E.G. Claeys

Transition metal chemistry III. A more exact method for evaluation of Co stretching force constants of pentacarbonyl complexes of transition metals, based on the cotton and kraihanzel force field

Within the framework of exact secular equations, a rigorous algebraic method for calculating all the CO stretching force constants of the complexes of general formula LM(CO)5 is possible yielding at once all the solutions, whether physically acceptable or not. This method does not imply interation and there is no need for estimating good initial approximations.

Transition metal chemistry V. Calculation of CO stretching force constants of cis disubstituted group VI metal carbonyls and (organo) group IV metal iron carbonyl complexes with lolca C2v symmetry

Abstract Using the Cotton and Kraihanzel force field, a more exact direct method is applied for calculating the CO stretching force constants of substituted metal carbonyls of general formula cis -L 2 M(CO) 4 (M = Mo, W, Cr; L = phosphine or amine) and of complexes of formula [R 2 MFe(CO) 4 ] 2 (M = Si, Ge, Sn or Pb),(R 3 Sn) 2 Fe(CO) 4 , R 4 M 3 [Fe(CO) 4 ] 4 (M = Sn or Pb) and M[Fe(CO) 4 ] 4 (M = Ge, Sn or Pb).

Force constant calculations for pyramidal four-atom molecules—I The pyramidal XY3 molecules As(CH3)3, AsCl3 and AsBr3

Using Wilsons FG matrix technique, general valence force constants and Urey—Bradley force constants of As(CH3)3, AsCl3 and AsBr3, all molecules of the type XY3, have been calculated from published Raman data and structural parameters. It appears however that the molecule As(CH3)3 cannot be approached by the Urey—Bradley force field. So the comparative study of the bonding characteristics is limited to the general valence force field data.

Infrared and carbon-13 NMR study of phosphine monosubstituted group VI B metal carbonyls

Abstract IR and 13 C NMR data are presented for a series of LM(CO) 5 compounds with L = (CH 3 ) 3 P, (C 2 H 5 ) 3 P and (C 6 H 5 ) 3 P for M = Cr, Mo, W and L = PCl 3 , C 6 H 5 PCl 2 and (C 6 H 5 ) 2 PCl for M = Cr. The correlation between the A 1 (eq) ν(CO) stretching frequency and the sum of Tafts σ * i,X parameters for the phosphorus substituents is discussed in terms of σ- and π-bonding. Relative inductive and mesomeric parameters, derived according to both the treatment of Graham and of Dobson, are compared. A linear correlation has also been found between ν(CO) and δ 13 C(O) for axial as well as equatorial CO groups. Finally 2 J PMC(O) ax , 2 J PMC(O) eq and 1 J WC(O) eq are discussed in view of the recent literature; a negative sign is proposed for some PC(O) coupling constants in LCr(CO) 5 compounds in order to obtain logical trends for the carbonyls of the three transition metals Cr, Mo and W.

Transition metal chemistry IV. Calculation of force constants of substituted group VIIA metal carbonyls in the CO stretching region

Abstract A rigorous algebraic method, based on the Cotton and Kraihanzel force field, is presented for the direct calculation of CO stretching force constants of Group VIIA metal carbonyls of general formula [LM(CO) 4 ] 2 (M = Mn, Tc, Re; L a bridging ligand).

Phosphorus-31 NMR study of phosphine monosubstituted group VIB metal carbonyls

Abstract The 31 P chemical shift and coupling constants are reported for a series of carbonyl compounds of the type LM(CO) 5 , with M = Cr, Mo, W, and L = a tertiary phosphine: (CH 3 ) 3 P, (C 2 H 5 ) 3 P, (C 6 H 5 ) 3 P, (3-XC 6 H 4 ) 3 P (with X = F, Cl) and (4-XC 6 H 4 ) 3 P (with X = F, Cl, CH 3 ). For the chromium carbonyls the PCl 3 , C 6 H 5 PCl 2 and (C 6 H 5 ) 2 PCl derivatives have also been studied. The theory of Ionin was used to explain the chemical shift. Where possible, the coordination chemical shift was interpreted in terms of σ and π bonding between P and M. These parameters were discussed by comparison with the corresponding phosphine—BCl 3 adducts. J PW is shown to be mainly dependent on inductive effects and J PH and J PF to change upon complexation of the free phosphine, according to the rule of Bent.

Transition metal chemistry : VII. Calculation of CO stretching force constants and separation of mesomeric and inductive effects for LM(CO)5 complexes

Abstract Refined values of the CO stretching force constants for monosubstituted metal pentacarbonyl complexes have been obtained by rigorous direct methods of calculation. The following compounds have been treated by this method: manganese carbonyl complexes, halogenometal pentacarbonyls, some recently prepared aminocarbene complexes [RHN(Me)C]Cr(CO) 5 , carbene pentacarbonyl compounds [R(OC 2 H 5 )C]M(CO) 5 (R = CH 3 , n-C 4 H 9 and M = Cr, W), phosphacarborane metal carbonyls of general formula (CH 3 ) 4 N[B 9 H 10 CHE M(CO) 5 ] with E = P, As and M = Mo, W, Cr and arsine pentacarbonyl complexes of Cr, Mo and W. Using the more exact carbonyl stretching force constants obtainable from such calculations, relative σ and π Graham parameters for a series of LMn(CO) 5 compounds have been derived. The relative importance of σ and π bonding in some organotin derivatives is discussed.

Transition metal chemistry VI. Calculation of force constants in the CO stretching region of cis-disubstituted group VI metal carbonyls and iron and carbonyl complexes with C2v symmetry

For complexes of the type cis-L2M(CO)4 (M = Mo, W, Cr; L = a phosphine, arsine or amine), (RHg)2Fe(CO)4 (R = Me, Bu) and (R3M)2Fe(CO)4 (M = Pb, Sn, Si or Ge) all the CO stretching force constants are calculated using a rigorous algebraic procedure based on the Cotton and Kraihanzel force field.

Force constant calculations for pyramidal four-atom molecules—II Pyramidal ZXY2 molecules CH3AsX2 and (CH3)2AsX (X Cl, Br)

Abstract General valence force constants of CH3AsX2 and (CH3)2AsX (with X  Cl, Br) have been derived from the experimental vibrational spectra and the molecular parameters, applying the FG matrix method of W ilson . As the approximation of V enkateswarlu and S undaram for molecules of the type ZXY2 could not stand here, an adapted framework of F matrix elements is proposed. The group of physically acceptable force constants in this series of analogous XY3 and ZXY2 molecules is discussed.

Organo group VB chemistry: Part VI. On the electric dipole moments of some substituted tertiary phenylphosphines, -arsines, -stibines and -bismuthines

Abstract The dipole moments of the following series of tertiary substituted aryl-group VB compounds were measured: ( a ) (C 6 H 5 ) 3 M and (XC 6 H 4 ) 3 M with M = P, As, Sb, Bi and X = 4-F, 4-Cl, 4-CH 3 , 3-F, 3-Cl; and ( b ) (3-XC 6 H 4 ) 3− n PR n with R = C 6 H 5 , 4-FC 6 H 4 and X = F, Cl. These experimental molecular moments are discussed as a consistent set of data that allows the calculation, within the framework of the vectorial additive method, of suitable group moments, bond moments and configurational parameters.