a large excess of amine, a single boron product was obtained, [NH2iPr2][B(O2CNiPr2)4], 1, while with a lower excess a mixture of 1 and of the dinuclear derivative [B2(O2CNiPr2)6], 2, was produced. By heating in vacuo at 60 °C, solid 1 slowly converted to 2. The transformation was reversible, 2 giving 1 back with di-iso-propylamine under carbon dioxide at atmospheric pressure. The molecular structure of both compounds was established by X-ray diffraction methods. Compound 1 is constituted by ion-pairs where the ammonium cation is hydrogen-bonded to the mononuclear anion. Compound 2 is a dinuclear species with two bridging carbamato ligands. In both derivatives, boron shows tetrahedral coordination. As IR- and 1H NMR spectra of the two species are well differentiated, it is possible to monitor the interconversion of 1 and 2 by both spectroscopic methods

Complexes of calcium halides with 1,2-dimethoxyethane (DME)

The solvento calcium bromide CaBr2(DME) has been prepared by reacting anhydrous calcium acetate with acetyl bromide in dimethoxyethane (DME), while refluxing a suspension of CaCl2 in DME/SOCl2 gave CaCl2(DME), high yields being secured in both cases. Crystals of the ionic [CaBr(DME)2(H2O)2]Br (1), were shown to contain heptacoordinated calcium(II) with bidentate DME. Two polymorphs of the mononuclear, CaBr2(DME)2(MeCOOH) (2), differing for their packing efficiency, have been studied by X-ray diffractometry. Compound 2 loses one DME and the coordinated acetic acid under vacuum at 30 C, yielding CaBr2(DME). Coordinated DME in CaX2(DME) was found to be substituted by nitrogen bases in toluene, the adducts CaX2py2 (X = Cl, Br), CaBr2(DMEDA)2, (DMEDA = N,N0-dimethylethylenediammine) and CaBr2(L–L–L) [L–L–L = 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine)] being obtained in good yields

Halo-carbonyl complexes of palladium, platinum and gold

In this review we summarize some recent literature data concerning synthetic procedures, properties, structure, reactivity and applications of halo-carbonyl complexes of palladium, platinum and gold, taking into consideration that the organometallic chemistry of these metals, with a particular attention to the halo-carbonyls, has been reviewed 20 years ago [F. Calderazzo, J. Organomet. Chem. 400 (1990) 303]. A brief overview of the early studies is provided

Competition between carbon monoxide and alkenes in chloro complexes of platinum(II)

ABSTRACT : Mono-olefins (cyclohexene or 1-octene) and di-olefins (cyclo-octadiene, COD, or norbornadiene, NBD) react with cis-PtCl2(CO)2 leading, respectively, to partial and complete displacement of coordinated carbon monoxide. The reactions have been monitored by gasvolumetric methods and by IR and NMR spectra. Equilibrium constants at 21 °C for the monoolefins, as determined by IR spectroscopy in 1,2-dichloroethane are: (2.4 ± 0.5) ´ 10-3 and (2.8 ± 0.4) ´ 10-2 for cyclo-hexene and 1-octene, respectively. Thermodynamic data were obtained by UV spectroscopy between 288 and 313 K, with the following values of DH0 (kJ mol-1) and DS0 (J mol-1 K-1): (30 ± 4) and (51 ± 15) for cyclohexene and (36 ± 2) and (95 ± 8) for 1-octene