A. Sacco

Tetrahedral complexes of cobalt(I)

Abstract The preparation and properties of halogenotris(tertiaryphosphine)cobalt complexes, CoXL 3 (X = Cl, Br, I; L = PPh 3 , PBuPh 2 , PBzPh 2 ), are described. The electronic spectra and the mangetic moments of these compounds provide strong evidence for a tetrahedral configuration both in the solid state and in solution. The reaction of these compounds with carbon monoxide, which gives CoX(CO) 2 L 2 , and with carbon tetrachloride, which gives CoX 2 L 2 and C 2 Cl 4 , are discussed.

Hidrido-complexes of iron(IV) and iron(II)

Abstract The preparation and properties are described of hydrido-complexes of iron(IV), FeH 4 L 3 (L=PetPh 2 , PBuPh 2 ) and of iron(II), FeH 2 (PEtPh 2 ) 3 , FeHCl(dp) 2 , FeH 2 (dp) 2 [dp=C 2 H 4 (PPh 2 ) 2 ].

Nitrogen fixation. I. Hydrido- and nitrogen-complexes of cobalt

Abstract The preparation and properties are described of hydrido-complexes of cobalt(III), CoH 3 L 3 (L = P(C 6 H 5 ) 3 , P(C 6 D 5 ) 3 , PEtPh 2 , PEt 2 Ph). These compounds react with nitrogen at room temperature and atmospheric pressure giving stable hydrido nitrogen-complexes of cobalt(I), CoHN 2 L 3 . The chemical evidence concerning the presence of a CoH bond in these later compounds is reported.

Synthesis and reactivity toward gas molecules of chloro 2,6-di(diphenylphosphinomethyl)pyridine rhodium(I)

Abstract The synthesis of the title compound and of its adducts with O 2 , CO, CO 2 , SO 2 , tertiary phosphines is described. The reactions of the dioxygen adduct with sulfur dioxide and carbon monoxide are also reported.

Nitrosyltris(triphenylphosphine)rhodium and nitrosyltris(triphenylphosphine)cobalt as nitrosyl transfer reagents

Abstract Intermolecular transfer of the nitrosyl ligand in RhNOP 3 and CoNOP 3 to NiCl 2 P 2 , CoCIP 3 CoCl 2 P 2 , Co(dpe) 2 (ClO 4 ) 2 , FeCl 2 dpe [P = PPh 3 ;dpe= 1,2-bis-(diphenylhosphino)ethane] readily occurs atroom temperature. On treating RhNOP 3 with trityl and silver perchlorate, the cationic species [RhP 3 )(Me 2 - CO)] + and [Rh(NO) 2 P 2 ] + have been obtained. IR spectroscopic evidence of the formation of a nitrosyl bridge is cited.

Tetraco-ordinated complexes of cobalt(I)

Abstract The preparation and properties of cobalt(I) complexes of general formula Co(dp) 2 X [dp = C 2 H 4 (PPh 2 ) 2 ; X = Br, ClO 4 , BPh 4 ] are reported. The bromide derivative is tetraco-ordinated in polar solvents and pentaco-ordinated in non polar solvents, while the perchlorate and the tetraphenylborate are tetraco-ordinated both in solution and in the solid state. These compounds easily add hydrogen, carbon monoxide and sulfur dioxide. The reactions with benzoyl chloride and nitrogen monoxide are also reported.

2,6-Bis(diphenylphosphinomethyl)pyridine complexes of nickel(II), cobalt(II), iron(II)

Abstract Some new 2,6-bis(diphenylphosphinomethyl)pyridine (pnp) complexes of nickel(II), cobalt(II) and iron(II) were prepared and their physical properties were determined and compared with those of some previously described nickel(II) complexes. A pentaco-ordinate molecular structure (distorted tirgonal bipyramidal), instead of the previous square-planar, is now suggested for [Ni(pnp) 2 ] 2+ . For Ni(pnp)-(NCS) 2 , previously described as a mixture of low-spin and high-spin forms of a five-co-ordinated molecule, the interallogon formulation [Ni(pnp)NCS] [Ni(pnp)-(NCS) 3 ], which receives strong support from the experimental data, is suggested. The hexa-co-ordinated Ni(pnp)(NO 3 ) 2 , the penta-co-ordinated high spin Co(pnp)(NO 3 ) 2 and Fe(pnp)(NO 3 ) 2 , and the hexaco-ordinated low-spin [Co(pnp) 2 ](ClO 4 ) 2 and [Fe(pnp) 2 ](ClO 4 ) 2 are also described. The equilibrium constant for the hydration reaction of Ni(pnp)Cl 2 in n-BuOHH 2 O solution is determined.

Nitrosoarene complexes of rhodium(III), iridium(III), copper(I) and mercury(II). Use of XPS in determining the mode of bonding to transition metals

Abstract Some previously synthesized nitrosoarene complexes of known coordination mode have been studied by XPS spectroscopy. New nitrosoarene complexes of Rh III , Ir III , Cu I and Hg II have been synthesized and studied by both X-ray photoelectron and IR spectroscopy. A correlation was found between the value Δ E B (O-N) and the bonding mode of the nitroso ligand.

An example of a nitrogen-bonded arylnitroso complex. The crystal structure of RhCl(NBD)(p-BrC6H4NO)

The crystal structure of RhCl(NBD)(p-BrC6H4NO) has been determined by an X-ray diffraction study. The nitroso ligand is σ-(N) bonded, and the complex crystallizes in the triclinic space group P1 with a 7.667(4), b 9.373(4), c 9.611(3) A, α 94.81(2), β 94.37(1), γ 96.40(3)°, V 681.4(5) A3 and Z = 2. Final R and Rw indices are 0.0486 and 0.0573 for 1754 observed reflections. A correlation was found between the values of Δν (ν(NO)complex − ν(NO)free ligand) and the bonding mode of the nitroso ligands.

Dicyclohexylphosphido complexes of nickel(I)

The reduction of NiCl2(PCy2Ph)2 with Na in.dta toluene under N2 gives the dimeric Ni(1) phosphido- comples [Ni(μ-PCy2)(PCy2Ph)]2, while the same reaction carried out under CO gives the Ni(O) carbonyl-complex Ni(PCy2Ph)]2(CO)2. The CO displaces the phosphine ligand from the Ni(I) phosphidocomplex, affording the dimeric Ni(I) phosphido-carbonyl-complex [[Ni(μ-PCy2)(CO)2]2. A mechanism for the reaction leading to the dimeric Ni(I) phosphido-complex is suggested.