Boron–boron bond oxidative addition to rhodium(I) and iridium(I) centres

The reaction between the diborane(4) compound B2(1,2-O2C6H4)2 and either of the rhodium(I) complexes [RhCl(PPh3)3] or [{Rh(µ-Cl)(PPh3)2}2] afforded the colourless rhodium(III) bis(boryl) species [RhCl(PPh3)2{B(1,2-O2C6H4)}2]. Similar reactions have been carried out with the diborane(4) compounds B2(1,2-O2-4-ButC6H3)2, B2(1,2-O2-3,5-But2C6H2)2, B2(1,2-O2-3-MeC6H3)2, B2(1,2-O2-4-MeC6H3)2, B2(1,2-O2-3-MeOC6H3)2, B2(1,2-S2C6H4)2, B2(1,2-S2-4-MeC6H3)2 and B2[R,R-1,2-O2CH(CO2Me)CH(CO2Me)]2 affording analogous rhodium complexes all of which have been characterised spectroscopically. The complexes derived from the reactions with B2(1,2-O2C6H4)2 and B2(1,2-O2-3-MeC6H3)2 have also been characterised by X-ray crystallography, the structures comprising a five-co-ordinate rhodium centre with a square-based-pyramidal geometry in which the apical site is occupied by a boryl group and the phosphines are mutually trans in basal positions. Reactivity studies have also been carried out for [RhCl(PPh3)2{B(1,2-O2C6H4)}2]. Hydrolysis or alcoholysis with catechol afforded [RhH2Cl(PPh3)3] and either B2(1,2-O2C6H4)2(µ-O) or B2(1,2-O2C6H4)3 and addition of the phosphines PMe3, PEt3 and PMe2Ph afforded the new bis(boryl) compounds cis,mer-[RhCl(PMe3)3{B(1,2-O2C6H4)}2], [RhCl(PEt3)2{B(1,2-O2C6H4)}2] and cis,mer-[RhCl(PMe2Ph)3{B(1,2-O2C6H4)}2], the PEt3 complex having been characterised by X-ray crystallography and shown to be similar to the PPh3 complex. The iridium analogue [IrCl(PEt3)2{B(1,2-O2C6H4)}2] was also prepared from the reaction between [IrCl(PEt3)3] and B2(1,2-O2C6H4)2 and shown by X-ray crystallography to be isomorphous with the rhodium complex. Reactions between [RhCl(PPh3)2{B(1,2-O2C6H4)}2] and the phosphines PPri3, P(C6H11)3, 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis(dicyclohexylphosphino)ethane (dcpe) are also described although these do not result in new rhodium boryl complexes. The reaction between [{RhCl(dppe)}2] and B2(1,2-O2C6H4)2 afforded a compound tentatively assigned as [Rh(dppe)2{B(1,2-O2C6H4)}] with analogous compounds being formed with the diborane(4) compounds B2(1,2-O2-3-MeC6H3)2 and B2(1,2-O2-4-MeC6H3)2. Finally, the reaction between [Rh(PMe3)4]Cl and the diborane(4) compound B2(1,2-O2C6H4)2 is described which affords cis,mer-[RhCl(PMe3)3{B(1,2-O2C6H4)}2]. Analogous reactions with B2(1,2-O2-3,5-But2C6H2)2, B2(1,2-O2-3-MeC6H3)2 and B2[R,R-1,2-O2CH(CO2Me)CH(CO2Me)]2 afforded similar products.

[1]  Milton R. Smith,et al.  Efficient olefin diboration by a base-free platinum catalyst , 1997 .

[2]  L. J. Wright,et al.  Five-Coordinate Ruthenium(II) and Osmium(II) Boryl Complexes , 1997 .

[3]  K. Morokuma,et al.  Molecular Orbital Study of the Mechanism of Platinum(0)-Catalyzed Alkene and Alkyne Diboration Reactions , 1997 .

[4]  W. Leitner,et al.  GRIGNARD-ANALOGOUS RHODIUM PHOSPHANE COMPLEXES , 1997 .

[5]  N. C. Norman,et al.  Synthesis and Characterization of Rhodium(I) Boryl and Rhodium(III) Tris(Boryl) Compounds: Molecular Structures of [(PMe3)4Rh(B(cat))] and fac-[(PMe3)3Rh(B(cat))3] (cat = 1,2-O2C6H4) , 1997 .

[6]  S. Sakaki,et al.  Reaction of BX2−BX2 (X = H or OH) with M(PH3)2 (M = Pd or Pt). A Theoretical Study of the Characteristic Features , 1997 .

[7]  Milton R. Smith,et al.  Mechanistic investigation of stoichiometric alkyne insertion into Pt-B bonds and related chemistry bearing on the catalytic diborylation of alkynes mediated by platinum(II) diboryl complexes , 1996 .

