PMID- 24527706
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20150416
LR  - 20210209
IS  - 1520-5126 (Electronic)
IS  - 0002-7863 (Linking)
VI  - 136
IP  - 8
DP  - 2014 Feb 26
TI  - Iron-catalyzed dehydrocoupling/dehydrogenation of amine-boranes.
PG  - 3048-64
LID - 10.1021/ja410129j [doi]
AB  - The readily available iron carbonyl complexes, [CpFe(CO)2]2 (1) and CpFe(CO)2I 
      (2) (Cp = eta-C5H5), were found to be efficient precatalysts for the 
      dehydrocoupling/dehydrogenation of the amine-borane Me2NH.BH3 (3) to afford the 
      cyclodiborazane [Me2N-BH2]2 (4), upon UV photoirradiation at ambient temperature. 
      In situ analysis of the reaction mixtures by (11)B NMR spectroscopy indicated 
      that different two-step mechanisms operate in each case. Thus, precatalyst 1 
      dehydrocoupled 3 via the aminoborane Me2N horizontal lineBH2 (5) which then cyclodimerized to 
      give 4 via an off-metal process. In contrast, the reaction with precatalyst 2 
      proceeded via Me2NH-BH2-NMe2-BH3 (6) as the key intermediate, affording 4 as the 
      final product after a second metal-mediated step. The related complex 
      Cp2Fe2(CO)3(MeCN) (7), formed by photoirradiation of 1 in MeCN, was found to be a 
      substantially more active dehydrocoupling catalyst and not to require 
      photoactivation, but otherwise operated via a two-step mechanism analogous to 
      that for 1. Significantly, detailed mechanistic studies indicated that the active 
      catalyst generated from precatalyst 7 was heterogeneous in nature and consisted 
      of small iron nanoparticles (</=10 nm). Although more difficult to study, a similar 
      process is highly likely to operate for precatalyst 1 under photoirradiation 
      conditions. In contrast to the cases of 7 and 1, analogous experimental studies 
      for the case of photoactivated Fe precatalyst 2 suggested that the active 
      catalyst formed in this case was homogeneous. Experimental and computational DFT 
      studies were used to explore the catalytic cycle which appears to involve 
      amine-borane ligated [CpFe(CO)](+) as a key intermediate.
FAU - Vance, James R
AU  - Vance JR
AD  - School of Chemistry, University of Bristol, Cantock's Close , Bristol BS8 1TS, 
      U.K.
FAU - Schafer, Andre
AU  - Schafer A
FAU - Robertson, Alasdair P M
AU  - Robertson AP
FAU - Lee, Kajin
AU  - Lee K
FAU - Turner, Joshua
AU  - Turner J
FAU - Whittell, George R
AU  - Whittell GR
FAU - Manners, Ian
AU  - Manners I
LA  - eng
PT  - Journal Article
DEP - 20140214
PL  - United States
TA  - J Am Chem Soc
JT  - Journal of the American Chemical Society
JID - 7503056
EDAT- 2014/02/18 06:00
MHDA- 2014/02/18 06:01
CRDT- 2014/02/18 06:00
PHST- 2014/02/18 06:00 [entrez]
PHST- 2014/02/18 06:00 [pubmed]
PHST- 2014/02/18 06:01 [medline]
AID - 10.1021/ja410129j [doi]
PST - ppublish
SO  - J Am Chem Soc. 2014 Feb 26;136(8):3048-64. doi: 10.1021/ja410129j. Epub 2014 Feb 
      14.