A survey of the use of Os-187 satellite subspectra in H-1 and P-31{H-1} spectra of triosmium carbonyl clusters is reported. By varying evolution delays in HMQC spectra of [Os-3(mu-H)(2)(CO)(10)] we have selectively extracted the values for (1)J(Os,H) and (2)J(Os,H), respectively. An analysis of the principal modes of phosphine coordination in triosmium clusters demonstrates that P-31{H-1} Os-187 satellite subspectra are diagnostic for equatorial coordination [(1)J(Os, P) = 211-223 Hz] or for axial coordination (perpendicular to the plane of the cluster) [(1)J(Os, P) approximate to 147 Hz]. Chelating and bridging diphosphines yield Os-187 satellite subspectra which are the sum of A(2)X and AA'X spin systems. If significant P-P coupling is present, the AA'X component requires simulation. All observed (2)J(Os,P) trans-equatorial couplings fall in the range 38-65 Hz
Os-187 subspectra in H-1 and P-31{H-1} spectra of triosmium carbonyl clusters
AIME, Silvio;GOBETTO, Roberto;SALASSA, LUCA;
2002-01-01
Abstract
A survey of the use of Os-187 satellite subspectra in H-1 and P-31{H-1} spectra of triosmium carbonyl clusters is reported. By varying evolution delays in HMQC spectra of [Os-3(mu-H)(2)(CO)(10)] we have selectively extracted the values for (1)J(Os,H) and (2)J(Os,H), respectively. An analysis of the principal modes of phosphine coordination in triosmium clusters demonstrates that P-31{H-1} Os-187 satellite subspectra are diagnostic for equatorial coordination [(1)J(Os, P) = 211-223 Hz] or for axial coordination (perpendicular to the plane of the cluster) [(1)J(Os, P) approximate to 147 Hz]. Chelating and bridging diphosphines yield Os-187 satellite subspectra which are the sum of A(2)X and AA'X spin systems. If significant P-P coupling is present, the AA'X component requires simulation. All observed (2)J(Os,P) trans-equatorial couplings fall in the range 38-65 Hz
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