Fred Basolo

Vibrational assignments for metal ammines

Abstract The infra-red spectra of a number of di-, tetra-, and hexammine metal complexes have been measured as solids in KBr wafers. The spectra are analysed in terms of known assignments for similar methyl compounds, and a generalized assignment is obtained for the metal-ammine complexes. The assigned frequency region for a given type of vibration appears generally to be quite insensitive to the co-ordination number and the nature of the metal.

The indenyl ligand effect on the rate of substitution reactions of Rh(η-C9H7)(CO)2 and Mn(η-C9H7)(CO)3

Carbonyl substitution by triphenylphosphine (PPh3) in the indenyl compounds Rh(η-C9H7)(CO)2 and Mn(η-C9H7)(CO)3 proceeds by a second order rate law which is first order in complex and first order in PPh3 and in both cases the rates are much faster than for the corresponding cyclopentadienyl complexes; for rhodium a rate enhancement of 108 is found for the indenyl compound over the corresponding cyclopentadienyl compound.

Mechanism of carbon monoxide substitution in metal carbonyl radicals: vanadium hexacarbonyl and its phosphine-substituted derivatives

La substitution de CO dans V (CO) 6 a lieu a, ou au-dessous de la temperature ordinaire pour former des composes V (CO) 5 L (L=phosphine ou phosphite). La substitution a lieu par un processus du 2eme ordre selon une loi de vitesse du 1er ordre par rapport a V (CO) 6 et au nucleophile phosphore

Associative substitution reactions of metal carbonyls

I thank Professor Croatto for kindly inviting me to contribute an article for this special issue commemorating the 100th volume of Inorganica Chirnica Acta. This journal is of particular interest to me because some of the seminal discussions on the need for such a journal took place in our laboratory the year (1963-64) Professor Belluco did postdoctoral research with us. I am also pleased to be asked to contribute because of my personal and professional ties with the Journal.

Acid catalysis of the hydrolysis of acetato-pentammine complexes of cobalt(III), rhodium(III) and iridium(III)

Abstract The syntheses of [M(NH3)5(RCOO)](ClO4)2 where M = Rh(III) or Ir(III) and RCOO− = CH3COO−, (CH3)3CCOO− or CF3COO− are described. The rates of hydrolysis of these complexes as well as the corresponding Co(III) systems were determined in acid, [H+] = 0·01 – 0·1 M. In all cases the rates of hydrolysis increase with increase of acid concentration. The mechanism of acid hydrolysis of these systems is discussed.

Recollections of early studies on platinum(II) complexes related to Chatt's contributions to coordination chemistry

Abstract An overview is reported on early research done in our laboratory on ligand substitution reactions of Pt(II) complexes. Some of the research was related to seminal work of Chatt on the subject, and one of our joint publications with him dealt with his view of the kinetic trans effect. Rate data on the reactions of trans-PtClL(PEt3)2 L = alkyl, aryl, or hydride) show that these ligands have a large trans effect. Since these ligands do not π bond, the results are explained in terms of the high polarizability of the ligands. Also described are reactions of different nucleophiles with trans-PtCl2 (pyridine)2 and its use as a standard to estimate values of nucleophilic constants ηPt0 for substitution reactions of Pt(II) complexes. The data obtained were consistent with Pt(II) being a class b or soft metal and preferring the more polarizable ligand atoms.

Rates of substitution reactions of some derivatives of hexacarbonylmolybdenum(0)

Abstract The rates of the reaction of cis -Mo(CO) 4 L 2 and trans -Mo(CO) 4 L 2 with 1,2-bis(diphenylphosphino)ethane(diphos), to yield Mo(CO) 4 (diphos) do not depend on the concentration of diphos. The rates of reaction increase with changes in L in the order: P(OC 6 H 5 ) 3 ⪡ P(C 6 H 5 ) 3 2 C 6 H 5 ??? PCl 3 . The complex Mo(CO) 4 (C 8 H 12 ) undergoes substitution reactions with neutral monodentate ligands having nitrogen or phosphorus as donor atoms to give Mo(CO) 4 L 2 . The reactions proceed according to the two-term rate law: Rate = k 1 [Mo(CO) 4 (C 8 H 12 )] + k 2 [Mo(CO) 4 (C 8 H 12 )][L] The rate decrease for changes in L in the order: P(n-C 4 H 9 ) 3 > 3,4-lutidine >4-picoline 3-picoline pyridine > 3-chloropyridine > PCl 2 C 6 H 5 > PCl 3 . The results are discussed in terms of the possible reaction mechanism.

Metal carbonyls—II Carbon monoxide and chloride exchange with some cyclopentadienyl metal carbonyls

Abstract The exchange reactions of 14CO with cyclopentadienyl metal carbonyls in solution have been studied. The nickel and cobalt cyclopentadienyl carbonyls exchange rapidly whereas the other compounds equilibrate very slowly. The exchange in (C5H5)2Ni2(CO)2 and C5H5Co(CO)2 depends on the carbon monoxide concentration and hence proceeds by a bimolecular displacement. The rates and mechanism are discussed and possible explanations are presented in terms of electronic structures, steric hindrance and MCO bond strengths. It is suggested that the results may provide some evidence in support of certain electronic differences between metals in the simple carbonyls and those in the “isoelectronic” cyclopentadienyl carbonyls. The chloride exchange with C5H5Fe(CO)2Cl in 5 per cent ethanol-water is second-order in the complex and independent of the chloride ion concentration. The reaction is very slow in benzene. An attempt is made to correlate the CO and chloride exchange results.

Kinetic studies of CO substitution of metal carbonyls in the presence of O-atom transfer reagents

Abstract Kinetic studies of CO substitution of metal carbonyls in the presence of O-atom transfer reagents show the reaction rates are first-order in metal carbonyl and in O-atom transfer reagent concentrations, but zero-order in entering-ligand concentration. This suggests an associative mechanism where a carbonyl C-atom is attacked by the O-atom of the reagent, affording the good leaving group CO2 and generating an active intermediate which readily reacts with the entering ligand to produce the monosubstituted product. Metal carbonyls that have been investigated include the mononuclear compounds M(CO)6 (M = Cr, Mo, W), M(CO)5L, and M(CO)5 (M = Fe, Ru, Os) as well as the cluster compounds (M3(CO)12 (M = Fe, Ru, Os), M2(CO)10 (M = Mn, Re), M3(CO)11 L (M = Fe, Ru, Os), and M4(CO)12 (M = Co, Ir). Most of the studies involve reactions with (CH3)3 NO, but other O-atom transfer reagents studied include C6H5IO, other amine oxides, pyridine oxides, (p-CH3OC6H4)2EO (E = Se, Te), (C6H5)3EO (E = P, As, Sb), and (C6H5)SO. Various factors relating to the metal carbonyls and to the O-atom transfer reagents that effect the rates of CO substitution are discussed.

Monomeric cobalt-oxygen complexes.

Some Schiff base complexes of cobalt(II) form stable cobalt-oxygen species in solution instead of the usual cobalt-oxygen-cobalt bridged complexes. These one-to-one adducts were isolated as crystalline solids and characterized by means of elemental analysis, magnetic properties, and molecular weight determinations.