create a pipe that does the split:

@Pipe({ name: "row" })
export class RowPipe implements PipeTransform {
  // input is an array of any
  // mod is the modulo, every mod items, create a row
  transform(input: any[], mod: number): any[][] {
    return input.reduce((previous, next, index) => {
      if (index % mod === 0)
        previous.push([next]);
      else
        previous[previous.length - 1].push(next);
      return previous;
    }, <any[][]>[]);
  }
}

then :

<ion-row *ngFor="row of jobs|row:2">
    <ion-col *ngFor="let job of row" width-50 class="job-item">{{ job.name }}</ion-col>                            
</ion-row>  

The best way to do this is by transforming the structure of your jobs array so that it is an array of arrays. Then the structure you want is easy:

<ion-row *ngFor='let row of jobRows'>
    <ion-col *ngFor="let job of row">{{ job.name }}</ion-col>                            
</ion-row>

Where you do the transformation is mostly dependent on your app, but you could do it in a pipe:

@Pipe({
    name: 'toRows'
})
export class ToRowsPipe implements PipeTransform {

    transform<T>(value: T[], perRow: number): T[][] {
        let rows: T[][] = [];
        for (let i = 0; i < value.length; i += perRow) {
            rows.push(value.slice(i, i + perRow))
        }
        return rows;
    }

}



<ion-row *ngFor='let row of jobs | toRows:2'>
    <ion-col *ngFor="let job of row">{{ job.name }}</ion-col>                            
</ion-row>

The simplest solution is to apply *ngFor on and give the size attribute as necessary. In your case, it would be 6 since the total is 12. So that creates rows of 2 columns each.

<ion-row>
 <ion-col *ngFor="let job of jobs" size="6">
  {{ job.name }}
 </ion-col>                            
</ion-row>