Heterobimetallic complexes from addition of molybdo- or tungstophosphine ligands to metal halides and by oxidative addition of molybdo- or tungsto-aryl iodides to low-oxidation state metal species

Summary Reaction of [M{HB(Me₂pyz)₃}(NO)X{NH(CH₂)₃PPh₂}] [M=Mo, X=I; M=W, X=Cl; HB(Me₂pyz)₃=tris(3,5-dimethylpyrazolyl)borate] with [Rh₂(CO)₄Cl₂], HgI₂ and CdCl₂ gave [{M{HB(Me₂pyz)₃}(NO)X[NH(CH₂)₃PPh₂]}₂-Rh(CO)Cl] and [{Mo{HB(Me₂pyz)₃}(NO)I[NH(CH₂)₃-PPh₂]}₂MX₂] (M=Hg, Y=I; M=Cd, Y=Cl). The di- or poly-meric species [Mo{HB(Me₂pyz)₃}(NO)I(p-OC₆H₄-HgCl)]_n is reported, and reaction of [Mo{HB(Me₂pyz)₃}-(NO)I(p-NHC₆ H₄I)] with [Pd(PPh₃)₄] and [Pt(C₂H₄)(PPh₃)₂] afforded [Mo{HB(Me₂pyz)₃}(NO)I{NHC₆H₄M(PPh₃)₂X}] (M=Pd, X=Br, I; M=Pt, X=I).     

Isocyanide complexes of molybdenum nitrosyl

Reaction of π-cyclopentadienylmolybdenum nitrosyl halide with CNR (R = alkyl) gives [(π-C₅H₅)Mo(NO)X₂(CNR)] (X = Br or I), [Mo(NO)(CNR)₅]X (X = I or PF₆) and [Mo(NO)(CNR)₄I]; treatment of [Mo(NO)(CNR)₅]I with R′NH₂ gives [Mo(NO)(CNR)₄ {C(NHR)(NHR′)}]I or [Mo(NO)(CNR)₄(NH₂R′)]I (R′ = alkyl) depending on temperature.     

Solvatochromism of Mono- and Dimolybdenum Coordination Compounds of Dipyridyloctatetraene and Linear Solvation Energy Relationship Models Based on the Kamlet-Taft and Drago Scales of Solvent Polarity

The heteroleptic molybdenum complexes [{Mo(NO)TpX}(n)()(L-L)] [Tp = HB(3,5-Me(2)C(3)HN(2))(3); X = Cl, I; L-L = 4-NC(5)H(4)(CH=CH)(4)C(5)H(4)N-4', n = 1, 2; X = Cl; L-L = {4,4'-NC(5)H(4)CH=CHC(Me)=CHCH=}(2), n = 2] have a low energy absorbance in their electronic spectra which exhibits solvatochromic shifts. These have been analyzed quantitatively by means of linear solvation energy relationships based on Kamlet-Taft solvatochromism parameters, as well as on Drago's "unified scale of solvent polarity". Each of these approaches leads to satisfactory linear models, in qualitative agreement with one another. The solvatochromism is due to a combination of increased solvent dipolarity/polarizability and solvent-to-solute hydrogen bonding, each preferentially stabilizing polar ground states compared with less polar excited states. The latter originate from metal-to-ligand charge transfer. Quantitatively, the Drago and Kamlet-Taft models differ somewhat. The former are statistically slightly better than those based on Kamlet-Taft parameters.     

The chemistry of cyclopentadienyl nitrosyl and related complexes of molybdenum,part 10(1). Cationic allyl complexes and attack thereon by nucleophiles

Summary The syntheses of [Mo(⁵-C₅H₅)(³-C₃H₄R)(CO)(NO)]⁺ (R=H, 1- or 2-Me) and [Mo(⁵-C₅H₅)(³-C₃H₅)(NCR)(NO)]⁺ (R=Me or Ph), by treatment of Mo(⁵-C₅H₅)(CO)₂(NO) with RC₃H₄Br and Ag⁺, and of Mo(⁵-C₅H₅)(³-C₃H₅)(NO)I with Ag⁺ in the presence of RCN, is described. Treatment of these cations with nucleophiles gives Mo(⁵-C₅H₅)(³-C₃H₅)(NO)X (X=halide, NCS or NCO), Mo(⁵-C₅H₅)(³-C₃H₅Q)(CO)(NO) (C₃H₅Q= propene ligand, Q= H, SCOMe, SEt, S₂CNMe₂, S₂CNEt₂, S₂CN(Bu-n)₂, C₅H₅, acac, OH, OMe or OAc), and [Mo(⁵-C₅H₅)(₂C₃H₅L)(CO)(NO)]⁺ (L=PEt₃, n-Bu₃P, PPh₃, PPh₂H, PMe₂Ph, C₅H₅N, 1-, 3- or 4-MeC₅H₄N and Me₂NNH₂). Reaction of [Mo(⁵-C₅H₅)(³-C₃H₅)(NCMe)(NO)⁺ with pyridine gave [Mo(⁵-C₅H₅)(³-C₃H₅)(pyr)(NO)]⁺, while treatment of [Mo(⁵-C₅H₅)(³-C₃H₅)(CO)(NO)]⁺ with PPh₃ in the presence of NaOEt afforded Mo(⁵-C₅H₅)(CO)(NO)(PPh₃). The¹H and¹³C n.m.r. spectra of these complexes are discussed particularly in relation to the occurrence ofexo andendo isomers of the allylic species. Comparison is made briefly between Mo(⁵-C₅H₅)(³-C₃H₅)(NO)I and Mo(C₅H₅)₂(NO)I.     

Rhenium(I) carbonyl complexes derived from tris(3,5-dimethylpyrazolyl)borate ion

Treatment of [Re(CO)₄Cl]₂ with K[HB(3,5-Me₂C₃HN₂)₃] giving Re{HB(3,5-Me₂C₃HN₂)₃} (CO)₃ and Re(3,5-Me₂C₃HN₂)₂(CO)₃Cl, and bromination of the former to give Re{HB(3,5-Me₂-4-BrC₃N₂)₃}(CO)₃, without displacement of CO, is described.