[8]  N. C. Norman,et al.  Oxidative addition of a B—B bond by an iridium(I) complex: molecular structure of mer-cis-[Ir(PMe3)3Cl(Bcat)2] , 1996 .

[9]  N. C. Norman,et al.  Synthesis and molecular structure of the paramagnetic Co(II) bis(boryl) complex [Co(PMe3)3(Bcat)2 (cat = 1,2,-O2C6H4) , 1996 .

[10]  Xiaoming He,et al.  Reactivity of Tungstenocene with BB and BH Bonds versus CH Bonds , 1996 .

[11]  N. Miyaura,et al.  Platinum(0)-Catalyzed Diboration of Alkynes with Tetrakis(alkoxo)diborons: An Efficient and Convenient Approach to cis-Bis(boryl)alkenes , 1996 .

[12]  Xiaoming He,et al.  Boryls Bound to Iron Carbonyl. Structure of a Rare Bis(boryl) Complex, Synthesis of the First Anionic Boryl, and Reaction Chemistry That Includes the Synthetic Equivalent of Boryl Anion Transfer , 1996 .

[13]  N. C. Norman,et al.  SYNTHESIS AND CHARACTERIZATION OF PLATINUM(II)-BIS(BORYL) CATALYST PRECURSORS FOR DIBORATION OF ALKYNES AND DIYNES : MOLECULAR STRUCTURES OF CIS-(PPH3 )2PT(B-4-BUTCAT)2, CIS-(PPH3)2PT(BCAT)2, CIS-(DPPE)PT(BCAT)2, CIS-(DPPB)PT( BCAT)2, (E)-(4-MEOC6H4)C(BCAT)=CH(BCAT), (Z)-(C6H5)C(BCAT)=C(C6H5)(BCAT), , 1996 .

[14]  N. Miyaura,et al.  Palladium(0)-Catalyzed Cross-Coupling Reaction of Alkoxydiboron with Haloarenes: A Direct Procedure for Arylboronic Esters , 1995 .

[15]  Xiaoming He,et al.  Hydrocarbon Functionalization by Transition Metal Boryls , 1995 .

[16]  S. Westcott,et al.  Transition Metal Catalyzed Diboration of Vinylarenes , 1995 .

[17]  Milton R. Smith,et al.  Reactivity of Organoplatinum Complexes with C6H4O2B-BO2C6H4: Syntheses of a Platinum Diboryl Complex with, and without, Metathesis of Boron-Boron and Metal-Carbon Bonds , 1995 .

[18]  D. L. Ward,et al.  Synthesis of endo-Cp2TaH2(BO2C6H4) and exo-Cp2TaH2(BO2C6H4): Regioisomers of the First Tantalum Boryl Complexes , 1994 .

[19]  N. C. Norman,et al.  Oxidative addition of B-B bonds by rhodium(I) phosphine complexes: molecular structures of B2cat2 (cat = 1,2-O2C6H4) and its 4-But and 3,5-But2 analogs , 1994 .

[20]  J. Hartwig,et al.  A Continuum Resulting from Equilibrium between Two Structural Extremes in Tungstenocene and Niobocene Boryl and Hydridoborate Complexes. .pi.-Bonding in a d2 Boryl System and the First d0 Boryl Complex , 1994 .

[21]  N. Miyaura,et al.  Platinum(0)-catalyzed diboration of alkynes , 1993 .

[22]  N. Taylor,et al.  Synthesis and structures of the first transition-metal tris(boryl) complexes: iridium complexes (.eta.6-arene)Ir(BO2C6H4)3 , 1993 .

[23]  S. Westcott,et al.  Reactions of catecholborane with iridium complexes: molecular structure of trans-IrHCl(CO)(Bcat)(PPh3)2 , 1993 .

[24]  J. Hartwig,et al.  Transition metal boryl complexes: structure and reactivity of CpFe(CO)2Bcat and CpFe(CO)2BPh2 , 1993 .

[25]  S. Westcott,et al.  Nucleophile promoted degradation of catecholborane: consequences for transition metal-catalyzed hydroborations , 1993 .

[26]  S. Westcott,et al.  Insertion of alkenes into rhodium-boron bonds , 1993 .

[27]  K. Burgess,et al.  Reactions of catecholborane with Wilkinson's catalyst: implications for transition metal-catalyzed hydroborations of alkenes , 1992 .

[28]  Y. Jean,et al.  Theoretical study of the structures of electron-deficient d6 ML5 complexes. Importance of a .pi.-donating ligand , 1992 .

[29]  Ian D. Williams,et al.  Boryliridium and boraethyliridium complexes fac-[IrH2(PMe3)3(BRR')] and fac-[IrH(PMe3)3(.eta.2-CH2BHRR')] , 1990 .

[30]  Y. Jean,et al.  A theoretical study of the possible structures of d6 ML5 complexes , 1990 .